Radiation oncology part iv 20 7 ionization chambers

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Radiation Oncology Part IV 7.Ionization chambers, proportional counters and Geiger-Müeller counters are all gas filled radiation detectors. (a) Sketch a graph illustrating the operation of a gas filled detector plotting pulse amplitude against applied voltage. Indicate the regions on this graph which define the different detector types. (b) Discuss advantages and disadvantages of these detectors in the the field of radiation protection. (c) Give an example of an application for each type of detector (ie. ionization chamber, proportional counter, and G-M counter). 8.In the context of radiation protection: (a) Describe the design of an ionization chamber and its associated circuitry when used with an electrometer; (b) Describe the use of a portable ionization chamber for a radiation protection survey. 9.Describe: (a) A proportional counter; (b) The energy discrimination ability of a proportional counter; (c) How to calibrate a proportional counter as a tissue equivalent detector. 10. Describe: (a) A Geiger-Mueller (G-M) counter; (b) How to distinguish between beta and gamma radiation with a G-M counter; and (c) How to determine source strength of a beta emitter with a G-M counter. 11. (a) Briefly define or explain: (i) thermal neutrons; (ii) elastic collision; and (iii) recoil proton. (b) Describe the measurement of neutrons in the presence of X- or gamma rays. (c) Describe a BF3detector used to measure equivalent dose from neutrons. 12. (a) Briefly define or explain: (i) standard deviation and standard error; (ii) precision and accuracy of measurement; and (iii) relative and absolute uncertainty. (b) Describe the effect of background radiation on the precision of radiation measurements. 20
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CCPM Membership Examination Edition 11.0 Radiation Oncology Part IV 13.(a) Give the annual effective dose limits for stochastic effects recommended by ICRP Publication 103 for both occupational and public exposures. (b) Explain how effective dose is determined when the whole body is irradiated non-uniformly with a mixed radiation field. (c) Give four examples of tissue weighting factors. 14.The Canadian Nuclear Safety Commission specifies effective dose limits for three catagories of people: (i) Nuclear energy worker; (ii) Pregnant nuclear energy worker; and (iii) A person who is not a nuclear energy worker. (a) State the effective dose limits for the three groups and compare them to the effective dose from natural background. Include the time periods for which the limits apply. (b) Comment on how emergencies may affect dose limits. (c) What has been the largest driver of increased exposure to the public over the last 30 years? (d) Describe a campaign designed to decrease the population risk associated with the factor identified in (c). 15.(a) The Canadian Nuclear Safety Commission specifies equivalent dose limits. List the organs or tissues for which an equivalent dose limit exists, give the magnitude of the equivalent dose limit in mSv, and the time period for which this limit applies, for: (i)Nuclear energy worker; (ii) Any other person. (b) 21
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