Annual Report 2021
Radiation Safety and Quality Assurance Office
Hidenobu Tachibana, Kenji Hotta, Hiromi Baba, Kana Motegi, Ryo Takahashi, Ryo Onose, Seigo Kurokawa
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 FY2021, we launched image guided brachytherapy using an Ir-192 source and performed the treatments safely for cervical cancer. We worked on supporting several clinical trials for radiation oncology.
Research activities
We completed a multi-institutional trial for the clinical application of a new radiation dosimeter, a gel dosimeter for image guided brachytherapy.
Education
The department of radiation oncology in our hospital provides treatments using different radiations, and the difference in the radiations used requires 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. In FY2021, one medical physics resident joined our department.
Future Prospects
We will provide our clinical physics residents with a wealth of clinical and research experience. We will also perform several translational research projects for clinical application of gel dosimetry.
List of papers published in 2021
Journal
1. Watanabe Y, Maeyama T, Mizukami S, Tachibana H, Terazaki T, Takei H, Muraishi H, Gomi T and Hayashi S. Verification of dose distribution in high dose-rate brachytherapy for cervical cancer using a normoxic N-vinylpyrrolidone polymer gel dosimeter. J Radiat Res. 2022 Sep 16 1-11.
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. 2022 Jul;21(6):956-967.
3. 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. Radiol Phys Technol. 2022 Sep;15(3):264-270.
4. Hirotaki K, Moriya S, Tachibana H, Sakae T. Detection of anatomical changes using two-dimensional x-ray images for head and neck adaptive radiotherapy. Medical physics, 49:3288-3297, 2022
5. Raturi VP, Motegi A, Zenda S, Nakamura N, Hojo H, Kageyama SI, Okumura M, Rachi T, Ohyoshi H, Tachibana H, Motegi K, Ariji T, Nakamura M, Hirano Y, Hirata H, Akimoto T. Comparison of a Hybrid IMRT/VMAT technique with non-coplanar VMAT and non-coplanar IMRT for unresectable olfactory neuroblastoma using the RayStation treatment planning system-EUD, NTCP and planning study. Journal of radiation research, 62:540-548, 2021