Javaheri Negin, Yarahmadi Mehran, Refaei Abdollah, Aghamohammadi Ali
PhD Candidate, Department of Physics, Sanandaj Branch, Islamic Azad University, Sanandaj, Iran.
PhD, Department of Medical Physics, Faculty of Medicine, Kurdistan University of Medical Sciences, Sanandaj, Iran.
J Biomed Phys Eng. 2022 Oct 1;12(5):489-496. doi: 10.31661/jbpe.v0i0.1912-1008. eCollection 2022 Oct.
Normoxic polymer gels have been used as a three dimensional (3D) dosimeter in radiation therapy, recently. The sensitivity of these gels is important in dosimetry and their improvement can be also useful.
In this study, different modalities of gel reading were used and the structure of gel changed due to the best improvement of sensitivity. The sensitivities of the new formulation of Methacrylic acid gel (MAGAT) and N-isopropyl acrylamide (NIPAM) polymer gel dosimeters were studied using two different reading methods of magnetic resonance imaging (MRI) and X-ray computed tomography (X-ray CT).
In this experimental study, in addition to making the NIPAM polymer gel dosimeter, a new formulation of normoxic polymer gel dosimeter, which named MAGAT gel, was investigated. The gels were irradiated with 6 MV in low doses, including1, 1.5, 1.75, 2 and 2.5 Gy. MRI and X-ray CT did the reading of gel dosimeters a day after irradiation using an elevated protocol.
The dose sensitivities of 0.92 HGy and 0.47 HGy were obtained for new MAGAT and NIPAM polymer gel dosimeters, respectively, based on the X-ray CT reading modality. The use of MRI reading modality and the dose sensitivities were 0.74 SGy and 0.27 SGy for new MAGAT and NIPAM polymer gel dosimeters, respectively.
The new formulation of MAGAT polymer gel with a suitable protocol of gel reading has a better response.
近年来，常氧聚合物凝胶已被用作放射治疗中的三维（3D）剂量计。这些凝胶的敏感性在剂量测定中很重要，其改进也很有用。
在本研究中，使用了不同的凝胶读取方式，并且由于敏感性的最佳改善，凝胶的结构发生了变化。使用磁共振成像（MRI）和X射线计算机断层扫描（X射线CT）两种不同的读取方法，研究了甲基丙烯酸凝胶（MAGAT）和N-异丙基丙烯酰胺（NIPAM）聚合物凝胶剂量计新配方的敏感性。
在本实验研究中，除了制备NIPAM聚合物凝胶剂量计外，还研究了一种新配方的常氧聚合物凝胶剂量计，即MAGAT凝胶。凝胶以低剂量接受6 MV照射，剂量包括1、1.5、1.75、2和2.5 Gy。照射后一天，MRI和X射线CT使用改进方案读取凝胶剂量计。
基于X射线CT读取方式，新的MAGAT和NIPAM聚合物凝胶剂量计的剂量敏感性分别为0.92 HGy和0.47 HGy。使用MRI读取方式时，新的MAGAT和NIPAM聚合物凝胶剂量计的剂量敏感性分别为0.74 SGy和0.27 SGy。
具有合适凝胶读取方案的MAGAT聚合物凝胶新配方具有更好的响应。
