Abstract
Whole body irradiation of mice was performed with a set of single 2mm wide thin fan slit beams of electrons from a 45 MeV linear accelerator to investigate the effects of inhomogeneous irradiation on normal tissue. Beam intervals were adjusted to 0 mm, 1mm, 2mm, 3mm, and 4mm creating an inhomogeneous field, while the anesthesized mice were moved by a remote control device. The effect was analysed in terms of the LD50/30 relation to the beam intervals. Dosimetries were carried out using TLD rods and FCR imaging plates. Doses were indicated at the center of the slit beam on the surface of the acrylate phantom, irradiated by only a single slit beam. LD50/30 was 9.3Gy for a 0mm wide beam interval, 11.3Gy for 1mm, 15.0Gy for 2mm, 26.3Gy for 3mm, and 29.8Gy for 4mm. The relation between LD50/30 (Ld) and relative volume (Rv=a ratio of beam width/(beam width+beam interval)) was expressed by the following equation:
Ld=8.21×Rv-1.12.
The exponent value was-1.12. The results suggest that the product of LD50/30 and relative volume is nearly constant, and LD50/30 depends almost entirely on the integral dose received by a mouse, independent of the beam interval.
