Annual Report 2020
Section of Radiation Safety and Quality Assurance
Hidenobu Tachibana, Kenji Hotta, Hiromi Baba, Kana Motegi, Ryo Takahashi, Ryo Onose
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 can 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 not 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 FY2020, we supported the establishment of the clinical protocol for intensity modulated radiation therapy for cervical cancer, established the quality assurance method for the therapy, and started the treatment. We supported several clinical trials to radiation oncology.
Research activities
Our medical physicists participated in the Medical Physics Working Group of Radiation Oncology Group for the Japan Clinical Oncology Group (JCOG) and provided support related to radiation therapy planning and irradiation technology. We started a multicenter trial for the clinical application of a new radiation dosimeter, the gel dosimeter.
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.
Future Prospects
In photon beam radiation therapy, we will support the establishment of a clinical protocol for brachytherapy for in cervical cancer, establish a quality control method, and start treatment. In proton therapy, we will develop a high-precision treatment planning system that considers the biological effects. We will supply our clinical physicist residents with a wealth of clinical and research experience.
List of papers published in 2020
Journal
1. Raturi VP, Hojo H, Hotta K, Baba H, Takahashi R, Rachi T, Nakamura N, Zenda S, Motegi A, Tachibana H, Ariji T, Motegi K, Nakamura M, Okumura M, Hirano Y, Akimoto T. Radiobiological model-based approach to determine the potential of dose-escalated robust intensity-modulated proton radiotherapy in reducing gastrointestinal toxicity in the treatment of locally advanced unresectable pancreatic cancer of the head. Radiat Oncol, 15:157, 2020
2. Raturi VP, Tochinai T, Hojo H, Rachi T, Hotta K, Nakamura N, Zenda S, Motegi A, Ariji T, Hirano Y, Baba H, Ohyoshi H, Nakamura M, Okumura M, Bei Y, Akimoto T. Dose-Volume and Radiobiological Model-Based Comparative Evaluation of the Gastrointestinal Toxicity Risk of Photon and Proton Irradiation Plans in Localized Pancreatic Cancer Without Distant Metastasis. Front Oncol, 10:517061, 2020