Calculation of dose distribution with mini-computer

Several pannel discussions concerned with the use of the electric computer in radiotherapy have been recently hold, and their reports have been published. The use of the time-sharing system with the big machine would be reasonable for the rapid calculation of the dose distribution. If the accuracy of the results is clinically acceptable, the mini-computer will be able to applied in routine daily work instead of the time-consuming hand-calculation. In this paper, the outline of the application of the mini-computer for calculating the dose distribution in external irradiation was described. The system is so simple to use, and input errors can be easily found out and can be quickly corrected by the key board. Central axis data obtained directly from the dose measurements were stored as a function of the ratio between the field area and the perimeter of the field, which was presented by Sterling et al. The shift method was applied for the correction of the dose inhomogeneity factor in lung tissue. The decrement value and the correction factor for the wedge filters were also stored. The difference between the calculated value and the value obtained by the actual measurement at the 10 x 10 cm field with 6 MV X-ray, were 1% at the depth of 10 cm, and 3% at the depth of 25 cm. Access time were about 2 hours per patient at the most, therefore, 4-6 cases can be carried out in a day. (auth.)