Centre for Medical Radiation Physics, University of Wollongong, Wollongong NSW 2522, Australia. Ingham Institute for Applied Medical Research, Liverpool, NSW 2170, Australia.
Phys Med Biol. 2019 Sep 4;64(17):175015. doi: 10.1088/1361-6560/ab324b.
MRI-LINACs combine MRI and LINAC technologies with the potential for image guided radiation therapy with optimal soft-tissue contrast. In this work, we present the advantages and limitations of plastic scintillation dosimeters (PSDs) for relative dosimetry with MRI-LINACs. PSDs possess many desirable qualities, including magnetic field insensitivity and irradiation angle independence, which are expected to make them suitable for dosimetry with MRI-LINACs. An in-house PSD was used to measure field size output factors as well as a percent depth dose distribution and the beam quality index TPR at a [Formula: see text] cm field size. Measurements were repeated with a Scanditronix/Wellhofer FC65-G ionisation chamber and PTW 60019 microDiamond detector for comparison. Relative differences were calculated between the three detectors, where the mean difference in dose was 1.2% between the PSD and ionisation chamber, 1.9% between the PSD and microDiamond detector and 1.3% between the microDiamond detector and the ionisation chamber. The closeness between the three mean differences in doses suggests that PSDs are feasible for relative dosimetry with MRI-LINACs.
MRI-LINAC 结合了 MRI 和 LINAC 技术，具有潜在的图像引导放射治疗能力，可提供最佳的软组织对比度。在这项工作中，我们介绍了塑料闪烁体剂量计（PSD）在 MRI-LINAC 相对剂量学中的优势和局限性。PSD 具有许多理想的特性，包括对磁场不敏感和辐照角度独立，这有望使它们适合与 MRI-LINAC 进行剂量测定。我们使用内部的 PSD 来测量射野输出因子以及[Formula: see text]cm 射野的百分深度剂量分布和束质指数 TPR。为了进行比较，使用 Scanditronix/Wellhofer FC65-G 电离室和 PTW 60019 微 Diamond 探测器重复了这些测量。在三个探测器之间计算了剂量的相对差异，其中 PSD 和电离室之间的剂量平均差异为 1.2%，PSD 和微 Diamond 探测器之间的剂量平均差异为 1.9%，微 Diamond 探测器和电离室之间的剂量平均差异为 1.3%。三个剂量平均差异之间的接近表明 PSD 可用于 MRI-LINAC 的相对剂量学。
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