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32 Cards in this Set
- Front
- Back
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3 ways photons are attenuated?
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photoelectric
compton scatter pair production |
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Beam intensity formula
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It=Io e^-ux
u=LAC cm^-1 x= absorber |
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LAC depends on 3 things?
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energy
chemical compostion thickness |
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How to calculate LAC?
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u=.693/HVL or
u=ln^2HVL |
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Mass attenuation in cm^2/g
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LAC/density of absorber
or u/p |
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Theory of Bergonie and Tibondeau
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Increased radiosensitivity:
high division rate, young, unspecialized |
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Are these high or low sensitivity? Lymphocytes, erythroblasts, spermatogonia
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HIgh
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Are these high or low sensitivity? nerve, muscle, fibrocytes
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Low
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What level toelrance dose is 20-45Gy? what does it affect?
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Moderate; stomach, intestines, liver, kidneys
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What is a low tolerance dose?
What does it affect? |
10-20Gy; gonads, developing organs
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50-70Gy is considered what level tolerance dose? What does it affect?
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High; oral cavity, esophagus, rectum, salivary glands, bone, cartilage, CNS
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What is very high tolerance dose level, what does it affect?
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>75Gy; ureters, urethra, mature muscle, blood
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Increase dose rate, ? damage
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Increased
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Are critical organs usually the the target organs?
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no
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The organ that dictates the max dose for a study is the ?
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critical organ
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FDA governs what part of IRD?
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Pharmaceuticals
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NRC regulates what part of IRD?
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Nuclear reactor byproducts
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NIH regulates what part of IRD?
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blood
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Another name for classic IRD?
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Marinelli internal radiation dosimetry?
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Which one, MIRD or Marinelli, groups non penetrating and penetrating photons?
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Classic/marinelli
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What is the currently used IRD method?
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MIRD (medical IRD)
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Do shape, composition and location of organs affect IRD?
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Yes
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3 categories of MIRD?
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Biologic
Energy of RN Absorbed fraction of energy |
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MIRD category for uptake, distribution, retention and release of RP in body?
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Biologic
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MIRD category for penetrating or non-penetrating RP?
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Energy of RN
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MIRD category for energy that's absorbed by the target organ?
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Absorbed fraction of energy
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How is absorbed fraction of energy expressed?
Biologic? |
Gy/kg
uCi/hr |
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Wht MIRD category uses standard man?
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Absorbed fraction of energy
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What weight is standard man?
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70kg
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What is the benefit of fractionated doses of radiation therapy?
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Increased time for body to heal between doses
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4 R's of radiotherapy? Which are for killing cells, which for healing?
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Killing: Redistribution, reoxygenation
Healing: Regeneration repair |
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2 types of multiple fraction
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Hyperfractionation (same amt time, higher dose)
Accelerated hyperfractionation (less time) |
