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    • Section 1 Radiation Quantities Answers and Feedback

    • Section 1 Radiation Quantities Answers and Feedback 

      1. ANSWER: A
      FEEDBACK: When x-rays are absorbed in biologic material, the photon first interacts with an orbital electron of an atom of the material by the photo-electric (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. Electrons. 

      FEEDBACK: Système International (SI) units are the gray and the sievert. The gray is the unit of absorbed dose and is defined as 1J/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 

      3. ANSWER: 1-C, 2-B, 3-D, 4-A
      FEEDBACK: 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 1. 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 2. 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 3. 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 50 years A matches with 4. 

      4. ANSWER: 1-B, 2-D, 3-A, 4-C
      FEEDBACK: The unit of absorbed dose is the gray, defined as 1J/kg; B matches with 1. The unit of activity of a radionuclide is the becquerel, defined Radiation Biology Syllabus for Diagnostic and Interventional Radiologists 2007 28 as one disintegration per second; D matches with 2. 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 3. The collective effective dose is the sum of the effective doses for all members of a population. The unit is the person-sievert C matches with 4.  

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