Greer P B, Mortensen T M
Oncology Department, Auckland Hospital, New Zealand.
Med Dosim. 1997 Spring;22(1):43-6. doi: 10.1016/s0958-3947(96)00156-2.
The methods of determining the anterior-posterior isocentre location in pelvic radiotherapy are either by aligning lateral localization lasers to tattoo marks on skin, or by setting a constant daily couch-to-isocentre distance. While using the former method the day-to-day vertical couch movement was recorded and combined with measurements of day-to-day anterior-posterior patient movement made with an electronic portal imaging device to determine whether couch vertical movement contributes to anterior-posterior setup variation. Seven unimmobilized patients were studied, four supine prostate and three prone rectum patients. The two motions were found to be highly correlated (correlation coefficient = 0.82) which supports the constant couch-to-isocentre distance approach. When the day-to-day couch vertical movement was subtracted from the anterior-posterior movement results the setup variation was reduced in six of the seven patients.
在盆腔放射治疗中确定前后等中心位置的方法，要么是将侧向定位激光对准皮肤上的纹身标记，要么是设置每日固定不变的治疗床到等中心的距离。在使用前一种方法时，记录了每日治疗床的垂直移动情况，并将其与使用电子射野影像装置测量的患者每日前后移动情况相结合，以确定治疗床垂直移动是否会导致前后摆位变化。研究了7名未固定体位的患者，其中4名仰卧位前列腺癌患者和3名俯卧位直肠癌患者。发现这两种运动高度相关（相关系数 = 0.82），这支持了固定治疗床到等中心距离的方法。当从前后移动结果中减去每日治疗床垂直移动时，7名患者中有6名的摆位变化减小。
