Optimization of Spiral-Wobbler System for Heavy-Ion Radiotherapy

We propose an amplitude modulation wobbler-scatterer system, a so-called spiral-wobbler system, to produce a large irradiation field in a relatively short irradiation port for heavy-ion radiation therapy. The wobbler parameters, such as the wobbler-radius-modulation function, the wobbler radial frequency and the rotational frequency, are optimized and the uniformity of the irradiation field is estimated as the function of irradiation time. By using a wobbler radial frequency of 23 Hz, and a wobbler rotational frequency of 59 Hz, an irradiation field with a uniformity of ±3% can be obtained for an irradiation duration of 1 s. The spiral-wobbler system is applicable to respiration-gated irradiation.