辐射法制备Fricke凝胶剂量计

辐射剂量验证技术是肿瘤放射治疗过程中的关键技术,Fricke凝胶剂量计因其制备简单、组织等效性好正逐步成为研究的热点。本研究采用辐射交联"一步法"制备Fricke凝胶剂量计,利用傅里叶红外光谱仪(Fourier transform infrared spectrometer,FTIR)、X线衍射仪(X-ray diffractometer,XRD)与热重分析仪(Thermo-gravimetric analyser,TGA)等仪器对凝胶样品的化学结构和成分进行了分析,利用分子动力学模拟研究了亚铁离子在凝胶剂量计中的扩散行为,并在医用加速器下对凝胶进行辐照,利用多功能酶标仪测定凝胶的辐射剂量响应。结果表明,辐射法制备的Fricke凝胶剂量计中,聚丙烯酸链可以抑制亚铁离子在凝胶样品中的扩散行为,添加二甲酚橙(Xylenol orange,XO)可以改善Fricke凝胶剂量计的剂量敏感性。

Fricke gel dosimeter prepared by irradiation induced crosslinking method

Background:Radiotherapy is one of the main methods for treating cancer, and its efficiency depends heavily on accurate dose verification.Fricke gel dosimeters are fabricated from ferrous sulfate and polymer gel upon irradiation, with ferrous as a function of the absorbed radiation dose.Purpose: This study aims to explore the one-step irradiation induced crosslinking method to fabricate the Fricke gel dosimeter with polyacrylic acid as the frame, and study the structure and properties of the Fricke gel.Methods: The chemical structure and stability of gel is measured by Fourier transform infrared spectrometer (FTIR), X-ray diffractometer (XRD), Thermo-gravimetric analyser (TGA) and water absorption analyser. The diffusion behavior of Fe2+ in gel is measured by molecular dynamics simulation. And the dose response ability of Fricke gel dosimeter is analyzed by spectrophotometry. Results: Experimental results show thatthe coordination bonds between the ferrous ions and -COOH groups are proven by FTIR analysis, and the result of molecular dynamics simulation reveals that PAAc(Polyacrylic acid) chains can reduce the diffusion of ferrous ions.Conclusion: The dose response standard curves indicated Fricke gel dosimeter can be applied to dose verification in radiotherapy. In addition, the existence of xylenol orange (XO) can improve dose sensitivity of Fricke gel dosimeter.