S Kurokawa*, H Tachibana, T Akimoto, Radiation Safety and Quality Assurance division, National Cancer Center Hospital East, Kashiwa, JP

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  S Kurokawa

PO-GePV-T-269 (Sunday, 7/10/2022)   [Eastern Time (GMT-4)]

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Purpose: To evaluate dose uncertainty related to the transportation including temperature variation for a polymer gel dosimetry in terms of seasonality comparisons and inter-institution’s comparisons.

Methods: Six vials were filled with a VIPET gel manufactured by Triangle Products (Chiba, Japan). The three vials were sent to our institution and another institution. The two vials were irradiated for 5 Gy and 10 Gy using a 10 MV X-ray beams, respectively. The other vial was unirradiated (0 Gy). After irradiation, the gel in the vial was imaged on 1.5T MRI and R2 (spin–spin relaxation rate) image was created. Subsequently, the linear regression of dose-R2 values was obtained. Finally, dose uncertainty was computed.

Results: This study was performed in 34 institutions from July 2020 through July 2021. A total of 38 examinations were conducted. The average time from fabrication to irradiation was 73 hours (range: 45-172 hours). Seasonality comparisons of dose uncertainties of the gel for our institution shows that the uncertainties were constant throughout the year (mean ± 1.96σ; 3.3 ± 1.0% at 5 Gy and 4.0 ± 1.2% at 10 Gy). There was no statistical difference for dose uncertainties although the range of temperature during the study was 4.9-29.5 ℃. In inter-institutional comparisons, mean ± 1.96σ of the ratio of the dose uncertainty of other institutions against our institution were 1.1 ± 0.4 at 5 Gy and 1.0 ± 0.3 at 10 Gy with no significant difference. The greatest of the uncertainties was 9-12% for 5 Gy and 10 Gy when the gels were irradiated at 7 days after the fabrication.

Conclusion: In our study, dose uncertainties for transportation including temperature was negligible; however, time for transportation may worsen dose uncertainty. Thus, the polymer gel dosimeters should be used in two or three days after the fabrication.

Keywords

Polymer Gels, 3D, Gel Dosimeter

Taxonomy

TH- Radiation Dose Measurement Devices: 3D solid gel/plastic

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