Development of an advanced brachytherapy planning system with a personal computer, 1

A dose-distribution calculation system for the brachytherapy was developed with a personal computer. The system was made up of a 16 bits personal computer (NEC PC-9800 series) equipped with a light paneled digitizer (WACOM WT-5000). The operating system, MS-DOS ver. 2.1, was used and the programs were written by the compiler BASIC and the assembler. The followings are features of the system. Firstly, the system can be realized with low cost compared to a commercially available mini-computer system, that is, the initial cost of our system is about one tenth of the latter. Secondly, our system has high performances in the speed of calculation and data-transfer. For example, we adopted a table look-up method in order to minimize repeated calculations. And the dose-distribution tables are stored in a floppy disk with binary mode so as to transfer them quickly onto the memory. Thirdly, we adopted the table-data size of about 0.1 M bytes for insuring of the accuracy of the calculated dose-distribution. Fourthly, the gamma ray absorption within sources and their containers are considered in the calculation of the table data. The shape data of the container and the source are input with the digitizer and then the table data are calculated using the information. In this paper, functions of the system and the performances are described minutely. Moreover, the results of simulations for the accuracy of the calculated dose-distribution with regard to several calculation parameters, e.g., the mesh size for the table data and number of divisions of a line source, are shown. (author)