Choi D R, Ahn Y C, Kim D Y, Huh S J, Lee J I
Department of Radiation Oncology, Samsung Medical Center, Kangnam-Ku, Seoul, Korea.
Med Dosim. 1997 Spring;22(1):53-8. doi: 10.1016/s0958-3947(96)00151-3.
The accuracy in target localization of CT, MRI, and digital angiography and the isocentric deviation of linear accelerator were investigated for stereotactic radiosurgery. Twenty-five slice images using CT and MRI were obtained out of geometrical phantom which was designed to produce exact 3-dimensional coordinates of several points within a 0.1 mm error range. These diagnostic images were transferred to a 3-D treatment planning system through ethernet. Measured 3-D coordinates of these images from the planning system were compared to known values by geometrical phantom. Anterior-posterior and lateral films were taken by digital angiography for measurement of spatial accuracy. The accuracy of gantry isocenter aligned by laser localizer was also measured. Lead ball was located at the isocenter of linear accelerator and x-ray films were taken by 4-MV photon beam with gantry angles of 0, 90, 180 and 270 degrees, Overall procedure from CT scanning to treatment was carried out using the geometrical phantom. The target accuracy was verified by high energy x-ray portal film. The accuracy of diagnostic machines were within 2.1 mm except MR-axial images. In case of linear accelerator, the deviation of isocenter was within 0.7 mm. Finally, the total isocentric deviation of overall procedure was 1.3 +/- 0.5 mm (using CT localization).
针对立体定向放射外科手术，研究了CT、MRI和数字血管造影在靶点定位方面的准确性以及直线加速器的等中心偏差。从几何模型中获取了25张使用CT和MRI的切片图像，该模型设计用于生成误差范围在0.1毫米内的几个点的精确三维坐标。这些诊断图像通过以太网传输到三维治疗计划系统。将从计划系统测量的这些图像的三维坐标与几何模型的已知值进行比较。通过数字血管造影拍摄前后位和侧位片以测量空间准确性。还测量了由激光定位器对准的机架等中心的准确性。将铅球置于直线加速器的等中心处，使用4兆伏光子束在机架角度为0、90、180和270度时拍摄X线片。从CT扫描到治疗的整个过程均使用几何模型进行。通过高能X线射野片验证靶点准确性。除MR轴位图像外，诊断机器的准确性在2.1毫米以内。对于直线加速器，等中心偏差在0.7毫米以内。最后，整个过程的总等中心偏差为1.3±0.5毫米（使用CT定位）。
