Principles of Radiation Physics, Health, and Biology

SECTION 1: PRINCIPLES OF RADIATION PHYSICS, HEALTH, AND BIOLOGY

Instructions

Read the questions carefully. In some questions the answer being sought is related to an “is not” phrasing of the question. The answer choices are based on the statement(s) in the question that, with rare exceptions, are factual. On the other hand, the answer sections contain inaccurate or irrelevant, but seemingly plausible, selections and the goal is for the reader to recognize the one most correct answer. This may require the selection of the “all of the above” choice or the “none of the above” choice as the correct answer. Also, the reader should be wary of selecting the longest answer or the “C” choice. On the other hand, some of the correct answers are the longest or “C” choice. Also, the correct answer, such as the “B” choice, may occur several or more times in a row.

MULTIPLE CHOICE QUESTIONS

1. An atom is said to be neutral when:

A. It is ionized

B. There are more electrons than protons

C. The number of positive charges in the nucleus equals the number of negative charges of the orbital electrons

D. It has a positive charge

2. X-rays interact with matter to produce:

A. Ionization and desiccation

B. Ionization and excitation

C. Desiccation and excitation

D. Ionization and replication

3. Which electron is bound most tightly to the nucleus?

4. Electromagnetic radiation wavelengths are measured in:

5. Which of the following statements is true?

A. X-rays have wavelengths, frequencies, and velocities.

B. X-rays can be reflected like light.

C. X-rays have mass and carry a positive electric charge.

D. X-rays do not travel in straight lines.

6. Which of the following most adequately describes the radiation produced by high kilovoltages?

A. Short wavelengths of low frequency

B. Long wavelengths of high frequency

C. Short wavelengths of high frequency

D. High penetrating waves of low frequency

7. Secondary radiation is:

A. Less when kVp is increased

B. Most detrimental to the patient

C. Less deeply penetrating than primary radiation

D. Proportional to the square of the distance the operator stands from the patient

8. Pocket dosimetry is an example of:

A. Chemical dosimetry

B. Photographic dosimetry

C. Luminescent dosimetry

D. Biologic dosimetry

E. Air-ionization dosimetry

9. Which of the following is not applicable to thermoluminescent dosimetry?

E. Measurement of light

10. The long BID (cone) is recommended when using the paralleling technique because we can:

A. Use the shorter time intervals allowable with an electronic timer

B. Use a longer focal spot-film distance to compensate for a greater object-film distance to reduce magnification and distortion

C. Hold the film closer to the tooth so there is less magnification and a better image

D. Use a lower kVp

E. B and C

11. The paralleling technique is recommended over the bisecting-angle technique because:

A. Positioning the film is easier

B. It uses slower film

C. It gives a less-distorted picture of root length

D. It shortens developing time

E. A, B, and C

12. What is the main cause of foreshortening in the bisecting-angle technique?

A. Improper placement of the film

B. Improper horizontal angulation of the BID

C. Vertical angulation of the BID is excessive

D. Vertical angulation of the BID is insufficient

13. Which statement is the most correct?

A. The long BID is used with the paralleling or the bisecting-angle technique.

B. The long BID is used with the paralleling technique only.

C. The short BID is used with either the paralleling or the bisecting-angle technique.

D. Film holders are not necessary with the paralleling technique.

14. The intensity of x-radiation at any given distance from the source of radiation varies:

A. Inversely with the square of the distance

B. Directly with the square of the distance

C. Inversely with the distance

D. Directly with the distance

15. When an 8-inch target-film distance is changed to a 16-inch target-film distance (kVp and mA kept constant), the exposure time should be:

16. In hand processing, if you place the film in the fixer first, this results in:

17. A tire track or other pattern throughout the image results from:

A. Developer and fixer with different temperatures

B. Bending the film

C. Reversing the film to the beam

D. Fluoride

18. Fluoride contamination of a film from the operator’s fingers results in:

A. White marks

B. Black marks

C. Generally increased density

D. No change

19. The optimum time and temperature for hand development of film is:

A. 3 to 4 minutes at 70 degrees F

B. 4.5 to 5 minutes at 83 degrees F

C. 4.5 to 5 minutes at 65 degrees F

D. 4.5 to 5 minutes at 68 to 70 degrees F

20. To test for chemically fogged or age-fogged film:

A. Develop the film without exposing it

B. Develop the film after exposing it

C. Hold the film up to a bright safelight

D. Fix the film only

E. C and D

21. In manual processing, the fixing time for films is usually:

E. Dependent on the temperature

22. A radiographic film is underexposed. In manual processing, which of the following manipulations will produce diagnostically acceptable radiographs?

A. Overdevelopment

B. Sight-development

C. Treatment with Farmer’s reducer

D. None of the above

23. Which of the following are the components of Farmer’s reducer that can be used to decrease the radiographic density (too dark) in a processed film?

A. Sodium sulfite and hyposulfite

B. Sodium sulfite and potassium ferricyanide

C. Potassium bromide and potassium ferricyanide

D. Sodium thiosulfate and potassium ferricyanide

E. X-rays and duplicating film

24. Which is the hardening agent in film processing?

A. Acetic acid

B. Potassium bromide

C. Potassium alum

D. Potassium hydroxide

25. Which of the following tissues is most susceptible to radiation?

A. Nerve tissue

B. Muscle tissue

C. Brain tissue

D. Blood-forming tissue

26. Which of the following is the most radiosensitive?

A. Young bone

B. Nerve

C. Muscle

D. Reproductive organs

27. Which of the following is not a critical factor in the radiation response of cells?

A. Cellular differentiation

B. Size of cells

C. Metabolic activity

D. Mitotic rate

28. Which of the following effects can be associated with low-dose, whole body radiation?

29. Relative to radiation biology, the latent period is that period between:

A. Exposure of the film and development of the images

B. Exposure to radiation and the appearance of clinical symptoms

C. The states of cell rest and cell mitosis

D. Subsequent doses of x-radiation

30. Which of the following effects is not considered to be dependent on dose rate?

A. Death of the organism

B. Local somatic effects

C. Genetic effects

D. Fetal somatic effects

31. Which of the following is the earliest clinical symptom for an individual exposed to a mid-lethal radiation dose sufficient to cause acute radiation syndrome?

A. Nausea and vomiting

B. Diarrhea

C. Loss of hair

D. General discomfort

E. Fever

32. Which of the following is a unit of radiation absorbed dose expressed in joules per kilogram of irradiated tissue?

33. The doubling dose is that dose:

A. In which the LD-50 is doubled

B. In which the rads delivered are doubled

C. That causes a doubling of gene mutation

D. That causes a doubling of interactions along the track of a high-speed electron

34. For dental radiography, the recommended collimation of the radiation beam of the BID at the patient’s skin surface is:

35. A pregnant patient:

A. Should be advised of her legal rights before being irradiated

B. Should be warned about a possible miscarriage

C. Should never be irradiated for dental radiographs

D. May be irradiated for dental radiographs by taking the proper precautions

36. Which of the following reduces the radiation dose to the patient?

37. Which of the following is the most effective in reducing patient radiation dose?

A. Fast films

B. Proper collimation

C. Higher kilovoltage

D. Digital imaging

38. The electrons that revolve around the nucleus:

A. Have a positive charge

B. Have no charge; either positive or negative

C. Have a negative charge

D. Can be either positive or negative

39. Isotopes of an element have the same:

40. The transformer used to heat the filament of the x-ray tube is:

A. The autotransformer

B. The step-up transformer

C. The step-down transformer

D. The rechargeable DC battery circuit

41. At diagnostic levels, what percent of the electron energy is converted to x-radiation at the anode?

42. In a standard non-constant potential machine, about 70% of the radiation in the x-ray tube is:

43. The substance that is the most resistant to the passage of x-rays is:

44. X-rays are produced when:

A. The anode is heated above 3000 degrees C

B. The filament becomes positively charged

C. Electrons strike the cathode

D. Electrons strike the anode

45. The x-ray beam of a standard non-constant potential x-ray machine consists of photons of many different wavelengths, with the shortest wavelength photons determined by:

A. Milliamperage (mA)

B. Kilovoltage peak (kVp)

C. Filtration

D. Exposure time

46. The target material (in the anode) for dental x-ray tubes is:

47. In a standard dental x-ray unit, the quality of x-radiation produced during the exposure is controlled primarily by:

A. Exposure time

B. Kilovoltage peak (kVp)

C. Milliamperage (mA)

D. Inherent filtration

48. In a standard AC-type x-ray machine, a 0.5 (½) second exposure would produce how many impulses of x-radiation?

49. To reduce the amount of heat given off during x-ray production, the source of x-ray energy is surrounded by:

50. The number of electrons in a dental x-ray tube is determined by the:

A. Kilovoltage used

B. Distance between the filament and the target

C. Step-up transformer

D. Size of the focusing cup

E. Low-voltage circuit

51. The efficiency of x-ray production in an x-ray generating tube (i.e., the percentage of electron kinetic energy converted to x-rays) is directly related to the:

A. Z number of the target material

B. Operational kVp

C. Melting point of the target material

D. A and B

E. All of the above

52. Which of the following statements about radiation is true?

A. General radiation is Bremsstrahlung radiation.

B. Bremsstrahlung radiation is the same as characteristic radiation.

C. All atoms have the same characteristic radiation.

D. Characteristic radiation is produced when cathode electrons collide with electrons of the outermost shell.

53. To increase the penetrability of the x-ray rays, their wavelength should be:

A. Shortened by increasing the kVp

B. Shortened by decreasing the kVp

C. Lengthened by increasing the kVp

D. Shortened by increasing the mA

E. Lengthened by increasing the mA

54. In a constant potential (DC) x-ray machine, the x-ray beam is:

A. A continuous beam of radiation

B. A pulsating beam of radiation

C. A pulsating divergent beam of radiation

D. A continuous divergent beam

55. Which of the following statements is not correct?

A. X-rays can penetrate opaque matter.

B. X-rays are differentially absorbed by matter.

C. X-rays cannot ionize gasses.

D. X-rays affect photographic film emulsion much like light.

56. The number of oscillations or waves passing a point per second is known as the:

A. Heat capacity of an x-ray photon

B. Melting coefficient of an x-ray photon

C. The tube capacity of the x-ray machine

D. Frequency of an x-ray photon

57. The mean penetrability of an x-ray beam is not related to which of the following?

58. X-rays are a form of ionizing radiation. Ionization is:

A. The separation of the nucleus into positive and negative ions

B. Produced by photoelectric absorption only

C. Produced by the Compton effect and Bremsstrahlung only

D. Produced by photoelectric absorption and Compton scatter

59. The interaction in which the entire photon of x-radiation is removed from the beam by atomic interaction is known as:

A. The Thompson effect

B. The photoelectric effect

C. Compton scatter

D. Excitation

60. A recoil electron is produced during which of the following reactions?

A. The photoelectric effect

B. The Compton effect

C. Pair production

D. Photonuclear disintegration

61. The predominant mechanism of x-ray interaction with matter in the dental setting is:

A. Thompson (unmodified scatter)

B. The photoelectric effect

C. Compton scatter

D. Pair production

62. X-ray filters are usually made of:

63. Collimators are usually made of:

64. Dental x-ray machines that use 65 kVp are required to have a half-value layer (HVL) equivalent to at least:

65. The HVL is the amount of:

A. Lead necessary to absorb all of the radiation in the beam

B. Copper in the target needed to dissipate heat

C. Absorber necessary to attenuate the x-ray beam by one-half and is used to measure beam quality

D. Opening in the lead diaphragm needed to collimate the beam to its proper size

E. All of the above

66. The radiation weighting factor is used in the determination of which of the following radiation units?

67. The unit of x-radiation measurement that deals with the absorbed energy per kilogram of tissue is the:

68. A pocket dosimeter should be _________ before each use.

A. Checked for x-ray translucency

B. Sensitized with a standard radiation exposure

C. Loaded in the darkroom

D. Charged with the charging unit

69. Which of the following properties of x-rays is the basis for the rules of geometric projection?

A. X-rays travel at the speed of light.

B. X-rays travel in diverging straight lines from a point source.

C. The course of an x-ray photon can be diverted with an electromagnetic source.

D. X-rays can form a latent image on photographic film.

70. Regardless of the target-film distance, incorrect horizontal angulation will cause:

A. Elongation of the x-ray image

B. Foreshortening of the x-ray image

C. No significant change in the x-ray image

D. Overlapping of teeth in the x-ray image

71. The size of the focal spot in the x-ray tube influences radiographic:

72. Which of the following does not control total magnification (includes penumbra) of the radiographed object?

A. Focal spot-film distance

B. Focal spot size

C. Object-film distance

D. Cathode size

E. None of the above

73. The optical density of an intraoral film indicates the:

A. Degree of darkness in an image

B. Difference between observers

C. Speed of the screens

D. Kilovoltage used

E. None of the above

74. Optical density is a function of:

75. Subject contrast is primarily a function of:

A. kVp

B. kVp and mA

C. mA

D. kVp, mA, and exposure time

76. Fog affects the contrast of an intraoral film because it:

A. Decreases film density

B. Increases film density

C. Produces white stains on the film

D. Produces dark stains on the film

77. The primary advantage of the paralleling technique over the bisecting-angle technique is:

A. The increased anatomic accuracy of the image

B. The increased object-film distance

C. The greater magnification of the image

D. The long BID is easier to handle

78. Why is the long BID considered a necessary adjunct to the paralleling technique?

A. To avoid magnification of the image

B. To avoid shape distortion of the image

C. To reduce secondary radiation

D. The long BID is easier to handle

E. To avoid superimposition of structures

79. The technique that shows the upper and lower crowns and associated alveolar bone on the same radiograph is called the:

A. Retro-coronal technique

B. Bitewing technique

C. Bisecting-angle technique if a BID indicator is not used

D. Paralleling technique if a BID indicator is used

E. C and D

80. If a satisfactory radiograph was produced using a target-film distance of 8 inches and an exposure time of 5 impulses, what would be the correct exposure time for a target-film distance of 16 inches?

81. In the bisecting-angle technique, the central ray of the beam is directed:

A. Perpendicular to the long axis of the object

B. Parallel to the long axis of the object

C. Perpendicular to a line bisecting the angle formed by the object and the film packet

D. Perpendicular to the film packet

82. Which of the following is a correct statement about intensifying screens?

A. Thinner phosphor layers result in faster screens.

B. Thinner phosphor layers result in more unsharpness.

C. Thicker phosphor layers result in faster screens.

D. Thicker phosphor layers result in less unsharpness.

83. BID (cone) cutting (partial image) on a radiograph is caused by:

A. Underexposure

B. Improper exposure technique

C. A damaged BID

D. Improper coverage of the film with the beam of radiation

84. A cassette:

A. Emits light

B. Is a container for films and screens

C. Is an instrument to align the BID

D. Records the patient’s exposure

85. Intensifying screens are used with extraoral and panoramic films to:

A. Increase the exposure time

B. Improve image quality

C. Decrease the radiation to the patient

D. Increase the kVp

86. The efficiency with which film responds to x-ray exposure is known as film sensitivity or film speed. Which speed range is the best for reducing radiation to the patient?

87. A film is stripped from its packet and exposed to light. After processing it will:

88. Which of the following films can be used intraorally and extraorally?

89. Which of the following will not produce film fog?

A. Unprotected films in the x-ray room or x-ray equipped operatory

B. Films stored for a long time in an unsafe place

C. Light leaks in the darkroom

D. Films stored in a refrigerator in the lab

90. Which of the following will produce film fog?

A. Light leaks in the darkroom

B. Films stored for a long time in an unsafe place

C. Unprotected films in the x-ray room or x-ray equipped operatory

D. All of the above

91. The primary purpose of the lead foil in the back of the film packet is to:

A. Eliminate penumbra

B. Absorb remnant radiation after film exposure

C. Identify film placed backwards (back to front)

D. Stiffen the x-ray packet

92. The base material used in dental films is:

A. Sodium thiosulfate

B. Metol

C. Cellulose acetate

D. Gelatin

93. Radiographic film emulsion is:

A. Cellulose acetate

B. Gelatin

C. Gadolinium oxyphosphate

D. Gelatin and silver bromide

94. Sensitization specks:

A. Are defects in the gadolinium oxyphosphate crystals

B. Are defects in the silver bromide crystals

C. Act as electron traps

D. A and C

E. B and C

95. In hand processing, films should be washed in running water for at least:

96. What is the cause of yellow or brown stains appearing on films some time after processing?

A. Aged film

B. Improper exposure technique

C. Films stored in a hot place

D. Incomplete fixing and washing

97. The latent image consists of the accumulation of:

A. Electrons in exposed silver bromide crystals

B. Atomic silver at the sensitized specs

C. Atomic silver in gelatin molecules

D. Electrons in exposed silver bromide crystals and in the gelatin molecules

98. The safety of a darkroom safelight depends on the:

A. Distance of the safelight from the workbench

B. Time the films are exposed to the safelight

C. Wattage of the bulb in the safelight

D. Speed of the film

E. All of the above

99. Differences between manual and automatic processing include which of the following?

A. Processing solution chemistry

B. Solution temperature

C. Solution concentration

D. Time to completion of processing

E. All of the above.

100. During the processing of Insight “F” speed film in the private dental office, which of the following is the most important source of film fog?

A. Secondary radiation to the dental operatory

B. Unsafe safelight

C. Developing solutions that are too cold

D. Use of an automatic processor

101. The theory that explains cellular damage by x-rays is the:

A. Direct action poison chemical theory

B. Indirect action poison chemical theory

C. Bremsstrahlung theory

D. Indirect non-ionizing theory

102. Theoretically the biologic response to a given dose of radiation would be greater (more severe) with:

A. The tissue being anoxic at the time of irradiation

B. A higher dose rate

C. A smaller area of tissue exposure

D. Lower linear energy transfer (LET)

103. Which of the following x-ray photons (x-rays) are most apt to be absorbed by the skin?

A. Central x-ray photons

B. Filtered x-ray photons

C. Long wavelength x-ray photons

D. Short wavelength x-ray photons

104. The first clinically observable reaction to radiation overexposure is:

A. Loss of hair

B. Reddening of the skin (erythema)

C. Cataract formation

D. Agenesis of blood cells

105. In intraoral periapical radiography, which of the following is currently (2004) under consideration for abolition?

A. Round, open-ended BIDs of any length

B. ANSI “D” speed film

C. The protective apron for the patient

D. None of the above

E. All of the above

106. Ionization occurs:

A. When atoms lose electrons; they become deficient in negative charges and therefore behave as positively charged atoms

B. When atoms gain electrons; they become positively charged

C. When an atom loses its nucleus

D. Only when a K-orbit electron is ejected and replaced with an L-orbit electron

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Tags: Exercises in Oral Radiology and Interpretation 4e

Jan 12, 2015 | Posted by mrzezo in Oral and Maxillofacial Radiology | Comments Off

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12: Principles of Radiation Physics, Health, and Biology

SECTION 1: PRINCIPLES OF RADIATION PHYSICS, HEALTH, AND BIOLOGY

Instructions

MULTIPLE CHOICE QUESTIONS

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12: Principles of Radiation Physics, Health, and Biology

SECTION 1: PRINCIPLES OF RADIATION PHYSICS, HEALTH, AND BIOLOGY

Instructions

MULTIPLE CHOICE QUESTIONS

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