AlDahlawi Ismail, Prasad Dheerendra, Podgorsak Matthew B
Department of Radiation Medicine, Roswell Park Cancer Institute, Buffalo, NY, USA.
Department of Physiology and Biophysics, State University of New York, Buffalo, NY, USA.
J Appl Clin Med Phys. 2017 May;18(3):67-72. doi: 10.1002/acm2.12073. Epub 2017 Apr 17.
The Gamma Knife Icon comes with an integrated cone-beam CT (CBCT) for image-guided stereotactic treatment deliveries. The CBCT can be used for defining the Leksell stereotactic space using imaging without the need for the traditional invasive frame system, and this allows also for frameless thermoplastic mask stereotactic treatments (single or fractionated) with the Gamma Knife unit. In this study, we used an in-house built marker tool to evaluate the stability of the CBCT-based stereotactic space and its agreement with the standard frame-based stereotactic space. We imaged the tool with a CT indicator box using our CT-simulator at the beginning, middle, and end of the study period (6 weeks) for determining the frame-based stereotactic space. The tool was also scanned with the Icon's CBCT on a daily basis throughout the study period, and the CBCT images were used for determining the CBCT-based stereotactic space. The coordinates of each marker were determined in each CT and CBCT scan using the Leksell GammaPlan treatment planning software. The magnitudes of vector difference between the means of each marker in frame-based and CBCT-based stereotactic space ranged from 0.21 to 0.33 mm, indicating good agreement of CBCT-based and frame-based stereotactic space definition. Scanning 4-month later showed good prolonged stability of the CBCT-based stereotactic space definition.
伽玛刀Icon配备了集成式锥形束CT（CBCT），用于图像引导的立体定向治疗。CBCT可用于在无需传统侵入性框架系统的情况下通过成像来定义Leksell立体定向空间，这也使得伽玛刀装置能够进行无框架热塑性面罩立体定向治疗（单次或分次）。在本研究中，我们使用自制的标记工具来评估基于CBCT的立体定向空间的稳定性及其与基于标准框架的立体定向空间的一致性。在研究期间（6周）开始、中间和结束时，我们使用CT模拟机通过CT指示盒对该工具进行成像，以确定基于框架的立体定向空间。在整个研究期间，该工具还每天使用Icon的CBCT进行扫描，并且CBCT图像用于确定基于CBCT的立体定向空间。使用Leksell GammaPlan治疗计划软件在每次CT和CBCT扫描中确定每个标记的坐标。基于框架的和基于CBCT的立体定向空间中每个标记均值之间的向量差大小在0.21至0.33毫米之间，表明基于CBCT的和基于框架的立体定向空间定义具有良好的一致性。4个月后的扫描显示基于CBCT的立体定向空间定义具有良好的长期稳定性。
