IMRT质量控制剂量验证方法研究
发布时间：2018-11-23 12:57
【摘要】：调强放射治疗(IMRT)是目前先进的放射治疗技术之一,在我国应用比较广泛,在IMRT提高肿瘤治疗效果和患者生命质量的同时,国外也报道了IMRT由于放疗剂量错误而导致的放疗事故,国际原子能机构(IAEA)等国际组织对IMRT实施剂量的准确度给予了更严格的要求。因此,做好IMRT执行前的质量控制(QC)剂量验证工作,具有重要的实际意义。 IMRT剂量验证新型工具——一维矩阵探测器,具有使用方便、高效等优点,已成为当前领域研究的热点,但在国内对其质量控制研究工作报道较少。因此,本研究选取一种二维电离室矩阵探测器作为研究对象,首先研究其在光子束下较全面的剂量学特性,包括测量重复性、长期稳定性、剂量率依赖性、剂量响应线性和电离室间响应一致性等,建立起质量控制检测方法,其次将二维矩阵探测器与参考电离室进行剂量测量比对,最后将二维矩阵探测器在IMRT剂量验证中进行应用。 二维矩阵探测器在不同能量(60Coγ,6MV、10MV和15MVX)射线下测量重复性0.3%,在60Co丫射线下半年测量稳定性0.5%,表明其具有良好的测量可信度;在不同能量X射线下,加速器出束10-250cGy和60Coγ射线下测量,矩阵电离室线性0.5%;在剂量率为100MU/min～600MU/min下测量最大偏差为1.3%,显示矩阵剂量率依赖性较小；矩阵不同电离室剂量响应偏差1%；矩阵电离室与参考电离室测量比对显示,测量偏差≤0.57%;矩阵电离室与参考电离室在4cm×4cm～20cm×20cm不同方形野下测量输出因子结果基本一致；分析两种应用二维矩阵探测器进行剂量验证的方法,发现机架角0°计划与非0°计划(实际照射)验证剂量分布与计划剂量分布符合较为理想。 以上实验结果表明,二维矩阵探测器具有良好的剂量学特性,是放疗技术质量控制的有力工具。通过实验建立一套包括校准、比对的质量控制方法，，为以后对IMRT质量控制剂量验证设备进行质量控制打下基础。实施机架角非0°计划照射更贴近实际照射情况,建议采取非0°剂量验证方法进行IMRT剂量验证。
[Abstract]:Intensity modulated radiotherapy (IMRT) is one of the advanced radiotherapy techniques, which is widely used in China. While IMRT improves the effect of tumor treatment and the quality of life of patients, Foreign countries have also reported the radiation accident caused by the wrong dose of IMRT. The International Atomic Energy Agency (IAEA) and other international organizations have imposed more stringent requirements on the accuracy of the dose of IMRT. Therefore, it is of great practical significance to do the quality control (QC) dose verification before IMRT execution. One-dimensional matrix detector, a new tool for IMRT dose verification, has become a hot spot in current research field because of its advantages of convenience and high efficiency. However, there are few reports on its quality control in China. Therefore, a two-dimensional ionization chamber matrix detector is chosen as the research object. Firstly, the dosimetric characteristics of the detector under photon beam are studied, including repeatability, long-term stability and dose-rate dependence. The method of quality control detection is established based on the linearity of dose response and the consistency between ionization chamber and so on. Secondly, the two dimensional matrix detector is compared with the reference ionization chamber. Finally, the two-dimensional matrix detector is applied to the IMRT dose verification. The repeatability of the two-dimensional matrix detector was 0.3 at different energy (60Co 纬, 6MV 10MV and 15MVX), and the stability was 0.5 in the second half of the 60Co ray, which showed that it had good reliability. Under different energy X-ray, the matrix ionization chamber was measured under 10-250cGy and 60Co 纬 rays, and the maximum deviation was 1.3 when the dose rate was 100MU/min~600MU/min, which showed that the matrix dose-rate dependence was small. The dose response deviation of different ionization chambers is 1. The comparison of matrix ionization chamber and reference ionization chamber shows that the measurement deviation is less than 0.57.The results of matrix ionization chamber and reference ionization chamber are basically consistent under different square fields of 4cm 脳 4cm~20cm 脳 20cm. Two methods of dose verification using 2-D matrix detector are analyzed. It is found that the verification dose distribution and the planned dose distribution of the frame angle 0 掳plan and non-0 掳plan (actual irradiation) are in good agreement with each other. The experimental results show that the two-dimensional matrix detector has good dosimetry characteristics and is a powerful tool for quality control of radiotherapy technology. A set of quality control methods including calibration and comparison were established through experiments, which laid a foundation for the quality control of IMRT quality control dose verification equipment in the future. The implementation of frame angle non-0 掳planned irradiation is closer to the actual irradiation situation. It is suggested that the method of non-0 掳dose verification should be adopted for IMRT dose verification.
【学位授予单位】：中国疾病预防控制中心
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：R730.55
[Abstract]:Intensity modulated radiotherapy (IMRT) is one of the advanced radiotherapy techniques, which is widely used in China. While IMRT improves the effect of tumor treatment and the quality of life of patients, Foreign countries have also reported the radiation accident caused by the wrong dose of IMRT. The International Atomic Energy Agency (IAEA) and other international organizations have imposed more stringent requirements on the accuracy of the dose of IMRT. Therefore, it is of great practical significance to do the quality control (QC) dose verification before IMRT execution. One-dimensional matrix detector, a new tool for IMRT dose verification, has become a hot spot in current research field because of its advantages of convenience and high efficiency. However, there are few reports on its quality control in China. Therefore, a two-dimensional ionization chamber matrix detector is chosen as the research object. Firstly, the dosimetric characteristics of the detector under photon beam are studied, including repeatability, long-term stability and dose-rate dependence. The method of quality control detection is established based on the linearity of dose response and the consistency between ionization chamber and so on. Secondly, the two dimensional matrix detector is compared with the reference ionization chamber. Finally, the two-dimensional matrix detector is applied to the IMRT dose verification. The repeatability of the two-dimensional matrix detector was 0.3 at different energy (60Co 纬, 6MV 10MV and 15MVX), and the stability was 0.5 in the second half of the 60Co ray, which showed that it had good reliability. Under different energy X-ray, the matrix ionization chamber was measured under 10-250cGy and 60Co 纬 rays, and the maximum deviation was 1.3 when the dose rate was 100MU/min~600MU/min, which showed that the matrix dose-rate dependence was small. The dose response deviation of different ionization chambers is 1. The comparison of matrix ionization chamber and reference ionization chamber shows that the measurement deviation is less than 0.57.The results of matrix ionization chamber and reference ionization chamber are basically consistent under different square fields of 4cm 脳 4cm~20cm 脳 20cm. Two methods of dose verification using 2-D matrix detector are analyzed. It is found that the verification dose distribution and the planned dose distribution of the frame angle 0 掳plan and non-0 掳plan (actual irradiation) are in good agreement with each other. The experimental results show that the two-dimensional matrix detector has good dosimetry characteristics and is a powerful tool for quality control of radiotherapy technology. A set of quality control methods including calibration and comparison were established through experiments, which laid a foundation for the quality control of IMRT quality control dose verification equipment in the future. The implementation of frame angle non-0 掳planned irradiation is closer to the actual irradiation situation. It is suggested that the method of non-0 掳dose verification should be adopted for IMRT dose verification.
【学位授予单位】：中国疾病预防控制中心
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：R730.55
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