RT

Level II Questions 1.

Low voltage X-ray tubes are generally fitted with windows made of: A. Plastic. B. Beryllium. C. D. Lead.

2.

A monochromatic X-ray beam: A. B. C. D

3.

Glass.

Is a narrow beam used to produce high-contrast radiographs Is also referred to as a heterogeneous X-ray beam. Is a beam containing only characteristic X-radiation Is a beam consisting of a single wavelength.

The general method of producing X-ray involves the sudden deceleration of high velocity electrons in a solid body called a: A. Focus cup.

Filament. Target. D 4.

If it were necessary to radiograph a 7-inch thick steel product, which of the following gamma-ray sources would most likely be used? A. B. C. D.

5.

Cathode.

Cobalt-60 Thulium-170 Iridium-192 Cesium-137

A cobalt-60 gamma-ray source has an approximate practical thickness limit of:

A. B. C. D.

2 ½ inches of steel or its equivalent. 4 inches of steel or its equivalent. 9 inches of steel or its equivalent. 11 inches of steel or its equivalent. 6. The absorption of gamma rays from a given source when passing through matter depends on:

A. B. C. D.

The atomic number, density, and thickness of the matter The young’s modulus value of the matter. The Poisson’s ratio value of the matter. The specific activity value of the source. 7. The fact that gasses, when bombarded by radiation, ionize and become electrical conductors make them useful in:

A. B. C. D.

X-ray transformers. X-ray tubes Masks Radiation detection equipment. 8.

The velocity of electrons striking the target in an X-ray tube is a function of:

A. B. C. D.

The atomic number of the cathode materials The atomic number of the filament material. The voltage difference between the cathode and anode. The current flow in the rectifier circuit. 9. The uneven distribution of developed grains within the emulsion of a processed X-ray film causes the subjective impression of:

A. B. C. D.

Graininess Streaks. Spots. White scum. 10.

Cobalt –60 is reported to have a half – life of 5,3 years. By how much should exposure time be increased (over that used initially to produced excellent radiographs when the cobalt-60 source was new) when the source is two years olds?

A. B. C. D.

No change in exposure time needed. Exposure time should be about 11 percent longer Exposure time should be about 31 percent longer Exposure time should be about 62 to 100 percent longer. 11. A source of iridium-192, whose half-life is 75 days, provides an optimum exposure of a given test object today in a period of 20 minutes. Five months from now, what exposure time would be required for the same radiographic density, under exposure conditions?

A. B. C. D.

10 minutes 20 minutes 1 hour and 20 minutes. 6 hours Not: If questions 10 or 11 are used on a test, the examinee should be furnished semi logarithmic coordinate paper 12

Of the following, the source providing the most penetrating radiation is:

Cobalt-60 220kVp X-ray tube 15 MeV X-ray betatron. Electrons from iridium-192. The gamma-ray intensity at one foot from a one curie source of radioactive cobalt-60 is nearest: A. B. C. D.

15 roentgens per hour. 1,000 roentgens per hour. 1 roentgen per minute. 10 milliroents per day.

D-36, A-15-13

The focal spot in an X-ray tube:

A. B. C. D.

Is inclined at an angle of 30o from the normal to the tube axis. Is maintained at a high negative voltage during operations. Should be as large as possible to ensure a narrow beam of primary radiation. Should be as small as possible without unduly shortening the life of the tube.

F-9, 10

In an X-ray tube, the filament and focusing cup are the two essential parts of the 0.001293 grams of dry air is known as: A. B. C. D.

Anode. Cathode. Rectifier. X-ray transformer.

F-9

16 The quantity of radiation which will produce, by means of ionization, one electrostatic unit of electricity in 0.001293 grams air is known as: A. B. C. D.

A millicurie. A gamma. A roentgen A curie.

F-15

The specific activity of an isotopic source is usually measured in: A. B. C. D.

Million electron volts. Curies per gram. Roentgens per hour. Counts per minute.

E-2-19,A-15-5

Which of the following isotopes has the longest half-life? A. B. C. D.

Thulium-170 Cobalt-60 Iridium-192 Cesium-137.

E-3-16, A-15-13

The primary form of energy conversion when electrons strike a target in an X-ray tube results in the production of: Primary X rays. Secondary X rays Short wavelength X rays.

E-3-6

20. The slope of a straight line joining two points of specified densities on a characteristic curve of s film is film is known as the A. B. C. D.

Speed of the curve. Latitude. Average gradient. None of the above.

F-126

An X-ray film having wide latitude also has, by definition: Poor definition. Low contrast High speed None of the above.

F-67 to 69

The purpose for circulating oil in some types of X-ray tubes is: A. B. C. D.

To lubricate moving parts. To absorb secondary radiation. To decrease the need for high current. To dissipate heat. 23

A. B. C. D.

A-16-24

X-ray tubes is rated for a maximum of 250 kVp. This tube may be operated at a maximum of:

An X-ray tube is rated for a maximum of 250 kVp. This tube may be operated at a maximum of:

A voltage selector consisting of an iron core transformer with a single winding having a series of taps at various points o the winding is called:

a high-voltage transformer. A filament transformer An autotransformer A power transformer 29

A. B. C. D.

Thin sheets of lead foil in intimate contact with X-ray film during exposure increase film density because:

250,000 volts peak voltage 250 kV effective voltages. 250,000,000 volts rms voltage. 28

A. B. C. D.

F-29

Dissipate heat. Protect the operator from high-voltage shock. Shield the tube from secondary radiation. Increase the efficiency of the rectifier. 27

A. B. C.

One method of reducing radiographic contrast is to:

They fluoresce and emit visible light which helps expose the film. They absorb the scattered radiation. They prevent backscattered radiation from fogging the film. They emit electrons when exposed to X-and gamma radiation which help darken the film. 26

A. B. C. D.

A-16-24

Increase the distance between the radiation source and the object. Decrease the distance between the object and the film. Decrease the wavelength of the radiation used. Increase development time within manufacturer’s recommendations. 25

A. B. C. D.

An X-ray tube with a small focal spots is considered better than one with a large focal spot when it is desires to obtain:.

Greater penetrating power Better definition. Less contrast. Greater film density. 24

A. B. C. D.

F-29

In X-ray radiography, alternating current must be changed to pulsating direct current in order to satisfy the need for unidirectional current. This change may be accomplished y:

Transformers. Rectifiers. Anodes Cathodes. 30

F-11

When radio graphing to the 2-2T quality level, an ASTM penetrameter for 2-5-inches steel has a thickness of:

A. B. C. D.

One –half inch. 2.5 mils 5 mils. 50 mils.

C-E94

Valve tubes are used in X-rays equipment to: Provide necessary rectification. Activate and deactivate the X-ray tube. Heat the filaments in the X-ray tube. Adjust the size of the target.

A-14-6, B-96, 97

32 A good cobalt-60 radiograph is made on a 3-inch steel casting using an exposure time of 10 minutes and a source-tofilm distance of 36 inches. It is necessary to change the source-to-film distance to 24 inches, what exposure time would produce a similar radiograph if all other conditions remain the same. A. B. C. D.

1.6 minutes 4.4 minutes 6.4 minutes 8.8 minutes.

F-47

33 When sharp, black, bird-foot shaped marks which are known not to correspond with any discontinuities appear at random on radiographs, they are probably caused by: A. B. C. D.

Prolonged development in old developer Exposure of the film by natural cosmic ray shower during storage. Static charges caused by friction. Inadequate rinsing after fixing.

F-148

The adjustment of tube current in conventional x-ray tube circuits is made by: A. B. C. D.

Adjusting the filament heating current. Adjusting the target-to-cathode distance. Inserting resistance in the anode lead. Opening the shutter on the X-ray tube port.

F-9

In comparison with lower-voltage radiographs, high-energy radiographs show: A. B. C. D.

Greater contrast Greater latitude. Greater amount of scatter radiation relative to primary beam intensity. None of above.

A-23-4,5

Filter used at the port of the X-ray tube: A. B. C. D.

Intensity the filament heating current Filter short wavelength X-ray beams to provide “softer” radiation. Provide the most readily adjusted means of modifying X-ray intensity. Filter out “soft” radiation to provide a more homogeneous X-ray beam.

F-42

37 An ASTM pentameter for use when inspecting a one-half inch thick steel plate to the 2-2T quality level using a 15-inch source-to film distance would be made of: A. B. C. D.

5 mil thick aluminum. 50 mil thick aluminum or steel. 10 mil thick steel. 2 mil strip of any metallic material. 38

C-E94

The kilo voltage applied to an X-ray tube affects. A. B. C. D. 20-4

The quality of the beam. The intensity of the beam Both A and B above. Neither A nor B above.

Filters placed between the X-ray tube and specimen tend to reduce scatter radiation undercutting the specimen: by absorbing the longer wavelength components of the primary beam. By absorbing the shorter wavelength component of the primary beam.

A-

By absorbing backscatter radiation. By decreasing the intensity of the beam. Besides serving as a filter, screens of high atomic number, such as lead and lead antimony, also: decrease the source-to- firm distance needed for a proper radiograph. Provide some image intensifying action. Permit the use of higher speed film. Decrease the graininess in radiograph. 41.

The range of thickness over which densities are obtained that are satisfactory for interpretation is a measure of the:

Subject contrast of a radiograph. Sensitive of a radiograph Latitude of a radiograph. Definition of a radiograph. Almost all gamma radiography is performed with: Natural isotopes. Iridium-192 or cobalt-60 Radium. Thulium-170 43

The amount of unsharpness or blurring of radiograph is: A. B. C. D.

Directly proportional to the object-to-film distance and inversely proportional to the size of the focal spot. Directly proportional to the size of the focal spot and inversely proportional to the source-to-object distance. Inversely proportional to the object-to-film distance and directly proportional to the source-to-object distance. Inversely proportional to the size of the focal spot and object-to-film distance.

Images of discontinuity close to the source side of the specimen become less clearly defined as: A. B. C. D.

Source-to-object distance increase. The thickness of the specimen increase. The size of the focal spot decrease. The material used as a target.

The inherent filtration of an X-ray tube is a function of: A. B. C. D.

the thickness and composition of the X-ray tube port. The voltage setting of the instrument. The source-to-object distance. The material used as a target.

X-ray films with large grain size. A. B. C. D.

will produce radiographs better definition than film with small grain size. Have slower speeds than those with a relative small grain size. Have higher speeds than those with a relatively small grain size. Will take longer to expose properly than film with relatively small grain size.

As the effective energy of the radiation increases up to about 250 kV: A. B. C. D.

film graininess increases. Film graininess decreases. Radiographic definition increases. Film speed decreases.

The specific activity of cobalt-60 depends on: A. B. C. D.

the time the material has been in the reactor. The atomic number of the material. The gamma ray flux to which it was exposed. The young’s modulus value of the material.

The most commonly used target material in an X-ray tube is: A. B. C. D.

Copper Carbon Carbide Tungsten.

The purpose for including a disc-shaped target that rotates rapidly during operation in some X-ray is to: A. B. C. D.

Increase the intensity of X-radiation. Decrease the voltage needed for a specific quality of radiation. Increase the permissible load. None of the above answer is correct.

RT LEVEL II ANSWER SHEET Round the correct ANSWER NAME OF THE CANDIDATE : 1. 2. 3. 4. 5. 6. 7. 8. 9. 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. 35. 36. 37. 38. 39. 40. 41. 42. 43. 44. 45. 46. 47.

A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A

B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B

C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C

D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D

E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E

48. A 49. A 50. A

B B B

C C C

D D D

E E E