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Program Information

Review of Radiobiological Principles of Radiotherapy and Radiation Protection

C Orton

C Borras

C Orton1*, C Borras2*, (1) Wayne State University, Grosse Pointe, MI, (2) ,Washington, DC

TH-E-213AB-1 Thursday 1:00:00 PM - 1:55:00 PM Room: 213AB

Mechanisms by which radiation kills cells and ways cell damage can be repaired will be reviewed. The effect of radiobiological parameters which we can control for radiotherapy will be discussed including dose/fraction, number of fractions, time between fractions, overall treatment time, and the LET of the radiation. Reasons why we fractionate the way we do will be discussed, along with how sparing of normal tissues using conformal techniques might affect optimal fractionation. The linear-quadratic model for cell survival for high and low dose rate treatments and the effect of repopulation will be presented and discussed.

Radiation protection and the dose response of normal tissues will be reviewed, including effects on the developing embryo/fetus. The concepts of equivalent dose and effective dose in medical radiation protection, the Sv unit, and radiation and tissue-weighting factors will be presented. The latest information on human data on radiation-induced cancer, genetic effects and harmful tissue effects, especially cerebrovascular and cardiovascular diseases as well as cataract formation, published by the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR), the Biological Effects of Ionizing Radiation (BEIR) Committee and the International Commission on Radiological Protection (ICRP) will be examined. Estimates of risk per unit exposure will be presented. Their use in the development of radiation protection guidelines and standards will be discussed.

Learning Objectives:
1)To understand the radiobiological basis of radiation protection standards.
2)To define the radiation protection magnitudes and units, their values and their practical measurement.
3)To distinguish between stochastic and deterministic effects.

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