**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.__

2. ANSWER: A-FALSE, B-FALSE, C-TRUE, D-FALSE, E-TRUE

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 (*W*r). 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 (*W*r),
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 (*W*t ) 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 (*W*r), 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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