Quantitative Evaluation of the Robustness of Beam Directions Based on Power Spectral Analysis of Water-Equivalent Path Length Image in Charged Particle Therapy

Abstract

Objective: To investigate the quantitative evaluation of the robustness of particle beam directions against patient setup errors in charged particle therapy. Methods: Power spectral analysis of target water-equivalent path length (WEPL) images in beam's eye views was employed for quantitative evaluation of the robustness of beam directions. The relationship between the beam direction and the 0th moment of the power spectrum was calculated for estimating the robustness of each beam direction. We applied the proposed evaluation method to 7 head-region cancer patients. Results: The mean of the 0th moment at the conventional beam directions, which were empirically selected by a manual method, was smaller than that for the avoided beam directions with a statistically significant difference (p < 0.05), which means that the conventional beam directions were appropriate from the theoretical point of view. Conclusions: The results in this preliminary study may lead to quantitative selection of beam directions based on the relationship between the beam direction and the 0th moment derived from the target WEPL image in charged particle therapy.

Keywords::

• Charged Particle Therapy
• Relative Stopping Power (RSP)
• Water-Equivalent Path Length (WEPL)
• Optimum Beam Direction
• Patient Setup Error
• Power Spectrum

Additional information

Notes on contributors

Hidetaka Arimura

Hidetaka Arimura, received a BS in 1989 and an MS in 1991 in electronics and information engineering, and his PhD in engineering from Kyoto Institute of Technology in 1996. He is a currently working as an associate professor at Division of Quantum Radiation Science, Department of Health Sciences, Faculty of Medicine, Kyushu University, and also a certificated medical physicist. His research tasks are computer-aided diagnosis and image assisted radiation therapy based on medical image analysis and pattern recognition.

Genyu Kakiuchi

Genyu Kakiuchi, received a BS in 2011 and an MS in 2013 at Division of Quantum Radiation Science, Department of Health Sciences, Faculty of Medicine, Kyushu University. He is currently working as a radiological technologist at Ion Beam Therapy Center, SAGA Heavy Ion Medical Accelerator in Tosu (SAGA HIMAT) Foundation.

Yoshiyuki Shioyama

Yoshiyuki Shioyama, obtained his M.D. and Ph.D. degrees at Kyushu University. He was a professor in Department of Heavy Particle Therapy and Radiation Oncology, Graduate School of medical Sciences, Kyushu University from 2010–2013. Now he is a Deputy Director at Ion Beam Therapy Center, SAGA-HIMAT Foundation in Japan and also working as a certified radiation oncologist. His research tasks are clinical research of high-precision radiotherapy and particle beam therapy.

Shin-ichi Minohara

Shinichi Minohara, received his BS (1982) and MS (1984) in Electrical Engineering from Tokyo Metropolitan University, and PhD (1990) in Medical and Biomedical Engineering from the University of Tokyo, Japan. He is currently working as a head of medical physics group in Promotion division of Heavy Ion Facility, Kanagawa Cancer Center. In 1989–2011 he has been engaged in the research and development of heavy-ion radiation therapy system at National Institute of Radiological Science. Now, he is in charge of the i-ROCK project that is a new facility for heavy-ion radiotherapy.

Takahiro Nakamoto

Takahiro Nakamoto is currently a doctoral student in Department of Health Sciences, Graduate School of Medical Sciences, Kyushu University. He received a BS in 2012 and an MS in 2014 from Kyushu University. His research interests focus on medical image processing for radiation therapy.

Katsumasa Nakamura

Katsumasa Nakamura, received a PhD in 1994 in radiation biology from Kyushu University. He is a currently working as an associate professor at Department of Radiology, Kyushu University Hospital, and also a certificated radiation oncologist. His research task is radiation oncology including precise radiation technology.

Hiroshi Honda

Hiroshi Honda, Professor and Chairman, Department of Radiology, Kyushu University, Fukuoka, Japan is currently the President of Japan Radiological Society. Dr. Honda is also a member of the ISSSR. After completing a residency and fellowship in Radiology at Kyushu University, Dr. Honda moved to the Department of Radiology, Fukuoka Central Hospital, where he developed an interest in gastrointestinal radiology. He spent 3 years as a staff radiologist in the Department of Radiology, University of Iowa before moving back to Kyushu University in 1989 to the Assistant Professor, 1997 the Associate Professor and Vice Chairman, and 2002 the Professor and Chairman of the Department of Radiology at the Kyushu University.

Mutsumi Tashiro

Mutsumi Tashiro, received his B.Ed. in 1995, M.Ed. in 1997 from Tokyo Gakugei University, and Ph.D. in engineering from Osaka University in 2000. He is currently working as an assistant professor at Gunma University Heavy Ion Medical Center, and is also a certified medical physicist. His research tasks are system development and motion management for carbon-ion beam cancer therapy.

Tatsuaki Kanai

Tatsuaki Kanai, received a BS in 1972 and a MS in 1974 in physics from Tokyo University of Education, and PhD in physics from The University of Tsukuba in 1983. He is currently working as a special professor at Heavy Ion Medical Research Center, Gunma University. His research task is development of irradiation system of ion therapy and solving problems in a field of medical physics for ion therapy.

Hideki Hirata

Hideki Hirata, received a MD in 1977 and a PhD in 1985 in Kyushu University. He is working as a professor at Division of Quantum Radiation Science, Department of Health Sciences, Faculty of Medicine, Kyushu University, and also a Radiation Oncologist with Japanese Board. His research tasks are evaluation of radiation therapy technique based upon clinical outcomes.