1993 Volume 5 Issue 3 Pages 165-171
Total-skin electron-beam irradiation is suitable for the treatment of widespread skin lesions. To degrade electron-beam energy, a degrader is widely used for total skinelectron-beam irradiation. The effects of the source-degrader distance on dose distribution in total-skin electron beam-irradiation were investigated. Measurements include percentage depth dose, photon contamination, dose rate at surface and surface, beam intensity for various source-degrader distances. From the results, the main advantages of the large source-degrader distance are: a) decrease in X-ray contamination; b) higher dose rate at skin surfece. For example: with a 5 mm thick degrader: a) the X-ray contamination was 15% at a source-degrader distance of 100 cm and 8% at 350 cm; and b) the dose rate at the skin surface for a source-degrader distance of 350 cm is 2 times that for 100 cm. It is concluded that the degrader should be placed closer to the patients.
