Automatic registration of the prostate for computed-tomography-guided radiotherapy
Automatic registration of the prostate for computed-tomography-guided radiotherapy
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DOI：
10.1118/1.1608497
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发表时间：
2003-10-01
期刊：
影响因子：
3.8
通讯作者：
Dong, L
中科院分区：
文献类型：
--
作者：
Court, LE;Dong, L
集成计算机断层扫描（CT）/直线加速器（LINAC）组合的最新发展，其中CT扫描仪和LINAC使用相同的患者床，以及连接到LINAC机架的千伏锥束CT系统;意味着现在可以使用合适的硬件进行前列腺的CT引导定位。然而，临床实施目前由于缺乏鲁棒且准确的软件工具来比较用于治疗计划的CT图像中的前列腺的位置与其在日常CT图像中的位置而受到阻碍。计划CT图像与日常CT图像的手动配准可能是缓慢的，并且可能引入显著的用户间变化。我们开发了一种自动配准技术，该技术不会受到前列腺形状、大小或方向、直肠气体或膀胱充盈的变化的不利影响。在配准中使用的成本函数是针对使用原始医师绘制的大体肿瘤体积轮廓从规划CT图像提取的体积的每日CT图像与规划CT图像之间的逐个体素的CT数的平均绝对差。为了增强前列腺区域中的软组织对比度并减少直肠气体钙化和骨骼对配准的影响;从计算中过滤掉具有代表气体或骨骼的CT编号的体素：自动配准的结果与7名人类观察者的平均结果一致，左/右（RL）的标准差为0.5 mm、0.5 mm和1.0 mm，前/后（AP）和上级/下级（SI）方向，对于相对容易定位的患者。难以定位的患者在RL、AP和SI方向上的一致性（一个标准差）分别为0.6 mm、1.4 mm和1.9 mm。这些结果优于手动对齐技术报告的用户间不确定性，并接近报告的用户内不确定性。结果与原始治疗计划中的轮廓形状无关，减少了观察者间差异对前列腺轮廓的影响。该算法快速可靠，使整个CT定位过程在5-9分钟内完成。在来自7名患者的120个CT图像集中，发现失败率小于1%。该算法的使用将有助于CT引导下前列腺定位的临床实施。(C)2003年美国医学物理学家协会。
The recent development of integrated computed tomography (CT)/linear accelerator (LINAC) combinations, where the CT scanner and the LINAC use the same patient couch, and of kilovoltage cone-beam CT systems attached to the LINAC gantry; means that suitable hardware is now available for CT guided localization of the prostate. Clinical implementation is, however, currently impeded by the lack of robust and accurate software tools to compare the position of the prostate in the CT images used for the treatment plan with its position in the daily CT images. Manual registration of the planning CT images with the daily CT images can be slow and can introduce significant inter-user variations. We have developed an automatic registration technique that is not adversely influenced by changes in prostate shape, size or orientation, presence of rectal gas, or bladder filling. The cost function used in the registration is the mean absolute difference in CT numbers voxel-by-voxel between the daily CT image and the planning CT image for a volume extracted from the planning CT images using the original physician-drawn gross tumor volume contours. To enhance soft tissue contrast in the prostate region and to reduce the impact of rectal gas calcifications and bone on the registration; voxels with CT numbers that represent gas or bone are filtered out from the calculation: The results of the automatic registration agreed with the mean results of seven human observers, with standard deviations of 0.5 mm, 0.5 mm, and 1.0 mm in the left/right (RL), anterior/posterior (AP), and superior/inferior (SI) directions, respectively, for a patient that was relatively easy to localize. Agreement (one standard deviation) for a patient that was difficult to localize was 0.6 mm, 1.4 mm, and 1.9 mm in the RL, AP, and SI directions, respectively. These results are better than the interuser uncertainties reported for a manual alignment technique and are close to the reported intrauser uncertainties. The results are independent of the shape of contours in the original treatment plan, reducing the impact of interobserver variations in contouring the prostate. The algorithm is fast and reliable, allowing the entire CT localization process to take place in 5-9 minutes. In 120 CT image sets from seven patients, the failure rate was found to be less than 1%. The use of this algorithm will facilitate the clinical implementation of CT guided localization of the prostate. (C) 2003 American Association of Physicists in Medicine.