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radiobio review
review of 32, 33, 34
| Question | Answer |
|---|---|
| Ionization of living tissue can cause this | chemical and biologic damage to somatic and/or genetic cells |
| Non-threshold dose-response(dose effect) curve indicates this | there is no safe dose of radiation below which there will be no effects |
| Linear non-threshold dose response curve indicates this | stochastic responses (cancer, genetic effects) |
| linear non-threshold | is the curve of choice for occupational exposure |
| Stochastic | "all or nothing" |
| Late effects of radiation | carcinogenesis and genetic effects |
| Radiobiology | the study of the effects of ionizing radiation on biologic material at the cellular level |
| law of bergonie and tribondeau | stem (undifferentiated or precursor) cells, young, immature tissues, and highly mitotic cells are particularly radiosensitive |
| 1906 | bergonie and tribondeau |
| the most highly radiosensitive | very young cells stem cells and cells having the most reproductive activity |
| examples of highly radiosenstive tissues | intestinal epithelial cells, and cells of the rapidly developing embryo and fetus |
| energy | this is what radiation deposits as it passes through tissue |
| let | the rate at which energy is deposited as it passes through tissue (another means of expressing radiation quality and determining the radiation weighting factor) |
| as the let of radiation increases, the radiations ability to | produce biological damage also increases |
| rbe | relative biologic effectiveness |
| let and rbe are | directly related |
| diagnostic x rays are considered | low let radiation |
| the approximate let of x-rays | 3 keV/um |
| the target theory | specifies that DNA is the day sensitive molecule |
| direct effect | occurs with high let radiations and when ionization occurs at the dna molecule itself |
| indirect effect | occurs most frequently, happens when ionization takes place away from the dna molecule |
| single main chain/ side rail scission (break) on the DNA molecule | is repairable |
| double main chain/side rail scission | may repair with difficulty or may result in cell death |
| double main chain/side rail scission on the same "rung" of the DNA ladder | results in irreparable damage or cell death |
| faulty repair of main chain breakage | cross-linking |
| damage to the base itself or to the rungs connecting the main chains | can result in alteration of base sequences causing molecular lesion/point mutation |
| the majority(90%) of cell damage | is repairable |
| multiple hits to same cell are likely to leave | permanent damage |
| are somewhat insensitive to radiation exposure | muscle and nervous tissues |
| the longer the period of time over which a dose of radiation is delivered | the less its effect |
| the greatest effect or irradiation will be observed | large quantity of radiation is delivered in a short time to the whole body |
| the greater this content of tissues, the greater the radiosensitivity | oxygen |
| this is most radiosensitive | fetal tissue and lympocytes |
| as an individual ages, | tissue sensitivity decreases |
| somatic effects | early or late, depending on the length of time between irradiation and manifestation of effects |
| late somatic effects | occur years after initial exposure cause by low, chronic exposure |
| examples of late somatic effects | bone malignancies, thyroid cancer, leukemia, skin cancers |
| cataract formation | one more example of somatic effects |
Created by:
hseratt
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