Week 8 A Chapter 37 Late Effects of Radiation Exposure

Week 8 A Chapter 37 Late Effects of Radiation Exposure -...

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Chapter 37 Late Effects of Radiation The early effects of radiation exposure are produced by high radiation doses. The radiation exposure from diagnostic radiology are low level and of low LET. They are chronic in nature because they are delivered intermittently and over a long period of time. Therefore the late effects of exposure are of great importance.
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Late Effects of Radiation Radiation exposure experienced by working in diagnostic radiology are low dose and low linear energy transfer (LET). Diagnostic imaging exposures are delivered intermittently over long periods. The principle late effects are radiation induced malignancy and genetic effects.
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Late Effects of Radiation Radiation protection guideline are based upon the late effects of radiation and on linear, nonthreshold dose response relationships. Most late effects are known as stochastic effects. The response is of an increasing incidents and not severity response to increased exposure. There is no threshold for a stochastic response.
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Epidemiologic Studies Studies of large numbers of people exposed to toxic substances require considerable statistical analysis. Epidemiologic studies of people exposed to radiation are difficult because The actual exposure dose is usually not known. The frequency of response is low.
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Epidemiologic Studies The results of radiation epidemiologic studies do not carry the statistical accuracy that observations of early effects do.
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Local Tissue Effects Skin In addition to the early effects of erythema and desquamation and late-developing carcinoma, chronic irradiation of the skin can result in severe nonmalignant changes. Early radiologists who did fluoroscopy without protective gloves developed very callused, discolored an weathered appearance to the skin of the hands and forearm. It would sometimes become brittle and severely crack or flake. It was called radiodermatitis . The dose necessary to produce the effect was very high and no observed in current practice.
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Radiodermitis
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Local Tissue Effects Chromosomes Irradiation of the blood forming organs can produce hematologic depression as an early response and leukemia as a late response. Chromosome damage of the circulating lymphocytes can produce early and late response.
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Local Tissue Effects Chromosomes The type and frequency of aberrations have been discussed earlier, however, even a low dose of radiation can produce chromosome aberrations that may not be apparent for many years after the exposure. Individuals accidentally exposed with high radiation doses continue to show chromosome abnormalities for 20 years after the exposure.
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Chromosomes The late effects may be due to radiation damage to the lymphocyte stem cells. These cells may not be stimulated into replication and maturation for many years. Cataracts
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This note was uploaded on 01/03/2012 for the course LC 232 taught by Professor Wilson during the Fall '08 term at Palmer Chiropractic.

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Week 8 A Chapter 37 Late Effects of Radiation Exposure -...

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