Department of Radiation Oncology, Cleveland Clinic Foundation, Cleveland, Ohio 44106.
Med Phys. 2013 Nov;40(11):111720. doi: 10.1118/1.4824924.
To evaluate the feasibility of daily dose monitoring using a patient specific atlas-based autosegmentation method on diagnostic quality verification images.
Seven patients, who were treated for prostate cancer with intensity modulated radiotherapy under daily imaging guidance of a CT-on-rails system, were selected for this study. The prostate, rectum, and bladder were manually contoured on the first six and last seven sets of daily verification images. For each patient, three patient specific atlases were constructed using manual contours from planning CT alone (1-image atlas), planning CT plus first three verification CTs (4-image atlas), and planning CT plus first six verification CTs (7-image atlas). These atlases were subsequently applied to the last seven verification image sets of the same patient to generate the auto-contours. Daily dose was calculated by applying the original treatment plans to the daily beam isocenters. The autocontours and manual contours were compared geometrically using the dice similarity coefficient (DSC), and dosimetrically using the dose to 99% of the prostate CTV (D99) and the D5 of rectum and bladder.
The DSC of the autocontours obtained with the 4-image atlases were 87.0% ± 3.3%, 84.7% ± 8.6%, and 93.6% ± 4.3% for the prostate, rectum, and bladder, respectively. These indices were higher than those from the 1-image atlases (p < 0.01) and comparable to those from the 7-image atlases (p > 0.05). Daily prostate D99 of the autocontours was comparable to those of the manual contours (p = 0.55). For the bladder and rectum, the daily D5 were 95.5% ± 5.9% and 99.1% ± 2.6% of the planned D5 for the autocontours compared to 95.3% ± 6.7% (p = 0.58) and 99.8% ± 2.3% (p < 0.01) for the manual contours.
With patient specific 4-image atlases, atlas-based autosegmentation can adequately facilitate daily dose monitoring for prostate cancer.
评估使用基于患者特定图谱的自动分割方法对诊断质量验证图像进行每日剂量监测的可行性。
本研究选择了 7 名接受基于 CT 轨道系统的每日成像引导的调强放射治疗的前列腺癌患者。手动勾画前 6 次和后 7 次每日验证图像的前列腺、直肠和膀胱。对于每个患者，仅使用计划 CT（1 图像图谱）、计划 CT 加前 3 次验证 CT（4 图像图谱）和计划 CT 加前 6 次验证 CT（7 图像图谱）构建三个患者特定的图谱。然后将这些图谱应用于同一患者的最后 7 次验证图像集，以生成自动轮廓。通过将原始治疗计划应用于每日射束等中心来计算每日剂量。通过 Dice 相似系数（DSC）比较自动轮廓和手动轮廓的几何形状，通过前列腺CTV 99%剂量（D99）和直肠和膀胱 D5 比较剂量学。
使用 4 图像图谱获得的自动轮廓的 DSC 分别为前列腺、直肠和膀胱的 87.0%±3.3%、84.7%±8.6%和 93.6%±4.3%。这些指标高于 1 图像图谱（p<0.01），与 7 图像图谱相当（p>0.05）。自动轮廓的每日前列腺 D99与手动轮廓相当（p=0.55）。对于膀胱和直肠，自动轮廓的每日 D5 分别为计划 D5 的 95.5%±5.9%和 99.1%±2.6%，而手动轮廓分别为 95.3%±6.7%（p=0.58）和 99.8%±2.3%（p<0.01）。
使用患者特定的 4 图像图谱，基于图谱的自动分割可以充分辅助前列腺癌的每日剂量监测。
