Annual Report 2019
Section of Radiation Safety and Quality Assurance
Hidenobu Tachibana, Kenji Hotta, Hiromi Baba, Kana Motegi, Ryo Takahashi
Introduction
Radiation therapy (RT) technologies have improved recently and will continue to progress. However, while advanced technology has provided higher accuracy and precision in RT, it has introduced more complex situations and difficulties in performing the treatment adequately. RT errors can occur at several time points from planning through treatment. The accuracy and precision of dose delivery in RT is important because there is evidence that a 7-10% change in the dose to the target volume may result in a significant change in tumor control probability. “Quality assurance in RT” is for all procedures that ensure consistency of the medical prescription, and safe fulfillment of that prescription, as regards the dose to the target volume, together with the minimal dose to normal tissue, minimal exposure of personnel and adequate patient monitoring aimed at determining the end result of the treatment.
The primary aim of the Section of Radiation Safety and Quality Assurance is to develop quality assurance programs for photon, electron and proton therapy machines as well as to check that quality requirements in photon and proton therapy products are met and to adjust and correct performance if the requirements are found not to have been met. The second aim is to install and establish advanced technologies in clinical practices in the Department of Radiation Oncology. Other goals are to develop high-precision RT as intensity modulated radiation therapy (IMRT), volumetric modulated arc therapy (VMAT), respiratory-gating radiation therapy (RGRT), marker-tracking RT, image-guided radiation therapy (IGRT), stereotactic RT, and proton beam therapy (PBT) in cancer treatment.
The Team and What We Do
We work on maintaining the quality of photon/electron/proton treatment equipment, conducting treatment planning for high precision treatments, introducing new radiation treatment technology that will benefit patients, and supporting clinical trials. In addition, we provide on-the-job training programs for quality assurance for radiotherapy to medical physicists and radiation therapists in Japan. In FY2019, we supported the establishment of the clinical protocol for stereotactic irradiation for multiple brain metastases and established the quality assurance method for it, and started the treatment. We worked on supporting several clinical trials for radiation oncology.
Research activities
Our medical physicists participated in the Medical Physics Working Group of the Radiation Oncology Group for the Japan Clinical Oncology Group (JCOG) and provided support related to radiation therapy planning and irradiation technology. We conducted joint research with a company for the clinical application of a new radiation dosimeter, the gel dosimeter, and published a paper in an authoritative journal on brachytherapy in the United States that it is highly effective in brachytherapy.
Education
The department of radiation oncology in our hospital provides treatments using different radiations, and the difference in the radiations used require different expertise of medical physicists. On the other hand, broad knowledge and experience in clinical practice are more important from the viewpoint of human resource development. In our section, there are medical physicists who specialize in photon/electron and proton beams, but we performed rotations so that both could perform clinical work with all of the different beams.
We established an on-the-job training program regarding the quality control method for photon therapy equipment in our hospital, and conducted it for a total of 6 years from 2014 to this year. There were 91 participants in 2019, and a total of 541 medical physicists and radiological technologists have taken it over the 6 years. We also educated students at the University of Tsukuba, Tokyo Women's Medical University, and Komazawa University about quality assurance in photon, electron, and proton therapy and research. In FY2020, a resident program for medical physicists will be started at the Hospital, the East Hospital, and the Center for Cancer Control and Information Services hospitals.
Future prospects
In the field of radiation therapy using photon beams, we will support the establishment of a clinical protocol for intensity-modulated radiation therapy for advanced lung cancer and esophageal cancer, establish a quality control method, and start treatment. In the field of proton therapy, we will develop a high-precision treatment planning system that takes biological effects into consideration. We will provide our clinical physics residents with a wealth of clinical and research experience.
List of papers published in 2019
Journal
1. Tachibana H, Watanabe Y, Mizukami S, Maeyama T, Terazaki T, Uehara R, Akimoto T. End-to-end delivery quality assurance of computed tomography-based high-dose-rate brachytherapy using a gel dosimeter. Brachytherapy, 19:362-371, 2020