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rad protection
applenton/lange 8th ed review
Question | Answer |
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1. what is used to account for the differences in tissue sensitivity to ionizing radiation when determining effective dose (E)? | Tissue weighting factor (Wt) represents the relative tissue radiosensitivity of irradiated material (muscle vs intestinal epithelium vs bone) |
2. According to the National Council on Radiation Protection and Measurements (NCRP) the monthly gestational dose-equivalent limit for embryo/fetus of a pregnant radiographer is: | 5 mSv |
3. a time of 1.5 minutes is required for a particular fluoroscopic examination, whose exposure rate is 275 mR/h. what is the approximate radiation exposure for the radiologic staff present in the fluoroscopy room during the examination? | 6.87 mR |
4. if the exposure rate to an individual standing 4.0 m from a source of radiation is 10 mR/h, what will the dose received after 20 min at a distance of 6m from the source? | 1.48 mR (using inverse square law) |
5. All of the following statements regarding mobile radiographic equipment are true except? | exposure switches must be the two-stage type (the exposure switch must be of the 'dead man' type that is, the exposure will terminate should the switch be released |
6. what cell type has the greatest radiosensitivity in the adult human | lymphocytes |
7. guidelines for the use of protective shielding state that gonadal shielding should be used | if the patient has reasonable reproductive potential, and when the gonads are within 5cm of the collimated field |
8. the interaction between ionizing radiation and the target molecule that is most likely to occur is the: | indirect effect indirect effect occurs when ionization takes place away from DNA molecule in cellular water |
9. what is the approximate entrance skin exposure (ESE) for the average anteroposterior (AP) supine abdomen radiograph? | 300 mrad |
10. all of the following are generally used to help reduce patient dose except: 1. grid 2. collimator 3. gonad shield | grid |
11. how will xray photon insensitivity be affected if the source-to-image distance (SID) is doubled? | its intensity increases four times |
12. what is established annual occupational dose-equivalent limit for the lens of the eye | 150 mSv (15 rem) |
13. occupational radiation monitoring is required when it is possible that the individual might receive more than: | one-tenth the annual dose limit |
14. Sources of natural background radiation contributing to the whole-body radiation dose include: | terrestrial radionuclides and internal radionuclides |
15. irradiation of water molecules within the body and their resulting breakdown is termed: | radiolysis |
16. which of the following contributes most to occupational exposure? A. photoelectric effect B. compton scatter C. classic scatter D. thompson scatter | compton scatter |
17. which of the following are used to account for differences in tissue characteristics when determining effective dose to biologic material? | tissue weighting factor (Wt) |
18. the xray interaction with matter that is responsible for the majority of scattered radiation reaching the image receptor (IR) is | compton scatter |
19. the exposure rate to a body 4ft from a source of radiation is 16 R/h. what distance from the source would be necessary to decrease the exposure to 6 R/h? | 7 ft (inverse square law) |
20. with miliamperes (mA) increased to maintain output intensity, how is the ESE affected as the source-to-skin distance (SSD) is increased? | the ESE increases |
21. late radiation-induced somatic effects include: 1. thyroid cancer 2. cataracts 3. genetic mutations | all of them |
22. each time an x-ray beam scatters, its intensity at 1m from the scattering object is what fraction of its original intensity? | 1/1000 |
23. according to the NCRP the annual occupational whole-body dose equivalent limit is: | 50 mSv |
24. a tld would use what crystal? | lithium fluoride |
25. sources of secondary radiation include: | leakage and scatter radiation |
26. all of the following have an effect on patient dose except: A. kilovoltage B. miliampere-seconds C. focal size D. inherent fioltration | focal size (the effect of focal spot size is principally on radiographic sharpness it has no effect on patient dose) |
27. the photoelectric effect is more likely to occur with: 1. absorbers having a high z number 2. high-energy incident photons 3. positive contrast media | 1 and 3 |
28. all of the following radiation-rexposure responses exhibit a non-linear threshold dose-response relationship except: a. skin erythema b. hematologic depression c. radiation lethality d. leukemia | radiation lethality |
29. in radiation protection, the product of absorbed dose and the correct modifying factor (radxQF) is used to determine A. roentgen (C/kg) B. rem (Sv) C. curie (Cu) D. radiation quality | rem (dose -equivalent. it is the only unit of measurement that expresses the dose-effect relationship) |
30. which of the following is recommended for the pregnant radiographer? | wear a second dosimeter under the lead apron |
31. the annual dose limit for medical imaging personnel includes radiation from: 1. occupational exposure 2. background radiation 3. medical xrays | occupational exposure |
32. which of the following anomalies is (are) possible if an exposure dose of 40 rad (400mGy) were delivered to a pregnant uterus in the third week of pregnancy 1. skeletal anomaly 2. organ anomaly 3. neurologic anomaly | organ anomaly |
33. the effects of radiation on biologic material depend on several factors. if a quantity of radiation is delivered to a body over a long period of time, the effect: | will be less than if it were delivered all at one time |
34. medical and dental radiation accounts for what percentage of the general public exposure to human made radiation? | 90% |
35. whaich of the following is (are) composed of nondividing differential cells? 1. neurons and neuroglia 2. epithelial cells 3. lymphocytes | neurons and neuroglia (nondividing differential cells are specialized, mature cells that do not undgergo mitosis) they are rendered radioresistant. the adult nervous system is composed of nondividing cells and is the most radioresistent system in adult |
36. how does filtration affect the primary beam? | it increases the average energy of the primary beam |
37. what is the minimum lead requirement for lead apron, according to the NCRP | 0.50 mm Pb |
38. an optically stimulated luminescence dosimeter contains which of the following detectors? | aluminum oxide |
39. immature cells are referred to as: 1. undifferentiated cells 2. stem cells 3. genetic cells | undifferentiated cells and stem cells |
40. what is the term used to describe x-ray photon interaction with matter and the transference of part of the photon's energy to matter? | scattering |
41. what is the approximate ESE for the average upright PA chest radiograph using 115 kvp and a grid? | 20 mrad |
42. to be in compliance with the radiation safety standards, the fluoroscopy exposure switch must: | be the dead man type |
43. primary radiation barriers must be at least | 7 ft |
44. the annual dose limit for occupational exposed individuals is valid for | beta, x and gamma radiations |
46. patient dose increases as fluoroscopic | FOV decreases |
48. what unit of measure is used to express ionizing rdiation dose to biologic material | Rem (Sv) |
49. LET is best defines as: | a method of expressing raiation quality, a measure of the rate at which radiation energy is transferred to soft tissue |
52. Biologic material is least sensitive to irradiation under which of the following conditions? | anoxic |
54. which type of dose-response relationship represents radiation-induced leukemia and genetic effects | linear, nonthreshold |