Department of Physical Sciences, Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia.
Radiother Oncol. 2010 May;95(2):191-7. doi: 10.1016/j.radonc.2010.01.010. Epub 2010 Feb 26.
To determine intra-fraction displacement of the prostate gland from imaging pre- and post-radiotherapy delivery of prostate cancer patients with three implanted fiducial markers.
Data were collected from 184 patients who had two orthogonal X-rays pre- and post-delivery on at least 20 occasions using a Varian On Board kV Imaging system. A total of 5778 image pairs covering time intervals between 3 and 30 min between pre- and post-imaging were evaluated for intra-fraction prostate displacement.
The mean three dimensional vector shift between images was 1.7 mm ranging from 0 to 25 mm. No preferential direction of displacement was found; however, there was an increase of prostate displacement with time between images. There was a large variation in typical shifts between patients (range 1 +/- 1 to 6 +/- 2 mm) with no apparent trends throughout the treatment course. Images acquired in the first five fractions of treatment could be used to predict displacement patterns for individual patients.
Intra-fraction motion of the prostate gland appears to be a limiting factor when considering margins for radiotherapy. Given the variation between patients, a uniform set of margins for all patients may not be satisfactory when high target doses are to be delivered.
通过对接受放射治疗的前列腺癌患者的三个植入式基准标记物进行治疗前和治疗后的影像学检查，确定前列腺在治疗过程中的位置移动。
共收集了 184 名患者的数据，这些患者使用瓦里安在线千伏成像系统（Varian On Board kV Imaging system）至少在 20 次治疗前后进行了两次正交 X 光检查。共评估了 5778 对图像对，这些图像对在治疗前后的时间间隔为 3 至 30 分钟，以评估前列腺在治疗过程中的位移。
图像之间的三维向量平均移动为 1.7 毫米，范围为 0 至 25 毫米。未发现位移的优先方向，但随着图像之间的时间增加，前列腺的位移会增加。患者之间的典型移动变化很大（范围为 1 +/- 1 至 6 +/- 2 毫米），整个治疗过程中没有明显的趋势。在治疗的前五轮中获取的图像可以用于预测个别患者的位移模式。
考虑放射治疗的边界时，前列腺的内部运动似乎是一个限制因素。鉴于患者之间的差异，当需要高靶剂量时，对所有患者使用统一的一组边界可能无法令人满意。
