Radiographic Interpretation: Coursework 3

WORLD CENTRE FOR MATERIALS JOINING TECHNOLOGY
Radiographic Interpretation
Coursework 3
Answer all questions
1. Kilovoltage, exposure time and source to film distance are three of three most important
X-ray exposure factors. A fourth such exposure factor is:
A. focal spot size

B. temperature
C. filament-to-focal spot distance
D. milliamperage
2. In making an isotope exposure in an unshielded area, you find the dose rate 6 feet from
the source is 1200 Mr/hr. What would be the dose rate at 24 feet?
A. 75 mr/hr
B. 100 mr/hr
C. 200 mr/hr
D. 300 mr/hr
3. A source of iridium-192, whose half life is 75 days, provides an optimum exposure of a

given test object today with an exposure 20 minutes. Five months from now, what
exposure time would be required for the same radiographic density, under similar
exposure conditions?
A. 10 minutes
B. 20 minutes
C. 1 hour and 20 minutes
D. 6 hours
4. In an X-ray tube, the filament and focusing cup are the two essential parts of the:
A. anode
B. cathode
C. rectifier
D. X-ray transformer
5. The absorption of gamma-rays from a given source when passing through matter depends
on:
A. the atomic number, density and thickness of the matter

B. the Young's modulus value of the matter
C. the Poisson's ratio value of the matter
D. the specific activity value of the source
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6. The fact that gases, when bombarded by radiation, ionise and become electrical
conductors make them useful in:
A. X-ray transformers
B. X-ray tubes
C. masks
D. radiation detection equipment
7. Cobalt-60 has a half life of 5.3 years. By how much should exposure time be increased
(over that used when the source was new) when the source is two years old?
A. no change in exposure time is needed

B. exposure time should be about 11 per cent longer
C. exposure time should be about 37 per cent longer
D. exposure time should be from 62 to 100 per cent longer
8. The focal spot in an X-ray tube:
A. is inclined at an angle of 30 from the normal to the tube axis

B. is maintained at a high negative voltage during operations
C. should be as large as possible to ensure a narrow beam of primary radiation
D. should be as small as possible without unduly shortening the life of a tube.
9. Materials which are exposed to gamma or X-rays below a few million volts:
A. should not be handled for at least 3 minutes after exposure has ceased.
B. should be stored in a lead-lined room
C. will not be dangerous to handle after exposure to radiation has ceased
D. should be monitored by means of a Geiger counter.
10. If an exposure time of 60 seconds was necessary using a 50cm SFD for a particular
exposure, what time would be necessary if a 25cm SFD distance is used and all other
variables remain the same?
A. 120 seconds
B. 30 seconds
C. 15 seconds
D. 240 seconds
11. If it was necessary to radiograph a 7 inch thick steel product, which of the following
gamma-ray sources would most likely be used?
A. cobalt-60
B. thulium-170
C. iridium-192
D. caesium-137
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12. An iridium 192 gamma-ray source has a practical thickness limit of:
A. 2 inches of steel or its equivalent

B. 3 inches of steel or its equivalent
C. 4 inches of steel or its equivalent
D. 5 inches of steel or its equivalent
13. The velocity of electrons striking the target in an X-ray tube is a function of:
A. the atomic number of the cathode material

B. the atomic number of the filament material
C. the voltage difference between the cathode and anode
D. the current flow in the rectifier circuit
14. Two x-ray machines operating at the same nominal kV and ma settings:
A. will produce the same intensities and qualities of radiation

B. will produce the same intensities and may produce different qualities of radiation
C. will produce the same qualities but may produce different intensities of radiation
D. may give not only different intensities but also different qualities of radiation.
15. When referring to a 1T,2T or 4T hole in the ASME Boiler Code, ASTM, or armed forces
penetrameter, the T refers to:
A. the part thickness

B. the penetrameter thickness
C. the time of exposure
D. the time for developing
16. Images of discontinuities close to the source side of the specimen become less clearly
defined as:
A. source-to-object distance increases

B. the thickness of the specimen increases
C. the size of the focal spot decreases
D. the thickness of the specimen decreases
17. A general rule governing the application of the geometric principles of shadow formation
states that:
A. the X-rays should proceed from as large a focal spot as other consideration will allow
B. the distance between the radiation source and the material examined should be as
small as practical
C. the film should be as far as possible from the object being radiographed
D. the central ray should be as nearly perpendicular to the film as possible, to preserve
spatial relationships.
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18. Although there may be other reasons for using calcium tungstate screens in industrial
radiography, they are most usually used to:
A. improve definition and resolution in radiographic images

B. improve contrast in radiographic images
C. increase exposure speed
D. make films respond to multi-million volt radiation.
19. Excessive exposure of film to light prior to development of the film will most likely result
in:
A. a foggy film
B. poor definition
C. streaks
D. yellow stain
20. White crescent-shaped marks on an exposed film are most likely caused by:
A. crimping film after exposure

B. crimping film before exposure
C. sudden extreme temperature change while processing
D. warm or exhausted fixer
21. Reticulation resulting in a puckered or netlike film surface is probably caused by:
A. crimping film after exposure

B. sudden extreme temperature change while processing
C. water or developer on unprocessed film
D. excessive object-film distance
22. Frilling or loosening of the emulsion from the base of the film is most likely caused by:
A. water or developer on unprocessed film

B. low temperature of processing solutions
C. developer solution contamination
D. warm or exhausted fixer solution
23. As a check on the adequacy of the radiographic technique, it is customary to place a

standard test piece on the source side of the specimen.This standard test piece is called a:
A. reference plate
B. lead screen
C. penetrameter
D. illuminator
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24. If a viewer is reflecting an incident light of 3000cd/m2, when a radiograph is placed on a

viewer the transmitted light was 120cd/m2 . Calculate the density of the radiograph.
A. 1.39
B. 2.39
C. 1.15
D. 1.30
25. Lead foil screens are used in radiography:
A. to improve the quality of the radiograph by preferentially reducing the effect of scatter
radiation
B. to reduce the exposure time
C. both A. and B. are reasons for using lead foil screens
D. neither A. nor B. are reasons for using lead foil screens
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WORLD CENTRE FOR MATERIALS JOINING TECHNOLOGY

Answer all questions

A. focal spot size

3. A source of iridium-192, whose half life is 75 days, provides an optimum exposure of a

A. the atomic number, density and thickness of the matter

Page 1 RI-cw3 doc.

A. no change in exposure time is needed

8. The focal spot in an X-ray tube:

A. is inclined at an angle of 30 from the normal to the tube axis

Page 2 RI-cw3 doc.

A. 2 inches of steel or its equivalent

A. the atomic number of the cathode material

A. will produce the same intensities and qualities of radiation

A. the part thickness

A. source-to-object distance increases

Page 3 RI-cw3 doc.

A. improve definition and resolution in radiographic images

A. crimping film after exposure

A. crimping film after exposure

A. water or developer on unprocessed film

23. As a check on the adequacy of the radiographic technique, it is customary to place a

Page 4 RI-cw3 doc.

24. If a viewer is reflecting an incident light of 3000cd/m2, when a radiograph is placed on a

25. Lead foil screens are used in radiography:

Page 5 RI-cw3 doc.

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