RT2

Question 1

1. Atoms of the same element that have different numbers of neutrons are called of the element.
   a. molecules
   b. isotopes
   c. isotones
   d. isomers

Answer 1

b. isotopes

Question 2

2. The number of positive charges on the nucleus of an atom equals the:
   a. number of neutrons.
   b. atomic number.
   c. number òf photons.
   d. atomic weight.

Answer 2

b. atomic number.

Question 3

3. Unlike beta and alpha particles, neutrons have no:
   a. charge.
   b. mass.
   c. spin.
   d. half-life.

Answer 3

a. charge.

Question 4

4. Radiation scattering increases as:
   a. the energy of the incident radiation decreases.
   b. the size of the radiation field decreases.
   c. the angle of scatter increases.
   d. pair production is eliminated.

Answer 4

a. the energy of the incident radiation decreases.

Question 5

5. A consequence of a series of single events occurring as a radiation beam passes through material is a decrease in intensity. The process is called:
   a. photoelectric effect.
   b. ionization.
   c. absorption.
   d. half-value thickness.

Answer 5

c. absorption.

Question 6

6. The number of ion pairs produced by particle per unit path is called:
   a. secondary ionization.
   b. total ionization.
   c. specific ionization.
   d. roentgen.

Answer 6

c. specific ionization.

Question 7

7. Pair production occurs when electromagnetic radiation consists of photons in what energy range?
   a. 0.025 to 0.1 MeV
   b. 30 to 50 Mev
   c. 1.02 MeV or greater
   d. 0.1 to 1.0

Answer 7

c. 1.02 MeV or greater

Question 8

8, In the photoelectric interaction process:
a. electrons are emitted.
b. characteristic X-rays are emitted.
c. secondary photons are emitted.
d. an electron-positron pair is produced.

Answer 8

a. electrons are emitted.

Question 9

9. The compton interaction process is characterized by:
   a. absence of secondary radiation.
   b. no transfer of energy upon interaction.
   c. production of an electron-positron pair,
   d. partial transfer of energy upon collision.

Answer 9

d. partial transfer of energy upon collision.

Question 10

10. The major component of scatter is the low-energy electromagnetic radiation produced by photons weakened in the:
    a. photoelectric process.
    b. compton process.
    c. pair production process.
    d. ionization process.

Answer 10

b. compton process.

Question 11

11. The increase in radiation passing through matter due to scatter In the forward direction is called:
    a. buildup.
    b. reduction factor.
    c. backscatter.
    d. bremsstrahlung.

Answer 11

a. buildup.

Question 12

12. High-energy photons of 1.02 MeV or greater typically interact with matter by which one of the following?
    a. Photoelectric process.
    b. Compton process.
    c. Pair production process.
    d. Thermionic process.

Answer 12

c. Pair production process.

Question 13

13. In which of the following processes will some energy of the interacting photon be used to dislodge the electron from the K or L shell and the remainder be used to give the electron kinetic energy?
    a. Photoelectric process.
    b. Compton process.
    c. Pair production process.
    d. Ionization process.

Answer 13

a. Photoelectric process

Question 14

14. According to accepted theory, the spots at which the latent image is localized on the emulsion are local concentrations of:
    a. silver sulfide.
    b. silver bromide.
    c. silver iodide.
    d. silver nitrate.

Answer 14

a. silver sulfide.

Question 15

15. The bunsen-roscoe reciprocity law, which states that the developed film density depends only on the product of radiation intensity times exposure duration, fails for:
    a. direct gamma-ray exposures.
    b. fluorescent screen exposures.
    c. lead screen exposures.
    d. direct X-ray exposures.

Answer 15

b. fluorescent screen exposures.

Question 16

16. In photofluorography, where a fluoroscopic screen is used for radiographic imaging, it is important to choose a screen that has a visible light emission that is relatively high at the X-ray wavelengths to be used and that:
    a. matches the wavelength sensitivity of the human eye.
    b. has a minimum decay time.
    c. can be viewed directly without the use of leaded glass or mirrors.
    d. matches the wavelength sensitivity of the particular image detector being used.

Answer 16

d. matches the wavelength sensitivity of the particular image detector being used.

Question 17

17. When comparing fluorescent intensifying screens with lead foil screens, the primary advantage is:
    a. improved image resolution.
    b. markedly increased exposure times.
    c. markedly decreased exposure times.
    d. relative insensitivity to scattered radiation.

Answer 17

c. markedly decreased exposure times.

Question 18

18. Fluoroscopy of a specimen using a 140 kVp 10 mA X-ray source results in an intensity of 660 mSv/min (66 R/min) at the screen surface. Of the screen brightness values and approximate screen colors below (for the stated radiation level), which represents the most desirable screen for use in direct viewing fluoroscopy?
    a. brightness — 9.8 Ix (0.91 ftc); color — green
    b. brightness - 8.5 Ix (0.79 ftc); color — yellow
    c. brightness - 7 Ix (0.65 ftc); color — blue
    d. brightness — 4.6 Ix (0.43 ftc); color - green

Answer 18

b. brightness - 8.5 Ix (0.79 ftc); color — yellow

Question 19

19. Unlike other commercially available X-ray intensification systems, the direct X-ray pickup tube:
    a. has quantum energy losses exceeding a factor of 500.
    b. has extremely low sensitivity.
    c. converts the X-ray image directly into an electrical signal.
    d. converts X-rays to light and light to electrical signals.

Answer 19

c. converts the X-ray image directly into an electrical signal.

Question 20

20. A fundamental difficulty of fluorescent imaging is the relatively low brightness level of the images. Electronic fluoroscopy can help to eliminate this problem by all but which one of the following?
    a. Using X-ray tubes of lower operating potential.
    b. Using an image tube.
    c. Using X-ray tubes of greater effective loading.
    d. Using the X-ray television system.

Answer 20

a. Using X-ray tubes of lower operating potential.

Question 21

21. The roentgen is defined as the amount of:
    a. radiation emitted by 1 Ci of Ir-192 at a distance of 1 m (3.3 ft).
    b. X- or gamma radiation of 0.1 PJ (1 erg) of energy in 1 g of dry air at standard temperature and pressure.
    c. X- or gamma radiation that will produce
    1 electrostatic unit of charge in 1 cm3 of dry air at standard temperature and pressure.
    d. X- or gamma radiation absorbed by 1 cm3 of water at 0 °C (32 °F) and 101 kPa (760 mm of Hg).

Answer 21

c. X- or gamma radiation that will produce
1 electrostatic unit of charge in 1 cm3 of dry air at standard temperature and pressure.

Question 22

22. X-ray generators built to provide X-rays at very low energy levels are used in special areas in nondestructive testing. The single section X-ray tubes in these low voltage units are usually built with thin windows of what material to permit soft X-rays to emerge from the vacuum envelope?
    a. Beryllium.
    b. Germanium.
    c. Selenium.
    d. Heat-resistant glass.

Answer 22

a. Beryllium.

Question 23

28. The focal spot should be as small as conditions permit, in order to obtain:
    a. the sharpest possible definition.
    b. the minimum size of the unit.
    c. the maximum energy density.
    d. the maximum grain size.

Answer 23

a. the sharpest possible definition

Question 24

29. The focusing cup of the cathode in an X-ray tube determines the size of the electron beam by:
    a. surrounding the emerging beam with an electronic field that repels the beam into a more localized form.
    b. limiting the maximum amperage of the filament current.
    c. reducing the negative charge on the glass walls of the tube caused by secondary electrons scattered by the target.
    d. controlling the electric field between the anode and the cathode.

Answer 24

a. surrounding the emerging beam with an electronic field that repels the beam into a more localized form.

Question 25

30. Early X-ray tubes used a cold cathode from which electrons were released by: a. reflection from the target in the anode of the tube. b. increasing the kilovoltage. c. positive ion bombardment. d. heating a filament.

Answer 25

c. positive ion bombardment.

Question 26

31. The betatron accelerates electrons by: a. radio-frequency energy. b. magnetic induction. c. use of a nonconducting charging belt. d. resonating the high voltage to the frequency of the AC power.

Answer 26

b. magnetic induction.

Question 27

32. What method is not used for generation of X-rays in the multimillion volt range? a. Electrostatic generator. b. Betatron. c. Linear accelerator. d. Selenium target generator.

Answer 27

d. Selenium target generator.

Question 28

33. In a betatron, electrons are accelerated by which of the following? a. Field emission. b. High-frequency magnetic field. c. High-frequency electrical wave. d. Accelerating magnets.

Answer 28

b. High-frequency magnetic field.

Question 29

34. In a linear accelerator, the electrons are accelerated by which of the following? a. High-frequency electrical wave. b. Accelerating magnets. c. Neutron bombardment. d. Changing magnetic fields of an AC electromagnet.

Answer 29

a. High-frequency electrical wave.

Question 30

35. In a high-voltage generator of the electrostatic van de graaff type, by which method are the particles accelerated? a. Accelerating magnets. b. High-frequency electrical waves. c. Static negative charges. d. High-frequency radio waves.

Answer 30

c. Static negative charges.

Question 31

36. Flash X-ray tubes are usually designed to produce electrons for acceleration by which one of the following methods? a. Hot emission. b. Cold-cathode field emission. c. Changing magnetic field of a transformer primary. d. High-frequency electrical waves.

Answer 31

b. Cold-cathode field emission.

Question 32

37. Tungsten is the preferred target material for X-ray tubes used in industrial X-ray machines because it provides a double advantage. One of the advantages is that: a. the efficiency of the tungsten material in the production of X-rays is proportional to its atomic number. b. it has a low melting point. c. the efficiency of the tungsten material in the production of X-rays is inversely proportional to its atomic number. d, it has a high curie point.

Answer 32

a. the efficiency of the tungsten material in the production of X-rays is proportional to its atomic number.

Question 33

38. The efficiency of the target material in the production of X-rays is proportional to: a. kilovoltage. b. spacing of electrodes. c. atomic number. d. Avogadro's number.

Answer 33

c. atomic number.

Question 34

39. In choosing a suitable metal for a target material, the principal properties to be considered are all but which one of the following? a. High atomic number. b. High melting point. c. High thermal conductivity. d. High vapor pressure.

Answer 34

d. High vapor pressure.

Question 35

40. Another way to alleviate the localized heating of the target is with a: a. rotating anode. b. hot anode. c. hooded anode. d. line-focus anode.

Answer 35

a. rotating anode.

Question 36

41. An important design consideration of X-ray tubes, based on the low efficiency of X-ray production, is: a. target angle. b. focal spot size. c. accelerating voltage. d. heat dissipation.

Answer 36

d. heat dissipation.

Question 37

42. In choosing a suitable metal for an X-ray tube target, which of the following is not a property that is normally considered? a. Atomic number. b. Melting point. c. Mass attenuation coefficient. d. Thermal conductivity.

Answer 37

c. Mass attenuation coefficient.

Question 38

43. Of the isotopes listed below, which is a fission fragment from the induced fission of Ur-235? a. Co-60 b. Cs-137 c. Ir-192 d. Tm-170

Answer 38

b. Cs-137

Question 39

44. Because it is frequently supplied as a water-soluble compound, which of the following is considered to have an additional radiological hazard potential associated with it? a. Co-60 b. Tm-170 c. Ir-192 d. Cs-137

Answer 39

d. Cs-137

Question 40

45. Which one of the following radioisotope sources would be the best choice for radiography of a steel specimen 9.5 mm (0.375 in.) thick from an energy standpoint? a. Co-60 b. Tm-170 c. Ir-192 d. Cf-252

Answer 40

b. Tm-170

Question 41

46. The half-life is a useful characteristic of a radioisotope. After 6 half-lives, the amount of decaying atoms is reduced to approximately what percent of the amount at the beginning? a. 2% b. 3% C. 6% d. 1%

Answer 41

a. 2%

Question 42

47. Generally, sources of high specific activity are more desirable because they have self-absorption. a. higher b. the same c. lower d. no

Answer 42

c. lower

Question 43

48. Radiation output, also known as dosage rate or characteristic intensity, is usually expressed as effective output in what unit per curie? a. RHM b. Rhr c. rms d. mR/h

Answer 43

d. mR/h

Question 44

49. Co-60 emits gamma rays of: a. 1.17 and 1.33 Mev b. 0.66 MeV c. 1.09 and 1.29 Mev d. 1.36 and 2.75 Mev

Answer 44

a. 1.17 and 1.33 Mev

Question 45

50. The principal gamma rays emitted by Ir-192 are: a. 0.66, 0.84, and 0.91 Mev b. 0.31, 0.47, and 0.60 Mev c. 0.08, 0.05, and 0.66 Mev d. 0.15, 1.12, and 0.18 Mev

Answer 45

b. 0.31, 0.47, and 0.60 Mev

Question 46

51. Which of the following is true for a smaller isotope source of higher specific activity? a. It suffers more from self-absorption of its own gamma radiation. b. There is more geometric unsharpness in the radiograph. c. It requires more safety margin. d. It allows shorter source-to-film distances.

Answer 46

d. It allows shorter source-to-film distances.

Question 47

52. Which of the following is an advantage of radiography with gamma rays as compared to X-rays? a. The complexity of the apparatus. b. The massive size of the radiation source. c. Requires fewer safety measures. d. Independence from outside power.

Answer 47

d. Independence from outside power.

Question 48

53. Suppose a radiograph is made using film whose characteristic graph is shown in Figure 4. The film is exposed for 12 mA per minute and has a density of 0.8 in the area of interest. It is desired to increase the density to 2.0. What milliamperage per minute would produce such a change? a. 19 b. 62 c. 50 d. It is impossible to determine from this data.

Answer 48

c. 50

Question 49

54. The agent that actually exposes a photographic grain (film) is: a. gamma and/or X-ray quantum. b. alpha particles. c. electrons. d. photon.

Answer 49

d. photon.

Question 50

55. Which of the following is governed by the source size, object-to-film distance, and source-to-object distance? a. Geometric unsharpness. b. Inherent unsharpness. c. Radiographic contrast. d. Effective graininess.

Answer 50

a. Geometric unsharpness

Question 51

56. Caution should be exercised to avoid removing film too rapidly from cartons, exposure holders, or cassettes. This would help to eliminate objectionable circular or tree-like black marks caused by: a. crimps. b. reticulation. c. static electricity. d. scratches.

Answer 51

c. static electricity.

Question 52

57. The obtainable counting speed using a scintillation counter is limited fundamentally by the: a. energy level of the incident radiation. b. intensity of the incident radiation. c. delay between electron excitation and de-excitation. d. spatial distribution of the incident quanta,

Answer 52

c. delay between electron excitation and de-excitation.

Question 53

58. The scintillations (light photons) emitted by a radiation detection phosphor are converted to electrical pulses by: a. a photomultiplier tube. b. an ionization chamber. c. a selenium photoelectric cell. d. a light-pulse amplifier.

Answer 53

a. a photomultiplier tube.

Question 54

59. In comparing electronic image intensifier systems that use TV presentation with those using solid-state screens and high-sensitivity closed-circuit TV systems, which of the following statements is false? a. The overall gain of an image intensifier/TV combination usually exceeds that of the screen/TV combinations. b. The overall resolution of the intensifier/TV combination usually exceeds that of the screen/TV combination. c. As the area of the viewed screen increases for either, the overall system gain must also increase. d. The single-crystal scintillating screens and the fine-grain fluorescent screens have better resolution than the electronic image intensifier tubes but much lower light output.

Answer 54

b. The overall resolution of the intensifier/TV combination usually exceeds that of the screen/TV combination.

Question 55

61. In the past, several companies have designed TV cameras with large face plates and phosphors that directly convert the received X-rays to electron scanning-beam variations. The thickness of the glass face plate is recognized to prevent use at lower kilovoltage applications, but use at higher kilovoltages has never gained acceptance either, compared with other techniques. Which of the following is not correct for this type of system? a. The quantum energy losses associated with converting the X-rays to electrical signals is improved over other systems by a factor of as much as 500 times. b. In comparison to systems using image orthicons with screens or with an image intensifier system, the image presented is noisier. c. The extreme simplicity of this system and need for few controls or adjustments makes maintenance easier than other types of systems using intermediate conversion. d. The extreme sensitivity of this system allows display of 2% IQIs over the range of 40-300 kVp.

Answer 55

d. The extreme sensitivity of this system allows display of 2% IQIs over the range of 40-300 kVp.

Question 56

62. One desirable property for a gas to be used in an ionization detector is a: a. low saturation potential at which recombination of positive ions with electrons becomes negligible. b. low ionization potential. c. density approximately equivalent to the density of the chamber walls. d. density equivalent to that of air at standard temperature and pressure.

Answer 56

a. low saturation potential at which recombination of positive ions with electrons becomes negligible.

Question 57

63. The greatest problem that arises in the routine use of a pocket dosimeter is: a. its relatively flat response to radiation of different energies. b. its inherently inconsistent sensitivity. c. electrical leakage that tends to discharge the electrometer and give false high readings. d. negative drift caused by changes in atmospheric conditions (temperature, humidity, etc.).

Answer 57

c. electrical leakage that tends to discharge the electrometer and give false high readings.

Question 58

64. As a portable radiation survey instrument, the main disadvantage of a geiger counter is its: a. nonlinear response with changes in radiation energy, b. large size and delicate construction. c. poor sensitivity to low radiation levels. d. warm-up drift during the first few minutes of operation.

Answer 58

c. poor sensitivity to low radiation levels.

Question 59

65. Air-filled proportional counters are used extensively for monitoring: a. gamma-ray activity. b. fast neutron activities. c. slow neutron activities. d. alpha/beta dose rates.

Answer 59

d. alpha/beta dose rates.

Question 60

66. An amplifier to be used in a survey instrument designed to measure high levels of radiation should have the following characteristics: a. a fast rise time and a linear response. b. a fast rise time and an exponential response. c. a slow rise time and a linear response. d. a slow rise time and an exponential response.

Answer 60

a. a fast rise time and a linear response.

Question 61

67. Which of the following detectors would be most suitable for use with a gamma- or X-ray energy spectrum analyzer? a. An ionization detector. b. A scintillation detector. c. A proportional detector. d. A geiger-müller counter.

Answer 61

b. A scintillation detector.

Question 62

68. Which of the following radiation measurement instruments does not employ gas detection as its operation mechanism? a. Proportional counter. b. Semiconductor detector. c. Ionization chamber. d. Geiger-müller counter.

Answer 62

b. Semiconductor detector.

Question 63

69. A system of X-ray thickness gaging in which X-rays are collimated and projected through a test item and the quantity of unabsorbed radiation is measured is referred to as: a. fluorescence method b. absorption differential method. c. attenuation buildup method. d. transmission method.

Answer 63

d. transmission method.

Question 64

70, Generally, the sensitivity and accuracy of thickness gaging of homogeneous materials by reflection methods is: a. superior to transmission gaging. b. superior to fluorescence methods. c. inferior to transmission gaging. d. approximately the same as with transmission gaging.

Answer 64

c. inferior to transmission gaging.

Question 65

71. The two types of detectors used most commonly in X-ray thickness gages are: a. fluorescent screens and ionization chambers. b. proportional counters and geiger counters. c. phosphor-photomultipliers and ionization chambers. d. fluorescent screens and phosphorphotomultipliers.

Answer 65

c. phosphor-photomultipliers and ionization chambers.c. phosphor-photomultipliers and ionization chambers.

Question 66

72. Sources of radioactive material used for radiography are required by regulation to be leak tested at intervals not to exceed: a. 3 months. b. 6 months. c. 12 months. d. 24 months.

Answer 66

b. 6 months.

Question 67

73. Distance is an effective means of external radiation protection because: a. air absorption reduces the radiation intensity. b. radiation intensity varies inversely as the square of the distance. c. X-rays and gamma rays have a finite range. d. the wavelength of the photons is decreased by their interaction with matter.

Answer 67

b. radiation intensity varies inversely as the square of the distance.

Question 68

74. X-ray photons differ from gamma photons of the same energy only in their: a. biological effect. b. origin. c. interaction. d. ability to produce an electron.

Answer 68

b. origin.

Question 69

75. The half-life of a radioactive substance is equal to the: a. reciprocal of the disintegration constant. b. average lifetime of an atom in the substance. c. time required for half of the original atoms to disintegrate. d. number of atoms present divided by the rate of decay.

Answer 69

c. time required for half of the original atoms to disintegrate.

Question 70

76. A tenth-value thickness for a specific gamma source is 25.4 mm (1 in.) of lead. The radiation intensity is 5000 mSv/h (500 R/h) at 609.6 mm (24 in.) from the source. How many millimeters (inches) of lead would be required to reduce the intensity to 50 gSv/h (5 mR/h) at 609.6 mm (24 in.)? a. 50.8 mm (2 in.) b. 127 mm (5 in.) c. 254 mm (10 in.) d. 101.6 mm (4 in.)

Answer 70

b. 127 mm (5 in.)

Question 71

77. Survey instruments used to monitor gamma radiation must be capable of measuring radiation in the range of: a. 1-2 mSv/h (100-200 mrem/h) b. 20-500 000 gsv/h (2-50 000 mR/h) c. 0-2000 psv/h (0-200 mR/h) d. 0.02-10 mSv/h (2-1000 mrem/h)

Answer 71

d. 0.02-10 mSv/h (2-1000 mrem/h)

Question 72

78. A radiation area refers to the perimeter of any area in which the radiation level exceeds: a. 20 YSv (2 mrems) b. 1 mSv (100 mrems) c. 50 gsv (5 mR) d. 5 mSv (500 mrems)

Answer 72

c. 50 gsv (5 mR)

Question 73

79. Radiographic sensitivity depends on the combined effects of two independent factors. One is radiographic contrast; the other is: a. radiation quality, b. density. c. IQI image. d. definition.

Answer 73

d. definition.

Question 74

81. Radiographic sensitivity is: a. a general or qualitative term referring to the size of the smallest detail which can be seen on a radiograph. b. only a measure of the contrast properties of the radiographic system. c. a term usually applied to the contrast properties of the radiographic system. d. a term that reflects film speed and contrast properties.

Answer 74

a. a general or qualitative term referring to the size of the smallest detail which can be seen on a radiograph.

Question 75

82. Radiographic sensitivity is totally controlled by: a. film and screen combinations. b. those factors that control radiographic contrast and definition. c. kilovoltage and milliamperage. d. kilovoltage and film processing.

Answer 75

b. those factors that control radiographic contrast and definition.

Question 76

83. The visibility of a certain image quality indicator (IQI) hole on the radiograph may mean that: a. a cavity of the same diameter will be visible. b. a cavity of half the hole diameter will be visible. c. a cavity of the same diameter may be invisible. d. the hole and cavity will have equal detectability.

Answer 76

c. a cavity of the same diameter may be invisible.

Question 77

84. The IQI is used to: a. determine the size of cracks and pores that can be detected. b. determine the crack depths that can be detected. c. determine critical discontinuity size. d. indicate the quality of the radiographic technique.

Answer 77

d. indicate the quality of the radiographic technique.

Question 78

85. The sensitivity requirement 2-2T represents: a. IQI thickness the specimen thickness with the required IQI hole 2% of the specimen thickness. b. IQI thickness 2% of specimen thickness with the required IQI hole 2x the IQI thickness. c. IQI thickness 2% of the specimen thickness with the required IQI hole 2% of the specimen thickness. d. IQI thickness 2% of the specimen thickness with the required IQI hole 4% of the IQI thickness.

Answer 78

b. IQI thickness 2% of specimen thickness with the required IQI hole 2x the IQI thickness.

Question 79

86. Radiographic sensitivity is not affected by: a. subject contrast. b. geometric and film graininess factors. c. film contrast. d. ambient temperature.

Answer 79

d. ambient temperature.

Question 80

87. The IQI should not be used to: a. judge the size or establish acceptance limits of discontinuities. b. judge the adequacy of a radiographic exposure. c. determine the adequacy of film/screen combinations. d. judge the adequacy of part-to-film distance,

Answer 80

a. judge the size or establish acceptance limits of discontinuities.

Question 81

88. Which of the following parameters does not directly affect radiographic definition? a. Focal spot or source size b. Density. c. Type of screen. d. Radiation quality.

Answer 81

b. Density.

Question 82

89. Using a filter at the X-ray tube, masking to lessen the thickness range, and a multiple-film technique are ways of correcting: a. low density. b. low latitude. c. poor definition. d. low radiographic contrast.

Answer 82

b. low latitude.

Question 83

90. Poor definition can be improved by doing all but which one of the following? a. Increase source-to-film distance. b. Use a smaller physical source size. c. Change from Class Il to Class I film. d. Change from lead to fluorescent screens.

Answer 83

d. Change from lead to fluorescent screens.

Question 84

91. Based on the characteristic curves of the films shown in Figure 5, which film provides the highest contrast? a. x b. y c. z d. Cannot be determined from the curves.

Answer 84

b. y

Question 85

92. Subject contrast depends on: a. mA, source strength, distance, and film type. b. film-screen type. c. nature of the specimen, radiation quality (kV), and the intensity and distribution of the scattered radiation. d. Lambert's law.

Answer 85

c. nature of the specimen, radiation quality (kV), and the intensity and distribution of the scattered radiation.

Question 86

93. Which of the following is a factor in radiographic contrast? a. Film type. b. Radiation quality. c. Degree of film development. d. X-ray energy.

Answer 86

d. X-ray energy.

Question 87

94. Film contrast refers to: a. the density difference in two adjacent regions of film. b. the steepness (slope) of the characteristic curve. c. the ratio of X-ray or gamma-ray intensities transmitted by two selected portions of a specimen. d. minimum perceptible density change.

Answer 87

b. the steepness (slope) of the characteristic curve.

Question 88

95. In general, the contrast of radiographic films (except those designed for use with fluorescent screens): a. increases continuously with film density in the usable density range. b. decreases as the density is increased. c. remains practically unchanged for different density levels. d. is inversely proportional to film density.

Answer 88

a. increases continuously with film density in the usable density range.

Question 89

96. The graininess of all films: a. increases as the kilovoltage is increased up to approximately 200 kV. b. decreases as the kilovoltage is increased. c. is not dependent on kilovoltage. d. is totally controlled by Lambert's law.

Answer 89

a. increases as the kilovoltage is increased up to approximately 200 kV.

Question 90

97. Specimens with uniform thickness and composition by definition have: a. high subject contrast. b. good definition. c. high film contrast. d. low subject contrast.

Answer 90

d. low subject contrast.

Question 91

98. The sharpness of outline in a radiographic image is called: a. definition. b. sensitivity. c. latitude. d. contrast.

Answer 91

a. definition.

Question 92

99. Poor radiographic definition is related to: a. focal spot size. b. source-to-film distance. c. poor film-screen contact. d. degree of film development.

Answer 92

d. degree of film development.

Question 93

100. Which of the following is not a factor to be considered to reduce geometric unsharpness? a. Source-to-film distance, b. Object-to-film distance. c. Source strength. d. Source size.

Answer 93

c. Source strength.

Question 94

101. Using Figure 6, determine the geometrical unsharpness under the following conditions. Maximum specimen thickness is 38 mm (1.5 in.), source-to-film distance is 1016 mm (40 in.), and the focal spot size is 1 mm (0.04 in.). The geometrical unsharpness is: a. 0.010 mm (0.0004 in.) b. 0.102 mm (0.004 in.) c. 0.051 mm (0.002 in.) d. 0.25 mm (0.01 in.)

Answer 94

c. 0.051 mm (0.002 in.)

Question 95

102. In the following equation for geometric unsharpness, what does Ug represent? a. Image size. b. Penumbra. c. Source-to-film distance. d. Specimen-to-film distance.

Answer 95

b. Penumbra.

Question 96

103. The size of the penumbral shadow can best be reduced by: a. using a larger diameter source. b. using a faster speed film. c. increasing the source-to-film distance. d. increasing the specimen-to-film distance.

Answer 96

c. increasing the source-to-film distance.

Question 97

104. Deviation from the true shape of an object as exhibited in its shadow image is called: a. definition. b. latitude. c. contrast. d. distortion.

Answer 97

d. distortion.

Question 98

105. Which of the following rules of shadow formation is not true? a. The effective focal spot or source size should be as small as practical. b. The distance between the focal spot or source and the test object should be as great as practical. c. The central ray should be as nearly perpendicular to the film as possible to preserve spatial relations. d. The test object's plane of maximum interest should be perpendicular to the plane of the film.

Answer 98

d. The test object's plane of maximum interest should be perpendicular to the plane of the film.

Question 99

106. Given an Ir-192 source 3 mm (0.13 in.) in diameter, a geometrical unsharpness of 0.5 mm (0.02 in.), and a material thickness of 63 mm (2.5 in.), determine the minimum source-to-object distance. a. 320 mm (12.6 in.) b. 620 mm (24.6 in.) c. 412.7 mm (16.25 in.) d. 460 mm (18.1 in.)

Answer 99

c. 412.7 mm (16.25 in.)

Question 100

107. Projection magnification resulting from increased object-to-film distance is also useful in reducing scatter radiation because of: a. increasing definition. b. reducing physical source size. c. the air gap. d. macroradiography.

Answer 100

c. the air gap.

Question 101

108. Magnification and geometric unsharpness: a. are actually the same thing. b. can be distinguished as follows: magnification refers to the degree of enlargement, and unsharpness refers to the penumbra. c. are not directly related. d. can be combined to yield total unsharpness.

Answer 101

b. can be distinguished as follows: magnification refers to the degree of enlargement, and unsharpness refers to the penumbra.

Question 102

111. Image distortion refers to: a. a combination of geometric unsharpness and magnification. b. deviation from the true shape of the object. c. magnification minus geometric unsharpness. d. a combination of graininess, unsharpness, and magnification.

Answer 102

b. deviation from the true shape of the object.

Question 103

112. Variation in the thickness of lead screens from 0.1 mm (0.005 in.) to 0.2 mm (0.01 in.): a. has very slight effect on intensification. b. has very significant effect on intensification. c. actually has no effect on intensification. d. only serves to increase geometric unsharpness.

Answer 103

a. has very slight effect on intensification.

Question 104

113. The bunsen-roscoe reciprocity law states that the product of a photochemical reaction is dependent only upon the product of the radiation intensity and the duration of exposure and is independent of the absolute values of either of these quantities separately. This law is invalid for which of the following? a. X-rays. b. Gamma rays. c. Fluorescent screens. d. Lead foil screens.

Answer 104

c. Fluorescent screens.