Dawson L A, Litzenberg D W, Brock K K, Sanda M, Sullivan M, Sandler H M, Balter J M
Department of Radiation Oncology University of Michigan, Ann Arbor, MI 48109-0010, USA.
Int J Radiat Oncol Biol Phys. 2000 Sep 1;48(2):319-23. doi: 10.1016/s0360-3016(00)00751-3.
To ensure target coverage during radiotherapy, all sources of geometric uncertainty in target position must be considered. Movement of the prostate due to breathing has not traditionally been considered in prostate radiotherapy. The purpose of this study is to report the influence of patient orientation and immobilization on prostate movement due to breathing.
Four patients had radiopaque markers implanted in the prostate. Fluoroscopy was performed in four different positions: prone in alpha cradle, prone with an aquaplast mold, supine on a flat table, and supine with a false table under the buttocks. Fluoroscopic movies were videotaped and digitized. Frames were analyzed using 2D-alignment software to determine the extent of movement of the prostate markers and the skeleton for each position during normal and deep breathing.
During normal breathing, maximal movement of the prostate markers was seen in the prone position (cranial-caudal [CC] range: 0.9-5.1 mm; anterior-posterior [AP] range: up to 3.5 mm). In the supine position, prostate movement during normal breathing was less than 1 mm in all directions. Deep breathing resulted in CC movements of 3.8-10.5 mm in the prone position (with and without an aquaplast mold). This range was reduced to 2.0-7.3 mm in the supine position and 0.5-2.1 mm with the use of the false table top. Deep breathing resulted in AP skeletal movements of 2.7-13.1 mm in the prone position, whereas AP skeletal movements in the supine position were negligible.
Ventilatory movement of the prostate is substantial in the prone position and is reduced in the supine position. The potential for breathing to influence prostate movement, and thus the dose delivered to the prostate and normal tissues, should be considered when positioning and planning patients for conformal irradiation.
为确保放射治疗期间的靶区覆盖，必须考虑靶区位置几何不确定性的所有来源。传统上，前列腺放疗未考虑因呼吸导致的前列腺运动。本研究的目的是报告患者体位和固定方式对因呼吸导致的前列腺运动的影响。
对4例患者在前列腺内植入不透射线标志物。在四个不同体位进行荧光透视检查：俯卧于α型托架、俯卧于水凝胶模具、仰卧于平板、仰卧于臀部下方有假台面。对荧光透视影像进行录像和数字化处理。使用二维对准软件分析图像帧，以确定每个体位在正常呼吸和深呼吸时前列腺标志物及骨骼的运动范围。
正常呼吸时，俯卧位可见前列腺标志物最大运动（头脚[CC]范围：0.9 - 5.1 mm；前后[AP]范围：达3.5 mm）。仰卧位时，正常呼吸期间前列腺在各方向的运动均小于1 mm。深呼吸导致俯卧位（有和没有水凝胶模具）CC方向运动为3.8 - 10.5 mm。仰卧位时该范围降至2.0 - 7.3 mm，使用假台面时为0.5 - 2.1 mm。深呼吸导致俯卧位AP方向骨骼运动为2.7 - 13.1 mm，而仰卧位AP方向骨骼运动可忽略不计。
前列腺的通气运动在俯卧位时较大，在仰卧位时减小。在为适形放疗的患者进行定位和计划时，应考虑呼吸影响前列腺运动从而影响前列腺和正常组织所接受剂量的可能性。
