الفهرس 
ACKNOWLEDGEMENT
Experiment and ProcedureOnly 14 pages are availabe for public view
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Abstract
The aim of radiation therapy is to deliver the maximum possible dose to the tumor and minimum doses to the surrounding organs at risk (OAR). That can carry out by giving radiotherapy through certain radiation fields enable us to cover the tumor and protect OAR. According to this rule radiotherapy techniques evolved at the point of formation appropriate radiation field of the tumor. The beginning was through opening regular radiation fields by only the LINAC jaws which in the linear accelerator head. Then fields shaping is evaluated to include curves and regular / irregular forms, which was called custom block, by using of lead metal or metal alloys, such as Cerro bend, which melted and formed through templates and fixed in tray for each radiation field need to them.