Radiation Safety Manual

CHAPTER 1 -- PREFACE
The Rosario Medical Centre (RMC) strives to provide a safe and healthful environment for all persons
associated with the Medical Centre, including faculty, staff, students, and visitors. Attainment of this goal
requires the cooperation and commitment of all persons involved.

The University emphasizes safety education and training as the primary means of achieving this goal. While the
Radiation Safety Office, the department responsible for radiation safety functions within the University, provides
training and performs periodic safety inspections, department heads, faculty members, and supervisors are
directly responsible for maintaining an atmosphere that promotes full compliance with RMC’s safety policies and
procedures.

With regard to radiation safety matters, the Radiation Safety Committee, appointed by the President, establishes
radiation policies and procedures for RMC in accordance with requirements set forth by Local and National
regulatory agencies. Responsibility for carrying out these policies and procedures rests with the Radiation
Protection Officer.

Essential elements of RMC’s radiation safety program are presented in this Radiation Safety Manual. The safety
program has been carefully developed to assist all radiation users in utilizing the unique advantages of radiation
sources while meeting their safety responsibilities in as efficient and non-intrusive manner as possible. In
addition, radiation safety philosophy and regulations include an objective of maintaining all exposures at levels as
far below regulatory limits as can reasonably be achieved. RMC strongly supports this "As Low As Reasonably
Achievable" (ALARA) safety goal. The policies and procedures found in this manual were designed to promote
the achievement of this goal.

In this era of increasing concern for occupational safety and for the environment, it is essential that all members
of the R M C community become and remain thoroughly familiar with their responsibilities for compliance with
health and safety regulations, including these radiation safety policies and procedures. Please study the
contents of this manual. Know and practice these and all other safety rules. Thank you for your cooperation.

CHAPTER 2 -- RMC RADIATION SAFETY PROGRAM

INTRODUCTION
The Food and Drug Administration (FDA) Philippines, authorizes the Rosario Medical Centre to use radiation-
producing devices in diagnostic activities. RMC’s Radiation Safety Committee authorizes individuals to use
these devices

This manual summarizes the terms of RMC’s authorization to use various radiation producing devices. A copy
must be available in each Authorized facility where radiation-producing devices are used. Copies of special
precautions, regulations, and other operating procedures specified by the Radiation Safety Committee or
Radiation Protection Officer (RPO) must also be maintained available to personnel. Everyone involved with the
use of radiation- producing devices in any way is required to be familiar with the provisions of this manual.

RESPONSIBILITIES
Radiation Safety Committee:

The Radiation Safety Committee is responsible for establishing policies governing the procurement, use, storage
and disposal of radiation-producing devices. The Committee includes individuals experienced in the use of
radiation sources in medicine at RMC. The Committee consists of a Chairman, Radiation Protection Officer,
representatives of management and nursing services, duties include:

Monitoring the institutional program to maintain occupational doses as low as reasonably achievable
(ALARA). Reviewing and approving or disapproving an individual who is to be listed as the Radiation
 Protection Officer submitting a registration application.
Reviewing and approving, with the advice or consent of the Radiation Protection Officer, or disapproving,
procedures and radiation safety program changes prior to submittal to regulatory agencies.
Reviewing quarterly, with the assistance of the Radiation Protection Officer, occupational radiation exposure
records of personnel working with radiation.
Establishing a table of occupational dose levels that, if exceeded, shall initiate investigations and
considerations for action by the Radiation Protection Officer.
Reviewing quarterly, with the assistance of the Radiation Protection Officer, radiation incidents with respect to
cause and subsequent actions taken.
Reviewing annually, with the assistance of the Radiation Protection Officer, the radiation safety program.
• Reviewing quarterly, the Radiology Quality Assurance policy and ensuring its appropriateness to current
requirements.
• Reviewing corrective actions

The Committee meets at least once each calendar quarter. The Committee and its Chairman, is appointed by the
President as a sub-committee of the Environmental Health and Safety Committee, to which it provides reports at
least annually.

Radiation Protection Officer:

The Radiation Protection Officer has administrative responsibility for RMC’s radiation safety program. The
R P O a s s i s t s i n p r o v i d i n g a wide range of specific radiation protection services such as personnel
monitoring, facility surveys, maintenance of records required by Licensing Authorities, consultation on the safe
use of radiation producing devices and training.

The Radiation Protection Officer is responsible for investigating overexposures, accidents, losses, thefts,
unauthorized receipts, uses, transfers, disposals, and other deviations from approved radiation safety practice,
and implementing corrective actions as necessary. The Radiation Protection Officer is also responsible for
implementing written policies and procedures for the following:

using radiation producing devices safely

taking emergency action if control of radiation producing devices is
lost performance of periodic radiation surveys
performing checks of survey instruments and other safety equipment
training personnel who work in or frequent areas where radiation producing devices are used or
stored keeping copies of records and reports required by regulators
assisting the Radiation Safety Committee in the performance of its duties

Authorized Users

An Authorized User is an employee who has been approved to use radiation-producing devices by the Radiation
Safety Committee.

VENDOR RADIATION SAFETY

All vendors, who sell or service radiation-producing equipment at RMC, must have a radiation safety program
that includes at least the following:

Education about risks and hazards Appropriate use of PPE

Radiation monitoring (personnel) program and record keeping

The vendors must provide program documentation to RMC upon request.

Vendor representatives who are in the room during radiation-producing procedures must wear monitoring devices,
appropriate aprons and other shielding, and other PPE appropriate to the situation.

The company must provide the monitoring devices. The University will provide aprons, shields, and other PPE for
use by the vendor representatives.

If the vendor does not need to be in the procedure room, he/she should use the observation window.
CHAPTER 3 -- REGISTRATION
All machines capable of producing ionizing radiation must be registered with the RMC Radiation Safety
Committee. The following types must be registered:

Dental x-ray units

Diagnostic x-ray (radiographic, fluoroscopic and other diagnostic or
therapeutic units)
Any other equipment that may produce ionizing radiation

The Radiation Safety Committee will document the type, make, model, location, and maximum radiation output
of the device before installation. A copy of the radiation survey performed at the installation and acceptance
testing shall be maintained for inspection, including exposure rates in all adjacent rooms. Radiation surveys shall
be repeated after major maintenance, modification or relocation of the device.

To register the radiation-producing device, provide the Radiation Safety Office with a completed Registered form
(Appendix A).

Before installation of an x-ray device, a radiation shielding plan and specifications must be produced and filed
with the regulatory agency.

An initial radiation safety survey of the equipment and all adjacent rooms, shall be conducted and a copy maintained.
Similar radiation surveys shall be repeated after major maintenance, modification or relocation.

The Radiation Safety Committee must be notified prior to any device installation, maintenance, modification or
relocation, discontinuation or transfer of a radiation-producing device. Reports of transfer (surplus, sale, gift, etc.)
must include the name and address of the transferee.

CHAPTER 4 -- RADIATION WORKER REGISTRATION AND TRAINING

All radiation workers must complete a Radiation Worker Registration Form. This form provides essential
information for issuing a radiation monitoring badge, and provides information on training and experience. The
Radiation Protection Officer (or his/her designee) will review registration forms and schedule necessary training
sessions. The Radiation Safety Committee is to be informed of all changes in personnel working with radiation
sources. Radiation worker updates should be provided when a worker is added, deleted or transfers to another
Authorized User.

Training
All individuals using radiation-producing devices will receive radiation safety training offered by the RPO or
designee. Training must be completed within two months of joining RMC. In addition, individuals will be trained
on the operation of the particular radiation producing device he/she will be using and actions to take in the event
of an emergency.

Medical x-ray operators are certified by the PRC and no further training is required.

CHAPTER 5 -- RADIATION PROTECTION POLICIES AND PROCEDURES

Radiation producing devices do not make anything radioactive and do not produce radiation contamination
(certain particle accelerators may be an exception). External radiation exposure is from x-rays only (with the
possible exception of clinic or research accelerators). Applying basic radiation control measures can control the
external dose.

Radiation Control Measures

Time/Distance/Shielding: The principal objective of radiation protection is to ensure that the dose received by
any individual is as low as reasonably achievable (ALARA), while not exceeding the maximum permissible limit.
Any one, or a combination, of the following methods may achieve this objective:

Time. Limit the time of exposure. For illustrative purposes, a person entering a relatively high radiation field of
1000 millirem/hr, but for only 30 seconds, would receive a relatively low dose of 8 millirem. The maximum
permissible whole body dose is 5000 millirem per calendar year for occupational workers.

Distance. The inverse square law states that radiation intensity from a point source varies inversely as the
square of the distance from the source. The formula is:

I1 (D2)2 where I1, I2 = intensities

=
I2 (D1)2 and D1, D2 = distances

By increasing the distance between the source of exposure and an individual, the dose received can be
significantly reduced. When an individual doubles his/her distance from a source, the dose will usually be
reduced by approximately three-fourths.

Shielding. Absorbing material, or shields, can be incorporated to reduce exposure levels. The specific shielding
material and thickness is dependent on the amount and type of radiation involved. Lead shielding is generally used
for diagnostic and other low-energy x-rays, while concrete and steel are often used with higher energy sources
such as accelerators. The Radiation Safety Office will assist in designing and specifying appropriate shielding.

Exposure. The "strength" (killivoltage, milliamphreage, etc.) of the radiation source. By reducing the intensity of
the radiation used (lowering the current settings on a radiation producing machine), dose can be reduced.

The fundamental objectives of radiation protection measures are to limit exposure to external radiation to levels that
are always within the established dose limits, and as low as reasonably achievable.

Exposure Limits
External radiation levels should be kept to less than 0.1 millirem/hr at 5 centimeters from the source surface or
source housing and to levels as low as reasonably achievable.

For x-ray sources, the units of roentgens, rads, and rems may be considered equivalent.

Survey Instruments
To facilitate safe practice in RMC, the Radiation Safety Committee requires that an appropriate calibrated
survey meter be available in each authorized area. "Appropriate" in most cases means a thin window Geiger-
Mueller type meter (end window or pancake type) that will detect very low energy x-rays or an ion chamber
meter. A "laboratory area" may be one laboratory or a series of connecting laboratory spaces. Laboratories located
on different floors or in different buildings each need their own meter.

Instruments must be calibrated annually. The Radiation Safety Committee should be informed of the purchase
of a new instrument, repair of an instrument, or factory calibration of an existing instrument.

Posting and Labeling Requirements

The RPO is responsible for the posting of all lab or room radiation warning signs.

Inspections
The FDA, DOH and the Radiation Safety Committee may inspect x-ray machines periodically for safety practices
and regulatory compliance.

CHAPTER 6 -- PERSONNEL RADIATION EXPOSURE MONITORING

Personnel monitoring devices (film badges, TLD, pocket dosimeters, etc.) are provided by the Radiation Safety
Committee to measure an individual's radiation exposure from X-ray sources. The standard monitoring device is
a clip-on badge or ring badge bearing the individuals name, date of the monitoring period and a unique
identification number. The badges are provided, processed and reported through a commercial service
company, which meets current requirements.
Monitorinq Requirements: Radiation protection regulations and RMC policy require that appropriate personnel
monitoring equipment be provided to individuals who are likely to receive an annual radiation dose in excess of 10
percent of any of the following annual dose limits:

· Total effective dose equivalent of 5 rems

· Sum of the deep dose equivalent and the committed dose equivalent to an individual organ or tissue
(other than the lens of the eye) being equal to 50 rems
· Eye dose equivalent of 15 rem
· Shallow dose equivalent of 50 rems to the skin or to an extremity
· are less than 18 years of age and are likely to receive a radiation dose in any calendar quarter in
excess of 1 percent of the doses listed in (1) above.
· are radiation workers and have declared a pregnancy or planned pregnancy.
· enter a High Radiation Area (exposure to greater than 100 millirem in any one
hour). operate analytical X-ray devices (ring and whole body badges).
· meet special criteria as assessed by the Radiation Protection Officer or his/her delegated
representative.

Procedures for Monitoring Devices: A Radiation Worker Registration Form for each individual who may work
with radiation sources. This form provides for the basic information regarding training and experience and
personnel monitoring needs. Initial personnel monitoring decisions will be based on this information. Further
evaluations, and re-evaluations, will be made through radiation employee registration updates, application
reviews, personnel monitoring reports, ALARA investigations, surveys and individual interviews by responsible
Radiation Safety staff members.

Badges may be exchanged on a monthly or quarterly basis. Badges must be returned to the RPO by the tenth
of the month so that they may be properly processed.

The Radiation Protection Officer may require the use of pocket dosimeters, ring badges, or other monitoring
devices when particular procedures are in operation.

The RPO may request prior radiation dose histories from all past employers and will maintain all personnel
occupational radiation dose records.

It will be the responsibility of each individual badge recipient to wear and use the badge(s) properly.

Use of Personnel Monitoring Devices: The whole body badge (or other device) is to be worn on the body where
it will most likely approximate the radiation exposure to the head and torso of the wearer. A badge assigned for
whole body monitoring is not to be used to monitor the extremities (hands, forearms, feet, ankles). Separate
badges must be assigned for extremity monitoring. Only the individual assigned the badge shall wear it and
only at RMC facilities.
Generally, whole body badges are to be worn between the waist and the neck. When a protective apron is worn,
the badge is to be worn at the collar, outside the apron. The Radiation Protection Officer should be consulted for
advice in these circumstances.

Extremity monitoring badges (rings) are available in large or small sizes for the right or left hand. Ring badges should
be worn whenever working with applicable sources.

Exposure of a personnel monitoring device to deceptively indicate a dose delivered to an individual is prohibited by
state regulations.

Personnel Monitoring Reports: Exposure reports are currently monthly and quarterly. Each report includes the
name, monitoring period date, dose (millirem) for the immediate past period, current calendar quarter and
calendar year.

The personnel monitoring reports are on file in the Radiation Safety Office. They are available for all badged
employees to review. The reports are considered medical records and may not be released without written
consent.
RMC Pregnant Employee - Fetal Dose Policy: The RMC fetal dose policy incorporates safety information and
radiation dose guidelines for ensuring safe radiation limits for the embryo/fetus of occupationally exposed
employees. Pregnant radiation workers should notify the RPO in writing as soon as possible after learning of their
pregnancy.

A potentially harmful situation arises when a pregnant worker is exposed to radiation. Exposure of such a worker
to ionizing radiation from either external or internal sources would also involve exposure of the embryo or fetus. A
number of studies have indicated that the embryo or fetus is more sensitive than an adult, particularly during the
first three months after conception, when a woman may not be aware that she is pregnant.

Regulations require that special precautions be taken to limit exposure to radiation sources when an occupationally
exposed woman could be pregnant.

The current maximum permissible radiation exposure is 500 millirem for the duration of the gestation period, and the
monthly exposure should be limited to 50 millirem. Fetal monitoring (double badging) is available from the RPO

In order to be recognized as pregnant, for the purpose of exposure limits, a person must declare in writing to
RMC that she is pregnant.

It is recommended that the pregnant person avoid higher radiation exposure procedures such as x-ray fluoroscopy.

ALARA Levels and Notifications: There are two notification levels for the ALARA program, Level I and Level
II. Level I notifications involve a radiation worker receiving greater than 10 percent of the maximum allowable
dose (prorated for a month's exposure period). The recipient is notified in writing when their exposure meets
this level's criteria. The notification requests that the worker review their work procedures in order to reduce
exposure, if feasible.

Level II notifications involve a radiation worker receiving greater than 30 percent of the maximum allowable dose
(prorated for a month's exposure period). The recipient is notified when their exposure meets this level's criteria. In
addition to reviewing procedures as with Level I, Level II requires the worker to respond in writing to the RPO. The
response must include the cause of the exposure and a consideration of actions that may be taken to reduce
the probability of a recurrence.

Part of Body Notification Level I Notification Level II (mrem per

month)

Whole body (head, trunk), gonads,upper arms or 40 125

Lens of the Eye 125 375
Skin of whole body- extremities (hand, elbow,
lower arms or legs, foot, knee) 400 1250
Embryo-Fetus N/A 10
Overexposure: If an exposure exceeds the maximum allowable dose, the employee and supervisor will be
notified and the required reports will be filed with the relevant Health services .

CHAPTER 7 -- ALARA PROGRAM

RMC is committed to minimizing radiation exposure to all persons associated with RMC. Therefore, the As Low
As Reasonably Achievable (ALARA) philosophy is adopted as policy for RMC. The Radiation Safety
Committee, with the Radiation Protection Officer as its delegated representative, will develop and implement
policies and procedures to ensure radiation exposures are ALARA.

The following policies and procedures are utilized to keep radiation exposures ALARA:

The Radiation Safety Committee will review quarterly and annually radiation worker doses, investigating
ALARA notifications to determine whether exposures are being kept to a minimum.
The Radiation Protection Officer will brief management once per year regarding occupational exposure
levels.
The Radiation Safety Committee will carefully review applications for radiation producing devices to
ensure that the applicant is qualified and that the proposal incorporates the ALARA philosophy.
The Radiation Safety Committee will adopt investigation levels for occupational radiation exposures. When
these levels are exceeded, the Radiation Protection Officer will notify the recipient and review work
practices, etc., in order to attempt to lower the exposure if possible.
The Radiation Protection Officer will provide training classes to radiation workers and ancillary
personnel regarding the ALARA philosophy and methods to keep exposures ALARA.

CHAPTER 8 -- DENTAL X-RAY UNITS

In performing intra-oral dental radiography the following rules shall apply:

Each installation shall comply with the current RMC radiation regulations. Contact the RPO in advance for
consultation and guidance on new installations, reinstallations, and modifications, as well as other matters.

Film holding devices shall be used if, technique permits;

Neither the tube housing assembly nor the position-indicating device shall be hand-held during
an exposure; The x-ray system shall be arranged and operated in a manner that the useful beam
at the patient's skin does not exceed the dimensions specified.
Each patient undergoing dental radiography shall be draped with a protective apron of not less than 0.25
mm lead equivalent to cover the gonadal area;
Film of a USASI (USA) speed group rating of "D" or faster shall be used,
All dental radiographic x-ray systems registered after March 2, 1977, shall be provided with
electronic timers; and If patients are immobilized during an x-ray exposure, mechanical restraints
shall be used, if technique permits.

Dental x-ray facilities should be inspected once every three years unless certification or other reasons require a
different schedule.

CHAPTER 9 -- DIAGNOSTIC X-RAY UNITS

Technique Chart. In the vicinity of each x-ray system's control panel a chart shall be provided which specifies
pertinent examination information. The chart shall include but not be limited to the following:

The patient's anatomical size versus technique factors to be utilized;

The type and size of the film or film-screen combination to be used;
The type and focal distance of the grid to be used, if used;
The source to image receptor distance to be used, and
The type and location of gonadal shielding to be used, if used.
Personnel in X-ray Room. Except for patients who cannot be moved out of the room, only staff and ancillary
personnel required for the medical procedure or training shall be in the room during the radiographic exposure.
The patients and personnel shall be protected as follows:

Other than the patient being examined, individuals in the x-ray room shall be positioned so that no part of the
body not protected by five-tenths (0.5) mm lead equivalent, is struck by the useful beam.
Staff and ancillary personnel shall be protected from direct scatter radiation by protective aprons or
whole body protective barriers of not less than 0.25 mm lead equivalent;
Patients who cannot be removed from the room shall be protected from the direct scatter radiation by
whole body protective barriers of not less than 0.25 mm lead equivalent or shall be so positioned that the
nearest portion of the body is at least two (2) meters from both the tube head and the nearest edge of the
image receptor; and
If a portion of the body of staff or ancillary personnel is potentially subjected to stray radiation which results
in that individual receiving one-quarter (1/4) of the maximum permissible dose as defined in these
administrative regulations, additional protective measures may be required as appropriate (improved
shielding, rearrangement of setup, etc.).
Patients shall be held in accordance with Medical Center and Radiation Safety Committee policy:

When an x-ray examination is performed in the patient’s room, or for difficult patients in the trauma setting, the
radiologic technologist sometimes needs assistance in positioning the patient. Since the need for assistance is
highly variable and unpredictable, Diagnostic Radiology is not staffed to provide the extra hands necessary to
complete these exams successfully. The standard practice is for the patient’s care team or a family member to
provide this extra assistance with positioning. RMC policy requires that persons who are not routinely exposed to
radiation or a family member provide this assistance, to the maximum extent practicable, since it would
unacceptably increase the risk of adverse health effects already borne by workers who are routinely exposed to
radiation as part of their job duties. The amount of radiation received by a person providing positioning
assistance is very low and is considered by the radiation safety community to be safe, especially when the
precautions mentioned below are observed.

Radiologic technologists who request positioning assistance will make every effort to keep the radiation exposure of
those providing assistance to levels that are as low as reasonably achievable. The assisters (staff or family
members) will be shown how to position themselves in the safest and most effective way. A lead apron and lead
gloves will be given to the assister, and the assister will stand so that they are outside of the primary radiation
beam to the greatest extent practicable. Pregnant staff or family members will not be used to provide positioning
assistance. No one person will be asked to routinely hold patients. An assister who is already wearing a film
badge will position the badge at the collar outside the apron during the procedure.

Fluoroscope Procedures
Operating Procedures and Auxiliary Equipment. The following operating procedures and auxiliary equipment shall be
utilized, if applicable, in the operation of a fluoroscopic x-ray system:

Fluoroscopy performed by technologists shall be under the direction of a radiologist and be exclusively for
localization purposes;
Spot film images shall be obtained only under the direction of a licensed practitioner of the healing
arts; Protective gloves of at least 0.25 mm lead equivalent shall be readily available to the
fluoroscopist during every examination;
Protective aprons of at least 0.25-mm lead equivalence shall be worn by the fluoroscopist and by persons
in the fluoroscopic room except the patient during each examination;
Fluoroscopic x-ray systems designed strictly for fluoroscopy shall not be used for spot filming or
radiography; and Dental fluoroscopic x-ray systems without image intensification shall not be used.
Appendix A -- GLOSSARY
Absorbed Dose the amount of energy imparted to matter by ionizing radiation per unit mass of irradiated material.
The unit of absorbed dose is the Rad, which is 100 ergs/gram.
Absorption the phenomenon by which radiation imparts some or all of its energy to any material through which it
passes.
Acute Exposure the absorption of a relatively large amount of radiation (or intake of radioactive material) over a
short period of time.
Acute Health Effects prompt radiation effects (those that would be observable within a short period of time) for
which the severity of the effect varies with the dose, and for which a practical threshold exists.
Adult an individual 18 or more years of age.
ALARA (acronym for As Low As Reasonably Achievable) making every reasonable effort to maintain exposures to
radiation as far below the dose limits as is practical consistent with the purpose for which the licensed activity is
undertaken, taking into account the state of technology, the economics of improvements in relation to state of
technology, the economics of improvements in relation to benefits to the public health and safety, and other
societal and socioeconomic considerations, and in relation to utilization of nuclear energy and licensed materials in
the public interest.
Atom smallest particle of an element that is capable of entering into a chemical reaction.
Attenuation the process by which a beam of radiation is reduced in intensity when passing through some
material. It is the combination of absorption and scattering processes and leads to a decrease in flux density of
the beam when projected through matter.
Background Radiation ionizing radiation arising from radioactive material other than the one directly under
consideration. Background radiation due to cosmic rays and natural radioactivity is always present. There may
also be background radiation due to the presence of radioactive substances in other parts of the building, in the
building material itself, etc. charged particle emitted from the nucleus of an atom during radioactive decay. A
negatively charged beta particle is identical to an electron. A positively charged beta particle is called a positron.
Bremsstrahlung electromagnetic (x-ray) radiation produced by the deposition of charged particles in matter.
Secondary photon radiation (x-ray) produced by the deceleration of charged particles through matter.
Calibration determination of variation from standard, or accuracy, of a measuring instrument to ascertain necessary
correction factors. The check or correction of the accuracy of a measuring instrument to assure proper
operational characteristics.
Chronic Exposure the absorption of radiation (or intake of radioactive materials over a long period of time), i.e.,
over a lifetime.
Committed Effective Dose Equivalent the sum of the products of the weighting factors applicable to each of the
body organs or tissues that are irradiated and the committed dose equivalent to these organs or tissues.
Controlled Area an area, outside of a restricted area but inside the site boundary, access to which can be limited
by the licensee for any reason.
Declared Pregnant Worker a woman who has voluntarily informed her employer, in writing, of her pregnancy
and the estimated date of conception.
Decontamination the reduction or removal of contaminating radioactive material from a structure, area, object, or
person. Decontamination may be accomplished by (1) treating the surface to remove or decrease the
contamination, (2) letting the material stand so that the radioactivity is decreased as a result of natural decay,
and (3) covering the contamination to shield or attenuate the radiation emitted.
Deep Dose Equivalent applies to external whole-body exposure and is the dose equivalent at a tissue depth of
one centimeter (1000 mg/cm2).
Delayed Health Effects radiation health effects which are manifested long after the relevant exposure. The vast
majority are stochastic, that is, the severity is independent of dose and the probability is assumed to be proportional
to the dose, without threshold.
Dose or Radiation Dose a generic term that means absorbed dose, dose equivalent, effective dose equivalent,
committed dose equivalent, committed effective dose equivalent, or total effective dose equivalent, as defined in
other paragraphs of this section.
Dose Equivalent (HT) the product of the absorbed dose in tissue, quality factor, and all other necessary
modifying factors at the location of interest. The units of dose equivalent are the rem and the sievert (Sv). The
ICRP defines this as the equivalent dose, which is sometimes used in other countries.
Dose Rate the radiation dose delivered per unit of time. Measured, for example, in rem per hour.
Dosimeter a portable instrument for measuring and registering the total accumulated exposure to ionizing radiation.
(see dosimetry.)
Dosimetry the theory and application of the principles and techniques involved in the measurement and
recording of radiation doses. Its practical aspect is concerned with the use of various types of radiation
instruments with which measurements are made (see film badge; thermoluminescent dosimeter; Geiger-Mueller
counter).
Effective Dose Equivalent the sum of the products of the dose equivalent to the organ or tissue and the weighting
factors applicable to each of the body organs or tissues that are irradiated.
Electromagnetic Radiation a traveling wave motion resulting from changing electric or magnetic fields.
Familiar electromagnetic radiations range from x-rays (and gamma rays) of short wavelength, through the
ultraviolet, visible, and infrared regions, to radar and radio waves of relatively long wavelength. All
electromagnetic radiations travel in a vacuum with the velocity of light (see photon).
Electron Volt a unit of energy equivalent to the amount of energy gained by an electron in passing through a
potential difference of 1 volt. Abbreviated eV. X-ray energy is typically measured in keV. (thousand electron volts).
Exposure (1) Being exposed to ionizing radiation or radioactive material. (2) a measure of the ionization
produced in air by x or gamma radiation. It is the sum of the electrical charges on all ions of one sign produced in
air when all electrons liberated by photons in a volume element of air are completely stopped in air, divided by the
mass of air in the volume element. The special unit of exposure is the Roentgen.
External Dose that portion of the dose equivalent received from radiation sources outside the body.
Extremity hand, elbow, arm below the elbow, foot, knee, or leg below the knee.
Eye Dose Equivalent applies to the external exposure of the lens of the eye and is taken as the dose equivalent
at a tissue depth of 0.3 centimeter (300 mg/cm2 ).
Geiger-Mueller (G-M) Counter a radiation detection and measuring instrument. It consists of a gas-filled tube
containing electrodes, between which there is an electrical voltage but no current flowing. When ionizing
radiation passes through the tube, a short, intense pulse of current passes from the negative electrode to the
positive electrode and is measured or counted. The number of pulses per second measures the intensity of
radiation.
Gray The international (SI) unit of absorbed dose in which the energy deposited is equal to one Joule per
kilogram (1 J/kg). Half Value Layer the thickness of any specified material necessary to reduce the intensity of
an x-ray or gamma ray beam to one-half its original value.
Health Physics a term in common use for that branch of radiological science dealing with the protection of
personnel from harmful effects of ionizing radiation. The science concerned with the recognition, evaluation and
control of health hazards from ionizing and non ionizing radiation.
High Radiation Area an area, accessible to individuals, in which radiation levels could result in an individual
receiving a dose equivalent in excess of 0.1 rem (1 mSv) in one hour at thirty centimeters from the radiation source
or from any surface that the radiation penetrates.
Hot Spot the region in a radiation/contamination area in which the level of radiation/contamination is noticeably
greater than in neighboring regions in the area.
Inverse Square Law the intensity of radiation at any distance from a point source varies inversely as the square
of that distance. For example: if the radiation exposure is 100 Rem/hr at 1 inch from a source, the exposure will
be 0.01 Rem/hr at 100 inches.
Ionization the process by which a neutral atom or molecule acquires either a positive or a negative charge.
Ionization Chamber an instrument designed to measure the quantity of ionizing radiation in terms of the charge of
electricity associated with ions produced within a defined volume.
Ionizing Radiation alpha particles, beta particles, gamma rays, x-rays, neutrons, high speed electrons, high
speed protons, and other particles or electromagnetic radiation capable of producing ions.
Limits the permissible upper bounds of radiation exposures, contamination or releases.
Member of the Public an individual in a controlled or unrestricted area (who is not a radiation worker). However,
an individual is not a member of the public during any period in which the individual receives an occupational
dose.
Millirem (mrem) a sub multiple of the Rem equal to one-thousandth (1/1000th) of a Rem. (see Rem)
Minor an individual less than 18 years of age, as pertains to radiation exposure limits, works with radioactive
materials (not a member of the general public).
Monitoring the measurement of radiation levels, and the use of the results of these measurements to evaluate
potential exposures and doses.
Natural Radiation ionizing radiation, not from manmade sources, arising from radioactive material other than
the one directly under consideration. Natural radiation due to cosmic rays, soil, natural radiation in the
human body and other sources of natural radioactivity are always present. The levels of the natural radiation
vary with location, weather patterns and time to some degree.
Occupational Dose the dose received by an individual in the course of employment in which the individual's
assigned duties involve exposure to radiation and to radioactive material from licensed and unlicensed sources of
radiation, whether in the possession of the licensee or other person. Occupational dose does not include dose
received from background radiation, as a patient from medical practices, from voluntary participation in medical
research programs, or as a member of the general public.
Particle Accelerator any machine capable of accelerating electrons, protons, deuterons, or other charged
particles in a vacuum and of discharging the resultant particulate or other radiation into a medium at energies
usually in excess of 1 MeV.
Personnel Monitoring Badge a packet of photographic film, thermolumenisent material or other passive
systems used for the approximate measurement of radiation exposure for personnel monitoring purposes. The
badge may contain two or more detection elements of differing sensitivity, and it may contain filters to aid in
determining the types of radiation and the energy. Photon a quantum (or packet) of energy emitted in the form
of electromagnetic radiation. Gamma rays and x-rays are examples of photons.
Pocket Dosimeter a small ionization detection instrument that indicates radiation exposure directly. An auxiliary
charging device is usually necessary.
Principal Investigator (PI) a faculty member, assistant professor or higher (no visiting faculty), appointed by the
licensee, who has been approved through the Radiation Safety Committee for the purchase and use of
radioactive materials.
Protective Barriers barriers of radiation absorbing material, such as lead, concrete, plaster and plastic, that are
used to reduce radiation exposure.
Public Dose the dose received by a member of the public from exposure to radiation and to radioactive material
released by a licensee, or to another source of radiation. It does not include occupational dose or doses received
from background radiation, as a patient from medical practices, or from voluntary participation in medical research
programs.
Quality Factor (Q) a modifying factor that is used to derive dose equivalent from absorbed dose. It corrects for
varying risk potential due to the type of radiation.
Rad the special unit of absorbed dose. One rad is equal to an absorbed dose of 100 ergs/gram or 62.4 X 106
MeV per gram. Radiation Area an area, accessible to individuals, in which radiation levels could result in an
individual receiving a dose equivalent in excess of 0.005 rem (0.05 mSv) in one hour at thirty centimeters from
the radiation source or from any surface that the radiation penetrates.
Radiation Worker an individual who uses radioactive materials under the licensee’s control. Individuals must be
trained and have passed a radiation safety examination prior to beginning work with radioactive materials.
Radiography the making of shadow images on photographic film by the action of ionizing radiation.
Radiology that branch of medicine dealing with the diagnostic and therapeutic applications of radiant energy,
including x-rays and radioisotopes.
Radiosensitivity the relative susceptibility of cells, tissues, organs, organisms, or other substances to the injurious
action of radiation.
Reference Man a hypothetical aggregation of human physical and physiological characteristics arrived at by
international consensus. These characteristics may be used by researchers and public health workers to
standardize results of experiments and to relate biological insult to a common base.
Relative Biological Effectiveness for a particular living organism or part of an organism, the ratio of the absorbed
dose of a reference radiation that produces a specified biological effect to the absorbed dose of the radiation of
interest that produces the same biological effect.
Rem the special unit of dose equivalent. The dose equivalent in rem is numerically equal to the absorbed dose
in rads multiplied by the quality factor, distribution factor, and any other necessary modifying factors.
Restricted Area an area, access to which is limited by the licensee for the purpose of protecting individuals
against undue risks from exposure to radiation and radioactive materials. Restricted area does not include areas
used as residential quarters, but separate rooms in a residential building may be set apart as a restricted area.
Roentgen (R) the quantity of x or gamma radiation such that the associated corpuscular emission per 0.001293
gram of dry air produces, in air, ions carrying one electrostatic unit of quantity of electricity of either sign. Amount
of energy is equal to 2.58 x 10-4 coulombs/kg air. The Roentgen is a special unit of exposure.
Shallow Dose Equivalent applies to the external exposure of the skin or an extremity and is taken as the dose
equivalent at a tissue depth of 0.007 centimeter (7 mg/cm2 ) averaged over an area of one square centimeter.
Shielding Material any material which is used to absorb radiation and thus effectively reduce the intensity of
radiation, and in some cases eliminate it. Lead, concrete, aluminum, water and plastic are examples of
commonly used shielding material.
Sievert The international unit (SI) of dose equivalent (DE, human exposure unit), which is equal to 100 rem. It is
obtained by multiplying the number of grays by the quality factor, distribution factor, and any other necessary
modifying factors.
Somatic Effects of Radiation effects of radiation limited to the exposed individual, as distinguished from
genetic effects, which may also affect subsequent unexposed generations.
Stochastic Effects health effects that occur randomly and for which the probability of the effect occurring, rather
than its severity, is assumed to be a linear function of dose without threshold. Hereditary effects and cancer
incidence are examples of stochastic effects.
Survey an evaluation of the radiological conditions and potential hazards incident to the production, use,
transfer, release, disposal or presence of radioactive material or other sources of radiation. When appropriate,
such an evaluation includes a physical survey of the location of radioactive material and measurements or
calculations of levels of radiation, or concentrations or quantities of radioactive material present.
Terrestrial Radiation the portion of the natural radiation (background) that is emitted by naturally occurring
radioactive materials in the earth.
Thermoluminescent Dosimeter (TLD) crystalline materials that emit light if heated after being exposed to
radiation.
Unrestricted Area an area, access to which is neither limited nor controlled by the licensee.
Very High Radiation Area an area accessible to individuals, in which radiation levels could result in an individual
receiving an absorbed dose in excess of 500 rads (5 grays) in one hour at one meter from a radiation source or from
any surface that the radiation penetrates.
Whole Body for purposes of external exposure, head, trunk (including male gonads), arms above the elbow, or legs
above the knee.
X-rays penetrating electromagnetic radiations having wavelengths shorter than those of visible light. They are
usually produced by bombarding a metallic target with fast electrons in a high vacuum. In nuclear reactions it is
customary to refer to photons originating in the nucleus as gamma rays, and those originating in the extranuclear
part of the atom as x-rays. These rays are sometimes called Roentgen rays after their discoverer, W.C.
Roentgen.