Comparison between polymer gel dosimetry and calculated dose with small field in stereotactic irradiation

7th International Conference on 3D Radiation Dosimetry

Kawamura, H.^1,2 ; Shinoda, K.^3 ; Fuse, H.^4 ; Terunuma, T.^2,4 ; Miyamoto, K.^3 ; Sakae, T.^2,4 ; Matsumura, A.^2

Department of Radiological Sciences, Ibaraki Prefectural University of Health Sciences, 4669-2, Ami, Ami-machi, Inashiki-gun, Ibaraki, Japan^1

Graduate School of Comprehensive Human Science, University of Tsukuba, 1-1-1, Tennodai, Tsukuba, Ibaraki, Japan^2

Tsukuba Medical Center Hospital, 1-3-1, Amakubo, Tsukuba, Ibaraki, Japan^3

Proton Medical Research Center, University of Tsukuba, 2-1-1 Amakubo, Tsukuba, Ibaraki, Japan^4

关键词: Gel dosimetry;    Irradiation fields;    Line profiles;    Polymer gel dosimetry;    Polymer gels;    Stereotactic irradiations;    Stereotactic radiotherapy;    Treatment plans;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/444/1/012031/pdf
DOI  :  10.1088/1742-6596/444/1/012031

来源: IOP

【 摘 要 】

The purpose of this study is to investigate gel dosimetry for a small irradiation field in stereotactic radiotherapy. Treatment plans were generated by the Pinnacle3treatment plan system (TPS) for three different circular irradiated fields: 10 mm, 15 mm, and 20 mm. The polymer gels were irradiated to 6 Gy with 10-, 15-, and 20-mm-diameter collimators in 4 MV photon beams for stereotactic irradiation following TPS. Irradiated gels were evaluated with MRI at 1.5 T with R2 images. Firstly, the line profile of the irradiated center between TPS plan and the R2 image was compared. In the center profile at a dose calculated from the treatment plan, the full width at half maximum (FWHM) of 10-mm, 15-mm, and 20-mm collimators, were 13 mm, 19 mm, and 25 mm, respectively. In the center profile at R2 from the gel dosimetry, the FWHM were 13 mm, 20 mm, and 23 mm, respectively. Secondly, R2 images were converted to dosimetric maps to apply the gamma evaluation method. Comparison using gamma evaluation in the center of the irradiated plane between TPS plan and the dose map from the R2 image was performed. In gamma evaluation, when 3% and 3 mm criteria were used for comparison of the center plane of dose image from TPS and gel dosimetry, the pass ratio of the gamma criterion between calculated dose from the TPS and the dose map of irradiated gels in stereotactic irradiation was 98.6%. In comparison of the center profile and center plane, results of gel dosimetry were shown to have good agreement with the generated treatment plan dosimetric map for stereotactic irradiation.