MEDRADSC 2X03 Lecture Notes - Lecture 1: Attenuation Coefficient, Radiobiology, Radiation Therapy
5 Sep 2018
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Document Summary
Radiobiology study of action of ionizing radiation on living things. Safety in use of radiation controlling quantity received, body irradiated, conditions, minimizing detriment and maximizing benefit to us. Alara principle balances benefit of use of radiation, likelihood of detriment from radiation and cost of minimization of exposure. X-ray interactions with matter: exponential function, depends on, mass attenuation coefficient/linear attenuation coefficient, density of the material, thickness of the material. Compton scatter: uses an outer shell electron, uses high energy, the xray deflects at an angle with reduced energy (could be 0-80% less) but still free to interact with others. Radiation therapy ranges from 1. 02 mev the predominant types of interactions are: pair production. Incident photon approaches nucleus then it disappears and the energy is transformed to produce 2 particles negative and positive charged electron: photodisintegration, occurs at 5-10 mev. Incident photon penetrates nucleus and deposits energy excess energy in nucleus results in a particle being ejected.
