Patent ID: 8592778
Filing Date: 2013-11-26
Classification: A61N,G06N,G21H,G21K,H01J

Abstract:
1. A particle beam irradiation apparatus comprising: a scanning electromagnet that scans a charged particle beam accelerated by an accelerator and has a hysteresis; a scanning power source that outputs an excitation current for driving the scanning electromagnet; and an irradiation control apparatus that controls the scanning power source, wherein the irradiation control apparatus has a scanning electromagnet command value learning generator that (i) evaluates the result of a run-through, which is a series of irradiation operations through a command value for the excitation current outputted from the scanning power source without a patient present, (ii) updates the command value for the excitation current when the result of the evaluation does not satisfy a predetermined condition in order to perform another run-through, (iii) outputs to the scanning power source the command value for the excitation current when its evaluation result has satisfied the predetermined condition, and (iv) stores, in a storage apparatus, an updated command value that results in a run-through result satisfying the predetermined condition, for actual irradiation of a patient, wherein the scanning electromagnet command value learning generator comprises: a dose monitor for measuring a dose of the charged particle beam, wherein the command evaluator evaluates the command value by comparing a measured dose measured by the dose monitor with a target dose for the charged particle beam onto an irradiation subject to be irradiated, wherein an irradiation subject onto which the charged particle beam is irradiated is divided into magnetic-field small regions defined by the X-direction and Y-direction magnetic fields produced by the scanning electromagnet that is driven by the excitation current, wherein the command evaluator evaluates the command value by comparing the measured dose with the target dose for each defined magnetic-field small region, and wherein the command evaluator comprises a score table for scoring a dose error which is the difference between a measured regional dose and a target dose for each magnetic-field small region, the command evaluator evaluates the command value according to the score table's score, and in the score table, the absolute value of a score changing rate in the case where the measured dose exceeds the target dose is set to be larger than the absolute value of a score changing rate in the case where the measured dose is smaller than the target dose.