ArcCHECK Machine QA工具在医用直线加速器质量保证中的应用效果

目的探讨ArcCHECK Machine QA工具在医用直线加速器质量保证中的应用效果。方法利用ArcCHECK Machine QA工具和ArcCHECK体模对医用直线加速器进行性能测试,项目包括机架角度、机架旋转速度、机架旋转中心、多叶准直器和铅门位置的一致性、机架旋转出束时的平坦度和对称性,评估该工具在医用直线加速器质量保证中的应用效果。结果旋转模式下机架平均旋转速度为3.6 deg/s,最大偏差约0.5 deg/s;机架旋转等中心形成的平均半径为0.4 mm,多叶准直器与铅门的最大距离正、负差异平均值分别为0.7 mm、-0.7 mm;旋转出束模式下Y方向的平坦度为1.8%,Y方向的对称性为1.1%,X方向的对称性为4.3%。结论ArcCHECK Machine QA工具可用于医用直线加速器常规及容积调强出束性能质量保证。

基于QA BeamChecker Plus对加速器的日常质量保证

目的:通过分析照射野剂量参数的日常质量保证数据,探讨直线加速器照射野日检方法的可行性和必要性。方法:每天放射治疗前,用平行板电离室矩阵QA BeamChecker Plus(QABC+)测量加速器照射野相关参数与基准值的偏差,并对数据进行系统性分析,辅以二维电离室矩阵MatriXX进行平坦度和对称性的二次验证,评价指标包括中心轴剂量、平坦度、对称性。评价标准如下:剂量输出偏差≤±2%,平坦度偏差≤1%,对称性偏差≤±1%。结果:5个月的QABC+日常质量保证结果显示,6MV-X线的剂量输出稳定性合格率为99%,射野平坦度和轴向对称性基本保持不变;横向对称性偏差合格率为85.3%,与MatriXX测量结果一致。结论:基于质控设备QABC+的照射野日检方法是有效和可行的,它在保证每日放疗精确执行的同时,也为加速器的长期质量保证提供了依据。

英联邦高校混合学习质量保障审查工具探析

在教育信息化与疫情防控的双重背景下,世界各地的高校已经从传统的学习方式转向混合学习方式。为提升高校混合学习的实施质量,“英联邦学习共同体”制定了面向实施混合学习的高校的质量保障审查工具,简称QA审查工具,已在23个高校中实施。QA审查主要包括在线调查、现场审核和审查总报告等三个部分,基于对其构成、实施及特征的探析,我国高校混合学习质量保障工作应建立有效的质量保障机制,注重教师发展,重视对混合学习实施的研究。

医用电子直线加速器快速日检方法研究

该文研究设计了一个可用于不同放疗中心的基于电子射野成像设备(EPID)的快速加速器日检工具。该工具使用EPID快速获取多个方形开野的图像。加速器的主要日检参数由自主开发的软件自动分析这些影像来获取。实验结果表明,工具的检测结果与商用质控(QA)设备测量结果一样可靠,而测量效率更高。

Investigation of Error Detection Capabilities of Various Patient-Specific Intensity Modulated Radiotherapy Quality Assurance Devices

The capability of error detection of patient-specific QA tools plays an important role in verifying MLC motion accuracy. The goal of this study was to investigate the capability in error detection of portal dosimetry, MapCHECK2 and MatriXX QA tools in IMRT plans. The 9 fields IMRT for 4 head and neck plans and 7 fields IMRT for 4 prostate plans were selected for the error detection of QA devices. The measurements were undertaken for the original plan and the modified plans, where the known errors were introduced for increasing and decreasing of prescribed dose (±2%, ±4% and ±6%) and position shifted in X-axis and Y-axis (±1, ±2, ±3 and ±5 mm). After measurement, the results were compared between calculated and measured values using gamma analysis at 3%/3 mm criteria. The average gamma pass for no errors introduced in head and neck plans was 96.9%, 98.6%, and 98.8%, while prostate plans presented 99.4%, 99.0%, and 99.7%, for portal dosimetry, MapCHECK2 and MatriXX system, respectively. In head and neck plan, the shifted error detections were 1 mm for portal dosimetry, 2 mm for MapCHECK2, and 3 mm for MatriXX system. In prostate plan, the shifted error detections were 2 mm for portal dosimetry, 3 mm for MapCHECK2, and 5 mm for MatriXX system. For the dose error detection, the portal dosimetry system could detect at 2% dose deviation in head and neck and 4% in prostate plans, while other two devices could detect at 4% dose deviation in both head and neck and prostate plans. Portal dosimetry shows slightly more capability to detect the error compared with MapCHECK2 and MatriXX system, especially in the complicated plan. It may be due to higher resolution of the detector;however, all three-detector types can detect various errors and can be used for patient-specific IMRT QA.