Analysis on the photoneutron according to the varying factors and treatment planning in LINAC

As the use of high-energy photon by Linac is recently generalized, there are studies conducted actively on the generation of photoneutron. However, existing studies are lack verification of reliability, and focus only on fragmentary evaluation. Therefore, in this study, evaluation was performed not only on the photoneutron according to the energy, the field size, the dose, the doserate and the distance, but also on the photoneutron on the conventional plan, 3D CRT plan, and the VMAT plan. As a result, the photon energy and the radiation field were proportional in the photoneutron generation rate, and the distance showed inverse proportion. The treatment planning was proportional according to the sophistication, and the occurrence rate of the photoneutron dose exceeded the tolerance of 5% with 8% when the quality factor was applied. Therefore, the conversion factor value proposed in this study must be applied in the treatment planning.