Haworth A, Paneghel A, Bressel M, Herschtal A, Pham D, Tai K H, Oates R, Gawthrop J, Cray A, Foroudi F
The Peter MacCallum Cancer Centre, Melbourne, VIC, Australia; Sir Peter MacCallum Department of Oncology, University of Melbourne, Melbourne, VIC, Australia.
The Peter MacCallum Cancer Centre, Melbourne, VIC, Australia.
Clin Oncol (R Coll Radiol). 2014 Dec;26(12):789-96. doi: 10.1016/j.clon.2014.08.010. Epub 2014 Sep 18.
To evaluate the effect of incorporating daily ultrasound scanning to reduce variation in bladder filling before prostate bed radiotherapy. The primary aim was to confirm that coverage of the planning target volume (PTV) with the 95% isodose was within tolerance when the ultrasound-determined bladder volume was within individualised patient limits.
Cone beam computed tomography (CBCT) images were acquired on 10 occasions during the course of treatment to assess systematic changes in rectal or bladder volume as part of a standard offline image-guided radiotherapy (IGRT) protocol. In addition, through a two-part study an ultrasound scan of the bladder was added to the IGRT protocol. In the Part 1 study, the ultrasound-determined bladder volume at the time of treatment simulation in 26 patients was compared with the simulation computed tomography cranio-caudal bladder length. The relationship between the two was used to establish bladder volume tolerance limits for the interventional component of the Part 2 study. In the Part 2 study, 24 patients underwent ultrasound scanning before treatment. When bladder volumes were outside the specified limits, they were asked to drink more water or void as appropriate until the volume was within tolerance.
Based on the results of the Part 1 study, a 100 ml tolerance was applied in the Part 2 study. Seventy-six per cent of patients found to have bladder volumes outside tolerance were able to satisfactorily adjust their bladder volumes on demand. Comparing the bladder volumes with the CBCT data revealed that the bladder scanner correctly predicted that the target volume would be accurately targeted (using surrogate end points) in 83% of treatment fractions.
A simple hand-held ultrasound bladder scanner provides a practical, inexpensive, online solution to confirming that the bladder volume is within acceptable, patient-specific limits before treatment delivery, with the potential to improve overall treatment accuracy.
评估在前列腺床放疗前加入每日超声扫描以减少膀胱充盈差异的效果。主要目的是确认当超声测定的膀胱体积在个体化患者限度内时，计划靶区（PTV）的95%等剂量线覆盖范围在耐受范围内。
在治疗过程中进行了10次锥形束计算机断层扫描（CBCT）成像，以评估直肠或膀胱体积的系统变化，作为标准离线图像引导放疗（IGRT）方案的一部分。此外，通过一项分为两部分的研究，将膀胱超声扫描添加到IGRT方案中。在第1部分研究中，比较了26例患者在治疗模拟时超声测定的膀胱体积与模拟计算机断层扫描的膀胱头脚长度。利用两者之间的关系为第2部分研究的干预部分确定膀胱体积耐受限度。在第2部分研究中，24例患者在治疗前接受了超声扫描。当膀胱体积超出指定限度时，要求他们根据情况多喝水或排尿，直到体积在耐受范围内。
基于第1部分研究的结果，在第2部分研究中应用了100 ml的耐受限度。发现膀胱体积超出耐受范围的患者中有76%能够根据需要令人满意地调整膀胱体积。将膀胱体积与CBCT数据进行比较发现，膀胱扫描仪在83%的治疗分次中正确预测了靶区将被准确靶向（使用替代终点）。
一种简单的手持式超声膀胱扫描仪提供了一种实用、廉价的在线解决方案，用于在治疗前确认膀胱体积在可接受的、针对患者的限度内，有可能提高总体治疗准确性。
