通过在聚甲基丙烯酸甲酯凝胶剂量计中加入碘来提高 CT 扫描的灵敏度。

Sensitivity enhancement of methacrylic acid gel dosimeters by incorporating iodine for computed tomography scans.

机构信息

Department of Radiology, Cheng Ching Hospital at Chung Kang, Taichung, Taiwan; Department of Medical Imaging and Radiological Science, Central Taiwan University of Sciences and Technology, Taichung, Taiwan.

Department of Medical Imaging and Radiological Science, Central Taiwan University of Sciences and Technology, Taichung, Taiwan.

出版信息

Phys Med. 2019 Jul;63:1-6. doi: 10.1016/j.ejmp.2019.05.014. Epub 2019 May 22.

DOI:10.1016/j.ejmp.2019.05.014

PMID:31221400

Abstract

PURPOSE

Polymer gel dosimeters provide three-dimensional absorbed dose information and have gradually become a popular tool for quality assurance in radiotherapy. This study aims to incorporate iodine into the MAGAT-based gel as radiation sensitizer and investigate whether it can be used to measure the radiation dose and slice thickness for CT scans.

METHODS

The nMAGAT(I) gel was doped with 0.03, 0.05, and 0.07-M iodine. The absorbed dose was delivered using a CT scanner (Alexion 16, Toshiba Medical Systems, Japan) with tube voltages of 80, 100, 120, and 135 kVp. The irradiated nMAGAT(I) gel was read using a cone beam optical CT scanner to produce dose-response curves. The nMAGAT(I) gel was used to obtain the slice sensitivity profile (SSP) and the CT dose index (CTDI) for quality assurance of CT scans.

RESULTS

The 0.07-M iodine-doped nMAGAT(I) gel exhibited maximum sensitivity with the dose enhancement ratio of 2.12. The gel was chemically stable 24 h after its preparation, and the polymerization process was completed 24-48 h after the irradiation. For CT quality assurance, the full width at half maximum measured by the nMAGAT(I) gel matched the nominal slice thickness of CT. The CTDI at center, CTDI at peripheral, and weighted CTDI obtained by the nMAGAT(I) gel differed from those obtained by the ionization chamber by -4.2%, 3.1%, and 0.7%, respectively.

CONCLUSIONS

The nMAGAT(I) gel can be used to assess radiation doses and slice thickness in CT scans, thus rendering it a potential quality assurance tool for CT and other radiological diagnostic applications.

摘要

目的

聚合物凝胶剂量计可提供三维吸收剂量信息，已逐渐成为放射治疗质量保证的常用工具。本研究旨在将碘掺入基于 MAGAT 的凝胶中作为辐射增敏剂，并研究其是否可用于测量 CT 扫描的辐射剂量和切片厚度。

方法

nMAGAT（I）凝胶中掺杂了 0.03、0.05 和 0.07-M 碘。使用 CT 扫描仪（日本东芝医疗系统公司的 Alexion 16）以 80、100、120 和 135 kVp 的管电压输送吸收剂量。使用锥形束光学 CT 扫描仪读取辐照后的 nMAGAT（I）凝胶，以生成剂量响应曲线。使用 nMAGAT（I）凝胶获得切片灵敏度分布（SSP）和 CT 剂量指数（CTDI），以进行 CT 扫描质量保证。

结果

0.07-M 碘掺杂的 nMAGAT（I）凝胶的灵敏度最高，剂量增强比为 2.12。凝胶在制备后 24 小时内化学稳定，辐照后 24-48 小时完成聚合过程。对于 CT 质量保证，nMAGAT（I）凝胶测量的半高全宽与 CT 的标称切片厚度匹配。nMAGAT（I）凝胶获得的中心 CTDI、周边 CTDI 和加权 CTDI 与电离室获得的值分别相差-4.2%、3.1%和 0.7%。