基于传输图像统计模型的前列腺放射治疗的 2D-3D 配准。

2D-3D registration for prostate radiation therapy based on a statistical model of transmission images.

机构信息

Department of Radiology, Weill Medical College of Cornell University, New York, New York 10021, USA.

出版信息

Med Phys. 2009 Oct;36(10):4555-68. doi: 10.1118/1.3213531.

DOI:10.1118/1.3213531

PMID:19928087

Abstract

PURPOSE

In external beam radiation therapy of pelvic sites, patient setup errors can be quantified by registering 2D projection radiographs acquired during treatment to a 3D planning computed tomograph (CT). We present a 2D-3D registration framework based on a statistical model of the intensity values in the two imaging modalities.

METHODS

The model assumes that intensity values in projection radiographs are independently but not identically distributed due to the nonstationary nature of photon counting noise. Two probability distributions are considered for the intensity values: Poisson and Gaussian. Using maximum likelihood estimation, two similarity measures, maximum likelihood with a Poisson (MLP) and maximum likelihood with Gaussian (MLG), distribution are derived. Further, we investigate the merit of the model-based registration approach for data obtained with current imaging equipment and doses by comparing the performance of the similarity measures derived to that of the Pearson correlation coefficient (ICC) on accurately collected data of an anthropomorphic phantom of the pelvis and on patient data.

RESULTS

Registration accuracy was similar for all three similarity measures and surpassed current clinical requirements of 3 mm for pelvic sites. For pose determination experiments with a kilovoltage (kV) cone-beam CT (CBCT) and kV projection radiographs of the phantom in the anterior-posterior (AP) view, registration accuracies were 0.42 mm (MLP), 0.29 mm (MLG), and 0.29 mm (ICC). For kV CBCT and megavoltage (MV) AP portal images of the same phantom, registration accuracies were 1.15 mm (MLP), 0.90 mm (MLG), and 0.69 mm (ICC). Registration of a kV CT and MV AP portal images of a patient was successful in all instances.

CONCLUSIONS

The results indicate that high registration accuracy is achievable with multiple methods including methods that are based on a statistical model of a 3D CT and 2D projection images.

摘要

目的

在盆腔部位的外部射束放射治疗中，可以通过将治疗期间获取的二维投影射线照相术与三维计划计算机断层扫描（CT）进行配准来量化患者设置错误。我们提出了一种基于两种成像方式的强度值统计模型的 2D-3D 配准框架。

方法

该模型假设由于光子计数噪声的非平稳性质，投影射线照相术中的强度值是独立的，但不是同分布的。对于强度值，考虑了两种概率分布：泊松分布和高斯分布。使用最大似然估计，得出了两种相似性度量，即泊松最大似然（MLP）和高斯最大似然（MLG）分布。此外，我们通过比较从准确采集的骨盆人体模型的精确数据以及患者数据中得出的相似性度量与皮尔逊相关系数（ICC）的性能，研究了该基于模型的配准方法对于当前成像设备和剂量获得的数据的优点。

结果

所有三种相似性度量的配准精度均相似，超过了盆腔部位当前临床要求的 3 毫米。对于在前后（AP）视图中使用千伏（kV）锥形束 CT（CBCT）和 kV 投影射线照相术对人体模型进行的姿势确定实验，配准精度分别为 0.42 毫米（MLP）、0.29 毫米（MLG）和 0.29 毫米（ICC）。对于相同的人体模型的千伏 CBCT 和兆伏（MV）AP 端口图像，配准精度分别为 1.15 毫米（MLP）、0.90 毫米（MLG）和 0.69 毫米（ICC）。在所有情况下，均成功地对人体模型的千伏 CT 和 MV AP 端口图像进行了配准。