^<60>Co, ^<137>Cs短距離照射装置における表層線量分布

概要

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It is well known that the short-distance isotope unit is useful for treatment of head and neck and superficial lesions, and is convenient from the view point of protection problems of treatment head. However, in the short distance unit, the skin sparing effect is lowered due to electrons emitted from the source capsuel, cone and accessaries near the beam path. The surface dose distributions of ^<60>Co and ^<137>Cs gamma rays from the short-distance units were measured on following items, 1) Ratios of surface dose to maximum dept dose for various metals and their thicknesses. 2) Dependence of diaphragm-surface distance on surface dose distribution. 3) Dependence of filter lacation on surface dose distribution. 4) Dependence of field size on surface dose distribution. 5) Trial production of multi-leaf cone for ^<137>Cs unit. The following results were obtained. 1) The maximum depth dose for ^<60>Co was obtained at a depth of 3.8mm and for ^<137>Cs 1.2mm under the good condition. 2) 0.5mm copper filter for ^<60>Co and 0.25mm copper filter for ^<137>Cs were most effective for lowering the surface dose. 3) New producted multi-leaf cones for ^<137>Cs unit were very efficient for the lower surface dose.
社団法人日本放射線技術学会の論文
1966-10-31