Chan M F, Ayyangar K M
Department of Radiation Therapy, Medical College of Ohio, Toledo 43699, USA.
Med Phys. 1995 Jul;22(7):1171-5. doi: 10.1118/1.597612.
A detailed methodology has been developed to verify the three-dimensional (3D) radiation dose mapping of conformal therapy radiation treatment planning by FeMRI dosimetry. A phantom that consisted of a human skull filled with a 1-mM solution of ferrous sulfate and 0.1-N sulfuric acid gelled with 7.5% (by weight) gelatin was employed. With a spherical target volume in the head phantom, five noncoplanar conformal beams were designed through the use of a 3D treatment planning system developed in-house. The phantom was irradiated with a 6-MV linear accelerator to a total dose of 25 Gy delivered to the periphery of the target volume. The phantom and a set of calibration vials were scanned simultaneously in a GE 1.5T MR imager with six different multiscan inversion-recovery pulse sequences. The values of T1 were evaluated on a pixel-by-pixel basis through the use of custom-built software on a UNIX workstation and were converted to dose using calibration data. Comparisons of dose distributions between those measured by FeMRI and those calculated by 3D treatment planning show good agreement.
已经开发出一种详细的方法，用于通过铁磁共振成像（FeMRI）剂量测定法来验证适形治疗放射治疗计划的三维（3D）辐射剂量映射。使用了一个体模，该体模由一个填充有1 mM硫酸亚铁溶液和0.1 N硫酸并与7.5%（重量）明胶凝胶化的人类头骨组成。在头部体模中有一个球形靶区，通过使用内部开发的3D治疗计划系统设计了五条非共面适形射束。用6 MV直线加速器对头模进行照射，使靶区周边的总剂量达到25 Gy。在GE 1.5T磁共振成像仪中，使用六种不同的多扫描反转恢复脉冲序列同时扫描体模和一组校准瓶。通过在UNIX工作站上使用定制软件逐像素评估T1值，并使用校准数据将其转换为剂量。FeMRI测量的剂量分布与3D治疗计划计算的剂量分布之间的比较显示出良好的一致性。
