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59 Cards in this Set
- Front
- Back
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3 types of radiation dose response relationship graphs. |
Linear (straight-line nonthreshold) Linear-quadratic nonthreshold Linear threshold |
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The line passes through the graph's origin (0,0). The response to radiation is directly proportional to the radiation dose. There is no level of radiation dose where there is no biologic damage. |
Linear (straight-line nonthreshold) |
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The curve estimates the risk associated with low dose levels from low LET radiations. |
Linear quadratic nonthreshold |
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Line does not pass through origin of graph. Biologic response does not occur below a specific radiation dose. |
Linear threshold |
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Sigmoid s-shaped curve. Skin effects from high dose fluoroscopy follow this type of curve. Usually used in radiation therapy to demonstrate high dose cellular response. |
Nonlinear threshold |
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What radiation induced response is directly related to dose received? As dose increases, severity of response increases. |
Nonstochastic-deterministic effects |
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What radiation induced response is random occuring? Chance of occuring increases as exposure increases but not the severity of response. |
Stochastic-probabilistic effects |
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Which radiation dose response relationship graph do nonstochastic-deterministic effects follow? |
Nonlinear threshold |
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Which radiation dose response relationship graph do stochastic-probabilistic effects follow? |
Linear or linear-quadratic nonthreshold |
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The lowest layer of the epidermis consists of what type of cells? |
Basal cells which are stem cells |
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Skin cells are replaced at approximately what % by the basal cells? |
2% per day |
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Non malignant tissue damage? |
Erythema Desquamation Epilation |
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1st observable biologic response to radiation? |
Erythema |
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Peeling of the skin? |
Desquamation |
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Hair loss? |
Epilation |
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What is SED50? |
Skin Erythema Dose 50 The dose required to affect 50% of people irradiated. |
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What is the SED50 for humans? |
500 rad |
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What is generally the latent period of skin cancer? |
5-10 years. (Usually starts out as radio dermatitis. |
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Which requires a higher dose dose to produce a response? Whole body or part of the body? |
Part of the body |
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Local tissues affected immediately by irradiation..... |
Skin, gonads, bone marrow |
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What is the main function of the intestinal villi? |
Absorption |
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The depressions between adjacent villi are called? |
Crypts of lieberkuhn |
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What is the main function of the mucosal crypt of lieberkuhn? |
To provide new cells to replace the epithelium. |
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What is the mitotic activity of the crypts of lieberkuhn? |
Astronomical. 100 million cells a minute. |
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The intestinal linkng is resurfaced every? |
3-5 days |
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High levels of whole body radiation exposure leading to death (or recovery) within days or weeks? |
Acute radiation exposure |
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The 3 stages in order or ARS? |
Prodromal, latent, manifest |
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Symptoms that occur within hours of exposure and continue for 1-2 days. The immediate radiation sickness. |
Prodromal syndrome |
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Stage of ARS in which the person has no visible effects. |
Latent stage |
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Stage of ARS that describes the ways the body responds to radiation exposure. |
Manifest illness stage |
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3 groups that represent the ways the body responds to radiation exposure. |
Hematopoietic (bone marrow) GI syndrome CNS syndrome/neuromuscular |
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Doses of 100-1000 rads (1-10 Gy) result in which group of ARS? |
Hematopoietic (bone marrow) |
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Doses >10Gy (>1000 rads) results in which group of ARS? |
GI syndrome |
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Doses greater than 50 Gy (5000 rad) result in which group of ARS? |
CNS syndrome |
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Onset of manifest symptoms in CNS syndrome occur how soon after exposure? |
5-6 hours |
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The measure of radiation lethality? |
LD50/30 |
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Describe LD50/30 |
The dose of radiation to the WHOLE body that will result in death to 50% of the population irradiated within 30 days. |
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What is the LD50/30 for humans? |
300-400 rads (3-4 gy) |
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What describes the fact that as whole body radiation increases, time between exposure and death decreases? |
MST mean survival time |
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What is the MST for hematopoietic syndrome? |
MST is dose dependent |
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What is the MST for GI syndrome? |
Constant at 4 days |
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What is the MST for CNS syndrome? |
MST is dose dependent at hours to 3 days. |
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What are 2 stochastic (probablistic) late somatic effects? |
Carcinogenesis Embryologic (birth defects) |
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What is the nonstochastic (deterministic) late somatic effect? |
Cataractogenesis |
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Latent period for radiation induced cancer? |
2-40 years |
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4 major radiation induced cancers? |
Breast Thyroid Lung Leukemia |
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The average age of onset of breadt cancer? |
55-65 years |
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True or false? Radiation induced malignancies tend to appear at the same age as spontaneous malignancies of the same type. |
True |
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The risk to the fetus depends on what 2 factors? |
Gestational age at exposure Radiation dose |
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Irradiation in utero by diagnostic x rays appears to increase the spontaneous incidence of leukemia and childhood cancers in children up to 15 years of age by how much? |
1.5-2 times |
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Caused by unrepaired damage to DNA of reproductive cells? |
Mutations |
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4 diseases mutations can cause? |
Sickle cell anemia Cystic fibrosis Down syndrome Hemophilia |
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Agents that increase the frequency of mutations? |
Mutagens |
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4 examples of mutagens? |
Chemicals Viruses Elevated temperatures Ionizing radiation |
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Radiation induced genetic effects have which type of dose response relationship? |
Linear non-threshold |
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Which type of dose response relationship does cataractogenesis have? |
Non-linear threshold |
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Threshold for acute x ray exposure for cataractogenesis is? |
2 Gy |
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Threshold for fractionized exposure for cataractogenesis is? |
>10 Gy |
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Latent period for cataractogenesis is |
5-30 years. Avg. 15 years |
