CALCULATION OF BORON NEUTRON-CAPTURE CELL INACTIVATION IN-VITRO BASEDON PARTICLE TRACK STRUCTURE AND X-RAY-SENSITIVITY

The Monte-Carlo technique was used to perform quantitative microdosime tric model calculations of cell survival after boron neutron capture i rradiations in vitro. The high energy Li-7 and alpha-particles resulti ng from the neutron capture reaction B-10 (n,alpha)Li-7 are of short r ange and are highly damaging to cells. The biophysical model of the Mo nte-Carlo calculations is based on the track structure of these a-part icles and Li-7-ions and the xray sensitivity of the irradiated cells. The biological effect of these particles can be determined if the leth al effect of local doses deposited in very small fractional volumes of the cell nucleus is known. This lethal effect can be deduced from exp erimental data of cell survival after x-ray irradiation assuming a Poi sson distribution for lethal events. The input data used in a PC-based computer program are the radial dose distribution inside the track of the released particles, cell survival after x-ray irradiation, geomet ry of the tumor cells, subcellular B-10 concentration, and thermal neu tron fluence. The basic concept of this Monte-Carlo computer model is demonstrated. Validations of computer calculations are presented by co mparing them with experimental data on cell survival.