| 摘要 |
<p>Provided is an irradiation plan making method capable of obtaining a relatively robust plan in a shorter time than conventional methods. In the irradiation plan making method, pencil beams are scanned and overlapped on a per-spot basis while modulating the intensity by multiple field irradiation, and an irradiation plan is made to form a dose distribution on an irradiation target so that a previously input dose prescription is obtained, the irradiation target including an irradiated region to be irradiated with radioactive rays and a non-irradiated region not to be irradiated with the radioactive rays. When making the irradiation plan, a successive approximation iterative calculation is performed to derive an evaluation index value (E), which is compared with a preset threshold value (C). The successive approximation iterative calculation derives the evaluation index value (E) under a third condition that the gradient of the dose distribution given to the irradiation target from a previously input irradiation direction is suppressed, in addition to first and second conditions.</p> |
