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5th Edition

2007 Syllabus: Radiation Biology for Diagnostic and Interventional RadiologistsWayne R. Hedrick, PhD, Editor Canton, OhioMahadevappa Mahesh, PhD, Contributor Baltimore, Maryland

Contents

InstructionsTo use this interactive PDF, click once (with your mouse) on the section above that you wish to study. You will be forwarded to that part of the syllabus. This material may also be printed for your use.

Radiation Biology Syllabus for Diagnostic and Interventional Radiologists

2007

Preface

F

or the fifth edition of the syllabus, the general format of the fourth edition has been retained, with various topics updated. The principal change in format is the addition of references to support the correct answers. Informational content has been expanded to include magnetic resonance (MR) imaging and ultrasound. Current recommendations by the American College of Radiology with respect to safe MR practices are included. Questions are classified in the following sections: Radiation Biology/Effects, Radiation Safety/Protection, Magnetic Resonance Imaging, and Ultrasound. The conversion to a Web-based instructional publication will facilitate future and more frequent revisions.

The Radiological Society of North America is a nonprofit organization.2007

by the Radiological Society of North America, Inc

820 Jorie Boulevard, Oak Brook, IL 60523-2251 1-630-571-2670 FAX: 1-640-571-7837 RSNA.org

2007

Radiation Biology Syllabus for Diagnostic and Interventional Radiologists

QuestionsInstructions for Sample Questions Each question is one of the following types, as indicated immediately preceding the question:A Only one answer is correct B Match answers X True/Falseany number of answers may be True

I.RadiationBiology/EffectsA

X

1. The majority of the energy received by biologic material from x rays is transferred by A. B. C. D.A

5. Which of the following statements concerning chromosomal aberrations in stimulated peripheral lymphocytes are true? A. They can be used to assess whole-body radiation exposures B. They can be used to detect a dose of cGy C. They can be used to measure a total body dose of 0 Gy weeks after exposure D. The number of interchange aberrations is a linear function of dose for x raysX

Electrons Degraded gamma photons Protons Spallation products

2. The percentage of x-ray damage to biologic material mediated by free radicals is closest to A. B. C. D. E.A

0% 0% 0% 60% 90%

6. Chromosome changes induced by radiation include A. B. C. D. E.A

Acentric fragments Centric fragments Inversions Symmetric translocations Dicentrics

3. X-rayproduced chromosomal aberrations, such as dicentrics and rings, are generated as a consequence of A. A single chromosomal break interacting with itself B. Interaction of two separate chromosomal breaks C. High-dose events caused by a single electron D. Misreplication eventsA

7. The phase of the cell cycle that is most variable in length is A. B. C. D.A

G G M S

4. Cell killing by x rays correlates best with A. Damage to DNA bases B. The initial number of DNA double-strand breaks C. The final number of DNA double-strand breaks D. The number of thymine dimersA Only one answer is correct B Match answers

8. If an asynchronous population of cells is exposed to a single x-ray dose of 0 Gy, the surviving cells are partly synchronized because A. B. C. D. Radiation block occurs in the G phase Radiation block occurs in the S phase Most survivors are in the G phase Most survivors are in the late S phase

X True/Falseany number of answers may be True

Radiation Biology Syllabus for Diagnostic and Interventional Radiologists

2007

A

X

9. The most radiosensitive portion of the gastrointestinal tract to cell killing is the A. B. C. D. E.A

13. The likelihood of late stochastic effects following exposure to radiation is influenced by A. B. C. D.A

Esophagus Stomach Small intestine Large intestine Oropharynx

Radiation dose Linear energy transfer (LET) of the radiation Radiation dose rate Type of tissue exposed

10. The syndrome that is associated with the greatest sensitivity to x rays is A. B. C. D.A

14. The minimum dose range that results in an expected %0% prevalence of nausea following acute total-body irradiation is A. B. C. D.A

Bloom syndrome Ataxia telangiectasia Fanconi anemia Xeroderma pigmentosum

0.00. Gy 0.0. Gy 0.7. Gy More than 0 Gy

11. The shoulder in cell survival curves is MOST pronounced when cells are irradiated with A. B. C. D.A

15. The most likely consequence of an acute total body exposure to Gy of x rays is A. B. C. D. E.B

-MeV neutrons -MeV alpha particles -MeV electrons 00-MeV pi mesons

Diarrhea Decrease in lymphocyte count Epilation Sterility in a female Erythema

12. For a given total dose of x rays, a protracted exposure at a low dose rate is less effective in killing mammalian cells than an acute exposure at a high dose rate, primarily because A. B. C. D. Fewer free radicals are produced The mitotic cell cycle is shortened Cell division occurs during exposure Ion pairs recombine during extended exposure E. Repair of sublethal damage occurs during exposure

16. Match the items () with the doses (AD) (single acute x-ray exposures). . Dose producing the cerebrovascular syndrome . Estimated dose to double the natural mutation rate . Typical LD 0/ (ie, gastrointestinal death) . Typical LD 0/60 in humans A. B. C. D. 00 Gy 0 Gy Gy Gy

A Only one answer is correct

B Match answers

X True/Falseany number of answers may be True

2007

Radiation Biology Syllabus for Diagnostic and Interventional Radiologists

X

X

17. Which of the following effects would be seen as a consequence of a total body exposure to . Gy of x rays? A. Vision-impairing cataracts of the ocular lens B. Dicentric chromosomes in peripheral lymphocytes C. Skin erythema D. Ataxia E. Increased carcinogenesis from % to 0%X

21. Which of the following are true concerning radiation-induced sterility? A. An acute 0.-Gy dose of gamma rays can induce temporary sterility in males B. An acute .-Gy or greater dose of gamma rays can induce permanent sterility in females C. Radiation-induced permanent sterility in males leads to a loss of libido D. Radiation-induced sterility in females produces hormonal changes E. An acute -Gy dose of gamma rays will cause immediate sterility in males (ie, no latent period)X

18. An acute whole-body exposure of Gy of lowLET radiation will cause which of the following effects? A. B. C. D. E.X

Vomiting in 9% of those exposed Diarrhea in 9% of those exposed Temporary sterility in males Permanent sterility in females Decrease in lymphocyte count

22. Which of the following statements concerning radiation-induced heritable effects are true? A. Radiation-induced heritable changes are different from those that occur spontaneously B. Humans are much more sensitive to radiation than mice C. Risk estimates in humans are based largely on data from mice D. 0%0% of heritable changes in the population can be attributed to background radiation E. The doubling dose in humans is estimated to be 0.. Sv (acute exposure)A

19. Which of the following statements concerning total body irradiation of humans after an acute exposure to x rays are true? A. The LD 0/60 is between and Gy B. Seizures are likely if the dose exceeds Gy C. The nadir in white cell count following a dose of Gy will occur within 6 days D. Bone marrow transplants are likely to save persons exposed to more than GyA

20. The earliest clinically detectable effect of radiation on the skin is A. B. C. D. E. Epilation Pain Ulceration Erythema Depigmentation

23. A patient undergoes two CT scans of her abdomen; the dose was 0. Gy. If she subsequently becomes pregnant within year, what is the probability that the child will have a radiationinduced hereditary defect? A. B. C. D. Less than in ,000 in ,000 to in 00 in 00 to in 0 > 0%

A Only one answer is correct

B Match answers

X True/Falseany number of answers may be True

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Radiation Biology Syllabus for Diagnostic and Interventional Radiologists

2007

A

B

24. The dose-response relationship for solid tumors in the Japanese survivors used by the BEIR V and UNSCEAR committees has the form A. B. C. D. E.A

28. Match the type of exposure () with the type of radiation-induced cancer (AE). . Patients who are treated with radiation for ankylosing spondylitis . Patients who undergo fluoroscopy repeatedly during management of tuberculosis . Uranium workers . Dial painters who work with radium . Marshall Island inhabitants A. B. C. D. E.B

Linear with no threshold Linear with threshold Quadratic with no threshold Exponential Quadratic with threshold

25. Which of the following organs in children is most sensitive to the induction of both benign and malignant tumors by x rays? A. B. C. D.A

Leukemia Breast cancer Thyroid cancer Lung cancer Bone cancer

Bone marrow Breast Thyroid Lung

29. For each organ (), select the correct description of cancer incidence in the U.S. population (AD). . . . . A. B. C. D.X

26. Based on cancer risks in the BEIR V committee report, the number of cancer deaths in the general public in the United States as a result of nuclear power plant accidents is estimated to be closest to A. B. C. D.A

Prostate Thyroid Breast Kidney Low naturallow radiogenic Low naturalhigh radiogenic High naturalhigh radiogenic High naturallow radiogenic

0 00 ,000

27. The International Commission on Radiological Protection (ICRP) estimate of the total number of cases of cancer of all types produced by a total body exposure of a working population to Sv of low-LET radiation at a low dose rate is closest to A. B. C. D. in 00 in ,000 in 0,000 in 00,000

30. A -Gy exposure to a developing embryo when radiation is administered during A. weeks 8 of gestation is likely to induce abortions B. weeks 0 of gestation usually produces congenital abnormalities C. weeks can produce mental retardation D. weeks 6 is likely to induce congenital abnormalities

A Only one answer is correct

B Match answers

X True/Falseany number of answers may be True

2007

Radiation Biology Syllabus for Diagnostic and Interventional Radiologists

7

X

X

31. Which of the following statements concerning radiation-induced stochastic effects are true? A. The clinical severity of the effect increases with dose B. The probability that an individual will experience the effect increases with dose C. There is a well-defined threshold in dose D. The effect may arise from damage to a small number of cellsX

34. Which of the following statements concerning radiation oncogenesis are true? A. Generally, the mean latent period for radiation-induced leukemia is about 0 years B. Children are less sensitive than adults to the induction of leukemia C. Benign neoplasms can be induced after irradiation D. Solid tumors induced by radiation may appear years or more after exposure E. A whole-body dose of 0. Gy would be expected to increase the incidence of cancer from approximately 0% (the natural incidence) to approximately 0%B

32. Which of the following statements regarding the study of the atomic bomb survivors in Hiroshima and Nagasaki are true? A. Less than ,000 excess radiation-induced malignancies were found B. There was an increased risk of radiationinduced breast cancer C. There was an increased incidence of mental retardation in children exposed in utero D. No statistically significant excess heritable effects in children of those exposed were foundX

35. Match the consequence () with the stage of pregnancy (AC) when radiation would most likely be the cause. . Congenital malformations (other than in the central nervous system) . Death . Increased risk of cancer A. Preimplantation B. Organogenesis C. Fetal periodX

33. Risk estimates for radiation-induced cancer in humans are based on studies involving A. Patients treated with I- for hyperthyroidism B. Survivors of Hiroshima and Nagasaki C. Women developing breast cancer after multiple fluoroscopic examinations for tuberculosis D. Populations living near nuclear power plants

36. A therapeutic dose of I- to a patient with Graves disease who is weeks pregnant will A. Not result in hypothyroidism in the fetus B. Cause intrauterine demise with 90% probability C. Result in a % risk of leukemia in the mother D. Result in a 0% risk of solid tumors in the mother

A Only one answer is correct

B Match answers

X True/Falseany number of answers may be True

8

Radiation Biology Syllabus for Diagnostic and Interventional Radiologists

2007

X

X

37. A woman involved in a traffic accident complained of lower back pain and underwent anteroposterior and lateral lumbosacral spine radiography. She was subsequently found to be 0 weeks pregnant. Which of the following are true? A. The radiographs should not have been obtained B. A therapeutic abortion should be recommended C. If a radiation-induced defect occurs, it will most likely affect the central nervous system D. The offspring may be at increased risk for a childhood malignancy E. The fetus probably received an absorbed dose of 0.0. GyX

40. Which of the following statements concerning radiation-induced cataracts are true? A. Cataracts begin in the anterior portion of the lens B. A dose of Gy over years is likely to produce a cataract C. Prescription eyeglasses protect from 80% of the dose to the lens from diagnostic x rays D. Vision-impairing cataracts are preceded by asymptomatic opacities in the lens.X

41. Which of the following statements concerning radiation-induced cataracts are true? A. A cataract is a stochastic effect B. The minimum single acute dose of x rays that will produce a cataract is Gy C. A single dose of radiation is more likely to induce a cataract than the same amount of radiation administered in 0 fractions D. For a given dose, neutrons are more effective than gamma rays in producing cataractsX

38. A woman receives a dose of 0 mGy to the abdomen and pelvis and then learns she is 8 weeks pregnant. There is A. B. C. D.A

An increased risk of intrauterine death An increased risk of neonatal death A risk of microcephaly in the infant A risk of leukemia in the child

39. A -year-old woman undergoes cerebral angiography and a CT scan of the brain involving -mm-thick sections that include the orbits. The patients lifetime risk probability for radiationinduced cataracts is estimated to be A. B. C. D. E. 0% 0.0% 0.% .0% 0.0%

42. The explosion of a dirty bomb made from highly radioactive material, such as a cobalt-60 teletherapy source, can result in which of the following? A. Radiation dose sufficient to cause acute radiation injury B. Casualties contaminated with radionuclides C. Psychologic impact on the victims D. Casualties may present a potential hazard to medical personnel

A Only one answer is correct

B Match answers

X True/Falseany number of answers may be True

2007

Radiation Biology Syllabus for Diagnostic and Interventional Radiologists

9

II. RadiationSafety/Protection X

A

46. The biggest contributor to the effective dose to the U.S. population from natural causes is A. B. C. D. E. Rad Rem Sievert Curie GrayA

43. Which of the following units are SI units?

A. B. C. D. E.

Cosmic radiation Solar radiation Radon Potassium-0 in food Gamma ray emitters in building materials

X

44. A pregnant, occupationally exposed woman working in fluoroscopy shows a reading of mSv over 90 days to a badge worn on her collar over a lead apron. Which of the following are true? A. The Nuclear Regulatory Commission should be called B. She should no longer work with fluoroscopy C. The dose recorded does not exceed National Council on Radiation Protection and Measurements (NCRP) recommendations D. A therapeutic abortion is recommendedA

47. In the United States, the greatest source of exposure to ionizing radiations (collective effective dose) in the general population due to human activity is A. B. C. D. E.B

Video display terminals Fallout from nuclear weapons testing Nuclear waste disposal sites Medical and dental diagnostic radiation Nuclear reactor accidents

48. Match the quantities () with the doses (in millisieverts) (AD). . Average background radiation in the United States, including radon . Dose limit per month (NCRP) to an occupationally exposed worker who has declared her pregnancy . Dose received in flying across the Atlantic in a commercial jetliner . Genetically significant dose from medical radiation in the United States A. B. C. D. 0.0 0. 0.0 .0

45. Which of the four pie charts (AD) best describes the distribution of effective doses to the U.S. population as summarized by the NCRP?

A Only one answer is correct

B Match answers

X True/Falseany number of answers may be True

0

Radiation Biology Syllabus for Diagnostic and Interventional Radiologists

2007

X

A

49. Which of the following statements regarding radon are true? A. Concentrations are higher in the basement of a house than outside B. The BEIR VI committee estimates that radon is the cause of 0% of lung cancer cases in the United States C. Decay of radon involves emission of alpha particles D. The half-life is ,600 years E. The parent is radiumX

53. A worker in a nuclear medicine laboratory declares that she is months pregnant. What is the NCRP recommended limit for the remainder of the pregnancy? A. B. C. D. E.X

None 0.0 mSv/mo 0. mSv/mo mSv total 0 mSv total

54. For radiation protection purposes, 50. Which of the following statements concerning radon are true? A. Radon is a naturally occurring radioactive gas B. Radon contributes a larger average effective dose to the U.S. population than do medical x rays C. The action level recommended by the EPA is pCi/L D. The half-life of radon is ,600 years E. The effective radiation emitted by radon daughters is in the form of gamma raysA

A. the maximum permissible dose for hands reflects concern for cancer B. a whole-body low-dose-rate exposure has a cancer risk of %/Sv C. hands are nearly as radiosensitive as the eye D. low-dose-rate exposures are associated with a lower risk of cancer development than high-dose-rate exposuresB

55. For each of the following terms related to radiation protection (), select its appropriate definition (AD). . . . . Genetically significant dose Equivalent dose Effective dose Committed equivalent dose

51. Which of the following procedures is likely to result in the greatest radiation exposure of personnel? A. Chest radiograph obtained with a technologist in the room B. One CT section obtained with a technologist in the room C. Fluoroscopy of the abdomen for minutes D. Knee examination with MR imagingX

52. A genetically significant dose due to medical x rays involves the A. B. C. D. gonad doses age and sex of the patient number of persons exposed time of day at which the exposure is received

A. Dosimetric term used when the source of radiation exposure is from radioactive material located within the body B. The absorbed dose multiplied by a radiation weighting factor (Wr) appropriate for the type of radiation C. An index of the presumed effect of gonadal irradiation on the whole population D. The sum of the equivalent doses, weighted for the relative risk of cancer and hereditary effects, for all irradiated organs and tissues

A Only one answer is correct

B Match answers

X True/Falseany number of answers may be True

2007

Radiation Biology Syllabus for Diagnostic and Interventional Radiologists

B

X

56. For each type of exposure (), select the appropriate current NCRP-recommended maximum permissible dose (AD). (The choices AD may be used more than once.) . Annual occupational effective dose limit . Annual public equivalent dose limit (frequent exposure) . Monthly equivalent dose limit to a fetus after a pregnancy has been declared . Annual occupational equivalent dose limit for the lens of the eye A. B. C. D.B

59. Which of the following are NCRP recommendations concerning occupational exposure? A. No occupational exposure is allowed before the age of 8 years B. Medical radiation received by radiation workers is included in their maximum permissible dose C. ALARA (as low as reasonably achievable) does not apply to occupational exposure D. The purpose of the occupational maximum dose is to protect against both stochastic and deterministic effectsX

0. mSv mSv 0 mSv 0 mSv

60. Which of the following are considered patient dose-reduction techniques during interventional fluoroscopy? A. B. C. D. E. F. G. H.A

57. Match the quantities () with the corresponding units (AD). . . . . A. B. C. D.A

Absorbed dose Activity Equivalent dose Collective effective dose Sievert Gray Person-sievert Becquerel

Increased source-to-skin distance Use of last-image hold Variable pulse rate fluoroscopy Increased beam filtration Removal of grid Dose spreading Use of electronic magnification Use of geometric magnification

61. Which of the following is (are) considered to offer minimum protection to the fluoroscopist? A. B. C. D. Protective lead aprons Thyroid collars Ceiling-mounted lead glass shield Radiation-attenuating surgical gloves

58. The NCRP maximum permissible dose for the hands of radiation workers is based on A. estimates for cancer induction of the basal layer of the skin B. effects anticipated after acute exposures C. epidemiologic studies of nuclear power plant employees D. concern for deterministic effects

A Only one answer is correct

B Match answers

X True/Falseany number of answers may be True

Radiation Biology Syllabus for Diagnostic and Interventional Radiologists

2007

A

III.MagneticResonanceImagingA

62. Which potential adverse effect is expected to occur following a fluoroscopically guided interventional procedure in which a skin dose of Gy was delivered to a single site? A. B. C. D.A

No visible effect Temporary hair loss within hours Dry desquamation Damage to vascular structures

65. The usage of conventional metal detectors in MR environments is NOT recommended by the American College of Radiology (ACR). The basis for this recommendation considers all of the following except ________. A. Metal detectors are not necessary because low fringe fields exist with modern actively shielded superconducting magnets B. Metal detectors do not differentiate between ferromagnetic and nonferromagnetic metallic objects/implants/foreign bodies C. Metal detectors cannot detect a small metal fragment in the orbit or near the heart D. Metal detectors have variable sensitivity responseA

63. Which of the following imaging procedures for a pregnant patient will deliver the highest radiation dose to her 6-week-old fetus? A. Abdominal ultrasound B. Chest radiography (posteroanterior and lateral projections) C. Head CT (with and without contrast material) D. Kidney, ureter, bladder (KUB) radiography (four radiographs)A

64. Which of the following work activities is not recommended for a pregnant radiation worker? A. B. C. D. Nuclear medicine imaging Radioactive iodine treatments Fluoroscopy Portable radiography

66. What is the ACR recommendation regarding the pregnant MR imaging technologist or other health care practitioner working in the MR environment? A. Permitted to work in and around the MR environment during the second and third trimesters only B. Permitted to work in and around the MR environment throughout all stages of pregnancy C. Permitted to remain in the magnet room during actual data acquisition/imaging D. Should not enter the magnet room in response to an emergency

A Only one answer is correct

B Match answers

X True/Falseany number of answers may be True

2007

Radiation Biology Syllabus for Diagnostic and Interventional Radiologists

A

A

67. What is the ACR guideline regarding the MR imaging of pregnant patients? A. Pregnant patients can be accepted to undergo MR imaging at any stage of pregnancy B. Pregnant patients should not undergo MR imaging during the first trimester C. Gadolinium-based MR contrast agents can be routinely administered to pregnant patients D. Fast MR imaging sequences, such as echoplanar imaging, should be avoidedX

70. What is a quench with respect to the superconducting magnet? A. Uncontrolled loss of superconductivity B. Rapid boil-off of cryogens C. Requires the immediate evacuation of the patient and personnel from the magnet room D. All of the aboveA

68. Nephrogenic systemic fibrosis (NSF) has been associated with administration of gadoliniumbased MR contrast agents to patients with renal disease. What guidelines are recommended by the ACR when considering administering gadolinium-based MR contrast agents to a patient? A. Hematologic screening for glomerular filtration rate (GFR) prior to MR imaging B. No special treatment for patients with stage or chronic kidney disease C. Refrain from administering gadoliniumbased MR contrast agents to patients with stage , , or renal disease D. Immediate hemodialysis following administration of gadolinium-based MR contrast agents should be considered for any patient with severe or end-stage renal diseaseA

71. According to the Food and Drug Administration (FDA), a controlled access area must be established such that the fringe field outside this area does not exceed ________. For the safe operation of pacemakers, the magnetic field should be less than this value. A. B. C. D.X

0 G G G 0. G

72. In 988, the FDA reclassified MR diagnostic imagers as class II devices. New devices brought to the market had to demonstrate only that they were substantially equivalent to MR devices presently on the market. Safety guidelines pertaining to clinical MR imaging issued by the FDA include which of the following? A. B. C. D. Static magnetic field strength Time-varying magnetic fields Radiofrequency (RF) power deposition Acoustic noise levels

69. The presence of all the following metallic objects/ devices is considered a contraindication for MR imaging examination (meaning performance of MR imaging is not routine) except ________. A. Implantable cardioverter-defibrillator B. Implanted cardiac pacemaker C. Intracranial aneurysm clips composed of titanium D. Ferromagnetic foreign body in the eye E. Swan-Ganz catheters

A Only one answer is correct

B Match answers

X True/Falseany number of answers may be True

Radiation Biology Syllabus for Diagnostic and Interventional Radiologists

2007

A

A

73. The specific absorption rate (SAR) in units of watts per kilogram describes ________. A. Tissue heating induced by changes in magnetic field gradients B. Absorption of transmitted RF energy by tissue C. Attenuation of MR imaging signal by the patient D. Attenuation of the applied static magnetic field within the patientA

77. What deleterious biologic effects are associated with chronic exposure to magnetic field strengths produced by MR imagers (0. T)? A. B. C. D. Peripheral nerve stimulation Leukemia Congenital malformations None

IV.UltrasoundA

74. What is the principal source of MR-generated acoustic noise during MR imaging? A. B. C. D. Cryogen reclamation system Room air conditioners Vibrations of the gradient coils Thermoelastic expansion caused by the absorption of RF energy in the head

78. At the point of interest in the ultrasonic field, the instantaneous intensity is directly proportional to the square of the ________. A. B. C. D.A

Acoustic pressure Acoustic velocity Frequency Mass density

A

75. Current MR imagers produce time-varying magnetic fields (dB/dt), which can result in ________ in some patients. A. B. C. D.A

79. Which of the following describes intensity measurements using the unit of the decibel? A. Based on a logarithmic scale B. Measure of relative intensity C. A factor of two reduction in intensity corresponds to a -dB change D. Point of interest may be greater or less than the reference value E. All of the above

Induction of intense pain (brain stimulation) Cardiac stimulation Peripheral nerve stimulation All of the above

76. Local thermal injury to a patient during MR imaging can be caused by ________. A. Disconnected surface coil lead left on the patient B. Patient contact with the inner bore of the magnet C. Patients crossing their arms or legs in the MR imager D. Implanted metallic foreign objects in the patient E. All of the above

A Only one answer is correct

B Match answers

X True/Falseany number of answers may be True

2007

Radiation Biology Syllabus for Diagnostic and Interventional Radiologists

A

A

80. In 99, the American Institute of Ultrasound in Medicine (AIUM) and the National Electrical Manufacturers Association (NEMA) adopted the voluntary standard for the display of acoustic output information called the output display standard (ODS). What two acoustic output parameters, shown in real time on the monitor, were defined as indicators of the potential for biologic effect? A. Derated power and scan time B. Acoustic intensity averaged over the focal area and duty factor C. Mechanical index and thermal index D. Intensity index and thermal indexA

83. As the ultrasound beam propagates through tissue, the intensity decreases as sonic energy is absorbed and converted into heat. The increased temperature has the potential to cause irreversible tissue damage. The biologic response is a ________ phenomenon. A. B. C. D.A

Nonthreshold linear Nonthreshold quadratic Threshold (temperature only) Threshold (temperature and time)

84. Which of the following real-time scanner settings can affect the acoustic output index? A. B. C. D. E. F. G. H.A

81. In ultrasound, the acoustic output parameter thermal index (TI) indicates ________ for the current scanning parameters. A. Maximum temperature rise in tissue B. Minutes of exposure time before heating is too great C. Likelihood of inducing cavitation D. Acoustic power in milliwattsA

Time-gain compensation Frame rate Transmit power Frequency Gray-scale mapping All of the above A, C, D B, C, D

82. As the ultrasound beam propagates through tissue, the intensity decreases as sonic energy is absorbed and converted into heat. What factor(s) affect(s) the rate of temperature rise in tissue? A. B. C. D. E. F. Temporal average intensity Frequency Duration of exposure Pulse repetition frequency All of the above B, D

85. The output display standard of mechanical index (MI) increases in magnitude as the ________ is decreased. A. B. C. D.A

Acoustic pressure Acoustic velocity Frequency Peak intensity

86. According to the AIUM statement on Mammalian In Vivo Ultrasonic Biological Effects, no independently confirmed significant biologic effects have occurred with spatial peak, temporal average intensities below ________ for mammalian tissues exposed in vivo. Assume focused ultrasound. A. B. C. D. W/cm 00 W/cm mW/cm 00 mW/cm

A Only one answer is correct

B Match answers

X True/Falseany number of answers may be True

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Radiation Biology Syllabus for Diagnostic and Interventional Radiologists

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A

A

87. As the ultrasound wave propagates through tissue, regions of compression and rarefaction are created. Thus localized regions are subjected to increases and decreases in pressure in an alternating fashion, and these cause gas bubbles to exhibit dynamic behavior. This phenomenon is known as ________. A. B. C. D.A

90. What is the conclusion of the National Institutes of Health (NIH) regarding the appropriate use of ultrasound in obstetrics? A. Routine screening is recommended B. Ultrasound examination in pregnancy should be performed for a specific medical indication C. Ultrasound examination performed solely to satisfy the familys desire to obtain a picture of the fetus should be encouraged to enhance bonding between mother and child D. None of the aboveA

Radiation force Cavitation Ionization Fourier force

88. Multiple models have been developed for the thermal index (TI). These different models are necessary because temperature profiles in tissue are highly dependent on the presence of a strong absorber such as ________. A. B. C. D.A

Air Bone Fluid All of the above

91. According to recommendations by the NCRP, a risk-benefit decision should be considered when the mechanical index (MI) exceeds a value of ________ and the thermal index (TI) exceeds a value of ________. A. B. C. D. E. .0, .0 0., 0. 0., .0 .0, 0. None of the above; the NCRP makes no recommendations with respect to MIs and TIs

89. A number of epidemiologic studies of in utero ultrasound exposure have been conducted over the past 0 years. What is the conclusion of the NCRP regarding a causal relationship between diagnostic ultrasound and any adverse effect? A. Low birth weight is an adverse effect caused by in utero ultrasound exposure B. Dyslexia is an adverse effect caused by in utero ultrasound exposure C. Delayed speech development is an adverse effect caused by in utero ultrasound exposure D. Insufficient justification to warrant the conclusion that there is a causal relationship between diagnostic ultrasound and any adverse effect

A Only one answer is correct

B Match answers

X True/Falseany number of answers may be True

2007

Radiation Biology Syllabus for Diagnostic and Interventional Radiologists

7

AnswersI.Radiation Biology/Effects1. A 2. D 3. B 4. C 5. A-True B-False C-False D-False 6. A-True B-True C-True D-True E-True 7. A 8. D 9. C 10. B 11. C 12. E 13. A-True B- True C-True D-True 14. C 15. B 16. -A -D -B -C 17. A-False B-True C-False D-False E-False 18. A-False B-False C-True D-False E-True 19. A-True B-False C-False D-False 20. D 21. A-True B-True C-False D-True E-False 22. A-False B-False C-True D-False E-True 23. A 24. A 25. C 26. A 27. A 28. -A -B -D -E -C 29. -D -B -C -A 30. A-False B-False C-True D-True 31. A-False B-True C-False D-True 32. A-True B-True C-True D-True 33. A-False B-True C-True D-False 34. A-False B-False C-True D-True E-False 35. -B -A -C 36. A-True B-False C-False D-False 37. A-False B-False C-True D-True E-False 38. A-False B-False C-True D-True 39. A 40. A-False B-False C-False D-True 41. A-False B-True C-True D-True 42. A-True B-True C-True D-True

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Radiation Biology Syllabus for Diagnostic and Interventional Radiologists

2007

II.RadiationSafety/ Protection43. A-False B-False C-True D-False E-True 44. A-False B-False C-True D-False 45. B 46. C 47. D 48. -D -C -A -B 49. A-True B-True C-True D-False E-True 50. A-True B-True C-True D-False E-False 51. C 52. A-True B-True C-True D-False 53. C 54. A-False B-True C-False D-True

55. -C -B -D -A 56. -C -B -A -D 57. -B -D -A -C 58. D 59. A-True B-False C-False D-True 60. A-True B-True C-True D-True E-True F-True G-False H-False 61. D 62. C 63. D 64. B

III.Magnetic Resonance Imaging65. A 66. B 67. A 68. A-False B-True C-True D-True 69. C 70. D 71. B 72. A-True B-True C-True D-True 73. B 74. C 75. C 76. E 77. D

IV.Ultrasound78. A 79. E 80. C 81. A 82. E 83. D 84. H 85. C 86. A 87. B 88. B 89. D 90. B 91. C

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Radiation Biology Syllabus for Diagnostic and Interventional Radiologists

9

Explanation of AnswersI.RadiationBiology/EffectsQuestion1. When x rays are absorbed in biologic material, the photon first interacts with an orbital electron of an atom of the material by the photoelectric, or Compton, process to produce a fast recoil electron. The energy of this electron is lost through interactions with other atoms or molecules to produce biomolecular ions. The ensuing biochemical events may or may not lead to a biologic effect. Protons and spallation products are formed when neutrons are absorbed in tissue. The correct option is A (, pp 9; , pp 7). Question2. X rays are absorbed in biologic material to produce a recoil electron, as described in Question . This electron may interact directly with DNA to cause a strand break, but this is relatively unlikely because DNA constitutes a small proportion of the cell. The cell is mostly water, and the electron may ionize a water molecule close to the DNA. This leads to the chemical production of a free hydroxyl radical (OH), which diffuses to the DNA and causes a strand break. This accounts for about two-thirds of the biologic damage produced by x rays. The correct option is D (, p ). Question3. Dicentrics and rings are exchange type aberrations; in other words, they are formed by the illicit rejoining of two separate chromosome breaks. A dicentric is formed as a consequence of rejoining of breaks in two different chromosomes; a ring forms from the rejoining of breaks in the two arms of the same chromosome. The correct option is B (, pp ; , p 80). Question4. Damage to bases may represent a mutation, but it does not kill the cell. Thymine dimers are produced by ultraviolet radiation, not by ionizing radiations. Double-strand breaks are the most important lesions caused by x rays. Some are quickly and correctly repaired. Those that remain unrepaired or that rejoin illicitly to form an aberration may cause cell death. The correct option is C (, pp 8, 9, ). Question5. Lymphocytes from a blood sample can be stimulated to divide, and chromosomal aberrations can be scored at the first mitosis. The number of aberrations reflects the average effective total body dose. Option A is therefore true (, pp 8; , pp 90). The aberrations scored are of the exchange type, such as dicentrics, which require breaks in two chromosomes, so that the relation to dose is linear-quadratic. Hence, option D is false (, pp 8). The dose that can be detected depends on how many cells are scored, but for practical purposes, cGy is the lowest dose that can be detected. Option B is therefore false (, pp 8; , pp 90). Lymphocytes are very radiosensitive, die an interphase death, and disappear quickly after a large dose. A few days after exposure to 0 Gy, there would be few lymphocytes in circulation, so the system could not be used to assess dose. In any case, the person would have died a gastrointestinal death before weeks! Option C is therefore false (, pp 90; , pp 90). Question6. If a break occurs in two prereplication chromosomes, and pieces of chromatin without centromeres are exchanged, this is a symmetric translocation and is compatible with life (option D). If rejoining occurs so that the two pieces with centromeres join, this represents a dicentric (option E). If the two pieces without centromeres join, this forms an acentric fragment (option A). A small piece of chromatin with a centromere is a centric fragment. What usually happens is that a break occurs on each side of the centromere, and the two sticky ends join to form a ring chromosome; in other words, the centric fragment is often a ring (option B). When two breaks occur in the same piece of chromatin, and the piece isolated reverses and rejoins, this is called an inversion (option C). All options are true (, pp ). Question7. In most mammalian cells, mitosis itself (M) lasts about a half hour to an hour. The DNA synthetic phase (S) has a duration of 68 hours in rodent cells and about hours in human cells. G has a duration of a few hours. G is the phase that is most variable in length; it may last only an hour in cells that are dividing rapidly to repair damaged tissue, or it may be 0 days to weeks in, for example, the stem cells of resting skin. The correct option is A (, p 69).

0

Radiation Biology Syllabus for Diagnostic and Interventional Radiologists

2007

Question8. Cells in mitosis (M) or just before, in the G phase, are the most radiosensitive, while cells in late S are the most radioresistant. G cells are intermediate in radiosensitivity. When an asynchronous population of cells is exposed to x rays, most surviving cells will be from the most radioresistant moiety of the population, S. The correction option is D (, pp ). Question9. In the few humans who have died a gastrointestinal death as a consequence of total body irradiation, it is the small intestine that is most completely denuded. The correct option is C (, pp 90; , p 8). Question10. Xeroderma pigmentosum is characterized by sensitivity to ultraviolet radiation but not to x rays. Bloom syndrome and Fanconi anemia both exhibit genomic instability but are not particularly sensitive to either x rays or ultraviolet radiation. The characteristic of ataxia telangiectasia is sensitivity to x rays but not to ultraviolet radiation. The correct option is B (, p ). Question11. The shoulder of the survival curve (the component in the - formalism) is most pronounced for low linear energy transfer (LET) radiations and minimal for high-LET radiations. For a given particle, the LET goes down as the energy goes up. For a given energy, the LET increases with the mass of the particle. Electrons are by far the lightest of the particles listed; pi mesons are the next lightest, then neutrons, with alpha particles the heaviest. The correct option is C (, pp ; , pp 88). Question12. The number of free radicals produced is a function of dose and does not depend on dose rate; option A cannot be correct. Ion pairs recombine in fractions of a millisecond, so that is not a factor here; option D is incorrect. The mitotic cycle is lengthened, not shortened, by radiation; option B is incorrect. This leaves options C and E. If the dose rate is very low, cell survival would be dominated by cell division occurring during a prolonged exposure, and option C would be correct. However, for any practical dose rates, the dominant factor in the dose-rate effect is the repair of sublethal damage during a prolonged exposure. The correct option is E (, pp 77).

Question13. Stochastic effects are effects for which there is no threshold and for which the severity of the effects does not depend on dose, although the probability that the effects will occur does. Stochastic effects include heritable effects and carcinogenesis, but not cell killing. All biologic effects, stochastic or otherwise, depend on all four factors: dose, LET, dose rate, and type of tissue exposed. All options are correct (, pp 6, 96; , p 80). Question14. A total body dose in the range of 0.7. Gy results in nausea in %0% of persons exposed. At higher doses in the range of ..00 Gy, the prevalence increases to 0%70%. Above . Gy, moderate to severe nausea is expected in 0%90% of persons exposed. The correct option is C (, p 8). Question15. The lymphocyte count would be decreased by a dose of 0. Gy. A transient early erythema may be produced by a dose of Gy, with 6 Gy required for a robust erythema. Temporary epilation occurs after a dose of Gy and permanent epilation after 7 Gy. A dose of . Gy or more is required to produce sterility in the female. The correct option is B (, pp ). Question16. Three of the four options in this question relate to death by total body irradiation at differing dose levels. The LD 0/60 refers to the death of 0% of the exposed population in 60 days due to failure of the hematopoietic system. Its value is about Gy. C matches with (, p 7). LD 0/ refers to the dose required to kill humans by denuding the lining of the gastrointestinal tract. Its value is about 0 Gy. B matches with (, pp 90). Only a few examples of death by the cerebrovascular syndrome have ever been seen in humans; death occurs in about 8 hours, and the dose required is about 00 Gy. A matches with (, pp 89). The fourth option involves hereditary effects (ie, effects in offspring due to irradiation of parents). The dose required to double the natural or spontaneous mutation rate is about Gy. D matches with (, pp 6, 66).

2007

Radiation Biology Syllabus for Diagnostic and Interventional Radiologists

Question17. The minimum dose of x rays in an acute exposure likely to produce a vision-impairing cataract is Gy; option A is false (, p 8). Dicentric chromosomal aberrations in stimulated human peripheral lymphocytes can be observed at any dose above about 0. Gy; option B is true (, p ). A transient early erythema may be produced by a dose of about Gy, and a robust erythema requires 6 Gy; option C is false (, p 0). Ataxia is not a likely result of any dose, except perhaps hundreds of grays; option D is false (, pp 89). The risk estimate for radiation-induced cancer is 8%/Gy for an acute exposure. A % increase would require /8 Gy, or . Gy; option E is false (, p 6). Question18. Vomiting and other GI symptoms in the majority of individuals exposed require a dose of several grays; option A is false (, pp , ). Diarrhea indicates a supralethal dose (ie, a dose in excess of Gy); option B is false (, p ). Option C is true because temporary sterility in males occurs after a dose as low as 0. Gy (, p 66). However, permanent sterility in females requires a dose of Gy or more; option D is false (, p 66). A decrease in lymphocyte count would be observed at a dose as low as 0. Gy; option E is true (, p ). Question19. The dose that would kill 0% of a population as the result of failure of the hematopoietic system (ie, LD 0/60) is Gy; option A is true (, p 7). Seizures are not a feature of any radiation dose short of the central nervous system/cerebrovascular syndrome, which requires a dose in excess of 00 Gy; option B is false (, pp 89). The nadir of the white blood cell count, determined by the lifetime of mature circulating cells, is several weeks following irradiation; option C is false (, p ; , pp 90; , pp 6, ). Bone marrow transplants cannot save persons exposed to doses in excess of about 0 Gy, because they will die a gastrointestinal death; option D is false (, pp 90). Question20. Transient erythema is evident in hours, and the main wave of erythema occurs after 0 days. Epilation occurs after about weeks. Ulceration and depigmentation are late effects due to damage to the dermis. Pain would be secondary to extremely high doses. The correct option is D (, p 0; , pp 8980).

Question21. Temporary sterility in males occurs after a dose as low as 0. Gy; option A is true (, pp 7, 66). Permanent sterility in females occurs at doses of . Gy or more; option B is true (, pp 7, 66). Radiation-induced sterility in males does not affect hormone levels or libido; option C is false (, pp 7, 66). Radiation-induced sterility in females results in symptoms similar to those in normal menopause; option D is true (, p 7). Because the cells in the male reproductive system involve a hierarchy of cells in a self-renewal system, there is a latent period between irradiation and sterility; option E is false (, p 7). Question22. Mutations produced by radiation are indistinguishable from those that occur spontaneously; option A is false (, p 66). There is no statistically significant excess of hereditary effects in the children of the Japanese exposed to radiation by the atomic bombs, which indicates that humans are certainly not more sensitive than mice and might be less sensitive; option B is false (, p 6). Risk estimates for hereditary effects are based on the Megamouse project; option C is true (, pp 66). If Gy (or Sv) is required to increase the mutation rate by 00%, 0.0. Gy (or Sv) would be required to increase the mutation rate by 0%0%. However, the average background radiation in the United States is only mSv (ie, 0.00 Sv). Option D is false (, p 66). The doubling dose is the dose required to double the natural or spontaneous level of mutations. The BEIR committee quoted a range, 0.. Sv, while UNSCEAR quoted a single figure, Gy. Option E is true (, p 66). Question23. The risk estimate for the hereditary effects of radiation, based on a doubling dose of Gy, plus an allowance for multifactorial diseases, is estimated by the ICRP to be 0.%/Sv. (For x rays, sieverts and grays are interchangeable units, since the radiation weighting factor for x rays is unity.) The risk for a hereditary effect from an exposure of 0. Gy is therefore 0./00 0. = 0, a risk of in 0,000. The correct option is A (, p 66).

Radiation Biology Syllabus for Diagnostic and Interventional Radiologists

2007

Question24. Carcinogenesis by radiation is considered to be a stochastic process (ie, it is an all-or-nothing event). The severity of the response is not dose dependent, although the probability of it occurring is. There is no threshold (ie, there is no dose below which there is no risk). The BEIR V and UNSCEAR committees found that for solid tumors in the Japanese survivors, the excess cancer incidence was a linear function of dose, with no threshold. The leukemia data were best fitted with a linear-quadratic function of dose. The correct option is A (, pp , ). Question25. The thyroid is most sensitive to induction by radiation of both benign nodules and malignant tumors. None of the other tissues shows such an incidence of benign tumors due to x rays. The correct option is C (, pp 90; , pp 8, 90). Question26. At the time of the Three Mile Island accident, it was estimated that the number of cancer deaths due to the release of radioactive materials was about 0.! The closest and correct option is A (6, p ). Question27. The excess cancer risk estimated by the UNSCEAR and BEIR V committees was 8%/Sv, based on the data from the Japanese survivors. However, the Japanese survivors experienced an acute exposure. The ICRP uses a dose and dose-rate reduction factor (DDREF) of , so that the estimate of cancer risk at low doses and low dose rate, applicable to the radiation protection of a working population, is %/Sv. The correct option is A (, p 6). Question28. An excess incidence of leukemia was observed in patients with ankylosing spondylitis treated with x rays for the relief of pain. A matches with (, p 9). An excess of breast cancer was observed in patients who underwent fluoroscopy many times during the management of tuberculosis, first reported from Canada and later repeated in a New England study. B matches with (, p 0). Thyroid tumors, both benign and malignant, were observed in the inhabitants of the Marshall Islands in the Pacific as a

result of fallout from the testing of nuclear weapons. C matches with (, p 9). An excess of lung cancer is observed in underground miners, including uranium miners, who breathe radon, which concentrates in the environment of the mine. Radon is a noble gas with a half-life of about days. It decays to solid radioactive isotopes that stick to particles of dust and are deposited in the bronchi and lungs. These radionuclides emit alpha particles that irradiate the bronchial epithelium and may cause lung cancer. D matches with (, pp 0). Women employed as dial painters ingested radium by licking their brushes for the application of luminous paint to watches. Bone sarcomas and carcinomas of epithelial cells lining the paranasal sinuses and nasopharynx were observed in this exposed population. E matches with (, p 66). Question29. The prostate has a relatively high natural or spontaneous incidence of cancer in the United States, but a low risk of induction by radiation. D matches with (, p 88; , p 6). Thyroid cancer is relatively rare in the population, but both benign and malignant tumors are induced by radiation, especially in children and young people. B matches with (, pp 90). Breast cancer is relatively common in the U.S. population and is readily induced by radiation. C matches with (, p 0). Malignancies in the kidney are rare and do not figure prominently in any of the major populations exposed to radiation. A matches with (, p 88). Question30. Radiation-induced abortions after a -Gy exposure are very likely during weeks 0 of gestation but are unlikely during weeks 8; option A is false (, pp 6880). During weeks 0, radiation-induced abortions are likely, but congenital abnormalities are unlikely to occur until weeks 6; option B is false (, pp 6880). Although not high, the risk of mental retardation may occur during weeks (a risk level of about 0%/Sv); option C is true (, pp 6880). The risk of mental retardation is as much as 0%/Sv during weeks 8. During the period of organogenesis (6 weeks of gestation), congenital abnormalities are likely after a dose of Gy; option D is true (, pp 6880).

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Radiation Biology Syllabus for Diagnostic and Interventional Radiologists

Question31. In a general dictionary, stochastic is simply defined as random. In radiation protection, it has taken on a special specific meaning and applies to carcinogenesis and hereditary effects. A stochastic effect is an all-or-nothing effect. The severity of the effect is not dose related; option A is false (, pp 6). However, the probability of the effect occurring increases with dose; option B is true (, pp 6). There is no dose below which the effect cannot occur (ie, there is no threshold); option C is false (, pp 6). Damage to a small number of cells, even one cell, can cause the effect; option D is true (, pp 6). Question32. The total number of excess malignancies attributable to radiation at Hiroshima and Nagasaki is about 600; option A is true (, p 7). There was an increase in leukemia and many solid tumors, including those of the breast; option B is true (, p 0). Exposure in utero led to an increased incidence of reduced head diameter and mental retardation; option C is true (, p 7). While there is a trend, there was no statistically significant increase in hereditary (genetic) effects in the firstgeneration children of persons exposed; option D is true (, p 6). Question33. Risk estimates for radiation-induced cancer are based on studies of exposed populations in which there is a clear dose-related excess of cancer cases. Good examples include the survivors of the atomic bombs in Hiroshima and Nagasaki, as well as the women who underwent fluoroscopy many times during the management of tuberculosis; options B and C are true (, pp 78). Patients treated with I- show no clear dose-related excess of cancer or leukemia, nor do populations living near nuclear power plants; consequently, neither can be used to obtain risk estimates; options A and D are false (, pp 78).

Question34. Latency is the time between irradiation and the appearance of malignancy. For leukemia, the latent period is short, on the order of 7 years, while for solid tumors the latent period may be as long as 00 years. Option A is false (, p 8); option D is true (, p 8). Children are more sensitive than adults for some malignancies, while for others, there appears to be little difference with age. However, children are certainly not less sensitive than adults; option B is false (, p 6). Radiation induces benign as well as malignant tumors (thyroid tumors are the best example); option C is true (, p 80). The ICRP risk estimate for radiation-induced cancer in a working population at low dose and dose rate is %/Gy. A dose of 0. Gy would result in a cancer incidence of 0.%, not 0%; option E is false (, p 6). Question35. Animal experiments indicate that exposure to radiation during organogenesis leads to a wide spectrum of malformations; B matches with (, pp 697). During preimplantation, radiation appears to have an all-or-nothing effect; either the newly fertilized egg is killed, or it develops normally. Growth retardation and malformations do not result from irradiation at this time. A matches with (, pp 697). There is an increased risk of cancer due to exposure in utero; C matches with (, pp 697). Question36. Prior to 8 weeks after conception, the fetal thyroid does not take up iodine, so hypothyroidism will not occur in the fetus even from a therapeutic dose; option A is true (, pp 89). The total body dose to the conceptus from the administration of 0 mCi is less than 7 rad (70 mGy), which is too low to cause death; option B is false (, pp 89). The red marrow dose to the mother from the administration of 0 mCi is about 0.09 Sv. The absorbed dose to maternal organs other than the thyroid is typically not more than 0. Sv from a 0-mCi administration. The ICRP risk of all cancers from an acute dose of radiation is about 8%/Sv and for leukemia about %/Sv; both C and D are false (, pp 6).

Radiation Biology Syllabus for Diagnostic and Interventional Radiologists

2007

Question37. An accident situation in which injuries are possible justifies the small risks associated with diagnostic x rays; option A is false (7, pp ). A therapeutic abortion would not be justified; option B is false (7, pp ). On the basis of the Japanese survivors data, 8 weeks is the sensitive period for reduced head diameter and mental retardation. The doses are not large enough for this to be very likely, but if a radiation-induced defect occurred, it would involve the central nervous system; option C is true (, pp 7778). On the basis of the case-control studies of Stewart et al, even a few radiographs during pregnancy increase the risk of leukemia and childhood cancer; option D is true (, pp 7677). The dose to the fetus would be considerably less than 0. Gy; option E is false (7, pp ). Question38. Intrauterine death occurs as a result of irradiation during preimplantation (00 days), and neonatal death (ie, death at or about the time of birth) occurs because of irradiation during organogenesis (0 days to 6 weeks). Irradiation at 8 weeks is too late for this; options A and B are false (, pp 697). The data from persons exposed in utero at Hiroshima and Nagasaki show that irradiation to a sufficient dose may produce microcephaly (reduced head diameter) and mental retardation. The most sensitive time interval for these effects was 8 weeks. There was a less sensitive interval at weeks; option C is true (, pp 7677). The case-control studies of Stewart et al showed that even a few obstetric radiographs could lead to an elevation of risk of leukemia and childhood cancer; option D is true (, pp 7677). Question39. A multislice CT scan results in a dose to the lens of the eye of less than cGy. Cerebral angiography can contribute an additional dose of cGy to the lens of the eye. The minimum dose that will produce a cataract in a single exposure is about Gy. The correct option is A (, p 8).

Question40. In the lens, dividing cells are confined to the equatorial region. Progeny migrate to the posterior pole of the lens. Cells damaged by radiation lead to opaque fibers that congregate in the posterior pole; option A is false (, p 8). The minimum acute dose to produce a cataract is about Gy; Gy over years will certainly not result in a cataract; option B is false (, p 8). Prescription eyeglasses today are almost always plastic and absorb little radiation. Lead glass is required to significantly attenuate x rays; option C is false (, p 77). Vision-impairing cataracts take time to develop and are preceded by less-important opacities; option D is true (, pp 88). Question41. A stochastic effect is one in which the severity of the effect is independent of the dose and for which there is no threshold. In the case of a cataract, there is a practical threshold of Gy, and the severity of the cataract increases with the dose; option A is false (, pp 88). The minimum dose, in a single acute exposure, required to result in a cataract is indeed Gy; option B is true (, pp 88). Cataractogenesis by radiation shows a substantial dose-rate and fractionation effect (ie, a larger dose is required if it is protracted); option C is true (, pp 88). For a given dose, high-LET radiations, such as neutrons and heavy charged particles, are much more effective at inducing cataracts; option D is true (, pp 88). Question42. A dirty bomb is a dispersal device that causes purposeful dissemination of radioactive material over a wide area without a nuclear detonation. Potential sources of radioactive material for a dirty bomb include naturally occurring radionuclides (eg, radium, uranium, thorium), products of the nuclear fuel cycle, radioisotopes used in medicine, components of military systems, and radiation sources used in industry. Highly radioactive material such as nuclear fuel rods, cobalt-60 teletherapy sources, and industrial radiography units could deliver significant whole body exposure to those present, resulting in acute radiation syndrome. Contaminated-injured patients are anticipated from an explosive device that releases radioactive material. Patients with large amounts of radioactive contamination pose an exposure hazard to medical personnel. As an act of terrorism, the primary purpose of a dirty bomb is to inflict fear, destroy the sense of well-being, and disrupt community function. All options are true (, pp 9, 6, 7).

2007

Radiation Biology Syllabus for Diagnostic and Interventional Radiologists

II.RadiationSafety/ProtectionQuestion43. Systme International (SI) units are the gray and the sievert. The gray is the unit of absorbed dose and is defined as J/kg. The sievert is the unit of equivalent dose, or the product of dose in grays and the radiation weighting factor (Wr). The rad, rem, and curie are the old units, replaced in the SI system by the gray, sievert, and becquerel. Options C and E are true (, p 9). Question44. The maximum permissible doses recommended by the NCRP are effective doses. Also, the dose outside the lead apron does not reflect the dose under the lead apron. The dose under the lead apron is usually lower by about a factor of 0. The dose to the conceptus is more than a factor of two less than this because of protection from the mothers overlying tissues. Therefore, the actual dose to the conceptus is less than about 0. mSv for the 90-day period. This is less than 0.0 mSv to the conceptus per month, which is much lower than the 0.-mSv monthly limit recommended by the NCRP; option C is true. Option A is false for two reasons: (a) The dose to the conceptus is not at a level of true concern, and (b) the Nuclear Regulatory Commission (NRC) regulates exposures only to radionuclear by-product material. The NRC would be an improper agency to notify for exposures to x rays. The individual can continue to work in fluoroscopy as long as she maintains proper radiation management practices; option B is false. Since the radiation levels are well below any of concern, option D would be unconscionable (, p 77; 8; 9, p 8). Question45. Inhaled radon contributes a little more than half of the effective dose to the U.S. population, with the remainder approximately equally divided between medical radiation and background radiation arising from cosmic rays and from the ground. The correct option is B (0, p ). Question46. Radon is the largest single contributor to the effective dose; the effective dose is the product of the absorbed dose, the radiation weighting factor (Wr), and the tissue weighting factor (Wt ). The radiation weighting factor for the alpha particles emitted by radon progeny is 0, while the tissue weighting factor for the lung, the only tissue irradiated by radon progeny, is 0.. The correct option is C (0, p ).

Question47. Medical (including dental) radiation represents about a quarter of the effective dose to the U.S. population and is therefore by far the largest source of exposure from human activity. Natural background radiation is slightly greater. The correct option is D (0, p ). Question48. The effective dose from average background radiation, including radon, for the United States is about mSv per year; D matches with (0, p ). Once a pregnancy is declared, the NCRP dose limit to the conceptus is 0. mSv per month. Until a pregnancy is declared, there are no special dose limits other than those applicable to any radiation worker. C matches with (9, p 8). The effective dose received in flying across the North Atlantic in a commercial jetliner is about 0.0 mSv. This is due to the cosmic radiation at the altitude of about ,000 feet. A matches with (0, p ). The genetically significant dose (GSD) is the dose that if given to everyone in the U.S. population would result in the same number of mutations as would the actual variable dose received by part of the population during medical irradiation. The GSD is about 0. mSv. B matches with (0, p ). Question49. Radon tends to accumulate in the basement of a house as it seeps in from rocks and soil. This is particularly true in winter when the house is heated and the pressure inside is a little less than that outside. This draws radon into the house. In the outside air, radon dissipates. Option A is true. The BEIR VI best estimate of lung cancer deaths from radon was ,00 to ,800 per year, depending on which model is adopted. This is about 0% of the lung cancer deaths per year, which were about 7,990 in 00 in the United States. Option B is true. Two of the progeny of radon emit energetic alpha particles, which are thought to be the cause of lung cancer; option C is true. When radon decays into solid progeny, it does so with a half-life of about days; option D is false. The parent is indeed radium; option E is true (, pp 8990).

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Radiation Biology Syllabus for Diagnostic and Interventional Radiologists

2007

Question50. Radon is a naturally occurring radioactive gas that seeps out of the ground into mines and the basements of homes; option A is true. Radon constitutes about % of the effective dose to the U.S. population, which is about double that from medical x rays; option B is true. In the United States, the action level for radon (the maximum concentration in the lived-in area of a house above which modifications to the building are recommended) is pCi/L. This is lower than the action levels in Canada and Europe. Option C is true. The half-life of radon is about days; it is radium that has a half-life of about ,600 years; option D is false. Two of the progeny of radon emit energetic alpha particles, which are thought to cause lung cancer; option E is false (, pp 8990). Question51. Of the options given, fluoroscopy of the trunk of the body involves by far the largest dose to the operator. The correct option is C (, pp , 7, 769770). Question52. The genetically significant dose (GSD) is the dose that if given to everyone in the U.S. population would result in the same number of mutations as would the actual variable dose received by part of the population during medical irradiation. The GSD due to medical radiations, therefore, depends on the gonad doses, the age and sex of the patients, and the number of persons exposed; options A, B, and C are true. The time of day is obviously irrelevant; option D is false (, p 76; 0, p ). Question53. Until a worker declares a pregnancy, no special protection limits apply apart from those generally applicable to a radiation worker. Once a pregnancy is declared, the recommended limit is 0. mSv per month. If this is adhered to, the dose for the duration of the pregnancy would be similar to that allowed for an occasional exposure of a member of the general public. The mother may be a radiation worker, but the conceptus is not. The correct option is C (9, p 8). Questions54. Hands and legs are of concern for deterministic effects, which do not include cancer induction; option A is false (, p ). The risk of cancer from low-dose-rate exposures is about %/Sv; option B is true (; p 6). Hands are allowed a larger maximum dose (00 mSv) than the eyes (0 mSv) because the eyes are much more sensitive to radiation;

option C is false (, p ). Because of repair of damage, a low-dose-rate exposure is less effective than a high-dose-rate exposure; option D is true (, p 6). Question55. The genetically significant dose is the dose that if given to everyone in the U.S. population would result in the same number of mutations as would the actual variable dose received by part of the population during medical irradiation. It therefore gives some idea of the impact of gonadal radiation. C matches with (0, p ). Dose is a physical term, expressed as energy per unit mass. One gray of different types of radiation does not result in the same biologic effect. The equivalent dose is the product of dose and the radiation weighting factor (Wr), a dimensionless factor designed to reduce all radiation to a common scale. The unit is the sievert. One sievert of any kind of radiation produces the same biologic effect. B matches with (9, p 6). Different organs and tissues show different susceptibilities to the biologic effects of radiation. The effective dose is the sum of the products of equivalent dose and the tissue weighting factor (Wt ) for all organs or tissues exposed. D matches with (9, p ). In the case of an incorporated radionuclide, the dose is not delivered instantaneously but over a period of time depending on the half-life of the radionuclide. Committed equivalent dose takes that into account and is the effective dose integrated over 0 years. A matches with (9, p ). Question56. The maximum permissible effective dose for individuals occupationally exposed is 0 mSv per year; C matches with (9, p ). The public is allowed an exposure that is one-tenth of the occupational cumulative dose limit of 0 mSv per year; B matches with (9, p 6). After a pregnancy is declared, the maximum permissible dose per month to the conceptus is 0. mSv, so that during the duration of the pregnancy the dose is similar to that allowed a member of the general public as an occasional exposure (one-tenth of the annual occupational effective dose limit); A matches with (9, p 8). The limit for the eye of an occupationally exposed individual is 0 mSv, which is designed to prevent a deterministic effect; D matches with (9, p 6). Question57. The unit of absorbed dose is the gray, defined as J/kg; B matches with (9, p 9). The unit of activity of a radionuclide is the becquerel, defined

2007

Radiation Biology Syllabus for Diagnostic and Interventional Radiologists

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as one disintegration per second; D matches with (9, p 9). The equivalent dose is the product of absorbed dose in grays and the radiation weighting factor (Wr), which is a dimensionless factor. The unit is the sievert. A matches with (9, p 60). The collective effective dose is the sum of the effective doses for all members of a population. The unit is the personsievert. C matches with (, p 96; , p 7). Question58. The maximum permissible dose for the hands is 00 mSv because the main concern for the hands is not skin cancer but deterministic effects. Maximum permissible dose is based on low-doserate exposures, and nuclear power plant employees have not contributed to the database for hand exposure. The correct option is D (, p ). Question59. The minimum age for occupationally exposed workers is 8 years; option A is true (9, p ). It is assumed that medical radiation confers some benefit, so it is not included in the dose allowed to a person occupationally exposed; option B is false (9, p ). ALARA is intended to minimize occupational exposure; option C is false (9, p ). The purpose of radiation protection for those occupationally exposed is to prevent deterministic effects and limit stochastic effects to levels that are acceptable against a background of other risks in society; option D is true (9, p 9). Question60. The patient attenuates a fraction of the incident x rays. This fractional reduction in x-ray intensity is essentially independent of the patients position between the x-ray source and image receptor. Therefore, the automatic brightness control response is also independent of patient position. Changing the source-to-skin distance from 0 inches to inches can increase the entrance exposure rate by a factor of .8. Option A is true (, p 778). Many modern fluoroscopy systems have the capability to freeze the last image on the monitor after the x-ray exposure is terminated. This allows the physician to study the last image and plan the next task without radiation exposure to the patient. Option B is true (, p 778; , pp 9). During pulsed fluoroscopy, the x-ray beam is emitted as a series of short pulses rather than continuously. For continuous fluoroscopy, the video display is a constant 0 frames per second. At reduced frame rates, substantial dose reduction can be achieved. Images can be acquired at frames per second rather than

the usual 0 frames per second. Dose reduction is 0%. However, manufacturers may increase the radiation level per frame to achieve a more pleasing visual appearance, and the dose reduction may be only %. Nevertheless, pulsed fluoroscopy offers reduced exposure rate and improved image quality compared with continuous fluoroscopy (sampling time for each frame is less with pulsed fluoroscopy). Pulsed fluoroscopy can be performed at lower frame rates (0, 7., or frames per second). Low frame rates adversely affect the ability to display rapidly moving structures. Option C is true (, p 778; , pp 9). The design of the fluoroscopy system may incorporate operator-selectable filtration. Substantial reductions in skin dose, particularly for large patients, can be achieved by inserting appropriate metal filters (aluminum, copper, or other materials) into the x-ray beam at the collimator. Filtration reduces skin dose by preferentially removing lowenergy x rays, which generally do not penetrate the patient to contribute to the image. Option D is true (, pp 9). The presence of a grid improves contrast by absorbing scattered x rays. However, the dose to the patient is increased by a factor of two or more. For pediatric cases, the removal of the grid reduces the dose, with little degradation of image quality. Grids should be used with discretion when fluoroscopic studies are performed on children. These systems should have the capability for easy removal and reintroduction of the grid. Option E is true (, pp 9). In most interventional fluoroscopic procedures, the x-ray beam is directed toward a particular anatomic region for the bulk of the fluoroscopic time. Some reduction in maximum skin dose can be achieved by periodically rotating the fluoroscope to image the anatomy of interest from a different direction. This method tends to spread the entry dose over a broader area, thereby reducing the maximum skin dose. Option F is true (, p 70). A magnified image (reduced field of view) typically results in higher dose to the patient. There are two ways to magnify the image: geometric and electronic. The geometric method usually positions the patient closer to the x-ray source but can also be achieved by moving the image receptor farther away from the patient. The technique factors are driven higher for electronic magnification because a smaller area of the image receptor is utilized for image formation. Each method increases the entrance exposure rate. Options G and H are false (, p 7).

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Radiation Biology Syllabus for Diagnostic and Interventional Radiologists

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Question61. The use of protective clothing (aprons and thyroid collars) in addition to ceiling-mounted lead glass shields is well documented (, p 77). The transmission of x rays through radiation-attenuating surgical gloves is typically stated as 60%70% at 80 kVp. In clinical practice, this value is higher (less attenuating) because of beam geometry differences. By comparison, devices made with 0.-mm lead-equivalent material have a transmission of %. Radiation-attenuating surgical gloves offer minimal protection of the operators hands. The instantaneous dose from scatter radiation is reduced somewhat when the hands covered with one layer of glove material are located near the radiation field. However, the total time near the radiation field depends on the speed at which the procedure is performed, as well as the distance from the imaged anatomy when the x-ray beam is activated. The increased thickness of these gloves reduces dexterity and therefore can increase procedure time. The automatic brightness control system in fluoroscopy increases the radiation output to penetrate the glove when the hand is present in the beam. This can be confirmed by noting that anatomy is seen even though the glove is present. The dose to the hand is comparable to that when the radiation-attenuating glove is not present. The following statements are from Teaching Radiation Safety to Invasive Fluoroscopists by S. Balter, PhD ():Radiation-attenuating surgical gloves are available. They offer minimal protection to the operators hands. (There is a real myth around that these gloves eliminate hand exposure.) The automatic exposure control system often increases radiation output to penetrate the gloves. Anatomy is seen through , , or 6 layers of glove material. The operators hand is covered by a single layer of glove material.

Question62. On September 0, 99, the FDA issued a Public Health Advisory regarding radiationinduced skin injuries from fluoroscopic procedures. These injuries are usually delayed, so the physician cannot discern damage by observing the patient immediately after the treatment. The radiation dose required to cause skin injury is typically Gy for erythema (onset days after exposure) and temporary epilation (onset weeks after exposure). Additional fluoroscopy time above the threshold dose increases the severity of the skin injury: a dose of 6 Gy for main erythema (onset 0 days after exposure) and a dose of 0 Gy for moist desquamation (onset weeks after exposure). Vascular damage is expected for skin doses above 0 Gy. The procedures of concern are primarily interventional procedures during which fluoroscopy is used to guide instruments. The dose rate to the skin from the direct beam is typically between and rad/min (00 mGy/min) for continuous fluoroscopy. The maximum exposure rate permitted by the FDA is 0 R/min. The dose rate is usually reduced if pulsed fluoroscopy is employed. For units with a high-level fluoroscopy mode of operation, the maximum exposure rate to the skin from the direct beam is 0 R/min. Risk of skin injury is associated with prolonged fluoroscopy time. The time required to deliver a threshold dose for temporary epilation is typically greater than . hours in fluoroscopy (0.0 Gy/min). At maximum exposure rate, the time to deliver this dose to a single skin site is 0 minutes in normal mode and minutes in high-level fluoroscopy mode. Large patients are more susceptible to skin injury because automatic brightness control automatically changes (without operator intervention) the technique factors to increase the x-ray output. The correct option is C (, p 0; , p 80; , p ).

The cost of radiation-attenuating surgical gloves and the minimal dose reduction do not justify the use of these devices in a risk-versus-benefit radiation protection analysis. Radiation-attenuating surgical gloves provide a false sense of protection and are not recommended. The correct option is D (, p 7).

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Radiation Biology Syllabus for Diagnostic and Interventional Radiologists

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Question63. Since ultrasound is nonionizing radiation, no radiation dose is delivered to the fetus (, p ). Scattered radiation to the fetus from a head CT examination is less than 0.0 mGy (, pp 8080). The entrance exposure for a KUB radiograph is usually about 00 mR. By using a dose conversion factor of 0. rad/R for the fetus (depends on beam quality, patient size, and field size), the dose per radiograph is estimated to be 60 mrad (0.6 mGy). The chest radiographic examination is a very lowdose procedure requiring only an entrance exposure of 00 mR (0.0. mGy) for the posteroanterior projection and slightly more for the lateral projection (, p 798). Scattered radiation to the fetus would be considerably lower. The correct option is D (, p 798; 6, p ). Question64. For a declared pregnancy, the dose limit to the fetus is 00 mrem ( mSv). For fluoroscopy, portable radiography, and nuclear medicine imaging, the dose to the conceptus from occupational exposure to the mother will very likely be less than mSv if proper radiation protection practices are followed. Radioiodine treatments with I- sodium iodide are considered to place the fetus at higher probability of exceeding mSv and are potentially very hazardous in terms of uncontrolled release of the radioactive material. The fetal thyroid takes up radioiodine after age weeks. The correct option is B (8, pp 9).

Question66. Pregnant health care workers have not been shown to be at increased risk of adverse outcomes from exposure to static magnetic fields. Although pregnant health care practitioners are permitted to work in the MR environment, they should not remain within the magnet room during data acquisition/imaging. The recommendation to exit the MR magnet room during data acquisition/imaging is not based on reported studies of potential adverse effects but is a conservative approach based on a recognition that there are insufficient data regarding the effects of MR electromagnetic fields. Positioning patients, imaging, archiving, injection of contrast agent, and entering the MR magnet room in response to an emergency are considered acceptable activities for the pregnant health care worker. The correct option is B (, p 9; , pp 7879). Question67. On the basis of the currently available data, there is no association of cancer or any other deleterious effect with the use of clinical MR imaging during pregnancy. The ACR has adopted the policy that MR procedures may be performed during any stage of pregnancy if medically indicated. The use of ultrasound, the desired information and effect on the management of the patient, and the potential for delay are appropriate considerations for the selection of a pregnant patient for MR imaging. The MR procedure is considered appropriate if the information requested addresses the clinical problem or is necessary to manage potential complications for the patient and/or fetus; that is, the results of the MR examination can potentially affect the care of the patient and/or fetus during the pregnancy. The risk to the fetus from gadolinium-based contrast agents is unknown and may be harmful. MR contrast agents should not be routinely administered to pregnant patients. The ACR makes no recommendation regarding appropriate pulse sequences or imaging parameters. The correct option is A (, p 9).

III.MagneticResonanceImagingQuestion65. Actively shielded magnets are designed to decrease the surrounding fringe field so that siting concerns are reduced. Nevertheless, a strong magnetic field is present in the magnet room. Ferromagnetic materials (oxygen tanks, hemostats, scissors, etc) brought into the magnet room can become airborne as projectiles in the static magnetic field. Projectiles pose a serious risk to the patient and others in the magnet room. Patient screening and staff training are the most effective methods to exclude ferromagnetic materials from the magnet room. However, new ferromagnetic detection systems are capable of detecting small ferromagnetic objects external to the patient and can now differentiate between ferromagnetic and nonferromagnetic materials. The ACR recommends ferromagnetic detection systems as an adjunct to screening of patients and devices. The correct option is A (, p ).

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Radiation Biology Syllabus for Diagnostic and Interventional Radiologists

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Question68. The vast majority of patients with NSF were receiving therapy with dialysis or had stage or renal disease at the time of MR imaging with gadolinium-based contrast agents. The population at risk can be identified by an additional question regarding a history of renal disease or dialysis. Prospective hematologic screening is not warranted. Option A is false. No special treatment is recommended for patients with stage or chronic kidney disease (defined as GFR > 90 mL/min/.7 m or GFR between 60 and 89 mL/min/.7 m ). However, gadodiamide (Omniscan) is not recommended for a patient with any level of renal disease. Option B is true. A risk-benefit assessment for that particular patient with stage , , or renal disease should indicate a clear benefit for the administration of a gadolinium-based contrast agent. The default standard dose for these patients should be one-half the usual dose. A written order from the radiologist approving the examination is recommended. Informed consent should also be provided. Under these conditions, option C is true. If patients with severe to end-stage renal disease receive gadolinium-based contrast agents, prompt dialysis following MR imaging should be considered. Option D is true (, p 9). Question69. All implanted intracranial aneurysm clips composed of titanium and/or titanium alloy are acceptable for MR imaging without any additional testing. However, documentation of the composition in writing is necessary. The correct option is C (, pp , , 6). Question70. Quenching is the loss of superconductivity of the magnet coils, which is accompanied by the rapid escape of helium as evidenced by clouds or fog around the MR imager. Helium will displace oxygen in the room. All magnet rooms should have helium-venting equipment. The ACR, citing reliability concerns, does not currently recommend oxygen monitors in the magnet room. An uncontrolled quench is an emergency situation requiring the rapid removal of all personnel/patients from the magnet room. Site access must be restricted until the magnetic field has dissipated. The correct option is D (, pp ).

Question71. The need for controlled access is based on the potential risk from the attraction of objects containing ferromagnetic materials, torque on metallic materials, and the possible dysfunction of medical implants for persons with such devices inadvertently entering the area. Control may be established by barriers or signs based on the manufacturers recommendations. The correct option is B (6, p 7). Question72. Significant risk criteria were developed by the FDA to include static magnetic field over T, RF exposure sufficient to produce a core temperature increase of C, time-varying magnetic fields (dB/dt) sufficient to produce severe discomfort or painful stimulation, and peak acoustic noise over 0 dB. All options are true (6, p 6). Question73. During MR imaging, the patient absorbs a portion of the transmitted RF energy, which results in tissue heating. This could cause an elevation of core body temperature or a skin burn by localized heating. The specific absorption ratio (SAR) is the dosimetric means by which RF power absorbed per unit mass is characterized. The FDA has set limits for SARs to limit whole-body and local temperature rise. The SAR should not exceed W/kg for the whole body for minutes, W/kg averaged over the head for 0 minutes, 8.0 W/kg in g of tissue (head or torso) for minutes, and W/kg in g of tissue (extremities) for minutes. Alternatively, RF heating is considered acceptable if the core temperature increase is less than C and local heating is no greater than 8C in the head, 9C in the trunk, and 0C in the extremities. The SAR is proportional to the number of images acquired per unit of time and depends on patient dimensions, RF waveform, tip angle, and coil type. Patient heating also depends on ambient temperature, relative humidity, airflow rate, blood flow, and patient insulation. The correct option is B (, pp 667; , p 6; 6, p 6). Question74. Gradient magnetic fields are rapidly applied by passing currents through the gradient coils. In the presence of the static magnetic field, a current in the gradient coil creates a force on the coil, which causes the coil to vibrate. The mountings for coils also flex and vibrate in response to movement of the gradient coils. The result is acoustic noise in the form of loud knocking. The correct option is C (, p 9).

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Radiation Biology Syllabus for Diagnostic and Interventional Radiologists

Question75. Rapidly switched gradients allow improved image quality and faster acquisition. The potential physiologic response includes peripheral nerve stimulation, muscle movement, and discomfort. The thresholds for cardiac stimulation and brain stimulation are much greater than for peripheral nerve stimulation and are unlikely to occur with current MR systems. The correct option is C (, pp ). Question76. Focal heating and thermal injuries have been induced by time-varying RF magnetic fields during MR examination. The presence of a conductive loop (crossed arms, ECG leads or unconnected surface coil leads in contact with patients skin, etc) can produce induced electrical currents, which can cause thermal injury. Near the inner bore of the magnet, high levels of RF standing waves may form. The patient must be positioned so that there is no direct contact between the patients skin and the inner bore of the magnet. Absorption of RF energy by the metallic object creates a heated surface, which can cau