TQ07b-CT Simulator QA
4B02b-CT Simulator QA
Ching-Chong Jack Yang, PhD
Radiation Oncology Dept.
Monmouth Medical Center
300 2nd Ave
Long Branch, NJ 07740
CT has become an important front-end tool for radiation therapy practice and gradually replacing the conventional simulation devices in some clinics. Preparing CT Simulator accepting protocol and QA/QC process in a routine clinic could be a challenge for physicists. CT simulator not only acts as an imaging tool but also performs as a localization device using the associated software and lasers. Therefore, except for the image quality requirement, the geometrical accuracy is the focal point of the QA process. Quality assurance of a CT simulator should have the following components: 1) Initial acceptance testing; 2) Daily QA protocol; 3) Monthly QA protocol; and 4) Annual QA protocol. Quality of the acquired CT images are very important for image registration purposes of target and critical structures, however, the geometrical accuracy of coordinate system (isocenter management) is also the key for subsequent treatment planning accuracy. Lasers to correlate patient marking will be addressed and it needs to go through a thorough verification process for clinical implementation. CT number definition is also important for verification if inhomogeneity correction is clinically implemented with 3D planning module. The CT number can be a source for error if not properly calibrated. Using the CT simulation could increase the treatment delivery precision if the QA/QC were performed and maintained properly.
TQ07b-CT模拟质量保证
4B02b-CT模拟质量保证
Ching-Chong Jack Yang, PhD
Radiation Oncology Dept.
Monmouth Medical Center
300 2nd Ave
Long Branch, NJ 07740
CT已经成为放疗过程中的一个重要的前端工具并且在一些医院中逐渐取代了传统模拟机。对在一家普通医院工作的物理师来说，准备CT模拟机的接收测试规范和质量保证/质量控制程序也许是一个挑战。CT模拟机不仅是影像工具而且还与软件和激光灯配合起到定位装置的作用。因此，除了影像质量的要求外，几何精度也是质量保证程序的要点。CT模拟的质量保证应该包括以下几点： 1) 最初的验收测试；2) 每日的质量保证程序； 3) 每月的质量保证程序； 4) 每年的质量保证程序。采集的CT图像的质量对于靶区和重要器官的图像配准非常重要，但坐标系统（确定等中心位置）的几何精度也是随后的治疗计划的精度的关键因素。本讲还将介绍与患者标记相关联的激光灯将做着重介绍，为了临床使用需要对它进行一个全面的验证程序。CT值校准对于验证治疗计划系统处理组织不均匀性的能力也很重要。如果没有进行适当的校准，CT值会成为误差的来源。如果适当地进行和维护了质量保证/质量控制，使用CT模拟能够提高治疗实施的精度。