Sun Jidi, Dowling Jason A, Pichler Peter, Parker Joel, Martin Jarad, Stanwell Peter, Arm Jameen, Menk Fred, Greer Peter B
University of Newcastle, Newcastle, New South Wales, Australia.
J Appl Clin Med Phys. 2015 Mar 8;16(2):4848. doi: 10.1120/jacmp.v16i2.4848.
The purpose of this study was to investigate performance of the couch and coil mounts designed for MR-simulation prostate scanning using data from ten volunteers. Volunteers were scanned using the standard MR scanning protocol with the MR coil directly strapped on the external body and the volunteer lying on the original scanner table. They also were scanned using a MR-simulation table top and pelvic coil mounts. MR images from both setups were compared in terms of body contour variation and image quality effects within particular organs of interest. Six-field conformal plans were generated on the two images with assigned bulk density for dose calculation. With the MR-simulation devices, the anterior skin deformation was reduced by up to 1.7 cm. The hard tabletop minimizes the posterior body deformation which can be up to 2.3 cm on the standard table, depending on the weight of volunteer. The image signal-to-noise ratio reduced by 14% and 25% on large field of view (FOV) and small FOV images, respectively, after using the coil mount; the prostate volume contoured on two images showed difference of 1.05 ± 0.66 cm3. The external body deformation caused a mean dose reduction of 0.6 ± 0.3 Gy, while the coverage reduced by 22% ± 13% and 27% ± 6% in V98 and V100, respectively. A dedicated MR simulation setup for prostate radiotherapy is essential to ensure the agreement between planning anatomy and treatment anatomy. The image signal was reduced after applying the coil mount, but no significant effect was found on prostate contouring.
本研究的目的是利用来自10名志愿者的数据，调查为磁共振模拟前列腺扫描设计的治疗床和线圈支架的性能。志愿者使用标准磁共振扫描协议进行扫描，磁共振线圈直接绑在身体外部，志愿者躺在原始扫描台上。他们还使用磁共振模拟桌面和盆腔线圈支架进行扫描。比较了两种设置下的磁共振图像在身体轮廓变化和特定感兴趣器官内的图像质量影响方面的情况。在这两幅图像上生成了六野适形计划，并指定了体密度用于剂量计算。使用磁共振模拟设备后，前皮肤变形减少了1.7厘米。硬桌面可将后身体变形最小化，在标准桌面上，后身体变形可达2.3厘米，具体取决于志愿者的体重。使用线圈支架后，大视野（FOV）和小视野图像的图像信噪比分别降低了14%和25%；在两幅图像上勾勒出的前列腺体积相差1.05±0.66立方厘米。身体外部变形导致平均剂量降低0.6±0.3戈瑞，而V98和V100中的覆盖率分别降低了22%±13%和27%±6%。用于前列腺放疗的专用磁共振模拟设置对于确保计划解剖结构和治疗解剖结构之间的一致性至关重要。应用线圈支架后图像信号降低，但对前列腺轮廓勾画未发现显著影响。
