Survey of IMRT in Japan

Abstract

This study evaluated the current status, quality assurance (QA) and technique of intensity-modulated radiotherapy (IMRT) in Japan.IMRT is a new technique, introduced in the late 1990s. Since 2000, the number of institutions providing IMRT has increased. Therefore, to recognize the current status of IMRT in Japan, a nation-wide survey was conducted by the Japan 3-Dimensional Conformal External Beam Radiotherapy Group (J-CERG). The questionnaires, which consists of the clinical part and physics part, was sent by mail or e-mail to 835 institutions. By the end of Feb. 2021, 427 institutions and 534 institutions responded to the clinical part and physics part, respectively.In the clinical part, Two-hundreds and ninety-two (68%) institutions indicated that they have used IMRT technique for 44,409 cases out of 177,285 total in a year of 2019. Among these patients, 10,905 (25%) were prostate cancer, 7,772(18%) were head & neck cancer, 2,621 (6%) brain tumor, 2,027 (5%) lung tumor for SBRT, followed by liver tumor for SBRT, GYN cancer, esophageal cancer, breast cancer and GI tumor. The percentage of IMRT in all treatment was 75-100% in 18 institutions (6%), 50-75% in 22 institutions (8%), 20-50% in 144 institutions (49%), 10-20% in 68 institutions (23%), 5-10% in 28 institutions (10%), 5-1% in 11 institutions (4%) and < 1% in 2 institutions (1%). Target and OAR delineation was done by physician in 92% institutions and 69% institutions, respectively. In the physics part, 340 institutions (64%) use IMRT technique, and 80 institutions (24%) have commissioned their treatment planning systems with the beam data provided by the manufacturer. The measurement-based patient specific IMRT QAs are performed by 99% of institutions. The dose distribution measurement on films, 3D arrays, and 2D arrays are 42%, 41%, and 16%, respectively.The updated status of IMRT in 2019 in Japan was surveyed. The number of institutions where IMRT was started continuously increased in number.