Ghavami Seyed-Mostafa, Mesbahi Asghar, Pesianian Ismaeel, Shafaee Abbas, Aliparasti Mohammad-Reza
Radiology department, Paramedical school, Tabriz University of medical sciences, Tabriz, Iran.
Medical physics department, Medical school, Tabriz University of medical sciences, Tabriz, Iran.
Rep Pract Oncol Radiother. 2010 Nov 4;15(6):172-5. doi: 10.1016/j.rpor.2010.10.001. eCollection 2010.
Polymer gel dosimetry has been used extensively in radiation therapy for its capability in depicting a three dimensional view of absorbed dose distribution. However, more studies are required to find less toxic and more efficient polymers for application in radiotherapy dosimetry.
The purpose of this work was to evaluate the N-isopropyl acrylamide (NIPAM) gel dosimetric characteristics and optimize the protocol for X-ray computed tomography (CT) imaging of gel dosimeters for radiation therapy application.
A polymer gel dosimeter based on NIPAM monomer was prepared and irradiated with (60)Co photons. The CT number changes following irradiation were extracted from CT images obtained with different sets of imaging parameters.
The results showed the dose sensitivity of ΔN CT (H) = 0.282 ± 0.018 (H Gy(-1)) for NIPAM gel dosimeter. The optimized set of imaging exposure parameters was 120 kVp and 200 mA with the 10 mm slice thickness. Results of the depth dose measurement with gel dosimeter showed a great discrepancy with the actual depth dose data.
According to the current study, NIPAM-based gel dosimetry with X-ray CT imaging needs more technical development and formulation refinement to be used for radiation therapy application.
聚合物凝胶剂量测定法因其能够描绘吸收剂量分布的三维视图而在放射治疗中得到广泛应用。然而，需要更多研究来寻找毒性更低、效率更高的聚合物用于放射治疗剂量测定。
本研究旨在评估N-异丙基丙烯酰胺（NIPAM）凝胶剂量测定特性，并优化用于放射治疗的凝胶剂量计的X射线计算机断层扫描（CT）成像方案。
制备基于NIPAM单体的聚合物凝胶剂量计，并用钴-60光子进行照射。从使用不同成像参数集获得的CT图像中提取照射后CT值的变化。
结果显示NIPAM凝胶剂量计的剂量敏感度为ΔN CT（H）=0.282±0.018（H Gy-1）。优化后的成像曝光参数集为120 kVp和200 mA，层厚10 mm。凝胶剂量计的深度剂量测量结果与实际深度剂量数据存在很大差异。
根据当前研究，基于NIPAM的凝胶剂量测定法结合X射线CT成像在用于放射治疗应用时需要更多技术开发和配方优化。
