Annual Report 2022
Section of Radiation Safety and Quality Assurance
Hidenobu Tachibana, Kenji Hotta, Hiromi Baba, Kana Motegi, Ryo Takahashi, Toru Nakaichi, Shohei Mikasa, Riki Oshika, Miki Yonemura
Introduction
Radiation therapy (RT) technologies have improved recently and will continue to progress. Although 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 the planning through treatment. The accuracy and precision of dose delivery in RT is important given the 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, to check that quality requirements in photon and proton therapy products are met, and to adjust and correct the performance if the requirements are found not to be met. The second aim is to install and establish advanced technologies in clinical practices in the Department of Radiation Oncology. Our other goals are to develop high-precision RT such 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 maintain the quality of photon/electron/proton treatment equipment, provide treatment planning for high-precision treatments, introduce new radiation treatment technology that will benefit patients, and support clinical trials. In addition, we provide on-the-job training programs for radiotherapy quality assurance to medical physicists and radiation therapists in Japan. In FY2022, we installed a new TrueBeam linear accelerator and started radiotherapy treatment using it. We also supported several clinical trials related to radiation oncology.
Research Activities
After entering into a joint research agreement with a company for the clinical application of the new radiation measurement device, the gel dosimeter, we subsequently signed a licensing agreement and brought it to market.
Clinical Trials
1) Retrospective study on the effectiveness and safety of radiation therapy
2) Retrospective study on the prediction of adverse events in normal tissues in proton therapy
3) Retrospective study on the clinical implementation of robust treatment planning in intensity-modulated radiation therapy for head and neck cancer
Education
The Department of Radiation Oncology in our hospital provides treatments using different types of radiation, and the difference in the radiation types employed requires the varying 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 beam therapy, but we performed rotations so that both types of medical physicists could perform clinical work for the different types of beams. In FY2022, two medical physics resident joined our department.
Future Prospects
We are establishing a system to provide our medical physics residents with our abundant clinical and research experience. Additionally, we will conduct various studies regarding the clinical utilization of gel dosimeters to develop quality control methods necessary for clinical practice.
List of papers published in 2022
Journal
1. Tachibana H, Takahashi R, Kogure T, Nishiyama S, Kurosawa T. Practical dosimetry procedure of air kerma for kilovoltage X-ray imaging in radiation oncology using a 0.6-cc cylindrical ionization chamber with a cobalt absorbed dose-to-water calibration coefficient. Radiological physics and technology, 15:264-270, 2022
2. Tachibana H, Watanabe Y, Kurokawa S, Maeyama T, Hiroki T, Ikoma H, Hirashima H, Kojima H, Shiinoki T, Tanimoto Y, Shimizu H, Shishido H, Oka Y, Hirose TA, Kinjo M, Morozumi T, Kurooka M, Suzuki H, Saito T, Fujita K, Shirata R, Inada R, Yada R, Yamashita M, Kondo K, Hanada T, Takenaka T, Usui K, Okamoto H, Asakura H, Notake R, Kojima T, Kumazaki Y, Hatanaka S, Kikumura R, Nakajima M, Nakada R, Suzuki R, Mizuno H, Kawamura S, Nakamura M, Akimoto T. Multi-Institutional Study of End-to-End Dose Delivery Quality Assurance Testing for Image-Guided Brachytherapy Using a Gel Dosimeter. Brachytherapy, 21:956-967, 2022
3. Watanabe Y, Maeyama T, Mizukami S, Tachibana H, Terazaki T, Takei H, Muraishi H, Gomi T, Hayashi SI. Verification of dose distribution in high dose-rate brachytherapy for cervical cancer using a normoxic N-vinylpyrrolidone polymer gel dosimeter. Journal of radiation research, 63:838-848, 2022