2. Bremsstrahlung interactions = projectile electron completely avoids all orbital
electrons. The electron interacts with nuclear field of atom (because of its electric
field) and the closer the electron gets = more likely to interact.
4. Cumulative doses for radiation workers = 1 rem x age (or 10 mSv x age)
5. Photon interactions can occur with orbiting shells or the nucleus. Pair production
and photodisintegration occur with the atomic nucleus.
6. Primary barriers are likely to receive the primary beam directly. This requires
more shielding than secondary barriers that receive scatter or leakage radiation.
7. The “star-shot” pattern is used to check the collimator, couch, and gantry rotation
isocenters. It is checked using the EPIDs while rotation collimator, couch or
gantry individually.
8. Exposure (Roentgen): measures the total number of ionizations produced by
photons and occur in a unit mass of air (C/kg).
9. Klystrons and magnetrons provide a source of microwaves. The klystron
amplifies microwaves which are used to accelerate electrons (requires a
microwave oscillator). Magnetrons can generate microwaves. Machines have
either a klystron or a magnetron, but never both.
10. Distant metastasis of the prostate is rare, but if it does occur it includes bones
(more specifically the spine, which is the most common location). Other locations
include liver and lungs.
11. Flattening filters are made of high z# materials and helps to reduce the intensity
in the center of the beam in efforts to make the radiation beam more uniform or
homogenous.
, 13. ALARA = As Low As Reasonably Achievable (Used to reduce individual exposures
when possible).
14. The carina is the division or bifurcation of the primary bronchi and is located at
T4-T5.
15. Picket Fence Test = verifies MLC leaf position and is checked annually.
16. Ion chambers monitor beam output, beam symmetry and flatness for each
treatment beam/field delivered and for every patient, which makes it the most
frequent method of measurement.
17. TLD (thermoluminescent dosimeters) give an “in vivo” dose verification for
personnel monitoring. Ring badges are specifically used by those who handle
radioactive sources.
18. The head of the pancreas is the widest portion and sits to the right side of the
abdomen within the duodenal loop and this is where most cancers of the
pancreas arise.
19. Radiation beam intensity will decrease as distance increases due to beam
divergence. This is known as the inverse square law. At increased distances, the
radiation beam will be spread over a greater area and the intensity will be
decreased.
20.Geiger-Muller Detector: a portable, handheld, survey meter of radiation. It is not
a dose measuring device and cannot distinguish between beam energies, but
rather measures a rate of radiation (mR/h or counts per minute cpm). GM
counter is used to survey rooms for radiation but doesn’t actually measure the
amount of radiation. It is most commonly used to locate sources that have been
misplaced.
21. The recommended dose limit for the lens of the eye for the public exposure is <15
mSv or 1.5 rem.
22. The recommended dose limit for a radiation worker’s skin, hands, and feet is 500
mSv or 50 rem.
23. The pharynx consists of (from superior to inferior for anatomical purposes)
nasopharynx, oropharynx and laryngopharynx/hypopharynx. The terms
laryngopharynx and hypopharynx can be used interchangeably.
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