Influence of Bone Tissue upon Dose Distribution in High Energy Electron Beam Therapy

Abstract

The influence of the bone tissue on the homogeneity of dose distribution in high-energy electron beam therapy was evaluated by the absorption equivalent thickness (AET) of the bone against water. Bone specimens used had been obtained from the pelvis, sternum and ribs of four autopsy cases of cancer in fifty to sixty years of age. The energy dependency of absorption difference between the bone and water was practically negligible for the range of 16 to 31 MeV. The AET values were measured using 25 MeV electrons. The mean AET for nine specimens, of which the mean density was 1.18g/cm³, was 1.14. Therefore, the influence of bone absorption on dose distribution is regarded as practically insignificant in the electron beam radiotherapy of the chest wall or the pelvic region of cancer patients.