Engels Benedikt, Tournel Koen, Soete Guy, Storme Guy
Department of Radiotherapy, Oncology Centre University Hospital Brussels, Belgium.
Radiother Oncol. 2009 Mar;90(3):377-81. doi: 10.1016/j.radonc.2008.12.005. Epub 2009 Jan 13.
Assessment of rectal distention in a group of patients who are not receiving daily rectum emptying procedures during a course of prostate cancer radiotherapy to investigate which patients could benefit from daily rectum emptying.
Eighteen patients underwent daily megavoltage CT (MVCT) scanning with positioning based on bony anatomy. Emptying the rectum was only performed before planning CT and not during the actual treatment. The rectal average cross-sectional area (CSA) was determined on the MVCTs. The relative CSA (CSA(rel)) was defined as CSA on MVCT / CSA on planning CT. Additional prostate soft tissue matching was performed to verify the influence of rectal distention on prostate motion.
Two distinct subgroups could be defined a posteriori. One group had a limited and stable rectal distention with a CSA (mean+/-SD) of 6.6+/-2.1cm(2), in contrast with a second group with large and variable rectal filling with a CSA of 9.5+/-3.7cm(2) (p<0.01). Mean anterior-posterior prostate displacement was 0.4+/-2.4 mm in the stable group versus -2.4+/-6.1 mm in the unstable group (p<0.01). A mean CSA(rel) of 1.35 of the first 3 days as cut-off value allowed for a correct a priori classification of 90% and 85% of the patients from groups 1 and 2, respectively.
Based on a few measurements of the CSA by daily MVCT imaging at the first days of treatment, rectum emptying may be omitted in part of the patients.
评估一组在前列腺癌放射治疗过程中未接受每日直肠排空程序的患者的直肠扩张情况，以调查哪些患者可从每日直肠排空中获益。
18例患者接受基于骨骼解剖结构定位的每日兆伏级CT（MVCT）扫描。仅在计划CT扫描前进行直肠排空，实际治疗期间不进行。在MVCT上测定直肠平均横截面积（CSA）。相对CSA（CSA(rel)）定义为MVCT上的CSA/计划CT上的CSA。进行额外的前列腺软组织匹配以验证直肠扩张对前列腺运动的影响。
事后可定义出两个不同的亚组。一组直肠扩张有限且稳定，CSA（均值±标准差）为6.6±2.1cm²，而另一组直肠充盈量大且变化大，CSA为9.5±3.7cm²（p<0.01）。稳定组前列腺前后平均位移为0.4±2.4mm，不稳定组为-2.4±6.1mm（p<0.01）。以前3天的平均CSA(rel)为1.35作为截断值，分别对第1组和第2组中90%和85%的患者进行了正确的先验分类。
在治疗开始的几天通过每日MVCT成像对CSA进行几次测量后，部分患者可能无需进行直肠排空。
