Department of Radiation Oncology, Columbia University Medical Center, New York, NY, USA.
Department of Chemistry, Biochemistry, and Physics, Rider University, Skillman, NJ, USA.
J Appl Clin Med Phys. 2020 Mar;21(3):167-177. doi: 10.1002/acm2.12838. Epub 2020 Feb 26.
A novel radiochromic PRESAGE sheet (Heuris Inc.) with 3 mm thickness has been developed as a measurement tool for 2D dosimetry. Its inherent ability to conform to irregular surfaces makes this dosimeter advantageous for patient surface dosimetry. This study is a comprehensive investigation into the PRESAGE sheet's dosimetric characteristic, accuracy and its potential use as a dosimeter for clinical applications.
The characterization of the dosimeter included evaluation of the temporal stability of the dose linearity, reproducibility, measurement uncertainties, dose rate, energy, temperature and angular dependence, lateral response artifacts, percent depth dose curve, and 2D dose measurement. Dose distribution measurements were acquired for regular square fields on a flat and irregular surface and an irregular modulated field on the smooth surface. All measurements were performed using an Epson 11000XL high-resolution scanner.
The examined dosimeters exhibit stable linear response, standard error of repeated measurements within 2%, negligible dose rate, energy, and angular dependence. The same linear dose response was measured while the dosimeter was in contact with a heated water surface. Gamma test and histogram analysis of the dose difference between PRESAGE and EBT3 film, PRESAGE and the treatment planning system (TPS) were used to evaluate the measured dose distributions. The PRESAGE sheet dose distributions showed good agreement with EBT3 film and TPS. A discrepancy smaller than the statistical error of the two dosimeters was reported.
This study established a full dosimetric characterization of the PRESAGE sheets with the purpose of laying the foundation for future clinical uses. The results presented here for the comparison of this novel dosimeter with those currently in use reinforce the possibility of using this dosimeter as an alternative for irregular surface dose measurements.
一种新型的 3 毫米厚的光致变色 PRESAGE 薄片（Heuris Inc.）已被开发为二维剂量测量的工具。它能够与不规则表面贴合的固有能力使其成为患者表面剂量测量的优势。本研究全面研究了 PRESAGE 薄片的剂量学特性、准确性及其作为临床应用剂量计的潜力。
剂量计的特性包括评估剂量线性的时间稳定性、重复性、测量不确定度、剂量率、能量、温度和角度依赖性、横向响应伪影、百分深度剂量曲线和二维剂量测量。在平坦和不规则表面上的规则方形场以及在光滑表面上的不规则调制场进行了剂量分布测量。所有测量均使用 Epson 11000XL 高分辨率扫描仪进行。
所检查的剂量计表现出稳定的线性响应，重复测量的标准误差在 2%以内，剂量率、能量和角度依赖性可忽略不计。当剂量计与加热的水面接触时，测量到相同的线性剂量响应。通过 PRESAGE 和 EBT3 胶片之间的剂量差值的伽马测试和直方图分析，以及 PRESAGE 和治疗计划系统（TPS）之间的剂量差值的伽马测试和直方图分析，评估测量的剂量分布。PRESAGE 薄片的剂量分布与 EBT3 胶片和 TPS 吻合良好。报告的差异小于两个剂量计的统计误差。
本研究对 PRESAGE 薄片进行了全面的剂量学特性研究，为未来的临床应用奠定了基础。这里呈现的结果用于比较这种新型剂量计与目前使用的剂量计，进一步证实了使用这种剂量计作为不规则表面剂量测量的替代方法的可能性。
