メタアクリル酸メチル樹脂(アクリライト)の人体フアントームとしての適用性にについて(コバルト60γ線に対する)

Abstract

We discussed on the applicability of Acrylite as a body phantom in deep radiotherapy in the previous report, and now reported in telecobalt therapy in this paper. We measured the attenuation curves and percentage depth dose curves of various field sizes in water and Acrylite. The total linear absorption coefficient of Co^<60> gamma rays in Acrylite was 1.17 times greater than that in water in proportion of their electron densities, e.g.the mass absorption coefficients of both materials coincided each other practically. On the otherhand, the ratio of depths giving the same depth doses was about 1.1,which was lower than the ratio of the absorption coefficient, and was dependent on the field size in some degree. While they were somewhat different in the state of the scatter, Acrylite was available practically to the phantom in consideration that the thickness of Acrylite multiplied by 1.1 was equivalent to that of water. The dosage at the rotation centre in the human pelvis was measured and compared with the calculated one by the Quimby's method using the depth dose data in water and Acrylite. Then the effective body contour as Acrylite was determined by the transit dose measurement. Absorption and scatter in the human pelvis as whole was closer to Acrylite than water, and Acrylite was able to use as pelvic phantom as it was.