Abstract
Generally, electron therapy is applied to tumors on or close to the skin surface. However, this causes a variety of skin-related side effects. To alleviate the risk of these side effects, clinical treatment uses skin dosimeters to verify the therapeutic dose. However, dosimeters suffer from poor accuracy, because their attachment sites are approximated with the help of naked eyes. Therefore, a dosimeter based on a flexible material that can adjust to the contours of the human body is required. In this study, the reproducibility, linearity, dose-rate dependence, and percentage depth ionization (PDI) of PbO and HgO film-based dosimeters are evaluated to explore their potential as large-scale flexible dosimeters. The results demonstrate that both dosimeters deliver impressive reproducibility (within 1.5%) and linearity (≥ 0.9990). The relative standard deviations of the dose-rate dependence of the PbO and HgO dosimeters were 0.94% and 1.16% at 6 MeV, respectively, and 1.08% and 1.25% at 9 MeV, respectively, with the PbO dosimeter outperforming the 1.1% of existing diodes. The PDI analysis of the PbO and HgO dosimeters returned values of 0.014 cm (–0.074 cm) and 0.051 cm (–0.016 cm), respectively at 6 MeV (9 MeV) compared to the thimble chamber and R50. Therefore, the maximum error of each dosimeter is within the allowable range of 0.1 cm. In short, the analysis reveals that the PbO dosimeter delivers a superior performance relative to its HgO counterpart and has strong potential for use as a surface dosimeter. Thus, flexible monoxide materials have the necessary qualities to be used for dosimeters that meet the requisite quality assurance standards and can satisfy a variety of radiation-related applications as flexible functional materials.
Highlights
Electron beam therapy (EBT) has a short penetration depth, which makes it suitable for treating tumors close to the skin
For the HgO dosimeter, the relative standard deviation (RSD) was determined as 1.16% at 6 MeV and 1.25% at 9 MeV, under the same conditions adopted for the PbO dosimeter measurements
The percentage depth ionization (PDI) results showed that when comparing the thimble chamber and R50 value, the maximum errors associated with the PbO and HgO dosimeters were 0.014 cm and 0.051 cm, Evaluation of monoxide film-based dosimeters for surface dose detection in electron therapy respectively, at 6 MeV, and -0.074 cm and -0.016 cm, respectively, at 9 MeV
Summary
Electron beam therapy (EBT) has a short penetration depth, which makes it suitable for treating tumors close to the skin. Flexible PbO and HgO dosimeters were manufactured to evaluate the LINAC quality assurance (QA) with respect to reproducibility, linearity, dose-rate dependence, and percentage depth ionization (PDI). In this study, flexible unit cell sensors based on polycrystalline PbO and HgO materials manufactured by the PIB method were fabricated, with their performance compared and evaluated according to the radiation treatment QA requirements. The measured signal was normalized based on a dose rate of 200 MU, and the RSD (n = 3) for the value measured at 100 MU was calculated following the method reported in the diode study, and evaluated based on the reported diode error of 1.1% [18,19] At this time, the results of the diode were as in [18], which was conducted under similar evaluation conditions to this study. We compared the R50,dos results with a thimble chamber using the PDI conversion method
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