# Reasonably Achievable Equation

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RADIATION PROTECTION Introduction; 4.1. ALARA: “As Low As Reasonably Achievable” The application of radiation can aid the patient by providing doctors and other health care professionals with a medical diagnosis, but the exposure should be responsibly low enough to keep the statistical probability of cancers or sarcomas (stochastic effects ) below an acceptable level, and to eliminate deterministic effects(e.g. skin reddening or cataracts ).An acceptable level of incidence of stochastic effects is considered to be equal for a worker to the risk in another work generally considered to be safe. This policy is based on the principle that any amount of radiation exposure, no matter …show more content…

Using the mass attenuation coefficient instead of the linear attenuation coefficient, the attenuation equation can be rewritten: I=I_0 e^(-μ_m ρx) 4.2.3.3. Half Value Layer The half value layer (HVL) is the thickness of a shielding material required to reduce the intensity of radiation at a point to one half of its original intensity. It can be calculated by setting I = ½ I_0 and solving the attenuation equation for x: 0.5=e^(-μx_(1⁄2) ) x_(1⁄2)=-(ln⁡(0.5))/μ x_(1⁄2)=(0.693)/μ=HVL When the HVL is known rather than µ, the total attenuation from n half value layers can be calculated by using the following equation: I=I_0/2^n HVL for Various Materials when Radiation is from a Gamma Source; HVL, mm(inch) source concrete steel lead tungsten uranium Iridium-192 44.5 (1.75) 12.7 (0.5) 4.8 (0.19) 3.3 (0.13) 2.8