Question 1: Which of the following statements regarding ion chambers used in Diagnostic Radiology is incorrect?
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Reference: | Diagnostic Radiology Physics : A Handbook for Teachers and Students, DR Dance, S Christofides, ADA Maidment, ID McLean, KH Ng, International Atomic Energy Agency, 2014, 529-533 |
Choice A: | In Mammography, parallel plate ion chambers with a thin entrance window are typically used. |
Choice B: | Cylindrical pencil type ion chambers are mostly used for CT and dental dosimetry. |
Choice C: | Cylindrical and spherical ion chambers have negligible directional dependence. |
Choice D: | CTDI ion chambers are designed to produce correct readings when partially irradiated. |
Choice E: | Most ion chamber dosimeters used in Diagnostic Radiology are sealed chambers. |
Question 2: Many modern ion chamber dosimeters automatically convert readings (electrical charge or current) to air kerma by correcting for various factors. Which of the following factors is NOT corrected for? |
Reference: | Diagnostic Radiology Physics : A Handbook for Teachers and Students, DR Dance, S Christofides, ADA Maidment, ID McLean, KH Ng, International Atomic Energy Agency, 2014, 526-527
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Choice A: | Atmospheric temperature. |
Choice B: | Atmospheric pressure. |
Choice C: | X-ray beam spectrum. |
Choice D: | Exposure rate. |
Choice E: | Ion recombination. |
Question 3: The following is a list of important properties of dosimeters. Solid state dosimeters tend to perform worse in which regard, when compared to ion chambers? |
Reference: | Diagnostic Radiology Physics : A Handbook for Teachers and Students, DR Dance, S Christofides, ADA Maidment, ID McLean, KH Ng, International Atomic Energy Agency, 2014, 528-530
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Choice A: | Linearity. |
Choice B: | Sensitivity. |
Choice C: | Energy Dependence. |
Choice D: | Leakage current. |
Question 4: There are various definitions of x-ray tube peak voltage. Which of the following has been proposed as the standard quantity of kVp? |
Reference: | Diagnostic Radiology Physics : A Handbook for Teachers and Students, DR Dance, S Christofides, ADA Maidment, ID McLean, KH Ng, International Atomic Energy Agency, 2014, 546-547
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Choice A: | Practical peak voltage. |
Choice B: | Absolute peak voltage. |
Choice C: | Effective peak voltage. |
Choice D: | Average peak voltage. |
Question 5: Which of the following is a correct statement regarding solid state dosimeters?
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Reference: | Diagnostic Radiology Physics : A Handbook for Teachers and Students, DR Dance, S Christofides, ADA Maidment, ID McLean, KH Ng, International Atomic Energy Agency, 2014, 536-537
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Choice A: | Solid state dosimeters are less susceptible to radiation damage compared to ion chambers, and therefore need less frequent recalibrations. |
Choice B: | Solid state dosimeters tend to be more temperature and pressure dependent than ion chambers are. |
Choice C: | Most commercial solid state dosimeters at the present time are based on the MOSFET technology. |
Choice D: | Most commercial solid state dosimeters include backscatter and sidescatter in their readings. |
Question 6: All dosimeters used in clinical environment should have a calibration traceable to a recognized standard. Which of the following statements regarding the calibration process is correct?
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Reference: | Diagnostic Radiology Physics : A Handbook for Teachers and Students, DR Dance, S Christofides, ADA Maidment, ID McLean, KH Ng, International Atomic Energy Agency, 2014, 542-546
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Choice A: | Primary standards dosimetry laboratories (PSDLs) employ free air ionization chambers for the measurement of absorbed dose traceable to the fundamental SI unit (Gy). |
Choice B: | The secondary standards dosimetry laboratories (SSDLs) calibrate their reference instruments at PSDLs and use these as their local dosimetry standards. |
Choice C: | Most SSDLs use the substitution method to determine the calibration coefficient. |
Choice D: | A general purpose dosimeter is typically calibrated at the RQR5 beam condition, and correction factors are obtained for other RQR beam qualities. |
Choice E: | All of the above. |