PTW Detectors

IONIZING RADIATION
DETECTORS
Including Codes of Practice
2010/2011
PTW History and General Remarks
Looking back on a long history

PTW-Freiburg is an internationally operating company, manufacturing and marketing specialized dosimetry and quality control equipment for the medical radiology and health physics market. Founded in 1922, the company is located in Freiburg on the western side of the famous Black Forest mountains in southwestern Germany.
The evolvement of radiation detectors

1922 Compact chambers with fixed preamplifier Hammer Dosimeter 1927 Barrel type chambers as secondary transfer standards Kstner Dosimeter 1928 Shadow-free chambers Schattenfreie Kammer 1930 Pressurized radiation protection chambers Streustrahlenkammer 1932 Continuous monitoring therapy chambers Tubusrelais 1933 Water protected chambers for water phantom use Wasserphantom 1933 Capacitor chambers for wireless measurement Ionognom 1936 Waterproof sealed chambers for brachytherapy Mikrokammern 1950 Flat chambers for diagnostic radiology and mammography Flachkammern 1959 Transparent chambers for dose area product measurement DIAMENTOR 1971 Pressurized well type chambers for nuclear medicine CURIEMENTOR 1977 Parallel plate low energy chambers Soft X-ray Chambers 1980 Dedicated electron chamber Markus Chamber 1985 Single and multiple detectors for brachytherapy AM6 Detectors 1989 Pencil chamber for computed tomography CT Chamber 1993 Diamond detector for water phantom use Diamond Detector 1995 Liquid filled ionization chamber linear array LA 48 Array 1995 Diode detectors for diagnostic radiology DIADOS Detectors 1996 Well type chambers for brachytherapy source measurement HDR Chambers 1997 Ultracompact ionization chambers PinPoint Chambers 1999 Dosimetry diodes for water phantom use Dosimetry Diodes 2002 4 flat chamber for seed measurement SourceCheck 2003 2D ionization chamber array 2D-ARRAY seven29 2005 Ultracompact chamber with 3D characteristics PinPoint 3D Chamber 2005 Dedicated proton chamber Bragg Peak Chamber 2007 Liquid filled low volume chamber microLion Chamber 2008 High resolution chamber matrix STARCHECK
Our Operations
PTW-Freiburg designs, develops, manufactures and distributes high quality dosimetry and QC equipment mainly for use in the medical field, especially in radiation therapy, diagnostic radiology and nuclear medicine. The development and production of mechanical, electronic and software components are all done in house. Our products, especially the PTW ionization chambers, are well known throughout the world and are recognized for their workmanship and high level of quality. PTW-Freiburg is the market leader in its major product lines. The PTW distribution is organized internationally. A number of daughter companies and exclusive PTW representations are established in many countries around the world. We cooperate closely with official public agencies worldwide, and we participate actively in national and international work groups for the standardization of devices and procedures for dose measurement and quality control in radiation medicine.
Our History
In 1922, twenty-seven years after Rntgen discovered the X-rays, Professor Hammer from the Physics Institute of Freiburg University founded PTW to produce and market his development of an X-ray dosemeter based on the electrostatic relais, a revolutionary new electromechanical component for measuring very small electrical charges. In 1927, Dr. Herbert Pychlau took over the company and developed it during four decades into an internationally recognized manufacturer of quality dosemeters for medical radiology. PTW has developed and manufactured many generations of up-to-date products over the years, based on the newest technology. The company has grown continuously. Today, more than 230 employees worldwide achieve an annual turnover of 35 Million EUR.
General Remarks
1. All detectors described in this catalog are shipped with a PTW calibration certificate for one measuring quantity (please specify), valid for the stated reference radiation quality. 2. An instruction manual in English is included with every detector. 3. The cable length of the detectors is 1 m, if not stated otherwise. 4. All detectors in this catalog can be operated with a PTW extension cable up to 100 m in length. 5. For very accurate measurements a pre-irradiation dose of (1 ... 3) Gy is recommended for all therapy ionization chambers, even if the data sheet does not specify a mandatory pre-irradiation dose. 6. In case a detector is not used together with a PTW electrometer, the user must ensure that the polarizing voltage is applied by a current-limiting device with a maximum current of 0.5 mA. 7. Most detectors in this catalog are available with 3 different connecting systems (BNT, TNC and M type). 8. All technical data published in this catalog are typical data for the various detector types. Certain data of individual detectors may vary slightly within the ranges of tolerance. 9. Some former detector types are not included in this catalogue as they have been replaced by new types. The following table shows discontinued chamber types and their replacements. The technical data for the discontinued chambers listed in the table are mainly identical to those of their replacement types. Chamber name Farmer, PMMA/Al Farmer, all graphite Farmer graphite/Al Farmer, waterproof 0.125 cm3 flexible Discontinued type 30001 30002 30004 30006 31002 New type 30010 30011 30012 30013 31010 Chamber name 0.3 cm3 flexible 0.3 cm3 rigid stem 1 cm3 rigid stem PinPoint 0.015 cm3 PinPoint 0.03 cm3 Discontinued type 31003 23332 23331 31006 31009 New type 31013 30016 30015 31014 31015
Ionizing Radiation Detectors: Contents
Contents
Introduction
4
Therapy Detectors
Diagnostic Detectors
35
Health Physics Detectors
41
Quick View
55
Codes of Practice Index
71
95
The Physics
The Physics
General Aspects
Radiation detectors convert radiation energy into electrical energy. The electrical signal of a detector when irradiated is measured by an electrometer connected to the detector. By applying a certain detector specific calibration factor (e.g. Gy/C), the detector signal is related to a radiation dose value. Further correction factors depending on the detector characteristics and the beam quality may be used. A variety of detector types with different design for intensity measurements of ionizing radiation is available. The radiation detection for dosimetric purposes in the medical field of diagnostic radiology, radiotherapy and nuclear medicine is mainly based on three principles of measurement, realized by three different detector types: the ionization chamber, the semiconductor detector and the diamond detector.
Ionization Chamber
An ionization chamber basically consists of a gas volume between two electrodes connected to a high voltage supply of typically 100 V to 1000 V. In this gas volume ionizing radiation creates ion pairs. These, being positive and negative charge carriers, are attracted by the electrodes thus creating a current which can be measured by an electrometer. Gas (air) volumes vary from 0.01 cm3 to 10,000 cm3, corresponding currents can be between 10-14 A and 10-7 A. Using non-polar fluids, liquid-filled ionization chambers can be realized.
Semiconductor Detector
In silicon semiconductors a layer of n-type silicon is brought into contact with a layer of p-type silicon, allowing electrons to drift from the n to the p region of the detector thus creating an insulating intrinsic zone. Incident radiation frees electrons in the intrinsic zone (sensitive layer of the detector) which move to the positively charged p region, generating a current. This solar cell principle does not need an external bias voltage.
Diamond Detector
A high purity diamond can operate as a solid state ionization detector. Ionizing radiation can push electrons from the valence band to higher energy levels thereby first filling electron traps caused by impurities and then bringing electrons to the conductivity band. An external bias is needed to produce an ionization current very much like in an ionization chamber. A stable current can only be measured though after sufficient pre-irradiation to fill the traps.
The Detector Design
The Detector Design

Thimble Ionization Chamber
A thimble chamber (also known as compact chamber) consists of a central electrode and a cylindrical chamber wall with a spherical or conical end mounted on a cylindrical stem. A guard on central electrode potential leading up to the sensitive volume limits dark currents and stem effects.
Parallel Plate Ionization Chamber

A parallel plate chamber (also known as flat chamber) consists of a high voltage electrode plate and a measuring electrode plate confining the sensitive volume. A guard on central electrode potential around the measuring electrode plate limits dark current and perturbation effect.
Spherical Ionization Chamber

A spherical chamber consists of two concentric balls representing the central measuring electrode and the chamber wall and confining the sensitive volume. A guard on central electrode potential around the measuring electrode stem limits the dark current.
Well Type Ionization Chamber

A well type chamber consists of an outer housing with an inset cylindrical cavity - representing the chamber wall - to receive the measuring object. The measuring electrode also surrounds this cavity. A guard on central electrode potential around the measuring electrode stem limits the dark current.
Semiconductor Detector
A silicon semiconductor detector consists of a layered silicon disk with contact wires to the measuring instrument. This is embedded horizontally or vertically in protective and / or build-up material depending on the intended application to form a useful probe. This detector does not need an external bias voltage nor a guard.
Diamond Detector
A diamond detector consists of a diamond disk with contact wires to the measuring instrument. This is embedded vertically in water-equivalent protective material to produce a probe with the highest possible spatial resolution in axial direction for use in therapy beam analysis. A guard is lead up to the detector stem.
PTW Calibration Laboratory

As both the oldest and the largest manufacturer of ionization chambers and medical dosimetry equipment, PTW-Freiburg has always maintained a calibration laboratory for dosimetric measuring quantities. While being an integral part of the company and a key component of the PTW-Freiburg comprehensive quality assurance system, the calibration laboratory is also proud of its very own traditions and achievements. The PTW Calibration Laboratory as an independent functional unit today is recognized internationally as one of the leading Secondary Standard Dosimetry Laboratories of the world. improved versions of the Kstner Transfer Standard instrument in the PTW museum bear witness of that tradition. Internal traceability is proudly extended to the point of preserving the original measurement notes to every calibration performed since 1937. This traditional approach to quality today gives the laboratory the advantage of access to what is probably the largest database on calibrations of clinical dosimetry in the world.
Calibration facilities and instrumentation

Our facility is one of the largest, most modern commercial ionizing radiation calibration lab and repair facility in the world. In 2008 the space for the calibration lab is enlarged up to 900 sq. meters. Today the PTW calibration laboratory operates nine separate calibration benches for radiological and radiotherapy measurements ranging from small mammography and soft X-ray facilities up to 137Cs and the 74 TBq (2000 Ci) 60Co radiotherapy standard. Work at all these single calibration places is coordinated using a custom-made laboratory software for process control, data acquisition from the calibration monitors (UNIDOS instruments)
Front view of the PTW-Freiburg factory, calibration laboratory to the left. Chamber assembly building second
Origin and tradition

PTW-Freiburg was founded on May 9, 1922 for the purpose of manufacturing radiation therapy dosemeters based on the electrostatic relay invented by one of the founders, Prof. Hammer. Early photographs of the calibration laboratory show Hammer and Kstner dosimeters and their ionization chambers facing X-ray tubes supplied by open high-voltage leads. Calibration traceability to the National Laboratory (first PTR, now PTB) always was of prime importance. Original and
The calibration laboratory (below) seen from above
and calibration calculation for the department office writing the calibration certificates. As far as possible (for connector compatibility) the reference class UNIDOS electrometers are also used for the measurement of the customer chambers. The calibration in electrical measuring quantities of all electrometers used is also traceable to the PTB primary standard. Besides the dose and dose rate ranges the laboratory maintains facilities for the calibration of non-invasive kV-meters and nuclear medicine isotope calibrators.
Detail of the calibration laboratory approx. 1957
Quality and regulatory compliance

Both as part of PTW-Freiburg and as Secondary Standard Dosimetry Laboratory the PTW Calibration Laboratory is qualified by adherence to the most stringent QA standards. Current certifications comprise ISO 9001-2000, ISO 13485-2003, ISO 17025, and Annex II, Section 3 of the Directive 93/42/EEC (Medical Device Directive). Customers have the choice of Factory Calibration Certificate or Secondary Standard Calibration Certificate (DAkkS) for dose / dose rate calibrations. other secondary standard dosimetry laboratories are done on a regular basis. Traceability to PTB is maintained by calibration of six sets of dosimetry equipment every two years with comparative measurements and reports every three months. Comparison with IAEA is done by exchange of mailed TLD every year and occasional comparative measurements with ionization chambers. Deviations are always minimal. Participation in European Ring Comparisons (mostly also supplied with PTW equipment) continuously shows very successful results. TLD comparison measurements between IAEA and PTW both using the IAEA system and the PTW TLD audit probes have shown only minimal differences.
Setting up a chamber
Scope of work
Repair and electrical calibration of measuring instruments are mainly done for PTW dosimeters. This includes complete electrical recalibration of the modern electrometers through all their measuring ranges as well as early fault elimination by burn-in and comprehensive electrical safety tests. Whenever possible radiological calibrations include the adjustment of the instrument to directly display dose at the reference quality. Radiological calibrations are performed in the measuring quantities and radiation quality ranges as shown on page 8. For these calibrations every instrument from every manufacturer is accepted (as long as it works and physically fits within the beam). Special radiological calibrations are available upon request. In consequence the PTW laboratory is one of the busiest radiological calibration laboratories worldwide with over 10000 instruments calibrated every year.
Secondary Standard Laboratory/ Cooperation with IAEA and PTB

Having successfully participated in the regular comparisons for some years, since the year 2000 the PTW calibration laboratory is formally recognized as a Secondary Standard Dosimetry Laboratory in the IAEA/WHO SSDL network[1]. This so far is the latest expression of the extremely good and fruitful cooperation PTW has enjoyed with the IAEA Dosimetry Laboratory. (Since 1996 PTW has qualified and thrice requalified as preferred supplier of clinical dosimetry equipment to IAEA.) Another positive aspect of this cooperation is in the mutual discussion of procedures and equipment which has lead to the design or continued development of several dosimetry components as for example the PTW Farmer chambers. A similar close cooperation is traditionally maintained with the German National Laboratory, PTB. Joint development has lead to such successful results as the Bhm extrapolation chamber and the Roos electron chamber. In the German DKD service of secondary standard laboratories PTW was the first and only laboratory for dosimetric quantities[2]. PTW is also one of the oldest members of this service (since 1980).
[1] IAEA /WHO SSDL Newsletter No. 43 July 2000 page 43 (http://www.iaea.or.at/programmes/nahunet/e3/dmrp_e3_pub.html) [2] Physikalisch-Technische Bundesanstalt, DKD Deutscher Kalibrierdienst, Verzeichnis der Kalibrierlaboratorien, Ausgabe 3/2001: DKD-K-01501 (http://www.dkd.ptb.de)
300 kV X-ray installation with filter wheel
Comparison measurements
Comparison measurements both in the form of direct comparisons in the calibration chain and ring comparisons between laboratories of equal rank are essential in documenting and maintaining traceability for any calibration laboratory. At the PTW Calibration Laboratory comparisons both with primary laboratories and with
Calibration Specifications
Calibration Specifications
Therapy Detectors
Therapy Detectors
Therapy Detectors
Farmer Chamber (PMMA/Aluminum) Farmer Chamber (Graphite/Graphite) Farmer Chamber (Graphite/Aluminum) Farmer Chamber, waterproof Semiflex Chamber 0.125 cm3 Semiflex Chamber 0.3 cm3 Rigid Stem Chamber 0.3 cm3 Rigid Stem Chamber 1.0 cm3 Advanced Markus Chamber Markus Chamber Roos Chamber Bragg Peak Chamber PinPoint Chambers PinPoint 3D Chamber microLion Chamber Diamond Detector Dosimetry Diode P Dosimetry Diode E Soft X-Ray Chamber 0.02 cm3 Soft X-Ray Chamber 0.2 cm3 Soft X-Ray Chamber 0.005 cm3 SOURCECHECK Well-Type Chamber System Incorporated Detectors Radioactive Check Devices 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34
Therapy Detectors
Farmer Chamber
Type 30010
Classical therapy chamber for absolute dosimetry in high-energy photon, electron and proton beams
Features
Fully guarded chamber Sensitive volume 0.6 cm3, vented to air Acrylic wall, graphited Aluminum central electrode Radioactive check device (option) The 30010 Farmer chamber is a wide spread ionization chamber for absolute dose measurements in radiation therapy. Correction factors needed to determine absorbed dose to water or air kerma are published in the pertinent dosimetry protocols. The acrylic chamber wall ensures the ruggedness of the chamber. The chamber is designed for the use in solid state phantoms and therefore not waterproof.
Materials and measures: Wall of sensitive volume
0.335 mm PMMA, 1.19 g/cm3 0.09 mm graphite, 1.85 g/cm3 56.5 mg/cm2 radius 3.05 mm length 23.0 mm Al 99.98, diameter 1.1 mm PMMA, thickness 4.55 mm
Total wall area density Dimension of sensitive volume Central electrode Build-up cap
Ion collection efficiency at nominal voltage: Ion collection time 140 s Max. dose rate for 99.5 % saturation 99.0 % saturation Max. dose per pulse for 99.5 % saturation 99.0 % saturation Useful ranges: Chamber voltage Radiation quality 5 Gy/s 10 Gy/s 0.46 mGy 0.91 mGy
Specification
Type of product Application Measuring quantities Reference radiation quality Nominal sensitive volume Design Reference point Direction of incidence Nominal response Long-term stability Chamber voltage Polarity effect at
60Co
vented cylindrical ionization chamber acc. IEC 60731 absolute dosimetry in radiotherapy beams absorbed dose to water, air kerma, exposure
60Co
(100 ... 400) V 30 kV ... 50 MV photons (10 ... 45) MeV electrons (50 ... 270) MeV protons (5 x 5) cm2 ... (40 x 40) cm2 (10 ... 40) C (50 ... 104) F (10 ... 80) %, max 20 g/m3 (700 ... 1060) hPa
0.6 cm3 not waterproof, vented, fully guarded on chamber axis, 13 mm from chamber tip radial 20 nC/Gy 0.5 % per year 400 V nominal 500 V maximal < 0.5 % 2 % (70 kV ... 280 kV) 4 % (200 kV ... 60Co) 0.5 % for rotation around the chamber axis and for tilting of the axis up to 5 4 fA 1 pC/(Gycm)
Field size Temperature Humidity Air pressure
Ordering Information
TN30010-1 Farmer type chamber 0.6 cm3, PMMA/Al, connecting system BNT TW30010-1 Farmer type chamber 0.6 cm3, PMMA/Al, connecting system TNC TM30010-1 Farmer type chamber 0.6 cm3, PMMA/Al, connecting system M
Photon energy response Directional response in solid state phantom
Options
T48012 Radioactive check device
90Sr
T48002.3.003 Chamber holding device for check device
Leakage current Cable leakage
10
Therapy Detectors
Farmer Chamber
Type 30011
Pure graphite therapy chamber for absolute dosimetry in high-energy photon, electron and proton beams
Features
Fully guarded chamber Sensitive volume 0.6 cm3, vented to air Graphite wall Graphite central electrode Radioactive check device (option) The 30011 all graphite Farmer chamber is used for absolute dose measurements in radiation therapy in cases where a minimum of different materials in the radiation field is desired. Correction factors needed to determine absorbed dose to water or air kerma are published in the pertinent dosimetry protocols. Due to the sole use of graphite the energy response of the chamber at energies below 60Co varies stronger than that of chambers with an aluminum electrode. The chamber is designed for the use in solid state phantoms and therefore not waterproof.
Materials and measures: Wall of sensitive volume Total wall area density Dimension of sensitive volume Central electrode Build-up cap
0.425 mm graphite, 1.85 g/cm3 79 mg/cm2 radius 3.05 mm length 23.0 mm graphite, diameter 1.0 mm PMMA, thickness 4.55 mm
Specification
Type of product vented cylindrical ionization chamber acc. IEC 60731 absolute therapy dosimetry in solid state phantoms and air absorbed dose to water, air kerma, exposure
60Co
Application Measuring quantities Reference radiation quality Nominal sensitive volume Design Reference point Direction of incidence Nominal response Long-term stability Chamber voltage Polarity effect at
60Co
0.6 cm3 not waterproof, vented, fully guarded on chamber axis, 13 mm from chamber tip radial 20 nC/Gy 0.5 % per year 400 V nominal 500 V maximal < 0.5 % 12 % (280 kV ...
60Co)
TN30011-1 Farmer type chamber 0.6 cm3, C/C, connecting system BNT TW30011-1 Farmer type chamber 0.6 cm3, C/C, connecting system TNC
Options
90Sr
0.5 % for rotation around the chamber axis and for tilting of the axis up to 5 4 fA 1 pC/(Gycm)
11
Therapy Detectors
Farmer Chamber
Type 30012
Farmer chamber with graphite wall for absolute dosimetry in high-energy photon, electron and proton beams
Features
Fully guarded chamber Sensitive volume 0.6 cm3, vented to air Graphite wall Aluminum central electrode Radioactive check device (option) The 30012 Farmer chamber is intended for absolute dose measurements in radiation therapy. Correction factors needed to determine absorbed dose to water or air kerma are published in the pertinent dosimetry protocols. The graphite wall makes the chamber almost water-equivalent, the aluminum central electrode improves the energy response at energies below 60Co. The chamber is intended for the use in solid state phantoms and therefore not waterproof.
Materials and measures: Wall of sensitive volume Total wall area density Dimension of sensitive volume Central electrode Build-up cap
0.425 mm graphite, 1.85 g/cm3 79 mg/cm2 radius 3.05 mm length 23.0 mm Al 99.98, diameter 1.1 mm PMMA, thickness 4.55 mm
Specification
Type of product vented cylindrical ionization chamber acc. IEC 60731 absolute therapy dosimetry in solid state phantoms and air absorbed dose to water, air kerma, exposure
60Co
Application Measuring quantities Reference radiation quality Nominal sensitive volume Design Reference point Direction of incidence Nominal response Long-term stability Chamber voltage Polarity effect at
60Co
Field size Temperature Humidity
0.6 cm3 not waterproof, vented, fully guarded on chamber axis, 13 mm from chamber tip radial 20 nC/Gy 0.5 % per year 400 V nominal 500 V maximal < 0.5 % 2 % (70 kV ... 280 kV) 4 % (200 kV ... 60Co) 0.5 % for rotation around the chamber axis and for tilting of the axis up to 5 4 fA 1 pC/(Gycm)
Air pressure
TN30012-1 Farmer type chamber 0.6 cm3, C/Al, connecting system BNT TW30012-1 Farmer type chamber 0.6 cm3, C/Al, connecting system TNC
Options
90Sr
12
Therapy Detectors
Farmer Chamber
Type 30013
Waterproof therapy chamber for absolute dosimetry in high-energy photon, electron and proton beams
Features
Waterproof, fully guarded chamber Sensitive volume 0.6 cm3, vented to air Acrylic wall, graphited Aluminum central electrode Radioactive check device (option) The 30013 Farmer chamber is the standard ionization chamber for absolute dose measurements in radiation therapy. Correction factors needed to determine absorbed dose to water or air kerma are published in the pertinent dosimetry protocols. Its waterproof design allows the chamber to be used in water or in solid state phantoms. The acrylic chamber wall ensures the ruggedness of the chamber.
0.335 mm PMMA, 1.19 g/cm3 0.09 mm graphite, 1.85 g/cm3 56.5 mg/cm2 radius 3.05 mm length 23.0 mm Al 99.98, diameter 1.1 mm PMMA, thickness 4.55 mm
Specification
Type of product vented cylindrical ionization chamber acc. IEC 60731 absolute therapy dosimetry in water, solid state phantoms and air absorbed dose to water, air kerma, exposure
60Co
Application
Measuring quantities Reference radiation quality Nominal sensitive volume Design Reference point Direction of incidence Nominal response Long-term stability Chamber voltage Polarity effect at
60Co
Field size Temperature
0.6
cm3 Humidity Air pressure
waterproof, vented, fully guarded on chamber axis, 13 mm from chamber tip radial 20 nC/Gy 0.5 % per year 400 V nominal 500 V maximal < 0.5 % 2 % (70 kV ... 280 kV) 4 % (200 kV ... 60Co) 0.5 % for rotation around the chamber axis and for tilting of the axis up to 5 4 fA 1 pC/(Gycm)
TN30013 Farmer type chamber 0.6 cm3, waterproof, connecting system BNT TW30013 Farmer type chamber 0.6 cm3, waterproof, connecting system TNC TM30013 Farmer type chamber 0.6 cm3, waterproof, connecting system M
Photon energy response Directional response in water
Options
90Sr
13
Therapy Detectors
0.125 cm3 Semiflex Chamber

Type 31010
Standard therapy chamber for scanning systems and for absolute dosimetry
Features
Waterproof, semiflexible design for easy mounting in scanning water phantoms Minimized directional response Sensitive volume 0.125 cm3, vented to air Radioactive check device (option) The 31010 semiflexible chamber is the ideal compromise between small size for reasonable spatial resolution and large sensitive volume for precise dose measurements. This makes the 31010 chamber to one of the most commonly used chambers in scanning water phantom systems. The chamber volume of 0.125 cm3 gives enough signal to use the chamber also for high precision absolute dose measurements. The sensitive volume is approximately spherical resulting in a flat angular response and a uniform spatial resolution along all three axes of a water phantom.
0.55 1.19 0.15 0.82
mm PMMA, g/cm3 mm graphite, g/cm3
78 mg/cm2 radius 2.75 mm length 6.5 mm Al 99.98, diameter 1.1 mm PMMA, thickness 3 mm
Specification
60Co
vented cylindrical ionization chamber absolute dosimetry in radiotherapy beams absorbed dose to water, air kerma, exposure
60Co
(100 ... 400) V 66 kV ... 50 MV photons (10 ... 45) MeV electrons (50 ... 270) MeV protons (2 x 2) cm2 ... (40 x 40) cm2 (10 ... 40) C (50 ... 104) F (10 ... 80) %, max 20 g/m3 (700 - 1060) hPa
0.125 cm3 waterproof, vented, fully guarded on chamber axis, 4.5 mm from chamber tip radial 3.3 nC/Gy 1 % per year 400 V nominal 500 V maximal <1% 2 % (140 kV ... 280 kV) 4 % (140 kV ... 60Co) 0.5 % for rotation around the chamber axis and for tilting of the axis up to 10 4 fA 1 pC/(Gycm)
TN31010 Semiflex chamber 0.125 cm3, connecting system BNT TW31010 Semiflex chamber 0.125 cm3, connecting system TNC TM31010 Semiflex chamber 0.125 cm3, connecting system M
Options
90Sr
14
Therapy Detectors

Type 31013
Therapy chamber for scanning systems and for absolute dosimetry
Features
Waterproof, semiflexible design for easy mounting in scanning water phantoms Increased sensitive volume for low level measurements Sensitive volume 0.3 cm3, vented to air Radioactive check device (option) The 31013 semiflexible chamber is ideal for precise dose measurements and for the measurement of dose distributions in scanning water phantom systems. The chamber is used as an alternative for the 31010 chamber in cases where increased signal levels are required and spatial resolution along the axis of the chamber can be compromised.
0.55 1.19 0.15 0.82
Specification
60Co
vented cylindrical ionization chamber absolute dosimetry in radiotherapy beams absorbed dose to water, air kerma, exposure
60Co
0.3 cm3 waterproof, vented, fully guarded on chamber axis, 9.5 mm from chamber tip radial 10 nC/Gy 1 % per year 400 V nominal 500 V maximal <1% 2 % (140 kV ... 280 kV) 4 % (100 kV ... 60Co) 0.5 % for rotation around the chamber axis and for tilting of the axis up to 10 4 fA 1 pC/(Gycm)
TN31013 Semiflex chamber 0.3 cm3, connecting system BNT TW31013 Semiflex chamber 0.3 cm3, connecting system TNC TM31013 Semiflex chamber 0.3 cm3, connecting system M
Options
90Sr
15
Therapy Detectors
0.3 cm3 Rigid Stem Chamber

Type 30016
Therapy chamber for absolute dosimetry in high-energy photon and electron beams
Features
Fully guarded chamber Sensitive volume 0.3 cm3, vented to air Acrylic wall, graphited Aluminum central electrode Radioactive check device (option) The 30016 chamber is used for absolute dose measurements in radiation therapy in cases where the high volume of the 30015 chamber is not needed and a higher spatial resolution is needed. Correction factors needed to determine absorbed dose to water or air kerma are published in the pertinent dosimetry protocols. The acrylic chamber wall ensures the ruggedness of the chamber. The chamber is designed for the use in solid state phantoms and is therefore not waterproof.
0.35 mm PMMA, 1.19 g/cm3 0.135 mm graphite, 1.85 g/cm3 67 mg/cm2 radius 2.5 mm length 18 mm Al 99.98, diameter 0.85 mm PMMA, thickness 3 mm
Ion collection efficiency at nominal voltage: Ion collection time 84 s Max. dose rate for 99.5 % saturation 99.0 % saturation Max. dose per pulse for 99.5 % saturation 99.0 % saturation Useful ranges: Chamber voltage Radiation quality Field size Temperature 11.5 Gy/s 23.1 Gy/s 0.69 mGy 1.38 mGy
Specification
Type of product Application Measuring quantities Reference radiation quality Nominal sensitive volume Design Reference point Direction of incidence Nominal response Long-term stability Chamber voltage Polarity effect Photon energy response Directional response in solid state phantom vented cylindrical ionization chamber absolute dosimetry in radiotherapy beams absorbed dose to water, air kerma, exposure
60Co
(100 ... 600) V 70 kV ... 50 MV photons (6 ... 25) MeV electrons (5 x 5) cm2 ... (40 x 40) cm2 (10 ... 40) C (50 ... 104) F (20 ... 80) %, max 20 g/m3 (700 ... 1060) hPa
0.3
cm3 Humidity Air pressure
not waterproof, vented, fully guarded on chamber axis, 9.5 mm from chamber tip radial 10.5 nC/Gy 1 % per year 400 V nominal 600 V maximal 1% 2 % (70 kV ... 250 kV) 4 % (200 kV ... 60Co) 0.5 % for rotation around the chamber axis, 1 % for tilting of the axis up to 20 4 fA 1 pC/(Gycm)
TN30016 Rigid stem chamber 0.3 cm3, connecting system BNT TW30016 Rigid stem chamber 0.3 cm3, connecting system TNC TM30016 Rigid stem chamber 0.3 cm3, connecting system M
Options
T48012 Radioactive check device 90Sr T48002.3.004 Chamber holding device for check device
16
Therapy Detectors

Type 30015
High-volume therapy chamber for absolute dosimetry in high-energy photon and electron beams
Features
Fully guarded chamber Sensitive volume 1.0 cm3, vented to air Acrylic wall, graphited Aluminum central electrode Radioactive check device (option) The 30015 rigid stem chamber is used for absolute dose measurements in radiation therapy. Correction factors needed to determine absorbed dose to water or air kerma are published in the pertinent dosimetry protocols. The acrylic chamber wall ensures the ruggedness of the chamber. The chamber is designed for the use in solid state phantoms and is therefore not waterproof.
0.4 mm PMMA, 1.19 g/cm3 0.135 mm graphite, 1.85 g/cm3 73 mg/cm2 radius 3.95 mm length 22 mm Al 99.98, diameter 1.1 mm PMMA, thickness 3 mm
Ion collection efficiency at nominal voltage: Ion collection time 236 s Max. dose rate for 99.5 % saturation 99.0 % saturation Max. dose per pulse for 99.5 % saturation 99.0 % saturation Useful ranges: Chamber voltage Radiation quality Field size Temperature 1.5 Gy/s 2.9 Gy/s 0.25 mGy 0.49 mGy
Specification
Type of product Application Measuring quantities Reference radiation quality Nominal sensitive volume Design Reference point Direction of incidence Nominal response Long-term stability Chamber voltage Polarity effect Photon energy response Directional response in solid state phantom vented cylindrical ionization chamber absolute dosimetry in radiotherapy beams absorbed dose to water, air kerma, exposure
60Co
(100 ... 600) V 70 keV ... 50 MV photons (10 ... 45) MeV electrons (5 x 5) cm2 ... (40 x 40) cm2 (10 ... 40) C (50 ... 104) F (20 ... 80) %, max 20 g/m3 (700 ... 1060) hPa
1.0 cm3 not waterproof , vented, fully guarded on chamber axis, 11.5 mm from chamber tip radial 31.9 nC/Gy 1 % per year 400 V nominal 600 V maximal 1% 2 % (70 kV ... 250 kV) 4 % (200 kV ... 60Co) 0.5 % for rotation around the chamber axis, 1 % for tilting of the axis up to 20 4 fA 1 pC/(Gycm)
Humidity Air pressure
TN30015 Rigid stem chamber 1.0 cm3, connecting system BNT TW30015 Rigid stem chamber 1.0 cm3, connecting system TNC TM30015 Rigid stem chamber 1.0 cm3, connecting system M
Options
17
Therapy Detectors
Advanced Markus Chamber

Type 34045
Perturbation-free version of the famous classic Markus chamber for absolute dosimetry in high-energy electron beams
Features
Perturbation-free electron chamber Thin entrance window and waterproof protection cap Small-sized for high spatial resolution Sensitive volume 0.02 cm3, vented to air Radioactive check device (option) The 34045 Advanced Markus chamber is the successor of the well-known classic Markus electron chamber, equipped with a wide guard ring for perturbation-free measurements. The thin entrance window allows measurements in solid state phantoms up to the surface. The protection cap makes the chamber waterproof for measurements in water phantoms.
Materials and measures: Entrance foil Protection cap
0.03 mm PE (polyethylene CH2), 2.76 mg/cm2 0.87 mm PMMA, 1.19 g/cm3, 0.4 mm air
Total window area density 106 mg/cm2, 1.3 mm (protection cap included) Water-equivalent window thickness Sensitive volume Guard ring width 1.06 mm (protection cap included) radius 2.5 mm depth 1 mm 2 mm
Ion collection efficiency at nominal voltage: Ion collection time 22 s Max. dose rate for 99.5 % saturation 99.0 % saturation Max. dose per pulse for 99.5 % saturation 99.0 % saturation Useful ranges: Chamber voltage Radiation quality Field size Temperature Humidity Air pressure 187 Gy/s 375 Gy/s 2.78 mGy 5.56 mGy
Specification
Type of product Application Measuring quantity Reference radiation quality Nominal sensitive volume Design Reference point vented plane parallel ionization chamber absolute dosimetry in highenergy electron beams absorbed dose to water
60Co
(50 ... 300) V (2 ... 45) MeV electrons (3 x 3) cm2 ... (40 x 40) cm2 (10 ... 40) C (50 ... 104) F (10 ... 80) %, max 20 g/m3 (700 ... 1060) hPa
0.02 cm3 waterproof with protection cap, vented in chamber center on entrance foil, or 1.3 mm below surface of protection cap perpendicular to chamber plane 0.67 nC/Gy 1 % per year 300 V nominal 400 V maximal 1% for electrons 9 MeV 0.1 % for chamber tilting 10 4 fA 1 pC/(Gycm)
Direction of incidence Nominal response Long-term stability Chamber voltage Polarity effect Directional response in water Leakage current Cable leakage
TN34045 Advanced Markus electron chamber, 0.02 cm3, connecting system BNT TW34045 Advanced Markus electron chamber, 0.02 cm3, connecting system TNC TM34045 Advanced Markus electron chamber, 0.02 cm3, connecting system M
Options
T48010 Radioactive check device 90Sr T23343/11 Chamber holding device for check device
18
Therapy Detectors
Markus Chamber
Type 23343
Classic plane parallel chamber for absolute dosimetry in high-energy electron beams
Features
Thin entrance window and waterproof protection cap Small-sized for high spatial resolution Sensitive volume 0.055 cm3, vented to air Radioactive check device (option) The 23343 Markus chamber is manufactured in the original famous Markus design. Absorbed dose to water can be measured by applying correction factors for perturbation effects as published in pertinent dosimetry protocols. The thin entrance window allows measurements in solid state phantoms up to the surface. The protection cap makes the chamber waterproof for measurements in water phantoms.
Materials and measures: Entrance foil Protection cap
0.03 mm PE (polyethylene CH2), 2.76 mg/cm2 0.87 mm PMMA, 1.19 g/cm3, 0.4 mm air
Total window area density 106 mg/cm2, 1.3 mm (protection cap included) Water-equivalent window thickness Sensitive volume Guard ring width 1.06 mm (protection cap included) radius 2.65 mm depth 2 mm < 0.2 mm
Specification
Type of product Application Measuring quantity Reference radiation quality Nominal sensitive volume Design Reference point vented plane parallel ionization chamber absolute dosimetry in highenergy electron beams absorbed dose to water
60Co
0.055 cm3 waterproof with protection cap, vented in chamber center on entrance foil, or 1.3 mm below surface of protection cap perpendicular to chamber plane 2 nC/Gy 1 % per year 300 V nominal 400 V maximal 1% for electrons 9 MeV 0.1 % for chamber tilting 10 4 fA 3.5 pC/(Gycm)
(100 ... 300) V (2 ... 45) MeV electrons (3 x 3) cm2 ... (40 x 40) cm2 (10 ... 40) C (50 ... 104) F (10 ... 80) %, max 20 g/m3 (700 ... 1060) hPa
Direction of incidence Nominal response Long-term stability Chamber voltage Polarity effect Directional response in water Leakage current Cable leakage
TN23343 Markus electron chamber 0.055 cm3, connecting system BNT TW23343 Markus electron chamber 0.055 cm3, connecting system TNC TM23343 Markus electron chamber 0.055 cm3, connecting system M
Options
T48010 Radioactive check device 90Sr T23343/11 Chamber holding device for check device
19
Therapy Detectors
Roos Chamber
Type 34001
Waterproof plane parallel chamber for absolute dosimetry in high-energy electron and proton beams
Features
Perturbation-free, minimized polarity effect Waterproof, wide guard ring design Sensitive volume 0.35 cm3, vented to air Radioactive check device (option) The 34001 Roos chamber is the golden standard for absolute dose measurements in high-energy electron beams. Modern dosimetry protocols refer to the chamber's design and provide dosimetric correction factors. Its waterproof design allows the chamber to be used in water or in solid state phantoms. The Roos chamber is also well suited for the measurement of high-energy photon depth dose curves up to 2.5 mm below the water surface. The chamber can be used for dose measurements of proton beams.
Materials and measures: Entrance window
1 mm PMMA, 1.19 g/cm3 0.02 mm graphite, 0.82 g/cm3 0.1 mm varnish, 1.19 g/cm3 1.3 mm radius 7.5 mm depth 2 mm 4 mm
Total window area density 132 mg/cm2 Water-equivalent window thickness Sensitive volume Guard ring width
Ion collection efficiency at nominal voltage: Ion collection time 125 s Max. dose rate for 99.5 % saturation 99.0 % saturation Max. dose per pulse for 99.5 % saturation 99.0 % saturation Useful ranges: Chamber voltage Radiation quality 5.2 Gy/s 10.4 Gy/s 0.46 mGy 0.93 mGy
Specification
Type of product vented plane parallel ionization chamber acc. IEC 60731 absolute dosimetry in high-energy electron and proton beams absorbed dose to water
60Co
Application
(50 ... 300) V (2 ... 45) MeV electrons ... 25 MV photons (70 ... 250) MeV protons
60Co
Measuring quantity Reference radiation quality Nominal sensitive volume Design Reference point Direction of incidence Nominal response Long-term stability Chamber voltage Polarity effect Directional response in water Leakage current Cable leakage
Field size 0.35 cm3 waterproof, vented in chamber center, 1.1 mm below surface perpendicular to chamber plane, see label FOCUS 10 nC/Gy 0.5 % per year 200 V nominal 400 V maximal < 0.5 % 0.1 % for chamber tilting 10 4 fA 1 pC/(Gycm) Temperature Humidity Air pressure
(4 x 4) cm2 ... (40 x 40) cm2 (10 ... 40) C (50 ... 104) F (10 ... 80) %, max 20 g/m3 (700 ... 1060) hPa
TN34001 Roos electron chamber 0.35 cm3, connecting system BNT TW34001 Roos electron chamber 0.35 cm3, connecting system TNC TM34001 Roos electron chamber 0.35 cm3, connecting system M
Options
90Sr
T48004 Chamber holding device for check device
20
Therapy Detectors
Bragg Peak Chambers

Types 34070, 34073
Waterproof plane-parallel chambers for dosimetry in proton beams
34070
Features
Waterproof, wide guard ring design Sensitive volumes 10.5 cm3 and 2.5 cm3, vented to air The Bragg peak chambers are designed to measure the exact location of the Bragg peak in therapy proton beams. The large diameters of the chambers allow the measurement of the complete proton beam diameter (non-scanned) including the scattered protons. The chambers are waterproof and consequently can either be used in air behind a water column or in a water phantom. In water, both Bragg Peak chambers can be used for measurements of horizontal beams. Due to the thicker entrance and exit windows, the 34070 Bragg Peak chamber can additionally be used in vertical beams where measurements are performed in different water depths.
3.35 mm , 1.01 mm PMMA 0.02 mm graphite 0.1 mm varnish 4 mm, 1.3 mm radius 40.8 mm, 19.8 mm depth 2 mm 1.1 mm, 4 mm
Total window area density 411 mg/cm2, 133 mg/cm2 Water-equivalent window thickness Sensitive volume Guard ring width
Specification
Type of products Application Nominal sensitive volumes Design Reference point Direction of incidence Nominal response Chamber voltage Polarity effect Leakage current Cable leakage Cable length vented plane parallel ionization chambers relative dosimetry in highenergy proton beams 10.5 cm3, 2.5 cm3 waterproof, vented in chamber center, 3.5 mm from chamber surface perpendicular to chamber plane, see label 'Focus' 325 nC/Gy, 78 nC/Gy (at 60Co free in air) 400 V nominal 500 V maximal 1% 100 fA 1 pC/(Gycm) 2.5 m
(300 ... 500) V (70 ... 250) MeV protons diameter (3 ... 10) mm valid for both chamber types (10 ... 40) C (50 ... 104) F (10 ... 80) %, max 20 g/m3 (700 ... 1060) hPa
TN34070-2,5 Bragg peak chamber 10.5 cm3, connecting system BNT TW34070-2,5 Bragg peak chamber 10.5 cm3, connecting system TNC TM34070-2,5 Bragg peak chamber 10.5 cm3, connecting system M TN34073-2,5 Bragg peak chamber 2.5 cm3, connecting system BNT TW34073-2,5 Bragg peak chamber 2.5 cm3, connecting system TNC TM34073-2,5 Bragg peak chamber 2.5 cm3, connecting system M
21
Therapy Detectors
PinPoint Chambers
Type 31014, 31015
Ultra small-sized therapy chambers for dosimetry in high-energy photon beams
Features
Small-sized sensitive volumes of only 0.015 cm3 and 0.03 cm3, 2 mm and 2.9 mm in diameter, vented to air Very high spatial resolution when used for scans perpendicular to the chamber axis Aluminum central electrode Radioactive check device (option) The PinPoint chambers are ideal for dose measurements in small fields as encountered e.g. in IORT, IMRT and stereotactic beams. Relative dose distributions can be measured with very high spatial resolution when the chambers are moved perpendicular to the chamber axis. The waterproof, fully guarded chambers can be used in air, solid state phantoms and in water.
0.57 1.19 0.09 1.85
Total wall area density Dimensions of sensitive volume Central electrode Build-up cap
85 mg/cm2 radius 1 mm, 1.45 mm length 5 mm Al 99.98, diameter 0.3 mm PMMA, thickness 3 mm
Ion collection efficiency at nominal voltage: Ion collection time 20 s, 50 s Max. dose rate for 99.5 % saturation 99.0 % saturation Max. dose per pulse for 99.5 % saturation 99.0 % saturation Useful ranges: Chamber voltage Radiation quality Field size Temperature Humidity Air pressure 265 Gy/s, 29 Gy/s 580 Gy/s, 55 Gy/s 3.5 mGy, 1.2 mGy 7 mGy, 2.3 mGy
Specification
Type of products Application vented cylindrical ionization chambers dosimetry in high-energy photon beams with high spatial resolution absorbed dose to water, air kerma, exposure
60Co
(100 ... 400) V

60Co
Measuring quantities Reference radiation quality Nominal sensitive volume Design Reference point Direction of incidence Pre-irradiation dose Nominal response Long-term stability Chamber voltage Polarity effect Directional response in water
... 50 MV photons
0.015 cm3, 0.03 cm3 waterproof, vented, fully guarded on chamber axis, 3.4 mm from chamber tip radial, axial (31014) 2 Gy 400 pC/Gy, 800 pC/Gy 1 % per year 400 V nominal 500 V maximal 2% 0.5 % for rotation around the chamber axis, 1 % for tilting of the axis up to 20 (radial incidence) 15 (axial incidence) 4 fA 1 pC/(Gycm)
TN31014 PinPoint chamber 0.015 cm3, connecting system BNT TW31014 PinPoint chamber 0.015 cm3, connecting system TNC TM31014 PinPoint chamber 0.015 cm3, connecting system M TN31015 PinPoint chamber 0.03 cm3, connecting system BNT TW31015 PinPoint chamber 0.03 cm3, connecting system TNC TM31015 PinPoint chamber 0.03 cm3, connecting system M
Options
22
Therapy Detectors
PinPoint 3D Chamber
Type 31016
Ultra small-sized therapy chamber with 3D characteristics for dosimetry in high-energy photon beams
Features
Small-sized sensitive volume 0.016 cm3, vented to air Minimized directional response Aluminum central electrode Radioactive check device (option) The 31016 PinPoint 3D chamber is ideal for dose measurements in small fields as encountered e.g. in IORT, IMRT and stereotactic beams. Relative dose distributions can be measured with high spatial resolution in any direction. The waterproof, fully guarded chamber can be used in air, solid state phantoms and in water.
0.57 1.19 0.09 1.85
Total wall area density Dimensions of sensitive volume Central electrode Build-up cap
Specification
Type of product Application Measuring quantities Reference radiation quality Nominal sensitive volume Design Reference point Direction of incidence Pre-irradiation dose Nominal response Long-term stability Chamber voltage Polarity effect Directional response in water vented cylindrical ionization chamber dosimetry in high-energy photon beams absorbed dose to water, air kerma, exposure
60Co
(100 ... 400) V

60Co
0.016 cm3 waterproof, vented, fully guarded on chamber axis, 2.4 mm from chamber tip radial 2 Gy 400 pC/Gy 1 % per year 400 V nominal 500 V maximal 2% 0.5 % for rotation around the chamber axis, 1 % for tilting of the axis up to 110 4 fA 1 pC/(Gycm)
... 50 MV photons
(2 x 2) cm2 (30 x 30) cm2 (10 ... 40) C (50 ... 104) F (10 ... 80) %, max 20 g/m3 (700 ... 1060) hPa
TN31016 PinPoint 3D chamber 0.016 cm3, connecting system BNT TW31016 PinPoint 3D chamber 0.016 cm3, connecting system TNC TM31016 PinPoint 3D chamber 0.016 cm3, connecting system M
Options
90Sr
23
Therapy Detectors
microLion Chamber
Type 31018
Liquid filled ion chamber for dose distribution measurements in radiotherapy with high spatial resolution
1 pC/(Gycm) 1.3 m
Features
Liquid filled sensitive volume of 0.002 cm3 Suitable for dose scanning in radiotherapy beams with a superior spatial resolution Suitable for use in water Connector types: BNT, TNC or M The waterproof micro liquid ion chamber1 (microLion) has been specially designed for relative beam profile and depth dose curve measurements in a motorized water phantom. It is used for characterization of LINAC radiation fields where superior spatial resolution is desired, like stereotactic fields. Due to the liquid filling, the microLion chamber delivers a high signal in relation to its very small sensitive volume. The recommended chamber voltage of 800 V is delivered by an additional HV-Supply. The HV-Supply can be connected to the UNIDOSwebline or the latest version of the TANDEM dosemeters.
Cable leakage Cable length Materials and measures: Entrance window
0.5 mm polystyrene 0.28 mm graphite 0.02 mm varnish radius 1.25 depth 0.35 mm graphite
Total window area density 107 mg/cm2 Dimensions of sensitive volume Central electrode
Ion collection efficiency at nominal voltage: Ion collection time 5.3 ms Max. dose rate at f 190 Hz for 99.5 % saturation 13.1 Gy/min 99.0 % saturation 26.4 Gy/min Max. dose per pulse at f 190 Hz for 99.5 % saturation 1.36 mGy 99.0 % saturation 2.73 mGy Useful ranges: Chamber voltage Radiation quality Field size Temperature Humidity Air pressure
Specification
Type of product Application liquid filled ionization chamber dose distribution measurements in high-energy photon beams with high spatial resolution absorbed dose to water
60Co
(400 ... 1000) V

60Co
... 25 MV photons
Measuring quantity Reference radiation quality Nominal sensitive volume Design Reference point Direction of incidence Pre-irradiation dose Nominal response Long-term stability Chamber voltage Polarity effect Directional response in water
0.002 cm3 (exactly 1.7 mm3) liquid filled, waterproof on chamber axis, 0.975 mm from entrance window axial 3 Gy 9.8 nC/Gy 1 % per year 800 V nominal 1000 V maximal <1% 0.5 % for rotation around the chamber axis, 1 % for tilting of the axis up to 40 1 pA
TN31018-1,3 microLion chamber 0.002 cm3, connecting system BNT TW31018-1,3 microLion chamber 0.002 cm3, connecting system TNC TM31018-1,3 microLion chamber 0.002 cm3, connecting system M T16036 HV-Supply for ionization chambers, range 950 V T4316/U331 TBA detector holder
1 The microLion chamber was designed in collaboration with Gran Wickman and Thord Holmstroem, University of Ume, Sweden and is based on a well-tested and patented LIC concept.
Leakage current
24
Therapy Detectors
Diamond Detector
Type 60003
Waterproof diamond detector for dose measurements in high-energy photon and electron beams
5 pA 1 pC/(Gycm) 10 ns
Features
Very small sensitive volume of 1 to 6 mm3 and typically 0.3 mm thickness Good tissue-equivalence Suitable for dose scanning in IMRT and stereotactic fields because of its excellent spatial resolution The Diamond Detector, based on a naturally grown diamond, is a nearly tissue-equivalent radiation detector. It is designed for dose distribution measurements in highenergy photon and electron beams, featuring a favorable signal-to-noise ratio. Because of its small sensitive volume, the detector is applied for IMRT, stereotactic beams, brachytherapy and water phantom scanning, and is especially well suited for beams with very small field sizes or steep fluence gradients. The Diamond Detector responds with an excellent spatial resolution, low energy and temperature dependence, high sensitivity, nearly no directional dependence and high resistance to radiation damage. The cable length is 1.5 m.
Leakage current Cable leakage Charge collection time Measures: Sensitive area Thickness of sensitive area Water-equivalent window thickness Outer dimensions Useful ranges: Dose rate Radiation quality Temperature Humidity Air pressure diamond detector dosimetry in radiotherapy beams absorbed dose to water
60Co
(3 ... 15) mm2 (0.1 ... 0.4) mm 1.15 mm diameter 7.3 mm
(0.05 ... 30) Gy/min 80 keV ... 20 MV photons (4 ... 20) MeV electrons (10 ... 40) C (50 ... 104) F (10 ... 80) %, max 20 g/m3 (700 ... 1060) hPa
Specification
Type of product Application Measuring quantity Reference radiation quality Nominal sensitive volume Design
TM60003 Diamond Detector, connecting system M, cable length 1.5 m
(1 ... 6) mm3 waterproof, disk-shaped sensitive volume perpendicular to detector axis on detector axis, 1 mm from detector tip radial or axial (5 ... 15) Gy (50 ... 500) nC/Gy at higher depths than dmax, the percentage depth dose curves match curves measured with ionization chambers within 0.5 % + 100 V ( 1 %) 2 % for tilting 170
Reference point Direction of incidence Pre-irradiation dose Nominal response Energy response
Detector bias voltage Directional response
25
Therapy Detectors
Dosimetry Diode P
Type 60016
Waterproof silicon detector for dosimetry in high-energy photon beams up to field size 40 cm x 40 cm
0.5 % for rotation around the chamber axis, 1 % for tilting 20 100 fA 1 pC/(Gycm)
Features
Useful for measurements in small and large photon fields Excellent spatial resolution Minimized energy response for field size independent measurements up to 40 cm x 40 cm The 60016 Dosimetry Diode P is ideal for dose measurements in small photon fields as encountered in IORT, IMRT and stereotactic beams. The excellent spatial resolution makes it possible to measure very precisely beam profiles even in the penumbra region of small fields. The superior energy response enables the user to perform accurate percentage depth dose measurements which are field size independent up to field sizes of (40 x 40) cm2. The waterproof detector can be used in air, solid state phantoms and in water.
Directional response in water Leakage current Cable leakage Materials and measures: Entrance window
1 mm RW3, 1.045 g/cm3 1 mm epoxy 2.2 mm 1 mm2 circular 30 m thick diameter 7 mm, length 47 mm
Total window area density 221 mg/cm2 Water-equivalent window thickness Sensitive volume Outer dimensions
Specification
Type of product Application Measuring quantity Reference radiation quality Nominal sensitive volume Design p-type silicon diode dosimetry in radiotherapy beams absorbed dose to water
60Co
Useful ranges: Radiation quality Field size Temperature Humidity
60Co
... 25 MV photons
(1 x 1) cm2 ... (40 x 40) cm2 (10 ... 40) C (50 ... 104) F (10 ... 80) %, max 20 g/m3
0.03 mm3 waterproof, disk-shaped sensitive volume perpendicular to detector axis on detector axis, 2 mm from detector tip axial 9 nC/Gy 0.5 %/kGy at 6 MV 1 %/10 kGy at 15 MV 0.4 %/K at higher depths than dmax, the percentage depth dose curves match curves measured with ionization chambers within 0.5 % 0V negative
TN60016 Dosimetry Diode P, connecting system BNT TW60016 Dosimetry Diode P, connecting system TNC TM60016 Dosimetry Diode P, connecting system M
Reference point Direction of incidence Nominal response Dose stability Temperature response Energy response
Detector bias voltage Signal polarity
26
Therapy Detectors
Dosimetry Diode E
Type 60017
Waterproof silicon detector for dosimetry in high-energy electron and photon beams
0.5 % for rotation around the chamber axis, 1 % for tilting 20 100 fA 1 pC/(Gycm)
Features
Useful for measurements in all electron fields and for small photon fields Excellent spatial resolution Minimized energy response Thin entrance window for measurements in the vicinity of surfaces and interfaces The 60017 Dosimetry Diode E is ideal for dose measurements in small electron and photon fields as encountered in IORT, IMRT and stereotactic beams. The excellent spatial resolution makes it possible to measure very precisely beam profiles even in the penumbra region of small fields. The superior energy response enables the user to perform accurate percentage depth dose measurements which are field size independent up to field sizes of (40 x 40) cm2. The waterproof detector can be used in air, solid state phantoms and in water.
Directional response in water Leakage current Cable leakage Materials and measures: Entrance window
0.3 mm RW3, 1.045 g/cm3 0.3 mm epoxy 0.7 mm 1 mm2 circular 30 m thick diameter 7 mm, length 45.5 mm
Total window area density 68 mg/cm2 Water-equivalent window thickness Sensitive volume Outer dimensions
Specification
Type of product Application Measuring quantity Reference radiation quality Nominal sensitive volume Design p-type silicon diode dosimetry in radiotherapy beams absorbed dose to water
60Co
Useful ranges: Radiation quality Field size
60Co
(6 ... 25) MeV electrons ... 25 MV photons
(1 x 1) cm2 ... (40 x 40) cm2 for electrons (1 x 1) cm2 ... (10 x 10) cm2 for photons (10 ... 40) C (50 ... 104) F (10 ... 80) %, max 20 g/m3
Temperature Humidity
0.03 mm3 waterproof, disk-shaped sensitive volume perpendicular to detector axis on detector axis, 0.6 mm from detector tip axial 9 nC/Gy 0.5 %/kGy at 6 MV 1 %/kGy at 15 MV 0.5 %/kGy at 5 MeV 4 %/kGy at 21 MeV
TN60017 Dosimetry Diode E, connecting system BNT TW60017 Dosimetry Diode E, connecting system TNC TM60017 Dosimetry Diode E, connecting system M
Reference point Direction of incidence Nominal response Dose stability
Temperature response Energy response
0.4 %/K at higher depths than dmax, the percentage depth dose curves match curves measured with ionization chambers within 0.5 % 0V negative
Detector bias voltage Signal polarity
27
Therapy Detectors
0.02 cm3 Soft X-Ray Chamber

Type 23342
Thin window plane parallel chamber for dose measurements in superficial radiation therapy
Features
Ultra thin entrance window For low-energy photons from 8 keV to 35 keV Sensitive volume 0.02 cm3, vented to air Radioactive check device (option) The 23342 soft X-ray chamber is the golden standard for absolute dose measurements in low-energy photon beams as used in superficial radiation therapy. Correction factors needed for the determination of absorbed dose to water are available. The chamber is designed for the use in solid state phantoms.
Materials and measures: Entrance foil Sensitive volume
0.03 mm PE radius 1.5 mm depth 1 mm
Total window area density 2.76 mg/cm2
Specification
Type of product vented plane parallel ionization chamber acc. IEC 60731 absolute dosimetry in low-energy photon beams absorbed dose to water, air kerma, exposure 30 kV, HVL 0.37 mm Al (T30) 0.02 cm3 not waterproof, vented in chamber center of entrance foil underside perpendicular to chamber plane 1 nC/Gy 1 % per year 300 V nominal 500 V maximal 1 % for chamber tilting up to 20 10 fA 1 pC/(Gycm)
(100 ... 400) V (8 ... 35) keV X-rays (1 x 1) cm2 ... (40 x 40) cm2 (10 ... 40) C (50 ... 104) F (20 ... 80) %, max 20 g/m3 (700 ... 1060) hPa
Application Measuring quantities Reference radiation quality Nominal sensitive volume Design Reference point Direction of incidence Nominal response Long-term stability Chamber voltage Directional response Leakage current Cable leakage
TN23342 Soft X-ray chamber 0.02 cm3, connecting system BNT TW23342 Soft X-ray chamber 0.02 cm3, connecting system TNC TM23342 Soft X-ray chamber 0.02 cm3, connecting system M
Options
90Sr
28
Therapy Detectors

Type 23344
Features
Ultra thin entrance window For low-energy photons from 8 keV to 35 keV Sensitive volume 0.2 cm3, vented to air Radioactive check device (option) The 23344 soft X-ray chamber is used for absolute dose measurements in low-energy photon beams as used in superficial radiation therapy. The sensitive volume is larger than that of the 23342 chamber, giving a higher signal at the cost of a lower spatial resolution. Correction factors needed for the determination of absorbed dose to water are available. The chamber is designed for the use in solid state phantoms.
0.03 mm PE radius 6.5 mm depth 1.5 mm
Specification
Type of product vented plane parallel ionization chamber acc. IEC 60731 absolute dosimetry in lowenergy photon beams absorbed dose to water, air kerma, exposure 30 kV, HVL 0.37 mm Al (T30) 0.2 cm3 not waterproof, vented in chamber center of entrance foil underside perpendicular to chamber plane 7 nC/Gy 1 % per year 400 V nominal 500 V maximal 1 % for chamber tilting up to 20 10 fA 1 pC/(Gycm)
(100 ... 400) V (8 ... 35) keV X-rays (2 x 2) cm2 ... (40 x 40) cm2 (10 ... 40) C (50 ... 104) F (20 ... 80) %, max 20 g/m3 (700 ... 1060) hPa
Application Measuring quantities Reference radiation quality Nominal sensitive volume Design Reference point Direction of incidence Nominal response Long-term stability Chamber voltage Directional response Leakage current Cable leakage
Options
90Sr
29
Therapy Detectors

Type 34013
Features
Ultra thin entrance window For low-energy photons from 8 keV to 35 keV Extremely small size Sensitive volume 0.005 cm3, vented to air The 34013 soft X-ray chamber is used for absolute dose measurements in low-energy photon beams as used in superficial radiation therapy. The chamber's small size enables the user to perform measurements with excellent spatial resolution. Correction factors needed for the determination of absorbed dose to water are available. The chamber is designed for the use in solid state phantoms.
25 m PE radius 0.85 mm depth 0.75 mm
Ion collection efficiency at nominal voltage: Ion collection time 0.03 ms Max. dose rate for 99.5 % saturation 99.0 % saturation Max. dose per pulse for 99.5 % saturation 99.0 % saturation Useful ranges: Chamber voltage Radiation quality Field size Temperature Humidity Air pressure 0.99 kGy/s 1.9 kGy/s 4 mGy 10 mGy
Specification
Type of product Application Measuring quantities Reference radiation quality Nominal sensitive volume Design Reference point Direction of incidence Nominal response Long-term stability Chamber voltage Directional response Leakage current Cable leakage vented plane parallel ionization chamber absolute dosimetry in lowenergy photon beams absorbed dose to water, air kerma, exposure 30 kV, HVL 0.37 mm Al (T30) 0.005 cm3 not waterproof, vented in chamber center of entrance foil underside perpendicular to chamber plane 200 pC/Gy 1 % per year 400 V nominal 400 V maximal 5 % for chamber tilting up to 10 10 fA 1 pC/(Gycm)
(100 ... 400) V (8 ... 35) keV X-rays (0.5 x 0.5) cm2 ... (40 x 40) cm2 (10 ... 40) C (50 ... 104) F (20 ... 80) %, max 20 g/m3 (700 ... 1060) hPa
30
Therapy Detectors
SOURCECHECK
Type 34051
Flat ionization chamber for measuring the source strength of radioactive seeds and intravascular brachytherapy sources
Features
Measures the source strength with 4 geometry Accomodates the source inside the chamber volume Vented sensitive volume of 55 cm3 The SOURCECHECK ionization chamber is the ideal device for measuring the source strength of radioactive seeds, which are used in radiation therapy for permanent implantation into cancer tissue and of sources used in intravascular brachytherapy (IVB). It is specially designed to feature a full 4 geometry for high precision source strength measurements. A polystyrol guide tube is located in the center of the chamber to accommodate the radioactive source to be measured. The SOURCECHECK chamber makes it possible to measure single seeds or seed trains of up to 130 mm length. A wide guard ring reduces the influence of scattered radiation from the housing to improve the measuring accuracy. Since the sensitive volume is vented, air density corrections are required. For measurements, the SOURCECHECK chamber is connected to an electrometer like UNIDOS, UNIDOSwebline or UNIDOS E.
Materials and measures: Guiding tube Outer dimensions
Polystyrol, inner diameter 3.4 mm (minimum) width 220 mm depth 60 mm height 15 mm 200 g
Weight Useful ranges: Temperature Humidity Air pressure
(10 ... 40) C (50 ... 104) F (10 ... 80) %, max 20 g/m3 (700 ... 1060) hPa
TN34051 SOURCECHECK, connecting system BNT TW34051 SOURCECHECK, connecting system TNC TM34051 SOURCECHECK, connecting system M
Options
Adapters for single seeds Adapters for strands
Specification
Type of product Application vented flat ionization chamber source strength measurement of brachytherapy sources air kerma strength, apparent activity, exposure strength
125I,
Measuring quantities
Calibration Nominal sensitive volume Design Reference point Chamber voltage Nominal response Leakage current Cable leakage
others upon request
55 cm3 vented; 4 geometry center of longitudinal chamber axis 400 V 28.3 fA/MBq for 5 fA 1 pC/(Gycm)
125I
31
Therapy Detectors
Well-Type Chamber
Type 33004
Well-type ionization chamber for afterloading source strength measurements
Features
Vented sensitive volume of 200 cm3 Makes it possible to measure the source strength of afterloading sources according to AAPM TG-56 Accommodates suitable applicator adapters for commercial afterloading brachytherapy systems According to AAPM TG-56, the well-type chamber is required for the source strength measurement of radioactive afterloading sources. The recommended calibration factor is the air kerma strength (cGy m2/h). The PTW calibration certificate also includes factors for apparent activity (GBq or Ci) and exposure strength (R m2/h). Suitable applicator adapters and calibrations are available for the commercial standard afterloading systems. The calibration of the well-type chamber is traceable to NIST, USA, and PTB, Germany. For measurements, the chamber is connected to a sensitive electrometer (e.g. UNIDOS, UNIDOS E, MULTIDOS, TANDEM), which has a reading in pA, a wide dynamic range and an interval time function. The well-type chamber is suitable for the calibration of high dose rate (HDR) and pulsed dose rate (PDR) sources such as 192Ir. Calibrations for low dose rate sources (LDR) such as 137Cs are available upon request.
Measuring range
1.7 MBq ... 8.5 TBq for 192Ir with UNIDOS (the upper limit of the measuring range at 400 V for a saturation of 99.5 % is 4 TBq)
Measures: Inner well diameter Outer dimensions
32 mm height 190.5 mm base diameter 178 mm outer well diameter 93 mm 2.4 kg
Weight Useful ranges: Temperature Humidity Air pressure
(10 ... 40) C (50 ... 104) F (10 ... 80) %, max 20 g/m3 (700 ... 1060) hPa
TN33004 Well-type chamber, connecting system BNT TW33004 Well-type chamber, connecting system TNC TM33004 Well-type chamber, connecting system M
Specification
Type of product Application Measuring quantities vented well-type chamber calibration of afterloading sources air kerma strength, apparent activity, exposure strength
192Ir,
Options
Universal adapters for catheters with diameters between 0.7 and 7.2 mm Adapter for Nucletron microSelectron afterloaders (type 077.095)
Calibration Nominal sensitive volume Design Reference point Chamber voltage Change of response with source positioning change of 1 cm Leakage current
others upon request
200 cm3 vented sensitive volume 84.5 mm below chamber top 400 V nominal 500 V maximal <1% 0.5 pA
32
Therapy Detectors and Check Devices
System Incorporated Detectors for Radiotherapy

Besides the radiation detectors presented in this chapter, there are available a number of further detectors which are incorporated components of therapy dosemeters. Firstly there are detectors used for in-vivo dosimetry during therapeutic treatments to control the radiation load given to patients. Secondly state-of-the-art linear and planar detector matrices for dose distribution measurements of intensity modulated therapy beams (IMRT) are part of the PTW detector range.
Patient in-vivo Detectors

Semiconductor probes for in-vivo dosimetry are fixed to the patients body to measure the patient skin, entrance or exit dose during external radiation treatments. Three different detector types for photon energies and one type for electron measurements are available. Additionally a risk organ diode with increased sensitivity and homogeneous directional response is available.
LA48 Linear Chamber Array

The LA48 linear chamber array is designed specially for fast, accurate and reliable dynamic field dosimetry measurements of virtual wedges and multileaf collimators. It incorporates the latest development in fluid-filled ion chamber technology into an advanced ion chamber array. The combination of speed, accuracy and spatial resolution is simply not possible with other systems.
2D-Array seven29 Planar Chamber Array

The 2D-ARRAY seven29 is a new concept of an ion chamber matrix in a plane for IMRT verification and quality control in radiation therapy. There are 729 vented plane-parallel ion chambers located in a matrix of 27 x 27. Utilizing ion chambers avoids radiation defects, the major drawback of solid-state detectors.
STARCHECK Planar Chamber Array

STARCHECK is a precise and reliable tool for fast measurements in radiation therapy beams. Typical applications are quality control and LINAC beam adjustment. The 527 ionization chambers feature an excellent relative response stability, avoiding the need of frequent recalibration. The excellent spatial resolution of only 3 mm ensures precise measurements even in penumbra regions.
STARCHECKmaxi Planar Chamber Array

STARCHECKmaxi is a precise and reliable tool for fast measurements in radiation therapy beams. Typical applications are quality control and LINAC beam adjustment. The 707 ionization chambers feature an excellent relative response stability, avoiding the need of frequent recalibration. It combines the high-resolution of 3 mm as known from the STARCHECK with the ability to cover fields up to a size of 40 cm x 40 cm.
Details upon request
33
Therapy Detectors and Check Devices
Radioactive
90Sr
Check Devices
Radioactive check devices are used for air density corrections of vented ionization chambers and for constancy checks of the complete dosemeters including chamber. Appropriate holding devices to reproducibly adapt the various ion chambers to the radioactive check devices are available.
T48012 Check Device for Thimble Chambers

The check device type T48012 is specially designed for thimble chambers and includes an encapsulated 90Sr source with a low activity of 33 MBq. The sensitive volume of the inserted chamber is irradiated from all directions. The check device is supplemented by a thermometer for controlling its inside temperature. The source is equivalent to ISO class C64444.
T48010 Check Device for Flat Chambers

The check device type T48010 is specially designed for flat chambers and includes an encapsulated 90Sr source with a low activity of 20 MBq. The cylindrical source of the check device is placed near to the entrance window of the ion chamber by means of the appropriate holding device. The source is equivalent to ISO class C6X444.
34
SFD Chamber 75 cm3 SFD Chamber 6 cm3 CT Chamber Flat Chamber 30 cm3 System Incorporated Detectors
36 37 38 39 40
35
75 cm3 SFD Diagnostic Chamber

Type 34060
Shadow-free plane parallel chamber for absolute dosimetry in diagnostic radiology
Features
Shadow-free design for use with automatic exposure control / brightness control Sensitive volume 75 cm3, vented to air Suitable for measurements in front of and behind a phantom The 34060 SFD diagnostic chamber is a general purpose, high precision chamber for measurements in diagnostic radiology. The chamber complies with the standard IEC 61674. Its shadow-free design makes it possible to use the chamber even while the automatic exposure control or brightness control is activated. Together with an adequate diagnostic dosemeter the chamber features a wide dynamic range for measurements either in front of or behind a patient-equivalent phantom. The length of the mounted connection cable is 2.5 m.
0.6 mm polycarbonate, 1.55 g/cm3 0.002 mm graphite 0.32 g/cm3 0.9 mm radius 45.7 mm depth 2 x 5.71mm
Total window area density 93 mg/cm2 Water-equivalent window thickness Sensitive volume
Ion collection efficiency at nominal voltage: Ion collection time 1 ms Max. dose rate for 99 % saturation 95 % saturation Useful ranges: Chamber voltage Radiation quality Field size Temperature Humidity Air pressure 0.16 Gy/s 0.78 Gy/s
Specification
Type of product vented plane parallel ionization chamber acc. IEC 61674 absolute dosimetry in diagnostic radiology air kerma, exposure 70 kV, HVL 2.58 mm Al (RQR5) 75 cm3 not waterproof, vented in chamber center perpendicular to chamber plane, see label 'Focus' 2.8 C/Gy 0.5 % per year 200 V nominal 400 V maximal 2 % (50 ... 150) kV 1% 3 % for chamber tilting up to 15 5 fA 1 pC/(Gycm)
(100 ... 400) V (25 ... 150) kV X-rays (11 x 11) cm2 ... (40 x 40) cm2 (10 ... 40) C (50 ... 104) F (10 ... 80) %, max 20 g/m3 (700 ... 1060) hPa
Application Measuring quantities Reference radiation quality Nominal sensitive volume Design Reference point Direction of incidence Nominal response Long-term stability Chamber voltage Energy response Polarity effect at RQR/RQA5 Directional response Leakage current Cable leakage
TN34060-2,5 SFD diagnostic chamber 75 cm3, connecting system BNT TW34060-2,5 SFD diagnostic chamber 75 cm3, connecting system TNC TM34060-2,5 SFD diagnostic chamber 75 cm3, connecting system M
36
6 cm3 SFD Mammo Chamber

Type 34069
Shadow-free plane parallel chamber for absolute dosimetry in diagnostic radiology and mammography
Features
Shadow-free design for use with automatic exposure control Sensitive volume 6 cm3, vented to air Suitable for measurements in front of and behind a phantom The 34069 SFD mammo chamber is a high precision chamber for measurements in diagnostic radiology at high dose rates and in mammography. The chamber complies with the standard IEC 61674. Its shadow-free design makes it possible to use the chamber even while the automatic exposure control is activated. Together with an adequate diagnostic dosemeter the chamber features a wide dynamic range for measurements either in front of or behind a patient-equivalent phantom. The length of the mounted connection cable is 2.5 m.
0.32 mm PMMA, 1.19 g/cm3 0.002 mm graphite 0.32 g/cm3 0.4 mm radius 15.2 mm depth 2 x 4.21mm
Total window area density 38 mg/cm2 Water-equivalent window thickness Sensitive volume
Ion collection efficiency at nominal voltage: Ion collection time 550 s Max. dose rate for 99 % saturation 95 % saturation Useful ranges: Chamber voltage Radiation quality Field size Temperature Humidity Air pressure 0.53 Gy/s 2.65 Gy/s
Specification
Type of product vented plane parallel ionization chamber acc. IEC 61674 absolute dosimetry in diagnostic radiology air kerma, exposure 30 kV, HVL 0.337 mm Al (RQR-M3) 70 kV, HVL 2.58 mm Al (RQR5) 6 cm3 not waterproof, vented in chamber center perpendicular to chamber plane, see label 'Focus' 230 nC/Gy 2 % per year 200 V nominal 400 V maximal 2 % (25 ... 35) kV 1 % ( 2 %) 3 % for chamber tilting up to 15 5 fA 1 pC/(Gycm)
(100 ... 400) V (25 ... 150) kV X-rays (5 x 5) cm2 ... (40 x 40) cm2 (10 ... 40) C (50 ... 104) F (10 ... 80) %, max 20 g/m3 (700 ... 1060) hPa
Application Measuring quantities Reference radiation quality
TN34069-2,5 SFD mammo chamber 6 cm3, connecting system BNT TW34069-2,5 SFD mammo chamber 6 cm3, connecting system TNC TM34069-2,5 SFD mammo chamber 6 cm3, connecting system M
Nominal sensitive volume Design Reference point Direction of incidence Nominal response Long-term stability Chamber voltage Energy response Polarity effect at RQR-M3 (RQA-M3) Directional response Leakage current Cable leakage
37
3.14 cm3 CT Chamber

Type 30009
Vented cylindrical pencil chamber for dose length product measurements in computed tomography
Features
Pencil type chamber for measurements within a CT head or body phantom or in air Provides a sensitive measuring length of 10 cm Shows a homogeneous response over the whole chamber length The CT chamber type 30009 is a vented cylinder chamber designed for measurements of photon radiation in computed tomography. The typical measuring quantity is dose length product, which allows the determination of the CTDI1 and CTDIW2 according to IEC 61223-2-6
Materials and measures: Wall material Wall area density Dimension of sensitive volume Electrode
1 mm PMMA, graphite coated 120 mg/cm2 radius 3.5 mm length 100 mm Al tube, outer diameter 3 mm, inner diameter 2 mm
Ion collection efficiency at nominal voltage: Ion collection time 300 s Max. dose rate for 99.5 % saturation 99.0 % saturation Max. dose per pulse for 99.5 % saturation 99.0 % saturation Useful ranges: Chamber voltage Radiation quality Temperature Humidity Air pressure 0.9 Gy/s 1.9 Gy/s 0.14 mGy 0.35 mGy
Specification
Type of product Application Measuring quantities Reference radiation quality Nominal sensitive volume Design Reference point Direction of incidence Nominal response Chamber voltage vented pencil type chamber dosimetry in computed tomography air kerma length product, exposure length product 120 kV, HVL 5.00 mm Al (RQR9) 3.14 cm3
(100 ... 400) V (50 ... 150) kV (10 ... 40) C (50 ... 104) F (10 ... 80) %, max 20 g/m3 (700 ... 1060) hPa
not waterproof, vented, pencil type chamber center radial 14 nC/(Gycm) 100 V nominal 500 V maximal high voltage to be connected only with active current-limiting device (Imax < 0.5 mA) 5 % (70 ... 150) kV 2 % for tilting 170 10 fA 1 pC/(Gycm)
TN30009 CT chamber 3.14 cm3, connecting system BNT TW30009 CT chamber 3.14 cm3, connecting system TNC TM30009 CT chamber 3.14 cm3, connecting system M
1CTDI = Computed Tomography Dose Index 2CTDI = Weighted Computed Tomography Dose Index W Both definitions acc. IEC 60601-2-44
Energy response Directional response Leakage current Cable leakage
38
30 cm3 Flat Chamber

Type 233612
Flat ionization chamber for precise dose measurements in the useful X-ray beam
Features
Suitable for dose measurements of diagnostic X-ray qualities in air Can be used down to 35 keV radiation energy Comes with a holding stem for mounting in the radiation field The 30 cm3 flat chamber is especially designed for X-ray dose measurements in air down to 35 keV radiation energy. The maximal polarizing voltage is 500 V. The area density of the entrance window is 90 mg/cm2. A radioactive check device including check source and shielding is available to correct air density and carry out function tests. Using the appropriate holder, the check source can always be positioned and oriented at the same place on the chamber.
0.75 mm PMMA, graphite coated 0.05 mm graphite coated polyimide foil radius 23.5 mm depth 2 x 5.98 mm
Total window area density 90 mg/cm2 Electrode Dimension of sensitive volume
Ion collection efficiency at nominal voltage: Ion collection time 0.6 ms Max. dose rate for 99.5 % saturation 99.0 % saturation Useful ranges: Chamber voltage Radiation quality Temperature Humidity Air pressure 0.26 Gy/s 0.52 Gy/s
(300 ... 500) V (35 ... 75) keV X-rays (10 ... 40) C (50 ... 104) F (10 ... 80) %, max 20 g/m3 (700 ... 1060) hPa
Specification
Type of product Application Measuring quantities Reference radiation quality Nominal sensitive volume Design Reference point Direction of incidence plane Nominal response Chamber voltage vented plane-parallel ionization chamber absolute dosimetry in diagnostic radiology air kerma, exposure 70 kV, HVL 2.58 mm Al (RQR5) 30 cm3
TN233612 Flat chamber 30 cm3, connecting system BNT TW233612 Flat chamber 30 cm3, connecting system TNC TM233612 Flat chamber 30 cm3, connecting system M
not waterproof, vented in chamber center perpendicular to chamber 1 C/Gy 400 V nominal 500 V maximal high voltage to be connected only with active current-limiting device (Imax < 0.5 mA) 6 % (35 ... 75) keV 5% for chamber tilting up to 5 10 fA 1 pC/(Gycm)
Energy response Directional response in water Leakage current Cable leakage
39
Diagnostic and Nuclear Medicine Detectors
System Incorporated Detectors for Diagnostic Radiology

Besides the radiation detectors presented in this chapter, there are available a number of further detectors which are incorporated components of diagnostic dosemeters. There are detectors for patient dosimetry (DIAMENTOR) measuring the dose area product or semiconductor detectors for absolute dosimetry (DIADOS). Special ionization chambers for radiation leakage measurements amend the PTW detector range.
DIAMENTOR Patient Dosimetry Chambers

DIAMENTOR chambers for dose area product measurements are available in different sizes and types to cover a wide range of diagnostic X-ray installations. The chambers can easily be mounted to the X-ray collimator or are firmly installed parts of the X-ray installation. The transparent models do not interfere with the collimators light field diaphragm.
DIADOS Absolute Dosimetry Detectors

The DIADOS detectors are sturdy semiconductor detectors designed to withstand tough handling. They do not need air density correction or high voltage supply like ion chambers do and are suitable for acceptance tests and service quality checks as well. Two types are available, covering the conventional diagnostic or the mammography X-ray range.
XLS X-Ray Leakage Chamber

This rectangular plane parallel XLS ionization chamber is used as part of the XLS X-ray leakage system for radiation leakage measurements of diagnostic X-ray installations. Up to 18 of these chambers can be arranged for radiation leakage detection around X-ray tubes.
System Incorporated Detectors for Nuclear Medicine

Besides detectors used in nuclear medicine presented in other chapters, e.g. for radiation protection measurements, a special chamber as an incorporated component of the CURIEMENTOR system is available.
Well-type Chamber for CURIEMENTOR Isotope Calibrator

The CURIEMENTOR chamber is a pressurized well-type ionization chamber with nearly 4 measuring geometry. It is part of the CURIEMENTOR system which measures the activity of radioactive isotopes as used in diagnostic and therapeutic nuclear medicine and in intravascular brachytherapy.
40
Radiation Monitoring Chamber 0.1 l Radiation Monitoring Chamber 3 l Radiation Monitoring Chamber 50 l Spherical Chambers 1 and 10 l Spherical Chambers PS-10 and PS-50 Spherical Chamber TK-30 Cylinder Stem Chamber 30 cm3 Hp(10) Secondary Standard Chamber Reference Soft X-Ray Chamber Monitor Chambers for Calibration Facilities Monitor Chambers for X-Ray Therapy Units Bhm Extrapolation Chamber
42 43 44 45 46 47 48 49 50 51 52 53
41
0.1 Liter Radiation Monitoring Chamber

Type 32001
Cylindrical Al chamber for stationary and mobile radiation monitoring of high level gamma radiation
Features
Vented sensitive volume of 102 cm3 Suitable as radiation monitoring chamber Rigid construction for wall mounting Gamma energy range 80 keV to 1.3 MeV The 0.1 liter chamber is used for environmental radiation monitoring. The rigid and compact construction makes the chamber suitable for stationary radiation monitoring as well as for mobile operation in vehicles. The chamber is designed to measure very high dose rates of up to 4000 Sv/h (90 % saturation) as they may occur after nuclear accidents. Since the sensitive volume is open to the surroundings, air density correction is required for precise measurement. The chamber is fully guarded up to the sensitive volume. The cylindrical chamber is made of aluminum with 4 mm wall thickness. The ion-collecting electrode is made of aluminum too. The external chamber diameter is 60 mm and the length is approx. 150 mm. For the transfer of the measuring signal and the polarizing voltage, the chamber is supplied with two coaxial Fischer connectors. Via an optional adapter cable of 1.5 m length, the chamber can be connected to a dosemeter with M connector, which has input circuits on ground potential.
Materials and measures: Wall of sensitive volume Total wall area density Dimension of sensitive volume Central electrode Outer dimensions
4 mm Al, 2.85 g/cm3 1.14 g/cm2 radius 22.5 mm length 88 mm Al, diameter 25 mm diameter 60 mm length 150 mm
Ion collection efficiency at nominal range: Ion collection time 1.3 ms Max. dose rate for 99 % saturation 90 % saturation Useful ranges: Radiation quality Temperature Humidity Air pressure 355 Sv/h 3550 Sv/h
80 keV ... 1.3 MeV (10 ... 40) C (50 ... 104) F (10 ... 80) %, max 20 g/m3 (700 ... 1060) hPa
T32001 Radiation monitoring chamber 0.1 l, Fischer coax connectors
Specification
Type of product Application Measuring quantity Nominal sensitive volume Design Reference point Direction of incidence Nominal response Chamber voltage Energy response vented cylindrical ionization chamber radiation monitoring photon equivalent dose 102 cm3 not waterproof, vented chamber center radial 3 C/Sv 500 V nominal 10 % (Ephoton 80 keV)
Option
T7262/U10-1.5 Connection cable with M connector, length 1.5 m
Directional response in air 10 % for tilting perpendicular to the axis up to 20 Leakage current 50 fA
42
3 Liter Radiation Monitoring Chambers

Types 34031, 32004
Cylindrical polyethylene ionization chambers for stationary radiation monitoring of gamma radiation
Features
Vented sensitive volume of 3 liters Suitable as radiation monitoring chambers Gamma energy range 80 keV to 1.3 MeV The 3 liter chambers are used as stationary surveillance devices for environmental radiation monitoring. The chambers are designed to measure protection level dose rates. The chambers are fully guarded up to the sensitive volume. Since the sensitive volume is open to the surroundings, air density correction is required for precise measurement. The cylindrical chambers are made of graphite coated polyethylene with 4 mm wall thickness. The ion-collecting electrode is made of graphite coated polyethylene too. The external chamber diameter is 150 mm and the length is approx. 200 mm. For the transfer of the measuring signal and the polarizing voltage, the chambers are supplied with two coaxial connectors (model 34031) or one triaxial connector (model 32004). The maximal chamber polarizing voltage is 1000 V. The chamber model 34031 is supplied with an integrated adapter for positioning a radioactive check source of type T48010, which makes it possible to check the proper performance of the entire measuring system.
Materials and measures: Wall of sensitive volume Total wall area density Dimension of sensitive volume Central electrode Outer dimensions
4 mm PE graphite coated, 0.95 g/cm3 0.38 g/cm2 radius 71.25 mm length 200 mm graphite coated PE, diameter 28 mm diameter 150 mm length 200 mm
Ion collection efficiency at nominal range: Ion collection time 25 ms Max. dose rate for 99 % saturation 90 % saturation Useful ranges: Radiation quality Temperature Humidity Air pressure 0.95 Sv/h 9.5 Sv/h
Specification
Type of product Application Measuring quantity Nominal sensitive volume Design Reference point Direction of incidence Nominal response Chamber voltage Energy response vented cylindrical ionization chamber radiation monitoring photon equivalent dose 3l
T34031 Radiation monitoring chamber 3 l, Fischer coax connectors T32004 Radiation monitoring chamber 3 l, LEMO triax connector
Option
not waterproof, vented chamber center radial 100 C/Sv 1000 V nominal 10 % (Ephoton 80 keV) T7262/U10-1.5 Connection cable with M connector, length 1.5 m
43
50 Liter Radiation Monitoring Chamber

Type 7262
Cylindrical pressurized steel ionization chamber for stationary gamma radiation monitoring
Features
Sealed sensitive volume of 50 liters Suitable as stationary radiation monitoring chamber Gamma energy range 80 keV to 1.3 MeV The ionization chamber T7262 has a constructive volume of 5 liters filled with Argon gas at the pressure of 10 bar, resulting in an effective sensitive volume of 50 liters. This superior design makes the chamber very sensitive and enables performing low level gamma radiation measurements down to the natural radiation background. The chamber is used as highly sensitive stationary surveillance device for environmental radiation monitoring. The chamber is fully guarded up to the sensitive volume. Since the sensitive volume is sealed, no air density correction is required. The cylindrical 50 liter chamber is made of steel with 3.25 mm wall thickness and a 3 mm aluminum cover. The ion-collecting electrode is made of brass. The external chamber diameter is 195 mm and the length is 538 mm. The chamber is supplied with two coaxial Fischer connectors for the transfer of the measuring signal and the polarizing voltage. Via an optional adapter cable of 1.5 m length, the chamber can be connected to a dosemeter with M connector, which has input circuits on ground potential. The maximal chamber polarizing voltage is 1000 V.
3 mm Al, 2.7 g/cm3 3.25 mm steel, 7.85 g/cm3 3.361 g/cm2 radius 66.75 mm length 360 mm brass, diameter 17.5 mm diameter 195 mm length 538 mm
Total wall area density Dimension of sensitive volume Central electrode Outer dimensions
Ion collection efficiency at nominal range: Ion collection time 30 ms Max. dose rate for 99 % saturation 90 % saturation Useful ranges: Radiation quality Temperature Humidity Air pressure 1 mSv/h 10 mSv/h
T7262 Radiation monitoring chamber 50 l, Fischer coax connectors
Specification
Type of product Application Measuring quantity Nominal sensitive volume Design Reference point Direction of incidence Nominal response Chamber voltage Energy response pressurized cylindrical ionization chamber radiation monitoring photon equivalent dose 50 l sealed and pressurized, filled with Ar (10 bar) chamber center radial 2 mC/Sv. 1000 V nominal 10 % (Ephoton 80 keV)
Option
T7262/U10-1.5 Connection cable with M connector, length 1.5 m
44
1 and 10 Liter Spherical Chambers

Types 32002, 32003
Spherical ionization chambers for radiation protection level and low level measurement
32003
Features
Vented sensitive volumes of 1 liter and 10 liters Suitable for survey meter calibration and low level measurements Superior energy response, reproducibility, directional dependence and long-term stability Radioactive check device (option) The spherical chambers are designed for the measurement of ionizing radiation in the protection level range from 0.1 mSv/h to 0.3 Sv/h (model 32002) and in the low level range from 10 Sv/h to 30 mSv/h (model 32003). Superior features make the chambers suitable as standard chambers for calibration purposes. They fulfill the requirement for excellent reproducibility and long-term stability of the sensitive volumes. The spherical construction ensures a nearly uniform response to radiation from every direction. The energy response is very flat. This is achieved by the thin layer of aluminum on the inner wall surface, which provides for an increased photoelectric yield to compensate for the absorption of soft X-rays. The outer chamber diameters are 140 mm and 276 mm.
3 mm POM (32002) 2.75 mm POM (32003) (polyoxymethylene) 453 mg/cm2 (32002) 417 mg/cm2 (32003) graphite coated polystyrene, diameter 50 mm (32002) diameter 100 mm (32003) diameter 140 mm (32002) diameter 276 mm (32003)
Total wall area density Central electrode
Outer dimensions
Ion collection efficiency at nominal range: Ion collection time 37 ms (32002) 150 ms (32003) Max. dose rate for 99.5 % saturation 99.0 % saturation Max. dose per pulse for 99.5 % saturation 99.0 % saturation Useful ranges: Chamber voltage Radiation quality Temperature Humidity Air pressure (32002), (32003) 210 mSv/h, 13 mSv/h 420 mSv/h, 26 mSv/h (32002), (32003) 1.6 Sv, 0.3 Sv 3.1 Sv, 0.8 Sv
Specification
Type of product Application Measuring quantity Nominal sensitive volume Design Reference point Nominal response Chamber voltage Energy response Leakage current vented spherical ionization chambers radiation protection measurements photon equivalent dose 1 l (32002) 10 l (32003) not waterproof, vented chamber center 40 C/Sv (32002) 330 C/Sv (32003) 400 V nominal 500 V maximal 4 % (32002) 3 % (32003) 10 fA
(300 ... 500) V 25 keV ... 50 MeV (10 ... 40) C (50 ... 104) F (10 ... 80) %, max 20 g/m3 (700 ... 1060) hPa
Ordering information
TN32002 Spherical chamber 1 l, connecting system BNT TW32002 Spherical chamber 1 l, connecting system TNC TM32002 Spherical chamber 1 l, connecting system M TN32003 Spherical chamber 10 l, connecting system BNT TW32003 Spherical chamber 10 l, connecting system TNC TM32003 Spherical chamber 10 l, connecting system M
Options
T48010 Radioactive check device 90Sr T48001 Chamber holding device for check device
45
PS-50 and PS-10 Spherical Chambers

Types 32007S, 32008S
Primary standard spherical ionization chambers for radiation protection measurements
Features
Vented sensitive volumes of 50 cm3 and 10 cm3 Suitable as primary standard for radiation protection measurements Exact volume individually determined Designed in collaboration with the National Institute of Standards and Technology (NIST) The spherical graphite chambers PS-50 and PS-10 are vented ionization chambers for the use as primary standard for radiation protection measurements and for absolute dosimetry. The spherical graphite chambers have been designed in collaboration with the Radiation Interactions and Dosimetry Group at the National Institute of Standards and Technology (NIST). The exact volume of each chamber is individually determined. The homogeneity of the walls and electrodes is 0.06 mm. The chambers are constructed with a long rigid stem of approx. 29 cm length for easy mounting in the radiation beam. Air density correction is required for each measurement.
Materials and measures: Wall of sensitive volume Total wall area density Central electrode Outer dimensions
3.5 mm graphite 647 mg/cm2 graphite, diameter 3 mm diameter 53 mm (32007S) diameter 34 mm (32008S)
Ion collection efficiency at nominal range: Ion collection time 8.7 ms (32007S) 1.9 ms (32008S) Max. dose rate for 99,5 % saturation 90 % saturation Max. dose per pulse for 99.5 % saturation 99.0 % saturation Useful ranges: Chamber voltage Radiation quality Field size (square field) Temperature Humidity Air pressure (32007S), (32008S) 1.23 mGy/s, 26 mGy/s 2.46 mGy/s, 52 mGy/s (32007S), (32008S) 7.1 G, 33 Gy 14.2 Gy, 65 Gy
(400 1000) V
60Co, 137Cs
Specification
Type of product Application vented spherical ionization chambers primary standard for radiation protection measurements air kerma, photon equivalent dose 50 10 cm3 cm3 (32007S) (32008S)
(6 x 6) cm2 (32007S) (4 x 4) cm2 (32008S) (10 ... 40) C (50 ... 104) F (10 ... 80) %, max 20 g/m3 (700 ... 1060) hPa
Measuring quantity Nominal sensitive volume Design Reference point Nominal response Chamber voltage
TN32007S Spherical chamber PS-50, connecting system BNT TN32008S Spherical chamber PS-10, connecting system BNT
not waterproof, vented chamber center 1.73 C/Gy (32007S) 0.349 C/Gy (32008S) 1000 V nominal (32007S) 500 V nominal (32008S) 1000 V maximal
Directional response in air 0.5 % for rotation around the chamber axis and 1 % for tilting the chamber axis up to 60 (32007S) 1 % for tilting the chamber axis up to 50 (32008S) Leakage current 5 fA
46
Spherical Ionization Chamber TK-30

Type 32005
Spherical ionization chamber with a long rigid stem for radiation protection measurement
Features
Vented sensitive volume of 28 cm3 Suitable as high precision reference chamber for radiation protection dosimetry Very flat energy response within a wide range The spherical chamber TK-30 is designed as a reference chamber for absolute dosimetry to be used by secondary standard dosimetry laboratories (SSDL) and users with high quality requirements. It has very small variations of response with radiation quality from low X-ray energies up to high-energy photon radiation. The guard ring is designed up to the sensitive volume. The chamber is constructed with a long rigid stem of approx. 20 cm length for easy mounting in the radiation beam. Air density correction is required for each measurement.
3 mm POM (polyoxymethylene, graphited) 453 mg/cm2 radius 22 mm graphite coated PMMA, diameter 4.2 mm
Total wall area density Dimension of sensitive volume Central electrode
Ion collection efficiency at nominal range: Ion collection time 4.5 ms Max. dose rate for 99 % saturation 90 % saturation Max. dose per pulse for 99 % saturation Useful ranges: Chamber voltage Radiation quality Temperature Humidity Air pressure 29.4 Sv/h 294 Sv/h 26 Sv
Specification
Type of product Application Measuring quantity Nominal sensitive volume Design Reference point Direction of incidence Nominal response Chamber voltage Energy response vented spherical ionization chamber radiation protection measurements photon equivalent dose, exposure 27.9 cm3 not waterproof, vented chamber center radial 900 nC/Sv 400 V nominal 1000 V maximal 5 % (48 keV ...
60Co)
(200 ... 400) V 25 keV ... 50 MeV (10 ... 40) C (50 ... 104) F (10 ... 80) %, max 20 g/m3 (700 ... 1060) hPa
TN32005 Spherical chamber TK-30, connecting system BNT TW32005 Spherical chamber TK-30, connecting system TNC TM32005 Spherical chamber TK-30, connecting system M
Directional response in air 0.5 % for rotation around the chamber axis and 3 % for tilting of the axis up to 45 Leakage current 5 fA
47
30 cm3 Cylinder Stem Ionization Chamber

Type 23361
Cylindrical PMMA ionization chamber with a long rigid stem for radiation protection measurement
Features
Vented sensitive volume of 30 cm3 Suitable as high precision reference chamber for radiation protection dosimetry Very flat energy response within a wide range Radioactive check device (option) The cylinder stem chamber is designed as a reference chamber for absolute dosimetry to be used by secondary standard dosimetry laboratories (SSDL) and users with high quality requirements. It has very small variations of response with radiation quality from low X-ray energies up to high-energy photon radiation. The guard ring is designed up to the sensitive volume. The chamber is constructed with a long rigid stem of approx. 20 cm length for easy mounting in the radiation beam. An acrylic build-up cap with 3 mm wall thickness for in-air measurement in 60Co beams is included with each chamber, as well as a calibration certificate. Air density correction is required for each measurement. A radioactive check device and an appropriate holding device are available.
Materials and measures: Wall of sensitive volume Total wall area density Dimension of sensitive volume Central electrode Outer dimensions Build-up cap
1 mm PMMA, graphited 119 mg/cm2 radius 15.5 mm length 51 mm graphite coated Al, diameter 14 mm diameter 33 mm length 335 mm PMMA, thickness 3 mm
Ion collection efficiency at nominal range: Ion collection time 1.3 ms Max. dose rate for 99.5 % saturation 99.0 % saturation Max. dose per pulse for 99.5 % saturation 99.0 % saturation Useful ranges: Radiation quality Temperature Humidity Air pressure 60 mGy/s 120 mGy/s 50 Gy 100 Gy
30 keV ... 50 MeV (10 ... 40) C (50 ... 104) F (10 ... 80) %, max 20 g/m3 (700 ... 1060) hPa
Specification
Type of product Application Measuring quantity Nominal sensitive volume Design Reference point Direction of incidence Nominal response Chamber voltage Energy response vented cylindrical ionization chamber radiation protection measurements photon equivalent dose, exposure 30 cm3 not waterproof, vented on chamber axis, 27 mm from chamber tip radial 1 C/Gy 400 V nominal 500 V maximal 4 % (40 keV ...
60Co)
TN23361 Cylinder stem chamber 30 cm3, connecting system BNT TW23361 Cylinder stem chamber 30 cm3, connecting system TNC TM23361 Cylinder stem chamber 30 cm3, connecting system M
Options
T48010 Radioactive check device 90Sr T23237 Chamber holding device for check device
Directional response in air 0.5 % for for rotation around the chamber axis for tilting see diagram page 62 Leakage current Stem leakage 10 fA 1 pC/(Gycm)
48
Hp(10) Secondary Standard Chamber

Type 34035
Parallel plate ionization chamber for direct measurement of Hp(10) personal dose equivalent on a slab phantom
Features
Vented sensitive volume of 10 cm3 Measures the Hp(10) personal dose equivalent directly Suitable as a reference chamber for Hp(10) calibration The parallel plate ionization chamber model 340351 is integrated into a slab phantom to measure the Hp(10) radiation protection measuring quantity directly. The high performance chamber is designed to be used as a secondary standard chamber for calibration purposes. The beam calibration with the Hp(10) chamber makes it unnecessary to precisely determine the spectrum of the X-ray beam. The chamber comes uncalibrated; a primary standard calibration by PTB, the German National Laboratory, is available. The chamber set includes a phantom slab of 31 mm thickness with chamber assembly and an additional PMMA phantom slab of 120 mm thickness. Both sets available include an adapter cable to connect the chamber either to a dosemeter with M connector or with BNC connector and banana pin. The Hp(10) chamber should be used in connection with a high quality dosemeter such as UNIDOS, UNIDOS E or UNIDOSwebline to ensure best performance.
Materials and measures: Phantom material Outer dimensions chamber assembly additional slab phantom Useful ranges: Chamber voltage Radiation quality Temperature Humidity Air pressure
PMMA 300 mm x 300 mm height 31 mm height 120 mm
(300 ... 500) V (15 ... 1400) keV (10 ... 40) C (50 ... 104) F (10 ... 80) %, max 20 g/m3 (700 ... 1060) hPa
L981937 Hp(10) Secondary standard chamber type 34035, connecting system M L981938 Hp(10) Secondary standard chamber type 34035, connecting system BNC and banana pin
Option
PTB Primary standard calibration upon request
Specification
Type of product Application Measuring quantity Nominal sensitive volume Design Reference conditions Reference point vented parallel plate chamber radiation protection measurements Hp(10) personal dose equivalent 10 cm3 not waterproof, vented 20C, 1013 hPa 65 % rel. humidity chamber center, 13.5 mm below chamber surface or 15.5 mm below surface of integrated step cylinder 285 nC/Sv 400 V nominal 10 fA 1 pC/(Gycm)
1 Ankerhold, Ambrosi, Eberle A chamber for determining the conventionally true value of Hp(10) and H*(10) needed by calibration laboratories Rad. Prot. Dos. Vol. 96, Nos 1-3, pp. 133 - 137 (2001), Nucl. Techn. Publishing
Nominal response Chamber voltage Leakage current Cable leakage
49
100 cm3 Reference Soft X-Ray Chamber

Type 34047
Calibration grade plane parallel chamber for dose measurements in low-energy photon beams
Features
Ultra thin entrance window For low-energy photons from 5 keV to 20 keV Sensitive volume 100 cm3, vented to air The 34047 soft X-ray chamber is a reference chamber used in calibration laboratories. Its very thin entrance window makes it possible to measure photon radiation with energies down to 5 keV. Due to the large volume, the chamber gives reasonable and accurate signals. The chamber is designed for measurements free in air.
Materials and measures: Entrance foil
3.5 m PET (polyethylenterephthalat), graphite coated radius 39.9 mm depth 20 mm
Total window area density 0.5 mg/cm2 Sensitive volume
Ion collection efficiency at nominal voltage: Ion collection time 6.3 ms Max. dose rate for 99.5 % saturation 99.0 % saturation Useful ranges: Chamber voltage Radiation quality Field size Temperature Humidity Air pressure 2.1 mGy/s 4.2 mGy/s
Specification
Type of product Application Measuring quantities Reference radiation quality Nominal sensitive volume Design Reference point Direction of incidence Nominal response Long-term stability Chamber voltage Leakage current Cable leakage vented plane parallel ionization chamber absolute dosimetry in low-energy photon beams absorbed dose to water, air kerma, exposure 30 kV, HVL 0.37 mm Al (T30) 100 cm3 not waterproof, vented in chamber center of entrance foil underside perpendicular to chamber plane 4.8 C/Gy 1 % per year 400 V nominal 500 V maximal 10 fA 1 pC/(Gycm)
(300 400) V (5 ... 20) keV X-rays (15 x 15) cm2 ... (40 x 40) cm2 (10 ... 40) C (50 ... 104) F (20 ... 80) %, max 20 g/m3 (700 ... 1060) hPa
TN34047 Reference Soft X-ray chamber 100 cm3, connecting system BNT TW34047 Reference Soft X-ray chamber 100 cm3, connecting system TNC TM34047 Reference Soft X-ray chamber 100 cm3, connecting system M
50
Monitor Ionization Chambers

Types 34014, 786
Large size plane parallel transmission chambers for use as dose monitors combined with calibration facilities
Features
Vented sensitive volumes of 94 cm3 and 86 cm3 Include twin-sensitive volumes Shadow-free transmission chambers for dose monitoring with calibration facilities The circular plane parallel transmission chambers are used for dose monitoring in combination with calibration benches. The sensitive volumes are designed as twin-chambers with 2.5 mm measuring depth each and a diameter of 155 mm (model 786) or 148 mm (model 34014). The chamber walls and the electrodes are made of polyimide (PI) of 0.025 mm thickness each with graphite layer. The chambers are fully guarded. The external diameter of the chamber housing is 230 mm. Two holes with 6 mm threads serve for mechanical chamber fixation. Two chamber versions are available: model 786 is used together with dosemeters having the input circuits on ground potential, and model 34014 is used together with dosemeters having the input circuits on high voltage.
3 x 0.025 mm polyimide, graphite coated polyimide foil, graphite coated diameter 230 mm
Total window area density 3 x 3.55 mg/cm2 Electrode Outer dimensions
Ion collection efficiency at nominal voltage: Max. dose rate for 99.5 % saturation 8.5 Gy/s 99.0 % saturation 17 Gy/s (34014) 18 Gy/s (786) Max. dose per pulse for 99.5 % saturation 99.0 % saturation Useful ranges: Radiation quality Field size Temperature Humidity 590 Gy 1.19 mGy
(7.5 ... 420) kV X-rays 148 mm diameter (34014) 155 mm diameter (786) (10 ... 40) C (50 ... 104) F (10 ... 80) %, max 20 g/m3 (700 ... 1060) hPa
Specification
Type of product Application Measuring quantity Nominal sensitive volumes Design Nominal response Chamber voltage Leakage current vented plane parallel twin-chambers dose monitoring in calibration facilities exposure 86 cm3 (34014) 94 cm3 (786) not waterproof, vented depends on field size 400 V nominal 1 pA
Air pressure
TN34014 Monitor chamber, connecting system BNT TW34014 Monitor chamber, connecting system TNC TM786 Monitor chamber, connecting system M TB786 Monitor chamber, connecting system BNC and banana pin Monitor chambers with smaller diameter of sensitive volume upon request
51
X-ray Therapy Monitor Chamber

Type 7862
Large size plane parallel transmission chamber for use as dose monitor combined with X-ray therapy units
Features
Vented sensitive volume of 17.6 cm3 Shadow-free transmission chamber for dose monitoring with radiation therapy X-ray equipment The circular plane parallel transmission chamber model 7862 is used for dose monitoring in combination with radiotherapy X-ray units. The sensitive volume is designed as a very thin cylinder of 2.4 mm thickness and 96.5 mm diameter. The chamber wall and the electrode are made of polyimide (PI) of 0.05 mm thickness each with graphite layer, mechanically protected by another PI foil of 0.05 mm in front of each wall. The nominal photon energy range is 7.5 kV up to 420 kV and the leakage current is less than 1 pA. The chamber is fully guarded. The external diameter of the chamber housing is 119.5 mm. Three holes with 3.5 mm threads serve for mechanical chamber fixation. The transmission chamber model 7862 is used in connection with dosemeters having the input circuits on ground potential.
4 x 0.05 mm polyimide, graphite coated polyimide foil, graphite coated diameter 119.5 mm
Total window area density 4 x 7.1 mg/cm2 Electrode Outer dimensions
Ion collection efficiency at nominal voltage: Max. dose rate for 99.5 % saturation 10 Gy/s 99.0 % saturation 20 Gy/s Max. dose per pulse for 99.5 % saturation 99.0 % saturation Useful ranges: Radiation quality Field size Temperature Humidity Air pressure 640 Gy 1.29 mGy
(7.5 ... 420) kV X-rays 95 mm diameter (10 ... 40) C (50 ... 104) F (10 ... 80) %, max 20 g/m3 (700 ... 1060) hPa
Specification
Type of product Application Measuring quantity Nominal sensitive volume Design Nominal response Chamber voltage Leakage current vented plane parallel triple-chamber dose monitoring in X-ray therapy units exposure 17.6 cm3 not waterproof, vented depends on field size 400 V nominal 1 pA
TM7862 Monitor chamber for X-ray therapy units, connecting system M
52
Bhm Extrapolation Chamber

Type 23392
Low energy extrapolation chamber with adjustable volume depth for measurements of absorbed dose in soft tissue
Features
Measures absolute dose of beta radiation and X-rays in soft tissue equivalent material very precisely Includes a micrometer screw for the depth adjustment of the sensitive volume down to zero Suitable for beta calibration at PSDLs and SSDLs The Bhm extrapolation chamber is a high quality device for absorbed dose measurements of beta and low energy X radiation in certain depths below the surface of the entrance window. Primary standard dosimetry laboratories (PSDL) and secondary standard dosimetry laboratories (SSDL) use it for low energy radiation calibration. The dose is determined from the ionization density in a small air gap, the extrapolation chamber volume, embedded in tissue equivalent material (PMMA). The chamber is supplied with a very thin entrance window of 0.75 mg/cm2 and a collecting electrode of 30 mm in diameter. By means of the built-in micrometer screw, the collecting electrode surrounded by a guard ring of 15 mm can be moved to adjust the depth of the sensitive volume between 10.5 mm and 0.5 mm. The zero point of the chamber depth setting can be obtained by measuring the chamber capaciting charge C versus the chamber depth x and extrapolating C-1 towards x = 0. The chamber is equipped with two BNC sockets for signal and polarizing voltage. A connection cable from both BNC sockets to an electrometer with M type connector is available. An electrometer with the input circuits on ground potential is required. The extrapolation chamber comes in a protective storage case.
Materials and measures: Entrance window Measuring electrode Rear electrode Distance between electrodes
PET, graphite coated diameter 30 mm PMMA, graphite coated diameter 60.5 mm (0.5 ... 10.5) mm
Ion collection efficiency at nominal voltage: Ion collection time and dependent on electrode max. dose rate distance Useful ranges: Temperature Humidity Air pressure
(10 ... 40) C (50 ... 104) F (10 ... 80) %, max 20 g/m3 (700 ... 1060) hPa
T23392 Bhm extrapolation chamber T23392/U5 Connection cable for Bhm extrapolation chamber, connecting system M
Specification
Type of product Application Measuring quantity Nominal sensitive volume Design Reference point Nominal response Chamber voltage Leakage current Cable leakage extrapolation chamber according to Bhm absolute dosimetry of beta radiation and X-rays absorbed dose in soft tissue (0.353 ... 7.422) cm3 not waterproof, vented, fully guarded in chamber center of entrance foil underside dependent on electrode distance dependent on electrode distance 500 V maximal 1 pA 1 pC/(Gycm)
53
Notes
Notes
54
Quick View
Quick View
Product Family Quick View
Drawings and Diagrams International Standards Connector Design Overview of PTW Detectors
56 64 66 68
55
Drawings
Drawings
Farmer Chamber
30010
Farmer Chamber
30011
Farmer Chamber
30012
Farmer Chamber
30013
31010
31013
56
Drawings
30016
30015
Advanced Markus Chamber
34045
Markus Chamber
23343
Roos Chamber
34001
10.5 cm3 Bragg Peak Chamber
34070
57
Drawings
2.5 cm3 Bragg Peak Chamber
34073
PinPoint Chamber
31014
PinPoint Chamber
31015
PinPoint 3D Chamber
31016
microLion Chamber
31018
Diamond Detector
60003
58
Drawings
Dosimetry Diode P
60008
Dosimetry Diode E
60012
23342
23344
34013
SOURCECHECK
34051
59
Drawings
34060
Well-Type Chamber
33004
34069
3.14 cm3 CT Chamber
30009
30 cm3 Flat Chamber
233612
60
Drawings
0.1 Liter Radiation Monitoring Chamber
32001
34031
7262
Spherical Ionization Chamber TK-30
32005
1 Liter Spherical Ionization Chamber
32002
10 Liter Spherical Ionization Chamber
32003
61
Drawings
50 cm3 Spherical Ionization Chamber PS-50
32007S
10 cm3 Spherical Ionization Chamber PS-10
32008S
30 cm3 Cylinder Stem Ionization Chamber
23361
30 cm3 Cylinder Stem Ionization Chamber Directional response in air
23361
Hp(10) Secondary Standard Chamber
34035
Bhm Extrapolation Chamber
23392
62
Drawings
Monitor Ionization Chamber
34014
100 cm3 Reference Soft X-Ray Chamber
34047
Monitor Ionization Chamber
786
X-Ray Therapy Monitor Chamber
7862
63
International Standards
International Standards
The quality management system of PTW-Freiburg is certified according to the appropriate quality management standards. The medical and electric products are manufactured in strict accordance with valid international standards. The medical products are CE marked in accordance with the European Medical Device Directive MDD and have the 510(k) approval of the FDA, USA, (if applicable). They comply with the valid IEC standards within their defined range of use.
Quality Management
ISO 9001:2000 Quality management systems - Requirements ISO 13485:2003 Medical devices - Quality management systems Requirements for regulatory purposes ISO/IEC 17025:1999 General requirements for the competence of testing and calibration laboratories
AAPM TG-51, Report #67 Protocol for clinical reference dosimetry of high energy photon and electron beams AAPM TG-56, Report #59 Code of Practice for Brachytherapy Physics DIN 6800-2 Dosismessverfahren nach der Sondenmethode fr Photonen- und Elektronenstrahlung Teil 2: Ionisationsdosimetrie
Safety Requirements for Medical Devices

European Council Directive 93/42/EEC (Medical Device Directive MDD) of 14 June 1993 concerning medical devices European Council Directive 97/43/EURATOM of 30 June 1997 on health protection of individuals against the danger of ionizing radiation in relation to medical exposure IEC 60601-1 Medical electrical equipment - General requirements for safety IEC 6060-1-1 Medical electrical equipment - General requirements for safety - Collateral standard: Safety requirements for medical electrical systems IEC 60601-2-44 Medical electrical equipment - Particular requirements for the safety of X-ray equipment for computed tomography
Quality Assurance in Medical Radiology

AAPM TG-24, Report #13 Physical aspects of quality assurance in radiation therapy IEC 61223-2-6 Constancy tests X-ray equipment for computed tomography
Secondary Standard Calibration

IPEM Guidelines on dosimetry transfer instruments as a secondary standard dosemeter EAL-R2 Report No. 2, Edition 1, April 1997 Expression of the Uncertainty of Measurement in Calibration ICRU Report 60 Fundamental Quantities and Units for Ionizing Radiation
Dosimetry in Medical Radiology

IEC 60731 Medical electrical equipment - Dosemeters with ionization chambers as used in radiotherapy IEC 61674 Medical electrical equipment - Dosemeters with ionization chambers and/or semiconductor detectors as used in X-ray diagnostic imaging IAEA Report TRS-381 The Use of Plane Parallel Ionization Chambers in High Energy Electron and Photon Beams An International Code of Practice for Dosimetry IAEA Report TRS-398 Absorbed Dose Determination in External Beam Radiotherapy An International Code of Practice for Dosimetry based on Standards of Absorbed Dose to Water AAPM TG-25, Report #32 Clinical electron beam dosimetry
Abbreviations
AAPM American Association of Physicists in Medicine DIN Deutsches Institut fr Normung (German technical standards) EAL European Co-operation for Accreditation of Laboratories IAEA International Atomic Energy Agency ICRU International Commission on Radiation Units and Measurements IEC International Electrotechnical Commission IPEM Institute of Physics and Engineering in Medicine ISO International Organization for Standardization
64
Notes
Notes
65
Connectors
The Connector Design

The following overview of connecting systems facilitates the identification of the adequate connector to fit your measuring system. Outer shape, colors and the size of the housing may vary, depending on the production year and the manufacturer. Some connectors may have protective covers which veil the real shape of the connector. All connectors are displayed without such protective covers. The images are not full-scale. See table on page 67 for approximate outer connector diameters. Supply of detectors with BNC connectors with banana pin, BNC biax connectors and DIAMENTOR F type connectors upon request.
BNT Connector (N Type)
male
BNT Connector (n type)
female
TNC Connector (W type)
male
TNC Connector (w type)
female
Triax PTW Connector (M type)
male
Triax PTW Connector (m type)
female
BNC Connector with Banana Pin (B type)
male
BNC Connector with Banana Pin (b type)
female
BNC Connector
male
BNC Connector
female
66
Connectors
DIAMENTOR Connector (V type)
male
DIAMENTOR Connector (v type)
female
DIAMENTOR Connector (A type)
male
DIAMENTOR Connector (a type)
female
DIAMENTOR Connector (F type)
male
DIAMENTOR Connector (f type)
female
PTW can provide adaptation cables for all combinations of detectors shown above. In practice not all combinations make sense and are dangerous respectively. The reason for this is among other things, that the different connecting systems have diverse uses for the outer shielding of the cable. While some connecting systems use the cables outer shielding for the high voltage supply of the ionization chamber, other systems use it for the grounding of the chamber and connect it to the chamber housing. Unsuitable adaptation cables may result in improper grounding of the chamber and in the worst case in the risk of an electric shock. Touchable parts of the chamber may conduct high voltage. Adaptations between Triax PTW (M type) and BNC with Banana (B type) are problem-free. Likewise are adaptations between BNT (N type) and TNC (W type) systems in general unproblematic. The same applies to our different DIAMENTOR connecting systems. For all other combinations of connecting systems we strongly dissuade from using adaptation cables. Any use of such adaptation cables is definitely out of the intended use and left to the users responsibility. The following table shows the possible connector combinations used in radiation therapy. N, n N, n W, w M, m B, b W, w M, m B, b
Approximate outer connector diameters: Connector Type N, n W, w M, m B, b V, v A, a F, f Outer Diameter 15 mm, 14 mm 16 mm, 14 mm 25 mm, 24 mm 18 mm, 18 mm 15 mm, 16 mm 14 mm, 14 mm 18 mm, 19 mm
Suitable adaptation cable Unsuitable adaptation cable
67
Quick View
Guide to PTW Detectors

This guide gives a review of the complete range of PTW radiation detectors arranged in the order of their scope. Some of the detectors are suitable for various applications. Especially the ion chambers designed for absolute dosimetry in radiotherapy can also be used for therapy beam analysis. All ionization chambers are supplied with vented sensitive volumes, open to the surrounding, except the sealed 0.1 cm3 chamber models 23322 and 23323. The type numbers in brackets represent former chamber types with identical specification. Radiation detectors which are integrated components of radiation measuring systems such as LA48 Linear Array, DIAMENTOR or CURIEMENTOR, are not listet in this guide.
Radiation Therapy
30010 (30001) 30011 (30002) 30012 (30004) 30013 (30006) 31010 (31002) 31013 (31003) 30016 (23332) 30015 (23331) 34045 0.6 cm3 Farmer Chamber PMMA/Al 0.6 cm3 Farmer Chamber Graphite/Graphite 0.6 cm3 Farmer Chamber Graphite/Al 0.6 cm3 Farmer Chamber Waterproof 0.125 cm3 Semiflex Chamber 0.3 cm3 Semiflex Chamber 0.3 cm3 Rigid Stem Chamber 1 cm3 Rigid Stem Chamber 0.02 cm3 Advanced Markus Electron Chamber 0.055 cm3 Markus Electron Chamber Thimble chamber with acrylic wall and Al electrode for meas- page uring high-energy photon and electron radiation in air and 10 phantom material. BNT, TNC or M connector Thimble chamber with graphite wall and graphite electrode for measuring high-energy photon and electron radiation in air and phantom material. BNT or TNC connector Thimble chamber with graphite wall and Al electrode for measuring high-energy photon and electron radiation in air and phantom material. BNT or TNC connector Waterproof chamber with acrylic wall and Al electrode for measuring high-energy photon and electron radiation in air, water and phantom material. BNT, TNC or M connector page 11 page 12 page 13
Waterproof thimble chamber for measuring high-energy pho- page ton and electron radiation in air, water and phantom materi14 al. BNT, TNC or M connector Waterproof thimble chamber for measuring high-energy pho- page ton and electron radiation in air, water and phantom materi15 al. BNT, TNC or M connector Thimble chamber with 25 cm rigid stem for measuring highenergy photon and electron radiation in air and phantom material. BNT, TNC or M connector Thimble chamber with 25 cm rigid stem for measuring highenergy photon and electron radiation in air and phantom material. BNT, TNC or M connector page 16 page 17
Improved plane parallel chamber with thin membrane for page measuring high-energy electron radiation in water and phan18 tom material. BNT, TNC or M connector Classic plane parallel chamber with thin membrane for meas- page uring high-energy electron radiation in water and phantom 19 material. BNT, TNC or M connector page 20 page 21 page 21
23343
34001
Precision plane parallel chamber for absolute dosimetry of 0.35 cm3 Roos Electron Chamber high-energy electron radiation in water and phantom material. BNT, TNC or M connector 10.5 cm3 Bragg Peak Chamber 2.5 cm3 Bragg Peak Chamber Waterproof plane parallel chamber for measuring the exact location of the Bragg peak in proton beams. BNT, TNC or M connector Waterproof plane parallel chamber for measuring the exact loacation of the Bragg peak in horizontal proton beams. BNT, TNC or M connector
34070
34073
68
Quick View
31014
0.015 cm3 PinPoint Chamber 0.03 cm3 PinPoint Chamber 0.016 cm3 PinPoint 3D Chamber microLion Chamber
Ultra small-sized waterproof therapy chamber for dosmimetry page in high-energy photon beams. BNT, TNC or M connector 22 Small-sized waterproof therapy chamber for dosmimetry in high-energy photon beams. BNT, TNC or M connector page 22
31015
31016
Ultra small-sized waterproof therapy chamber with 3D page characteristics for dosmimetry in high-energy photon beams. 23 BNT, TNC or M connector Liquid filled ion chamber with very small sensitive volume for dose distribution measurements with high spatial resolution. BNT, TNC or M connector page 24
31018
60003
Diamond Detector
Waterproof small volume diamond detector for dose distribu- page tion measurements in high-energy photon and electron 25 beams. M connector Waterproof p-type Si diode detector for dose distribution measurements in high-energy photon beams. BNT, TNC or M connector Waterproof p-type Si diode detector for dose distribution measurements in high-energy electron and photon beams. BNT, TNC or M connector Plane parallel chamber with thin membrane for measuring therapeutic X-ray beams between 10 and 100 kV in air and phantom material. BNT, TNC or M connector Plane parallel chamber with thin membrane for measuring therapeutic X-ray beams between 10 and 100 kV in air and phantom material. BNT, TNC or M connector page 26 page 27 page 28 page 29
60016
Dosimetry Diode for Photons Dosimetry Diode for Electrons and Photons 0.02 cm3 Soft X-ray Chamber 0.2 cm3 Soft X-ray Chamber 0.005 cm3 Soft X-ray Chamber SourceCheck Source Strength Test Chamber Well-type HDR Chamber
60017
23342
23344
34013
Plane parallel chamber with thin membrane for measuring page small size therapeutic X-ray beams between 15 and 50 kV in 30 air and phantom material. BNT, TNC or M connector Flat chamber for source strength measurement of radioactive page interstitial therapy seeds and intravascular brachytherapy 31 sources. BNT, TNC or M connector Well-type chamber for source strength measurement of after- page loading sources. BNT, TNC or M connector 32
34051
33004
Diagnostic Radiology
34060 75 cm3 SFD Diagnostic Chamber Shadow-free plane parallel chamber for absolute dosimetry in diagnostic radiology. BNT, TNC or M connector page 36 page 37
34069
6 cm3 Shadow-free plane parallel chamber for absolute dosimetry SFD Mammo Chamber in diagnostic radiology and mammography. BNT, TNC or M connector 3.14 cm3 CT Chamber 30 cm3 Flat Chamber
30009
Vented cylindrical chamber for dose length product measure- page ments in computed tomography. BNT, TNC or M connector 38 Flat circular transmission chamber for dose measurements of page diagnostic X-rays in the energy range above 35 keV. 39 BNT, TNC or M connector
233612
69
Quick View
Health Physics
T32001 100 cm3 Cylindrical Chamber 3 Liter Cylindrical Chamber 50 Liter Cylindrical Chamber 1 Liter Spherical Chamber 10 Liter Spherical Chamber 50 cm3 Spherical Chamber PS-50 10 cm3 Spherical Chamber PS-10 30 cm3 Spherical Chamber 30 cm3 Cylindrical Chamber Hp(10) Secondary Standard Chamber 100 cm3 Reference Soft X-ray Chamber Cylindrical aluminum chamber for stationary high level gamma radiation measurement above 80 keV. Special connectors for signal and HV Cylindrical poly ethylene chamber for stationary low level gamma radiation measurement above 80 keV. Special connectors for signal and HV Cylindrical pressurized steel chamber for stationary lowest level gamma radiation measurement above 80 keV. Special connectors for signal and HV Spherical chamber, 140 mm diameter, for low level gamma radiation protection measurements in the energy range of 45 keV to 50 MeV. BNT, TNC or M connector page 42 page 43 page 44 page 45
T34031 T32004 T7262
32002
32003
Spherical chamber, 270 mm diameter, for lowest level gamma page radiation protection measurements in the energy range of 45 45 keV to 50 MeV. BNT, TNC or M connector Spherical chamber, 53 mm diameter, for primary standard radiation protection measurements in 60Co and 137Cs beams. BNT connector Spherical chamber, 34 mm diameter, for primary standard radiation protection measurements in 60Co and 137Cs beams. BNT connector Spherical chamber, 22 mm diameter, for gamma radiation protection measurements in the energy range of 25 keV to 1.3 MeV. BNT, TNC or M connector Cylindrical reference chamber, 31 mm diameter, for gamma radiation protection measurements in the energy range of 30 keV to 50 MeV. BNT, TNC or M connector page 46 page 46 page 47 page 48
32007S
32008S
32005
23361
34035 L981937 L981938 34047
Plane parallel reference chamber embedded in an acrylic slab page phantom for direct measurement of Personal Dose Equivalent 49 Hp(10). M or BNC/banana connector Circular plane parallel reference chamber for radiation protection measurements of 5 keV to 20 keV low energy X-rays. BNT, TNC or M connector page 50 page 51
TN34014 TW34014 TM786 TM7862
Transmission Circular transmission chambers of 155 mm resp. 148 mm Monitor Chambers for sensitive diameter for radiation monitoring of calibration Calibration Benches benches. BNT, TNC, M or BNC/banana connector Transmission Monitor Chamber for X-ray Therapy Units Bhm Extrapolation Chamber
Circular transmission chamber of 96.5 mm sensitive diameter page for radiation monitoring of X-ray therapy units. 52 M or BNC/banana connector Precision extrapolation chamber with adjustable depth of the page sensitive volume between 0.5 mm and 10.5 mm for dose 53 measurements of Beta and soft X-rays. BNC sockets
T23392
70
Codes of Practice
Codes of Practice
Absorbed Dose Determination in Photon and High Energy Electron Beams Based on Standards of Absorbed Dose to Water
1 Introduction 2 General Instructions
2.1 2.2 2.3 2.4 2.5 2.6 2.7 Corrected reading M Measuring phantoms Chamber positioning Air density Ion recombination Polarity effect Humidity 73 73 73 75 75 77 77 72
3 Kilovoltage X-Ray Beams

3.1 10 kV to 100 kV 3.2 100 kV to 300 kV 78 78
4 High Energy Photon Beams

4.1 IAEA TRS 398 4.2 AAPM TG-51 4.3 DIN 6800-2 80 82 83
5 High Energy Electron Beams

5.1 IAEA TRS 398 5.2 AAPM TG-51 5.3 DIN 6800-2 85 87 88
6 Measurements in Acrylic Phantoms

6.1 General 6.2 High energy photons 6.3 High energy electrons 91 91 91
7 References Appendix A: Summary of PTW Chamber Data
92 93
Disclaimer
Although the information in this document has been carefully assembled, PTW-Freiburg does not guarantee that this document is free of errors. PTW-Freiburg shall not be liable in any way for any consequence of using this document.
71
Absorbed Dose Determination in Photon and High Energy Electron Beams

Introduction
1 Introduction
This document constitutes an excerpt of procedures and data from various dosimetry protocols for the determination of absorbed dose to water using ionization chambers. As most modern dosimetry protocols (e.g. IAEA, AAPM, DIN) refer to ionization chambers calibrated in absorbed dose to water, this document does not describe dose determination with ionization chambers having other calibration factors.1 The chapters referring to high energy radiation describe the formalisms outlined in IAEA TRS 398, AAPM TG-51 and DIN 6800-2 as these dosimetry protocols are widely used, see references [IAEA 398], [AAPM 51] and [DIN 6800-2]. The chapter referring to kilovoltage X-ray beams describes only the formalism outlined in the DIN standards as IAEA TRS 398 differs only slightly from DIN, and AAPM TG-51 does not address this energy range. Although this document provides the reader with a concise overview of formulae and factors it shall not replace pertinent protocols and publications, nor is it intended to give all of the details that are important for accurate dosimetry. Also, the procedures outlined in this document are not the only ones described in the referenced literature, they constitute only one of several possibilities for absorbed dose determination. The present document is limited to the use of open (vented) ionization chambers the use of plane-parallel chambers in case of low energy X-ray beams the use of cylindrical chambers in case of medium energy X-ray beams PTW chambers if factors are given that depend on the design of the ionization chamber. NOTE The terms 'Markus Chamber', 'Advanced Markus Chamber' and 'Roos Chamber' are the propriety of PTW-Freiburg. The published data specific to these chambers are not valid for chambers manufactured by other companies, even if they are sold as 'Markus' or 'Roos' type chambers.
A summary of PTW chamber data is given in Appendix A.
Document D560.210.0 refers to chambers calibrated in Air Kerma, Absorbed Dose to Air, and Exposure.
72
72

General Instructions
2 General Instructions
2.1 Corrected reading M
All formulae in this document used for the determination of absorbed dose to water Dw refer to a dosemeter reading M which is corrected for the influence quantities given in chapters 2.4 - 2.7. The reader must compute the corrected reading M from the uncorrected reading M uncorr and the reading without irradiation M 0 by
M = (M uncorr M 0 ) k elec k TP k S k pol k h
2.3 Chamber positioning

2.3.1 General rules The dosemeter reading is obtained by positioning the ionization chamber at the point of interest in the phantom. Depending on the dosimetry protocol and radiation quality, either the effective point of measurement or the reference point of the ionization chamber is positioned at the point of interest. This document states the correct positioning method in each of the related chapters. The effective point of measurement is defined as a point on the axis of a cylindrical chamber in case of photon beams with energy < 1.33 MeV a point shifted by 0.5 r from the axis of a cylindrical chamber towards the focus2 in case of high energy photon and electron beams ( r is the inner radius of the measuring chamber volume) [IAEA 398, DIN 6800-2] a point at the center of the inner side of the entrance window of a plane-parallel chamber, independent of radiation quality. Care must be taken to scale the thickness of the entrance window to water-equivalent thickness. The reference point is defined as a point on the central axis of a cylindrical chamber as stated by the manufacturer a point at the center of the inner side of the entrance window of a plane-parallel chamber.
(2-1)
The correction factor k elec corresponds to the calibration factor of the electrometer if the electrometer readout is in terms of charge or current [IAEA 398, AAPM 51]. If the electrometer and the ionization chamber are calibrated together and the readout is in terms of Gy or Gy/s, a value of unity is to be used for k elec . The correction factors k TP , k S , k pol and k h are described in chapters 2.4 - 2.7. For absorbed dose determination, additional factors are to be applied to the corrected reading M as described in chapters 3 - 6.
2.2 Measuring phantoms

This document assumes that all measurements are made in a water phantom, except for chapter 3.1 where the measurements are made at the surface of an acrylic (PMMA) phantom. If measurements are nevertheless made in other than water phantoms, the measures described in chapter 6 are to be taken. It should be noted, however, that most dosimetry protocols prescribe measurements in water only.
To measure dose at a focus distance of x cm, the axis of the cylindrical chamber must be positioned at a focus distance of x cm + 0.5 r , i. e. the chamber must be shifted away from the focus, i.e. downstream.
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73

2.3.2 Plane-parallel chambers Plane-parallel chambers usually have entrance windows which are not exactly water-equivalent. For the correct positioning of a plane-parallel chamber in water, the geometrical thickness d p of the entrance window must be scaled to equivalent water thickness d w . The effective point of measurement is then located behind the water-equivalent thickness d w of the entrance window. The scaling of the geometrical thickness (e.g. plastic thickness) d p to water equivalent thickness d w is done by [IAEA 398]
dw = d p p w
according to (2-2) the water-equivalent thickness of the entrance window is d w = 1.06 mm , i.e. the effective point of measurement is located behind a 'water layer' of 1.06 mm from the chamber surface the measuring depth in water shall be z = 10 mm . As the entrance window contributes 1.06 mm , the chamber surface has to be positioned at a water depth of 10 mm 1.06 mm = 8.94 mm . 2.3.3 The TRUFIX system The task of positioning various types of ionization chambers precisely in their effective point of measurement can be quite challenging. The patented TRUFIX system (see Figure 1) facilitates this task considerably. TRUFIX can be used on automated PTW water phantoms (MP2, MP3 etc.) in connection with most PTW therapy detectors. A plastic tip lets you easily locate the water surface where the coordinate system is set to (0,0,0). Then the plastic tip is replaced by a holding device specific to each detector type, and the effective point of measurement is automatically placed at the tip's earlier position. The radius of cylindrical chambers, the waterequivalent window thickness of plane-parallel chamber windows and the chamber centers are automatically accounted for.
(2-1)
where p and w are the densities of the entrance window and water, respectively3. Using the area density p and w = 1 g / cm 3 , equation (2-1) can be written as
dw = p w = p 1 g/cm 3
(2-2)
The area density p of PTW plane-parallel chambers is given in Appendix A. For instance, the water-equivalent thickness of the entrance window of a Roos chamber type 34001 ( p = 132 mg / cm 2 ) is
d w = 1.32 mm . The entrance window of the Ad-
vanced Markus chamber (including protection cap, ( p = 106 mg / cm 2 ) has a water-equivalent thickness of d w = 1.06 mm . Example How to position the effective point of measurement of an Advanced Markus chamber with protection cap at a measuring depth of z = 10 mm in water: according to Appendix A, the area density of the entrance window, including the protection cap and air gap, is p = 106 mg / cm 2 Figure 1: The TRUFIX chamber positioning system.
DIN 6800-2 suggests to use the electron volume densities of the materials rather than the physical densities. The difference is neglected in this document.
74
74

2.4 Air density

2.4.1 The T&P method Open (vented) ionization chambers must be corrected for air density according to [IAEA 398]
k TP = P0 (273.2 + T ) P (273.2 + T0 )
kp and km must not be mixed up with correction
factors described in other chapters of this document.
2.5 Ion recombination

2.5.1 The two-voltage method Correction factors for insufficient charge collection in the measuring volume of the ionization chamber can be measured using the two-voltage method [IAEA 398, AAPM 51]. They depend on the geometry of the ionization chamber and on the dose rate or dose per pulse, respectively. For pulsed or pulsed-scanned radiation the correction factor k S can be determined from [IAEA 398]
kS = M1 / M 2 1 +1 V1 / V2 1
(2-3)
T and P are the temperature and pressure in the measuring environment, the reference values are P0 = 101.3 kPa and T0 = 20 o C . Note that in some countries the reference temperature given in the calibration certificate is 22 o C instead of 20 o C . AAPM TG-51 uses a value of 22 o C as reference and a value of P0 = 101.33 kPa for the reference pressure.
Care must be taken to ensure the use of correct values for the barometric pressure P existing in the measuring environment. Details can be found in the literature [Christ 2004]. 2.4.2 The check source method Instead of using (2-3) measurements in a radioactive check source can be made. The temperature of the check source and the ionization chamber must be the same as the temperature of the phantom in which the dose measurements are performed. The reference value kprotocol of the check source reading is given in the calibration certificate for a given date and for reference conditions (e.g. 101.3 kPa , 20 o C ). The reader must correct the reference value kprotocol for the decay of the radioactive material. Then an actual check source reading k measured is taken and the correction factor for air density is determined from
k TP = kprotocol kmeasured
(2-5)
where M1 and M 2 are the readings at two voltages V1 and V2 . V1 is the normally used voltage, and V2 is a voltage reduced by a factor of at least 3. Formula (2-5) is valid for k S < 1.03 . If k S 1.03 refer to chapter 2.5.2. For continuous radiation k S is taken from [IAEA 398]
kS =
(V1 / V2 )2 1 (V1 / V2 )2 (M1 / M 2 )
(2-6)
Formula (2-5) assumes a linear relationship between 1/ M and 1/ V , formula (2-6) a linear relationship between 1/ M and 1/ V 2 . New chambers should be tested in accordance with the following chapter. 2.5.2 Jaff diagrams A Jaff diagram represents the inverse reading 1/ M of an ionization chamber as a function of the inverse voltage 1/ V ( 1/ V 2 in case of continuous radiation). The reading M is corrected for polarity effect, i.e. M is the mean value of M + and M , see chapter 2.6. Figure 2 shows a Jaff diagram for pulsed radiation with the axes normalized to the usual voltage V1 and the corresponding reading M1 . 75
(2-4)
NOTE The results of (2-3) and (2-4) normally coincide better than 0.5 % . If not, the reason must be found. NOTE In the calibration certificates of PTW-Freiburg the reference reading kprotocol is described as kp , the
check reading
kmeasured
is described as
km .
75

1,030 1,025 1,020 1,015
The two-voltage method (see chapter 2.5.1) can be applied only if both voltages V1 and V2 are within the linear range of the Jaff diagram. If this is not the case, the ionization chamber should be operated at the highest voltage of the linear range of the Jaff diagram, and the correction factor k S should be determined by extrapolating the linear part of the Jaff diagram to an infinite voltage ( 1/ V = 0 ). It should be noted that operating an ionization chamber at a voltage other than stated in the calibration certificate may cause an error as the calibration factor sometimes depends on the applied voltage. 2.5.3 The DPP method
M 1/M
1,010 1,005 1,000 0,995 0,990 0,985 0,0 0,5 1,0 1,5 2,0 2,5 3,0 3,5 4,0 4,5
V 1/V
Figure 2:Jaff diagram of a typical Farmer chamber usually operated at V1 = 400 V . The regression line to the linear part intersects the M1 /M axis at 0.992 resulting in a correction factor kS = 1/0.992 = 1.008 . The dose per pulse was 0.974 mGy .
If the dose per pulse (DPP) of the accelerator at the point of measurement is known, the correction factor can be calculated by [DIN 6800-2]
kS = 1 + + DP U U
The useful range for the chamber voltage should be limited to the linear part of the Jaff diagram. This document suggests to measure Jaff diagrams at the lowest and at the highest dose per pulse or dose rate for each radiation quality, and to determine the linear range for the used ionization chamber from these diagrams.
(2-7)
DP is the absorbed dose to water per accelerator pulse, expressed in mGy , U is the chamber voltage in V , and the coefficients and are listed
in Table 1 [Bruggmoser 2007]. Formula (2-7) is only valid if the frequency of the accelerator pulses is smaller than the reciprocal of the ion collection time.
Chamber type
V 0.01 0.13 0.38 0.00 0.06 0.43 0.32
V / mGy
Dose per pulse Chamber voltage mGy V
PTW 30006/30013 Farmer PTW 23332/30016 0.3 cm Rigid PTW 31002/31010 0.125 cm Flexible PTW 23331/30015 1 cm Rigid PTW 34001 Roos PTW 34045 Advanced Markus PTW 23343 Markus
3.44 1.05 2.40 5.68 1.69 0.49 1.99
0.15 0.35 > 0.35 42 0.15 0.5 > 0.5 5.5 0.15 0.6 > 0.6 5.5 0.25 1.5 0.15 0.5 > 0.5 42 0.25 1.0 > 1.0 5.5 0.15 0.55 > 0.55 3.0
100 300 300 400 100 250 250 400 100 300 300 400 100 400 50 200 200 300 50 200 200 300 100 250 250 300
Table 1: Coefficients and for formula (2-7), applicable within the stated dose per pulse and voltage ranges, according to [Bruggmoser 2007, Bruggmoser 2008]. 76
76

2.6 Polarity effect

The polarity effect depends on the radiation beam quality Q . The correction factor can be determined by [IAEA 398, DIN 6800-2]
kpol=
[(M + +M ) / M + ]Q [(M ++M ) / M + ]Co
(2-8)
M + = positive reading obtained with the usual polarity M = positive reading obtained with the opposite polarity
The index Co refers to the readings obtained in a Co beam during calibration. This value is normally 60 not given in the calibration certificate. If Co is available the user should measure this value, if not, this value should be requested from the calibration laboratory [IAEA 398, AAPM 51] or should be measured with the lowest available photon energy [DIN 6800-2]. If the effect of this value is smaller than 0.3 % for 6 MV photon beams (or lower energy), the denominator in formula 2-8 can be set to 1, otherwise it must be taken into account [AAPM 51].
60
2.7 Humidity
A correction factor for humidity has to be applied 60 only if the Co calibration factor refers to dry air [IAEA 398]:
kh = 0.997
60
(2-9)
Usually the Co calibration factor refers to a relative humidity of 50 % ; in this case kh is taken as 1.000.
77
77

Kilovoltage X-Ray Beams
3 Kilovoltage X-Ray Beams

3.1 10 kV to 100 kV
Dw = k Q N w M Dw kQ
(3-1)
to use build-up foils, he should determine a correction factor for each beam geometry and radiation quality used.
= =
absorbed dose to water [DIN 6809-4] energy dependent correction factor, given in the calibration certificate for several radiation qualities. PTW offers calibrations at 15, 30, 50, and 70 kV calibration factor for absorbed dose to water for the reference radiation quality stated in the calibration certificate corrected reading of the dosemeter, see chapter 2.1. Measurements are to be made at the surface of an acrylic (PMMA) phantom. For measurements at other depths, water-equivalent material is to be added
Reference Condition
3.2 100 kV to 300 kV

Dw = kF k Q N w M Dw kF
(3-2)
Nw
= =
absorbed dose to water [DIN 6809-5] correction factor for field sizes other than 10 cm x 10 cm (or circular fields of 10 cm in diameter), see Table 3 energy dependent correction factor, given in the calibration certificate for several radiation qualities. PTW offers calibrations at 100, 140, 200, 280 kV, and 60 Co. If no calibration data specific to the chamber is available, use the values given in Table 2. This will increase the uncertainty of the measured value calibration factor for absorbed dose to 60 water for Co corrected reading of the dosemeter, see chapter 2.1
Reference Condition
kQ
Influence Quantity
Phantom material Chamber Depth Chamber positioning SSD Field size
PMMA plane-parallel, Type PTW 23342, 23344, or 34013 phantom surface outer surface of entrance window as stated in calibration certificate as stated in calibration certificate, or 3 cm x 3 cm at the measuring plane
Nw M
= =
Influence Quantity
water cylindrical 5 cm chamber axis 100 cm as stated in calibration certificate, or 10 cm x 10 cm at the phantom surface
NOTE DIN 6809-4 suggests the use of a 0.1 mm waterequivalent plastic foil in front of the ionization chamber when measuring above 50 kV. This foil should provide adequate build-up and eliminate low energy electrons scattered upstream. IAEA TRS 398 suggests total material thicknesses (build-up foils plus entrance window) depending upon radiation quality (IAEA Table 24. Foil thicknesses should read m). Ideally, the chamber and the build-up foils should be calibrated together, but this calibration is not available from PTW. If the user decides 78
78

Kilovoltage X-Ray Beams
Radiation Quality (Gen. Voltage, HVL) T100 T120 T140 T150 T200 T250 T280 (0.17 mm Cu) (0.28 mm Cu) (0.50 mm Cu) (0.85 mm Cu) (1.65 mm Cu) (2.5 mm Cu) (3.4 mm Cu)
60
PTW 23331, 30015 1.0 cm Rigid 1.025 1.017 1.008 1.000 0.998 0.998 0.996 1.000
PTW 23332, 30016 0.3 cm Rigid 1.045 1.002 0.996 1.000
PTW 31013, 31003 0.3 cm Flexible 1.025 0.999 0.994 1.000
PTW 31010, 31002 0.125 cm Flexible 1.025 0.999 0.994 1.000
Co
Table 2: k Q for the reference depth of 5 cm and the reference field size of 10 cm x 10 cm [DIN 6809-5]. The values for PTW 31002/31010 have been added by PTW-Freiburg. The values for the new chamber types PTW 30015 and PTW 30016 should be similar to those given in the DIN table for PTW 23331 and PTW 23332, respectively.
Radiation Quality
PTW 23331, 30015 1.0 cm Rigid 5 cm x 5 cm 15 cm x 15 cm 1.02 1.03 1.04 1.03 1.00 1.00 0.99 0.99
PTW 23332, 30016 0.3 cm Rigid 5 cm x 5 cm 15 cm x 15 cm 1.00 1.02 1.03 1.02 1.00 1.00 1.00 0.99
T100 T140 T200 T280
Table 3: Field size dependent correction factor kF at the reference depth of 5 cm [DIN 6809-5]. The values for the new chamber types PTW 30015 and PTW 30016 should be similar to those given in the DIN table for PTW 23331 and PTW 23332, respectively.
79
79

High Energy Photon Beams
4 High Energy Photon Beams

4.1 IAEA TRS 398
Dw = k Q N w M Dw kQ Nw M
(4-1)
NOTE In case TPR 20,10 values are not available, they can be determined from [IAEA 398]
TPR20,10 = 1.2661 PDD20,10 0.0595
= = = =
absorbed dose to water energy dependent correction factor, see Table 4 calibration factor for absorbed dose to 60 water for Co corrected reading of the dosemeter, see chapter 2.1
Reference Condition
where PDD20,10 is the ratio of the percent depth doses at 20 cm and 10 cm depth, respectively. The PDD values must be measured at SSD = 100 cm with a field size of 10 cm x 10 cm at the phantom surface.
For beam quality specification measurements with a cylindrical chamber, the chamber axis should be positioned at the measuring depth. It is allowed to use a plane-parallel chamber to determine beam quality.
Influence Quantity
Phantom material Chamber Depth
water cylindrical 10 cm (or 5 cm) for

TPR 20,10 < 0.7
10 cm for
Chamber positioning SSD / SDD Field size 100 cm
TPR20,10 0.7
chamber axis 10 cm x 10 cm SSD setup: field size defined at surface SDD setup: field size defined in detector plane
The tissue phantom ratio TPR 20,10 is measured for each nominal accelerating voltage. TPR20,10 is defined as the ratio M 20 / M10 of two ionization readings of a dosemeter at different depths. M 20 is obtained at 20 cm depth of water, M10 at 10 cm depth of water at a fixed source-detector-distance SDD = 100 cm and a field size of 10 cm x 10 cm at the depth of measurement.
80
80

Photon Beam Quality

TPR20,10
PTW 23331
PTW 23332
1.0 cm Rigid
0.3 cm Rigid
PTW 23333/ 30001/ 30010 Farmer
PTW 30002/ 30011 Farmer
PTW 30004/ 30012 Farmer
PTW 30006/ 30013 Farmer
PTW 31002/ 31010 0.125 cm Flexible
PTW 31003/ 31013 0.3 cm Flexible
0.50 0.53 0.56 0.59 0.62 0.65 0.68 0.70 0.72 0.74 0.76 0.78 0.80 0.82 0.84
1.004 1.003 1.000 0.999 0.997 0.993 0.990 0.988 0.985 0.982 0.978 0.971 0.964 0.956 0.945
1.004 1.003 1.001 0.999 0.997 0.994 0.990 0.988 0.984 0.980 0.976 0.968 0.961 0.954 0.943
1.004 1.003 1.001 0.999 0.997 0.994 0.990 0.988 0.985 0.981 0.976 0.969 0.962 0.955 0.943
1.006 1.004 1.001 0.999 0.997 0.994 0.992 0.990 0.987 0.984 0.980 0.973 0.967 0.959 0.948
1.006 1.005 1.002 1.000 0.999 0.996 0.994 0.992 0.989 0.986 0.982 0.976 0.969 0.962 0.950
60
1.002 1.002 1.000 0.999 0.997 0.994 0.990 0.988 0.984 0.980 0.975 0.968 0.960 0.952 0.940
1.003 1.002 1.000 0.999 0.997 0.994 0.990 0.988 0.984 0.980 0.975 0.968 0.960 0.952 0.940
1.003 1.002 1.000 0.999 0.997 0.994 0.990 0.988 0.984 0.980 0.975 0.968 0.960 0.952 0.940
Table 4: Typical k Q values for PTW cylindrical chambers [IAEA 398]. For Co beams k Q is 1.000. The new chamber types 31010 and 31013 have been added by PTW-Freiburg.
81
81

4.2 AAPM TG-51

(4-2)
= = = =
Reference Condition
At energies about 10 MV and above, a 1 mm lead foil (thickness 20 %) should be used when measuring the depth dose curve for the determination of %dd ( 10 )x . The lead foil should be placed (50 5) cm or if this is impossible, (30 1) cm above the phantom surface. The beam quality specifier is obtained from the corresponding value %dd (10)Pb by one of the following formulae lead foil at (50 5) cm and %dd (10)Pb 73 %
%dd (10) x = (0.8905 + 0.0015 %dd (10)Pb ) %dd (10)Pb
Influence Quantity
(4-3) lead foil at (30 1) cm and %dd (10)Pb 71 %

%dd (10) x = (0.8116 + 0.00264 %dd (10)Pb ) %dd (10)Pb
Phantom material Chamber Depth Chamber positioning SSD/SDD Field size
water cylindrical, no nylon-wall chambers 10 cm chamber axis 100 cm 10 cm x 10 cm SSD setup: field size defined at surface SDD setup: field size defined in detector plane
(4-4) If %dd (10)Pb is below the above thresholds, %dd (10 ) x equals %dd (10)Pb .
NOTE The lead foil is used for beam quality specification only. Remove lead foil for dose measurements.
The beam quality specifier %dd ( 10 )x is the percentage depth dose at 10 cm depth in a water phantom due to photons only. %dd ( 10 )x is defined at SSD = 100 cm for a field size of 10 cm x 10 cm at the phantom surface.
For beam quality specification measurements with a cylindrical chamber, the chamber axis must be shifted downstream by 0.6 r , where r is the inner radius of the measuring volume. It is allowed to use a plane-parallel chamber to determine beam quality.
Photon Beam Quality %dd ( 10 )x
PTW 23333/ 30001/30010 Farmer
PTW 30002/30011 Farmer
PTW 30004/30012 Farmer
PTW 30006/ 30013 Farmer
PTW 31002/ 31010 0.125 cm Flexible
PTW 31003/ 31013 0.3 cm Flexible
58.0 63.0 66.0 71.0 81.0 93.0
1.000 0.996 0.992 0.984 0.967 0.945
1.000 0.997 0.994 0.987 0.970 0.948
1.000 0.998 0.995 0.988 0.973 0.952
1.000 0.996 0.992 0.984 0.967 0.945

60
1.000 0.996 0.992 0.984 0.967 0.946
1.000 0.996 0.992 0.984 0.967 0.946
Table 5: Typical k Q values for PTW cylindrical chambers [AAPM 51]. For Co beams k Q is 1.000. The chamber types which are not listed in the TG-51 table have been added by PTW-Freiburg after investigating the differences between the corresponding k Q values in IAEA TRS 398. The values for Farmer chambers PTW 30006/30013 where taken from type 30001. They should not deviate by more than 0.3 % (compare [IAEA 398]). 82
82

4.3 DIN 6800-2

Dw = kr k Q N w M Dw kr
(4-5)
NOTE In case M10 and M 20 values are not available, Q can be determined from [DIN 6800-2]
Q = 1.2661 m 0.0595
= =
absorbed dose to water 1 + 0.03 r replacement correction factor ( r is the inner radius of the measuring volume of a cylindrical chamber, given in cm). kr is not applicable for planeparallel chambers). See Table 7 energy dependent correction factor, see Table 6 calibration factor for absorbed dose to 60 water for Co corrected reading of the dosemeter, see chapter 2.1
Reference Condition
kQ Nw M
= = =
where m is the ratio of the percent depth doses at 20 cm and 10 cm depth, respectively. The percent depth doses must be measured at SSD = 100 cm with a field size of 10 cm x 10 cm at the phantom surface.
For beam quality specification measurements with a cylindrical chamber, the chamber axis must be shifted downstream by 0.5 r , where r is the inner radius of the measuring volume. It is allowed to use a plane-parallel chamber to determine beam quality.
Influence Quantity
water cylindrical 5 cm for Co 10 cm for photons effective point of measurement, see chapter 2.3 95 cm for Co 100 cm for photons 10 cm x 10 cm at 5 cm 60 depth for Co 10 cm x 10 cm at phantom surface for photons
60 60
The beam quality index Q is to be measured for each nominal accelerating voltage. Q is defined as the ratio M 20 / M10 of two ionization readings of a dosemeter at different depths. M 20 is obtained at 20 cm depth of water, M10 at 10 cm depth of water at a fixed source-detector-distance SDD = 100 cm and a field size of 10 cm x 10 cm at the depth of measurement.
83
83

Beam Quality Index Q Chamber Type

PTW 23331 Rigid PTW 23332 Rigid PTW 23333 PTW 30001/30010 PTW 30002/30011 PTW 30004/30012 PTW 30006/30013 PTW 31002/31010 Flex PTW 31003/31013 Flex PTW 31014 PinPoint
0.50
0.53
0.56
0.59
0.62
0.65
0.68
0.70
0.72
0.74
0.76
0.78
0.80
0.82
0.84
1.0090 1.0053 1.0008 0.9987 0.9957 0.9907 0.9867 0.9841 0.9806 0.9771 0.9727 0.9652 0.9576 0.9487 0.9363 1.0071 1.0044 1.0015 0.9988 0.9962 0.9926 0.9880 0.9856 0.9812 0.9770 0.9727 0.9644 0.9570 0.9495 0.9376 1.0078 1.0048 1.0016 0.9988 0.9960 0.9922 0.9875 0.9850 0.9816 0.9772 0.9719 0.9645 0.9581 0.9494 0.9363 1.0078 1.0048 1.0016 0.9988 0.9960 0.9922 0.9875 0.9850 0.9816 0.9772 0.9719 0.9645 0.9571 0.9494 0.9363 1.0099 1.0058 1.0016 0.9988 0.9960 0.9922 0.9895 0.9870 0.9836 0.9802 0.9759 0.9685 0.9620 0.9533 0.9412 1.0099 1.0068 1.0026 0.9998 0.9980 0.9942 0.9915 0.9890 0.9856 0.9822 0.9779 0.9715 0.9640 0.9563 0.9432 1.0058 1.0038 1.0006 0.9988 0.9960 0.9922 0.9875 0.9850 0.9806 0.9762 0.9709 0.9635 0.9551 0.9464 0.9333 1.0065 1.0036 1.0006 0.9988 0.9961 0.9924 0.9877 0.9853 0.9809 0.9766 0.9713 0.9640 0.9556 0.9469 0.9339 1.0065 1.0036 1.0006 0.9988 0.9961 0.9924 0.9877 0.9853 0.9809 0.9766 0.9713 0.9640 0.9556 0.9469 0.9339 1.0052 1.0036 1.0012 0.9989 0.9977 0.9944 0.9912 0.9880 0.9839 0.9788 0.9737 0.9656 0.9574 0.9502 0.9388
PTW 31016 PinPoint 3D 1.0052 1.0036 1.0012 0.9989 0.9977 0.9944 0.9912 0.9880 0.9839 0.9788 0.9737 0.9656 0.9574 0.9502 0.9388
Table 6: k Q values for PTW cylindrical chambers [DIN 6800-2]. For Co beams k Q equals 1.000. The data for the 31016 PinPoint 3D have been added by PTW-Freiburg.
60
Chamber Type
Radius r [cm]
Correction Factor kr
PTW 0.6 cm Farmer PTW 0.125 cm Flexible PTW 0.3 cm Flexible PTW 23331 1.0 cm Rigid PTW 23333 1.0 cm Rigid PTW 31014 0.015 cm PinPoint PTW 31016 0.016 cm PinPoint 3D
0.305 0.275 0.275 0.395 0.250 0.100 0.145
1.009 1.008 1.008 1.012 1.008 1.003 1.004
Table 7: Radius of the measuring volume of PTW cylindrical chambers and values for the correction factor kr . For details see Appendix A.
84
84

High Energy Electron Beams
5 High Energy Electron Beams

5.1 IAEA TRS 398
5.1.1 Chambers calibrated at Co
60
10 cm x 10 cm 20 cm x 20 cm (5-1)
for R50 7 g / cm 2 for R50 > 7 g / cm 2
= = = =
From the depth ionization distribution measured with an air-filled ionization chamber, the quantity R50,ion is obtained. This quantity can be converted to R50 by
R50 = 1.029 R50,ion 0.06 g / cm2
(5-2)
( R50,ion 10 g / cm 2 )
R50 = 1.059 R50,ion 0.37 g / cm2
(5-3)
( R50,ion > 10 g / cm ) For beam quality specification measurements with a cylindrical chamber, the chamber axis must be shifted downstream by 0.5 r , where r is the inner radius of the measuring volume. For R50 < 4 g / cm 2 a plane-parallel chamber must be used.
Influence Quantity
Reference Condition
Phantom material
water (for beams with R50 < 4 g / cm 2 (approx. E 0 10 MeV ) a plastic phantom may be used) plane-parallel (for beams with R50 4 g / cm 2 (approx. E 0 10 MeV ) a cylindrical chamber may be used)
zref = 0.6 R50 0.1 g / cm 2 ( zref and R50 in g / cm2 )
Chamber
5.1.2 Cross-calibration
Depth Chamber positioning SSD Field size
effective point of measurement, see chapter 2.3 100 cm 10 cm x 10 cm at phantom surface, or that used for normalization of output factors, whichever is larger
IAEA TRS 398 recommends the cross-calibration of plane-parallel chambers against a cylindrical cham60 ber which is calibrated at Co. Dose measurements are performed under reference conditions (see chapter 5.1.1) using the highest available electron energy Qcross .
Step 1: measure a reference dose Dw,Qcross with a
cylindrical chamber which was calibrated at Co, following the procedure described in chapter 5.1.1.
Step 2: irradiate the plane-parallel chamber with the same dose. Take the plane-parallel chamber's corrected reading M and determine its calibration factor for the energy used for cross-calibration
N w,Qcross = Dw,Qcross M
60
The beam quality is specified by R50 , the depth in water at which the absorbed dose is 50 % of its value at the absorbed dose maximum4. R50 is to be measured under the above reference conditions, but at field sizes of at least
4
(5-4)
The mean energy E0 can be estimated by
E0 = 2.33 R50 ( R50 in g / cm2 and E0 in MeV).
85
85

Step 3: use the cross-calibrated plane-parallel chamber to measure dose at any electron energy Q other than Qcross
Dw = kQ kQcross N w,Qcross M
(5-5)
kQcross is the plane-parallel chamber's k Q value for
the cross-calibration energy Qcross . Values for k Q are obtained from Table 8.
Electron Beam Quality R50 [g/cm ]

2
PTW 23343 Markus
PTW 34045 Advanced Markus
PTW 34001 Roos
PTW 30001/ 30010 Farmer
PTW 30002/ 30011 Farmer
PTW 30004/ 30012 Farmer
PTW 30006/ 30013 Farmer
PTW PTW 31002/ 31003/ 31010 31013 3 0.125 cm 0.3 cm3 Flexible Flexible
1.0 1.4 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 7.0 8.0 10.0 13.0 16.0 20.0
0.925 0.920 0.916 0.913 0.910 0.907 0.904 0.901 0.899 0.894 0.889 0.881 0.870 0.860 0.849
0.966 0.956 0.945 0.938 0.932 0.926 0.921 0.917 0.912 0.909 0.905 0.899 0.893 0.883 0.871 0.861 0.849
0.965 0.955 0.944 0.937 0.931 0.925 0.920 0.916 0.912 0.908 0.904 0.898 0.892 0.882 0.870 0.860 0.848
0.911 0.909 0.907 0.905 0.904 0.901 0.898 0.893 0.885 0.877 0.868
0.916 0.914 0.912 0.910 0.909 0.906 0.903 0.897 0.890 0.882 0.873
0.920 0.918 0.916 0.915 0.913 0.910 0.907 0.902 0.894 0.887 0.877
0.911 0.909 0.907 0.905 0.904 0.901 0.898 0.893 0.885 0.877 0.868
0.912 0.910 0.908 0.906 0.905 0.901 0.898 0.893 0.885 0.877 0.867
0.912 0.910 0.908 0.906 0.905 0.901 0.898 0.893 0.885 0.877 0.867
Table 8: Typical k Q values for PTW plane-parallel and cylindrical chambers [IAEA 398] 5. The values for the Advanced Markus chamber and the Farmer chambers type 30006/30013 have been added by PTWFreiburg. They were calculated according to IAEA TRS 3986.
5 6
With corrigendum STI/DOC/010/398. For details refer to PTW's Technical Note D661.200.0.
86
86

5.2 AAPM TG-51

Q k Dw = Pgr kR ecal N w M 50
60
10 cm x 10 cm 20 cm x 20 cm (5-6)
for R50 8.5 cm for R50 > 8.5 cm
Dw
Q Pgr
= absorbed dose to water = correction for gradient effects, not needed for plane-parallel chambers. For cylindrical chambers with a cavity radius r the correction factor at the reference depth dref is obtained from Q Pgr = M (d ref + 0.5 r ) / M (d ref ) = electron quality conversion factor, see formulae (5-9) and (5-10)
From the depth ionization distribution measured with an air-filled ionization chamber, the quantity I50 is obtained. This quantity can be converted to R50 by
R50 = 1.029 I 50 0.06 cm R50 = 1.059 I 50 0.37 cm
(2 I 50 10 cm ) (5-7) (I 50 > 10 cm )
(5-8)
' kR 50
Chamber Type
k ecal
k ecal = photon-electron conversion factor, see Table 9 N w = calibration factor for absorbed dose to M
water for Co = corrected reading of the dosemeter, see chapter 2.1
60
Influence Quantity
Reference Condition
Phantom material Chamber
water plane-parallel preferred for R50 4.3 cm (10 MeV) plane-parallel mandatory for R50 2.6 cm (6 MeV)
d ref = 0.6 R50 0.1 cm
PTW 34001 Roos PTW 34045 Advanced Markus PTW 23343 Markus PTW 30001/30010 Farmer PTW 30002/30011 Farmer PTW 30004/30012 Farmer PTW 30006/30013 Farmer PTW 31003/31013 0.3 cm Flexible PTW 31002/31010 0.125 cm Flexible PTW 23331 1.0 cm Rigid PTW 23332/30016 0.3 cm Rigid
0.901 0.905 0.905 0.897 0.900 0.905 0.896 0.898 0.898 0.896 0.898
Depth Chamber positioning
chamber axis for cylindrical chambers, effective point of measurement for planeparallel chambers, see chapter 2.3 90 - 110 cm 10 cm x 10 cm at phantom surface for R50 8.5 cm (20 MeV), 20 cm x 20 cm at phantom surface for R50 > 8.5 cm
Table 9: Values of the photon-electron conversion factor k ecal . The values not listed in [AAPM 51] have been added by PTWFreiburg; they were calculated according to [Rogers 1998].
SSD Field size
For beam quality specification measurements with a cylindrical chamber, the chamber axis must be shifted downstream by 0.5 r , where r is the inner radius of the measuring volume. Cylindrical chambers should be used only for R50 > 4.3 cm . The electron quality conversion factor is obtained from the following formulae with R50 expressed in cm. For cylindrical chambers and 2 R50 9 cm
= 0.9905 + 0.071 e kR 50 and
R50 3.67
The beam quality is specified by R50 , the depth in water at which the absorbed dose is 50 % of its value at the absorbed dose maximum. R50 is to be measured under the above reference conditions, but at SSD = 100 cm and at field sizes at the phantom surface of at least
(5-9)
87
87

for well-guarded 2 R50 20 cm

k
R50
plane-parallel
chambers
and
5.3 DIN 6800-2

Dw = kr kE N w M
60
= 1.2239 0.145 (R50 )
0.214
(5-10)
(5-13)
5.2.2 Cross-calibration
Dw kr
AAPM TG-51 recommends the cross-calibration of plane-parallel chambers against a cylindrical cham60 ber which is calibrated at Co. Dose measurements are performed under reference conditions (see chapter 5.2.1) using the highest available electron energy Qcross .
Step 1: measure a reference dose Dw,Qcross with a
kE Nw M
cylindrical chamber which was calibrated at Co, following the procedure described in chapter 5.2.1.
Step 2: irradiate the plane-parallel chamber with the same dose. Take the plane-parallel chamber's corrected reading M and determine its calibration factor for the energy used for cross-calibration
60
= absorbed dose to water at zref = 1 + 0.03 r replacement correction factor ( r is the inner radius of the measuring volume of a cylindrical chamber, given in cm). kr is not applicable for plane-parallel chambers) k energy dependent correction factor, = kE E see chapter 5.3.3 = calibration factor for absorbed dose to 60 water for Co = corrected reading of the dosemeter at zref , see chapter 2.1
Reference Condition
Influence Quantity
Phantom material Chamber
water plane-parallel for R50 4 cm a cylindrical chamber can be used

zref (see chapter 5.3.2)
N w,Qcross =
Dw,Qcross M
(5-11) Depth Chamber positioning SSD Field size
Step 3: use the cross-calibrated plane-parallel chamber to measure dose at any electron energy Q other than Qcross
Dw =
' kR 50
50
effective point of measurement, see chapter 2.3 100 cm 20 cm x 20 cm at phantom surface
' kR
,Qcross
N w,Qcross M
(5-12)
5.3.2 Determination of R50 and zref

' ' kR is the plane-parallel chamber's k R value 50 ,Qcross 50
for the cross-calibration energy Qcross .

' kR values are obtained from formula (5-10). 50
R50 is defined as the depth at which the absorbed dose has dropped to 50 % of the maximum value. R50 is determined from the corresponding value R50,ion of a depth ionization curve, measured at SSD = 100 cm with a field size of 20 cm x 20 cm (optionally 10 cm x 10 cm for R50 7 cm ) R50 = 1.029 R50,ion 0.06 cm (R50,ion 10 cm) (5-14)
R50 = 1.059 R50,ion 0.37 cm (R50,ion > 10 cm) (5-15) The reference depth for dose measurements is defined as ( zref and R50 in cm)
zref = 0.6 R50 0.1
(5-16)
88
88

' " kE 5.3.3 Determination of k E = k E
5.3.4 Dose measurements at depths other than zref
' kE is independent of the chamber type ( R50 in cm) ' kE = 1.106 0.1312 (R 50 )0.214
The dose at depth z is determined by

Dw ( z ) = kr kE kNR N w M ( z )
(5-17)
(5-21)
a) from
" kE for plane-parallel chambers is determined
kE is the correction factor at zref as described in chapter 5.3.3, kNR is given by kNR = pcav ( z ) p sw ( z ) cav ( zref ) ,a ref
sw ,a ( z )
" kE
( p wall pcav )
R50 Co
( p wall pcav )
(5-18)
(5-22)
and The relevant factors are listed in Table 10.

Chamber type PTW 34001 Roos PTW 34045 Adv. Markus PTW 23343 Markus
sw ,a ( z ) =
( pcav )
R50
( pwall pcav )
( pwall )R 50
a + b x + c x + dy 1 + e x + fx + g x + h y
(5-23)
Co
where x = ln(R50 ) and y = z / R50 ( z and R50 in cm) and
1.000
0.981
a=
1.0752
b = - 0.50867 e = - 0.42806 h = - 0.1246
c = 0.08867 f = 0.06463
1.000
0.985
d = - 0.08402 g= 0.003085
1 0.037 e 0.27 R 50
0.982
The cavity perturbation factor depends on the chamber type a)

Roos and Advanced Markus chambers
pcav ( z ) = pcav ( zref ) = 1.000
Table 10: Perturbation correction factors for planeparallel chambers at the reference depth zref [Christ 2002, Kapsch 2007, DIN 6800-2].
" for cylindrical chambers at the reference b) kE depth zref is calculated from
b)
Markus chambers
pcav ( z ) = 1
z a R +b +c R50 + dz 50 1+ e
(5-24)
" kE =
( pcav pcel )
R50 Co
( p wall pcel )
(5-19)
and
( pcav )R50 = 1 0.217 r e 0.153R50
with z and R50 in cm and with (5-20) a = 0.1498 d = 4.0487 c) b = -21.7336 c = -4.3379
where r and R50 are given in cm. r can be taken from Table 7, ( p wall ) Co and ( pcel )R50 /( pcel )Co are listed in Table 11.
Cylindrical chambers
z 0.2852 R 50 1 1.271R 50 0.23
pcav ( z ) = 1 0.2155 r e
(5-25) with r , z and R50 in cm.

89
89

Chamber type PTW 23331 1 cm Rigid PTW 30015 1 cm Rigid PTW 23332 0.3 cm Rigid PTW 30016 0.3 cm Rigid PTW 23333 Farmer (3 mm build-up cap) PTW 23333 Farmer (4.6 mm build-up cap) PTW 30001/30010 Farmer PTW 30002/30011 Farmer PTW 30004/30012 Farmer PTW 30006/30013 Farmer PTW 31002/31010 0.125 cm Flexible PTW 31003/31013 0.3 cm Flexible PTW 31014/31015 PinPoint PTW 31016 PinPoint 3D
( p wall ) Co
1.001 1.000 1.001 0.999 1.001 1.001 1.001 0.991 0.991 1.001 1.001 1.001 0.998 0.998
( pcel ) R
( pcel ) Co
1.005 1.005 1.005 1.005 1.005 1.005 1.005 1.000 1.005 1.005 1.005 1.005 1.005 1.005
50
Table 11: Perturbation and central electrode correction factors for cylindrical chambers [DIN 6800-2]. Chambers not listed in DIN 6800-2 have been added by PTW-Freiburg.
90
90

Measurements in Acrylic Phantoms
6 Measurements in Acrylic Phantoms

6.1 General
For dosimetry in high energy photon or electron beams all dosimetry protocols described in this document (IAEA TRS 398, AAPM TG-51, DIN 6800-2) require absorbed dose measurements in real water. Solid state phantoms may only be used for routine QA measurements, and a transfer factor has to be established [AAPM 51]. The phantom should extend at least 5 cm beyond all sides of the field and at least 5 cm beyond the maximum depth of measurement [IAEA 398]. This chapter helps to establish transfer factors and 'equivalent' measuring depths for measurements in acrylic (PMMA, Perspex, C5H8C2) phantoms. source-detector-distance [AAPM 21] zw = 1.136 z p for Co - 35 MV
60
(6-1)
6.2.2 Excess scatter correction
In PMMA phantoms the fraction of scattered photons is increased compared with water phantoms. To convert measuring values from PMMA to water, the measuring value has to be multiplied by a correction factor kESC (Excess Scatter Correction). Table 12 shows kESC values as a function of accelerator voltage and field size [AAPM 21].
6.3 High energy electrons

Solid phantoms may be used below 10 MeV to determine absorbed dose at z ref [IAEA 398]. The measuring depth in water z w can be determined from the measuring depth in PMMA z p assuming the same source-detector-distance
zw = cpl zp = 1.120 zp
6.2 High energy photons

6.2.1 Conversion of measuring depth
Photon beams are attenuated and scattered differently in water and solid phantoms. To take these differences into account, correction procedures have to be carried out. Differences in photon beam attenuation are determined by the ratio of the mean linear attenuation coefficients of water and PMMA. The measuring depth in water z w can be determined from the measuring depth in PMMA z p assuming the same
(6-2)
cpl is the depth scaling factor and the nominal density of PMMA [IAEA 398]. The reading in the PMMA phantom Mp must be corrected by the fluence scaling factor hpl to obtain the equivalent reading in water M
M = hpl Mp = 1.009 Mp
(6-3)
Field size at depth (cm) Energy (MV)

60
Depth (cm) 5x5 10x10 20x20 30x30
Co 2 4 6
0.5 5.0 0.4 5.0 1.0 5.0 1.5 5.0
0.997 0.986 0.998 0.984 0.998 0.994 0.999 0.994
0.996 0.987 0.994 0.982 0.997 0.993 0.998 0.994
0.995 0.989 0.997 0.989 0.998 0.993 0.998 0.996
0.996 0.991
Table 12: kESC as a function of energy and field size. 91
91

References
7 References
[AAPM 21] A protocol for the determination of absorbed dose from high-energy photon and electron beams. AAPM Task Group 21. Med. Phys. 10(6), Nov/Dec 1983, 741ff AAPM's TG-51 protocol for clinical reference dosimetry of high-energy photon and electron beams. Med. Phys. 26 (9), September 1999, 1847-1870 Christ, Dohm, Bruggmoser, Schle: The use of plane-parallel chambers in electron dosimetry without any cross-calibration. Phys. Med. Biol. 47 (2002), N121-N126 Christ, Dohm, Schle, Gaupp, Martin: Air density correction in ionization dosimetry. Phys. Med. Biol. 49 (2004), 2029-2039 Bruggmoser, Saum, Schmachtenberg, Schmid, Schle: Determination of the recombination correction factor kS for some specific planeparallel and cylindrical ionization chambers in pulsed photon and electron beams. Phys. Med. Biol. 52 (2007), N35-N50 G. Bruggmoser, private communication DIN 6800: Dosismessverfahren nach der Sondenmethode fr Photonen- und Elektronenstrahlung; Part 2: Dosimetrie hochenergetischer Photonen- und Elektronenstrahlung mit Ionisationskammern, March 2008 DIN 6809: Klinische Dosimetrie; Part 4: Anwendung von Rntgenstrahlen mit Rhrenspannungen von 10 bis 100 kV in der Strahlentherapie und der Weichteildiagnostik, December 1988 DIN 6809: Klinische Dosimetrie; Part 5: Anwendung von Rntgenstrahlen mit Rhrenspannungen von 100 bis 400 kV in der Strahlentherapie, February 1996 The Use of Plane Parallel Ionization Chambers in High Energy Electron and Photon Beams. Technical Reports Series No 381. International Atomic Energy Agency Vienna, 1997 Absorbed Dose Determination in External Beam Radiotherapy: An International Code of Practice for Dosimetry Based on Standards of Absorbed Dose to Water. Technical Reports Series No. 398. International Atomic Energy Agency Vienna, 2000 Corrigendum STI/DOC/010/398 Kapsch, Bruggmoser, Christ, Dohm, Hartmann, Schle: Experimental Determination of pCo perturbation factors for plane parallel chambers. Phys. Med. Biol. 52 (2007), 7167-7181 Rogers, A new approach to electron-beam reference dosimetry. Med. Phys. 25 (3), March 1998, 310-320
[AAPM 51]
[Christ 2002]
[Christ 2004] [Bruggmoser 2007]
[Bruggmoser 2008] [DIN 6800-2]
[DIN 6809-4]
[DIN 6809-5]
[IAEA 381]
[IAEA 398]
[Kapsch 2007]
[Rogers 1998]
92
92

Appendix A: Summary of PTW Chamber Data

PTW Cylindrical Chambers
Type No. Chamber Name Measuring Volume [cm] 0.6 0.6 0.6 0.6 0.6 0.125 0.125 0.3 0.3 1.0 1.0 0.275 mm PMMA + 0.15 mm C 30010 30011 30002 30012 30004 30013 30006 31002 31010 31003 31013 23331 30015 Farmer, waterproof Flexible Flexible Flexible Flexible Rigid Rigid 0.335 mm PMMA + 0.09 mm C 0.55 mm PMMA + 0.15 mm C 0.55 mm PMMA + 0.15 mm C 0.55 mm PMMA + 0.15 mm C 0.55 mm PMMA + 0.15 mm C 0.40 mm PMMA + 0.15 mm C 0.4 mm PMMA + 0.135 mm C 23332 30016 31014 31015 31016 Rigid Rigid PinPoint PinPoint PinPoint 0.3 0.3 0.015 0.03 0.016 0.35 mm PMMA + 0.15 mm C 0.35 mm PMMA + 0.135 mm C 0.57 mm PMMA + 0.09 mm C 0.57 mm PMMA + 0.09 mm C 0.57 mm PMMA + 0.09 mm C Al 0.3 mm Al 0.3 mm Al 0.3 mm Al 2 mm Graphite coated Al 0.85 mm Al 1.5 mm Graphite coated Al 1.1 mm Al 1.5 mm Graphite coated Al 0.9 mm Al 1 mm Graphite coated Al 1.1 mm Al 1.1 mm Farmer Farmer, all graphite Farmer 0.425 mm C Al 1 mm 0.335 mm PMMA + 0.09 mm C 0.425 mm C C 1 mm Al 1.1 mm Al 1 mm Wall Electrode Wall Area Density [mg/cm] 45 (1) 57 (2) 79 (2) 79 (2) 57 (2) 78 (1) 78 (1) 78 (1) 78 (1) 60 (1) 73 (2) 54 (1) 67 (2) 85 (2) 85 (2) 85 (2) 1.45 1.45 1.0 2.5 2.5 3.95 3.95 2.75 2.75 2.75 2.75 3.05 3.05 3.05 3.05 Radius of Measuring Volume [mm] 3.05 Ion Collection Time at nominal HV 0.14 ms (400 V) 0.13 ms (400 V) 0.14 ms (400 V) 0.14 ms (400 V) 0.13 ms (400 V) 0.10 ms (400 V) 0.10 ms (400 V) 0.08 ms (400 V) 0.08 ms (400 V) 0.21 ms (400 V) 0.23 ms (400 V) 0.04 ms (400 V) 0.08 ms (400 V) 0.02 ms (400 V) 0.04 ms (400 V) 0.06 ms (400 V)
30001
Farmer
(1) Graphite density 0.82 g/cm (2) Graphite density 1.85 g/cm
93
93

PTW Plane Parallel Chambers

Type No. Chamber Name Measuring Volume [cm] 0.39 Entrance Window Electrode Diameter [mm] 1 mm PMMA + 0.02 mm C + 0.1 mm Varnish 34045 Advanced Markus 0.02 0.87 mm PMMA + 0.4 mm Air + 0.03 mm CH2 (Polyethylene) (3) 23343 Markus 0.057 0.87 mm PMMA + 0.4 mm Air + 0.03 mm CH2 (Polyethylene) (3) 23342 Soft X-Ray 0.02 0.03 mm CH2 (Polyethylene) 23344 Soft X-Ray 0.2 0.03 mm CH2 (Polyethylene) 34013 Soft X-Ray 0.0053 0.03 mm CH2 (Polyethylene) 1.7 2.8 0.75 13 2.8 1.5 3 2.8 1 0.02 ms (300 V) 0.04 ms (400 V) 0.01 ms (400 V) 5.3 106 2 0.09 ms (300 V) 5 106 1 0.02 ms (300 V) 15.6 Window Area Density [mg/cm] 132 Electrode Distance [mm] 2 Ion Collection Time at nominal HV 0.13 ms (200 V)
34001
Roos
(3) with protection cap in place
94
94
Index
Product Index
Product
2D-ARRAY Advanced Markus chamber Bhm extrapolation chamber Bragg peak chamber Check device CT chamber CURIEMENTOR chamber Cylinder stem chamber DIADOS detector Diagnostic flat chamber DIAMENTOR chamber Diamond detector Dosimetry diode Extrapolation chamber Farmer chamber Flat chamber Hp(10) secondary standard chamber In-vivo detectors LA48 Markus chamber microLion chamber
Page
33 18 53 21 34 38 40 48 40 39 40 25 26, 27 53 10-13 39 49 33 33 19 24
Product
Monitor chamber PinPoint chamber PS-10 spherical chamber PS-50 spherical chamber Radiation monitoring chamber Radioactive check device Reference soft X-ray chamber Rigid stem chamber Roos chamber Semiflex chamber SFD diagnostic chamber Soft X-ray chamber SOURCECHECK Spherical chamber STARCHECK TK-30 spherical chamber Transmission chamber Well-type chamber XLS chamber X-ray leakage system
Page
51, 52 22, 23 46 46 42-44 34 50 16, 17 20 14, 15 36, 37 28-30, 50 31 45-47 33 47 51, 52 32, 40 40 40
Item Number Index

The item numbers below are without the leading letters. For complete ordering numbers, indicating the connecting system, see the according product page.
Item #
16036 23236 23237 23238 23342 23343 23343/11 23344 23361 233612 23392 23392/U5 30009 30010 30011 30012
Page
24 29 48 28 28 19 18, 19 29 48 39 53 53 38 10 11 12
Item #
30013 30015 30016 31010 31013 31014 31015 31016 31018 32001 32002 32003 32004 32005 32007S 32008S
Page
13 17 16 14 15 22 22 23 24 42 45 45 43 47 46 46
Item #
33004 34001 34013 34014 34031 34035 34045 34047 34051 34060 34069 34070 34073 4316/U331 48001 48002.1.004
Page
32 20 30 51 43 49 18 50 31 36 37 21 21 24 45 14, 15
Item #
48002.1.007 48002.1.008 48002.3.003 48002.3.004 48004 48010 48012 60003 60016 60017 7262 7262/U10 786 7862 981937
Page
22 23 10-13 16, 17 20 34 34 25 26 27 44 42-44 51 52 49
95
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IONIZING RADIATION

PTW History and General Remarks

Looking back on a long history

The evolvement of radiation detectors

Ionizing Radiation Detectors: Contents

Health Physics Detectors

Codes of Practice Index

The Detector Design

The Detector Design

Parallel Plate Ionization Chamber

Spherical Ionization Chamber

Well Type Ionization Chamber

PTW Calibration Laboratory

PTW Calibration Laboratory

Calibration facilities and instrumentation

Origin and tradition

The calibration laboratory (below) seen from above

Detail of the calibration laboratory approx. 1957

PTW Calibration Laboratory

Quality and regulatory compliance

Secondary Standard Laboratory/ Cooperation with IAEA and PTB

300 kV X-ray installation with filter wheel

Materials and measures: Wall of sensitive volume

Field size Temperature Humidity Air pressure

Photon energy response Directional response in solid state phantom

T48002.3.003 Chamber holding device for check device

Leakage current Cable leakage

Field size Temperature Humidity Air pressure

T48002.3.003 Chamber holding device for check device

Photon energy response Directional response in solid state phantom

Leakage current Cable leakage

Field size Temperature Humidity

T48002.3.003 Chamber holding device for check device

Photon energy response Directional response in solid state phantom

Leakage current Cable leakage

Materials and measures: Wall of sensitive volume

Field size Temperature

cm3 Humidity Air pressure

Photon energy response Directional response in water

T48002.3.003 Chamber holding device for check device

Leakage current Cable leakage

0.125 cm3 Semiflex Chamber

Materials and measures: Wall of sensitive volume

0.55 1.19 0.15 0.82

mm PMMA, g/cm3 mm graphite, g/cm3

Field size Temperature Humidity Air pressure

Photon energy response Directional response in water

T48002.1.004 Chamber holding device for check device

Leakage current Cable leakage

0.3 cm3 Semiflex Chamber

Materials and measures: Wall of sensitive volume

0.55 1.19 0.15 0.82

mm PMMA, g/cm3 mm graphite, g/cm3

Field size Temperature Humidity Air pressure

Photon energy response Directional response in water

T48002.1.004 Chamber holding device for check device

Leakage current Cable leakage

0.3 cm3 Rigid Stem Chamber

Materials and measures: Wall of sensitive volume

cm3 Humidity Air pressure