Author(s)

Hiraku Kawamura^1,2,3*, Kazuya Shinoda⁴, Hiraku Fuse¹, Takaoki Takanashi², Yoshikazu Shimada¹, Yoshiyuki Ishimori¹, Masahiko Monma¹, Katsumi Miyamoto⁴, Hitoshi Sato¹, Tatsuya Fujisaki¹, Takeji Sakae⁵, Akira Matsumura⁵

¹Department of Radiological Sciences, Ibaraki Prefectural University of Health Sciences, Ibaraki, Japan.
²3D Gel Dosimeter Research Laboratory, Innovation Center, RIKEN, 2-1, Hirosawa, Wako, Saitama, Japan.
³Faculty of Health Sciences, Tsukuba International University, Ibaraki, Japan.
⁴Department of Radiological Technology, Tsukuba Medical Center Hospital, Ibaraki, Japan.
⁵Graduate School of Comprehensive Human Science, University of Tsukuba, Ibaraki, Japan.

Polymer gels are three-dimensional dosimetric tools. The purpose of the present study was to investigate the temperature dependence of polymer gels during scanning Magnetic Resonance Imaging. Prepared gels were irradiated with a 6MV X-ray beam at intensities ranging from 0 to 20 Gy in order to investigate their dose-R₂ and dose-R₁ responses. Irradiated gels were evaluated from 1.5-T magnetic resonance R₂ and R₁ images for each 5°C change in temperature from 5°C to 41°C, and then the four-field box technique irradiation plan was used to deliver a total dose of 4 Gy using the same beam weight in each direction to the prepared gels. The profile of the dose map generated from the four-field irradiated gel data at 20°C was then compared with the planned data. The dose-R₂ response curve was linear up to 20 Gy at 20°C, with a slope of 1.17 Gy-1˙s-1. The slopes of the fitted curves of the dose-R₂ decreased as gel temperature increased. The slopes of the dose-R₁ curves were more parallel than the slopes of the dose-R₂ curves between 5 and 41°C. The difference in the full width of half maximum of the gel profile data obtained using the four-field box technique at 20°C and the planned data were below 5% on average. The dose map from the irradiated gels obtained using the dose-R₂ curve was the same as that from the planned data under the same temperature conditions. Measurement of difference between various temperatures is significant with dose accuracy. It is suitable to evaluate the gel dosimeter under the thermal equilibrium condition, MRI room temperature from the point of view of the stability of the irradiated gels.

Polymer Gel Dosimetry, Temperature Dependence, MRI Scanning

Kawamura, H. , Shinoda, K. , Fuse, H. , Takanashi, T. , Shimada, Y. , Ishimori, Y. , Monma, M. , Miyamoto, K. , Sato, H. , Fujisaki, T. , Sakae, T. and Matsumura, A. (2018) Investigation of Temperature Dependence of Polymer Gels for Use with Scanning Magnetic Resonance Imaging. International Journal of Medical Physics, Clinical Engineering and Radiation Oncology, 7, 261-272. doi: 10.4236/ijmpcero.2018.72022.