Preliminary study on the parameter required for magnetic scanning irradiation in heavy ion radiotherapy

The relationship between the homogeneity of irradiation field created by magnetic scan in heavy-ion radiotherapy and the size and scanning step of beam spot was investigated by computer simulation. Two formulae for the beam intensity and irradiation time calculation respectively were derived from the slice-by-slice idea of heavy-ion radiotherapy. The simulation result shows that the homogeneity better than 95% can be achieved when the scanning step is smaller than the half width of beam spot. The suitable beam intensity, the maximum scanning speed and the minimum spot stay time were obtained as 0.48 nA, 1000 cm/s, 0.24 ms respectively