Department of Radiation Oncology, Mayo Clinic, Rochester, MN 55905, USA.
Int J Radiat Oncol Biol Phys. 2011 May 1;80(1):301-5. doi: 10.1016/j.ijrobp.2010.06.007. Epub 2010 Sep 23.
To present our single-institution experience with image-guided radiotherapy comparing fiducial markers and cone-beam computed tomography (CBCT) for daily localization of prostate cancer.
From April 2007 to October 2008, 36 patients with prostate cancer received intensity-modulated radiotherapy with daily localization by use of implanted fiducials. Orthogonal kilovoltage (kV) portal imaging preceded all 1244 treatments. Cone-beam computed tomography images were also obtained before 286 treatments (23%). Shifts in the anterior-posterior (AP), superior-inferior (SI), and left-right (LR) dimensions were made from kV fiducial imaging. Cone-beam computed tomography shifts based on soft tissues were recorded. Shifts were compared by use of Bland-Altman limits of agreement. Mean and standard deviation of absolute differences were also compared. A difference of 5 mm or less was acceptable. Subsets including start date, body mass index, and prostate size were analyzed.
Of 286 treatments, 81 (28%) resulted in a greater than 5.0-mm difference in one or more dimensions. Mean differences in the AP, SI, and LR dimensions were 3.4 ± 2.6 mm, 3.1 ± 2.7 mm, and 1.3 ± 1.6 mm, respectively. Most deviations occurred in the posterior (fiducials, 78%; CBCT, 59%), superior (79%, 61%), and left (57%, 63%) directions. Bland-Altman 95% confidence intervals were -4.0 to 9.3 mm for AP, -9.0 to 5.3 mm for SI, and -4.1 to 3.9 mm for LR. The percentages of shift agreements within ±5 mm were 72.4% for AP, 72.7% for SI, and 97.2% for LR. Correlation between imaging techniques was not altered by time, body mass index, or prostate size.
Cone-beam computed tomography and kV fiducial imaging are similar; however, more than one-fourth of CBCT and kV shifts differed enough to affect target coverage. This was even more pronounced with smaller margins (3 mm). Fiducial imaging requires less daily physician input, is less time-consuming, and is our preferred method for prostate image-guided radiotherapy.
介绍我们在单机构中应用影像引导放射治疗的经验，比较前列腺癌患者使用植入性金标和锥形束 CT（CBCT）进行日常定位的效果。
从 2007 年 4 月至 2008 年 10 月，36 例前列腺癌患者接受了调强放疗，每天使用植入的金标进行定位。在 1244 次治疗中，所有治疗前均进行了正交千伏（kV）门控成像。286 次治疗（23%）前还获得了 CBCT 图像。从 kV 金标图像中测量前后（AP）、上下（SI）和左右（LR）方向的移位。记录基于软组织的 CBCT 移位。使用 Bland-Altman 协议限差比较移位。还比较了平均和标准差的绝对差值。分析了开始日期、体重指数和前列腺大小等亚组。
在 286 次治疗中，81 次（28%）在一个或多个维度上的差异大于 5.0mm。AP、SI 和 LR 方向的平均差异分别为 3.4±2.6mm、3.1±2.7mm 和 1.3±1.6mm。大多数偏差发生在后部（金标 78%，CBCT 59%）、上部（79%，61%）和左侧（57%，63%）。AP 的 Bland-Altman 95%置信区间为-4.0 至 9.3mm，SI 为-9.0 至 5.3mm，LR 为-4.1 至 3.9mm。AP、SI 和 LR 的移位在±5mm 内的百分比分别为 72.4%、72.7%和 97.2%。成像技术之间的相关性不受时间、体重指数或前列腺大小的影响。
CBCT 和 kV 金标成像相似；然而，超过四分之一的 CBCT 和 kV 移位足以影响靶区覆盖。在使用更小的边缘（3mm）时，这种情况更为明显。金标成像需要更少的日常医生投入，耗时更少，是我们前列腺图像引导放疗的首选方法。
