About the Authors

Shinichi Shimizu

Affiliation Department of Radiation Oncology, Hokkaido University Graduate School of Medicine, Sapporo, Hokkaido, Japan

Naoki Miyamoto

Affiliation Department of Medical Physics, Hokkaido University Graduate School of Medicine, Sapporo, Hokkaido, Japan

Taeko Matsuura

matsuura@med.hokudai.ac.jp

Affiliation Section of Medical Physics, Hokkaido University Hospital Proton Beam Therapy Center, Sapporo, Hokkaido, Japan

Yusuke Fujii

Affiliation Hitachi, Ltd., Hitachi Research Laboratory, Omika, Ibaraki, Japan

Masumi Umezawa

Affiliation Hitachi, Ltd., Hitachi Research Laboratory, Omika, Ibaraki, Japan

Kikuo Umegaki

Affiliation Division of Quantum Science and Engineering, Hokkaido University Graduate School of Engineering, Sapporo, Hokkaido, Japan

Kazuo Hiramoto

Affiliation Hitachi, Ltd., Research & Development Group, Omika, Ibaraki, Japan

Hiroki Shirato

Affiliation Department of Radiation Oncology, Hokkaido University Graduate School of Medicine, Sapporo, Hokkaido, Japan

Competing Interests

The following is the patent relating to material pertinent to this article: “Moving body pursuit irradiating device and positioning method using this device”; Number: US6307914 B1; Issue Date: 2001-10-23; Inventors: Tatsuya Kunieda, Hiroki Shirato. Yusuke Fujii, Masumi Umezawa, and Kazuo Hiramoto are the permanent employees of Hitachi, Ltd. Their affiliation is as follows: Yusuke Fujii Hitachi, Ltd., Hitachi Research Laboratory. Masumi Umezawa Hitachi, Ltd., Hitachi Research Laboratory. Kazuo Hiramoto Hitachi, Ltd., Research & Development Group. The authors declare this does not alter their adherence to PLOS ONE policies on sharing data and materials.

Author Contributions

Conceived and designed the experiments: MU KU KH HS. Analyzed the data: SS NM TM. Contributed reagents/materials/analysis tools: SS NM YF. Wrote the paper: TM HS.