Carbon Ion Therapy for Ocular Melanoma: Development of Dedicated Nozzles for Orthogonal Two-port Treatment

[Purpose] To realize the orthogonal two-port treatment to ocular melanoma using carbon-ion beam, we developed detachable dedicated nozzles on vertical and horizontal beam snout. [Methods] HIMAC doesn’t have the exclusive treatment room for eye irradiation because the number of patients with ocular melanoma is a very few for Japanese and HIMAC is only one facility to treat the ocular melanoma by particle beam in Japan, e.g. 10-15 patients/year in HIMAC. The patient is set on the treatment couch at spine position that is same position at CT scanning for treatment planning. The details of treatment planning are reported separately in this meeting. Nozzles for eye-irradiation are attached to the forefront of fixed vertical and horizontal beam snouts that are routinely used for general clinical purpose of carbon-ion radiotherapy. Nozzles were designed to be easy to detach with high reproducibility. A pair of patient collimator and compensator is set on the nozzle. When we take the x-ray image at BEV for patient positioning, the part of the nozzle is shifted aside to keep a large x-ray field. Setting conditions of these devices are checked automatically, and linked to the beam-interlock system. [Results] Weights of vertical and horizontal nozzle were 12.0kg and 16.0kg, respectively. It is easy to detach the nozzle on the fixed beam snout, and the reproducibility of setting position by repeated detaches was less than +- 0.2mm. Nozzle position is possible to verify at each irradiation by the flat-panel x-ray image of hair cross-wire inside the nozzle. [Conclusions] Since April 2001, we have started the carbon-ion therapy for ocular melanoma at single port with 140MeV/u. At October 2005 we developed the lateral nozzle for carbon-170Mev/u, and begun the orthogonal two-port treatment to ocular melanoma. Over 60 patients with eye melanoma had already been treated successfully, and 7 patients were treated with the orthogonal two-field.PTCOG4

Status Report of Quality Assurance Program Activity for the Linear Accelerator at the National Institute of Radiological Sciences

We report on the quality assurance (QA) program for the linear accelerator (Linac). The dosimetric characteristics of the Linac were measured in clinical routines. The data collected at the National Institute of Radiological Sciences (NIRS) since August 2005 is presented. We examined this data over the short-, medium- and long term periods which enables the user to predict possible problems.The 5th Korea - Japan Joint Meeting on Medical Physics（第９６回日本医学物理学会学術大会