一种商用骨科金属伪影减少工具在头颈癌患者放射治疗中的评估。
Evaluation of a commercial orthopaedic metal artefact reduction tool in radiation therapy of patients with head and neck cancer.
作者信息
Kwon H, Kim K S, Chun Y M, Wu H-G, Carlson J N K, Park J M, Kim J-I
机构信息
1 Interdisciplinary Program in Radiation Applied Life Science, Seoul National University College of Medicine, Seoul, Republic of Korea.
2 Biomedical Research Institute, Seoul National University Hospital, Seoul, Republic of Korea.
出版信息
Br J Radiol. 2015 Aug;88(1052):20140536. doi: 10.1259/bjr.20140536. Epub 2015 May 20.
OBJECTIVE
To assess the image quality and dosimetric effects of the Philips orthopaedic metal artefact reduction (OMAR) (Philips Healthcare System, Cleveland, OH) function for reducing metal artefacts on CT images of head and neck (H&N) patients.
METHODS
11 patients and a custom-built phantom with metal bead inserts (alumina, titanium, zirconia and chrome) were scanned. The image was reconstructed in two ways: with and without OMAR (OMAR and non-OMAR image). The mean and standard deviation values of CT Hounsfield unit (HU) for selected regions of interest of each case were investigated for both images. Volumetric modulated arc therapy plans were generated for all cases. Gamma analysis of each dose distribution pair in the patient (1%/1 mm criteria) and phantom (2%/2 mm and 3%/3 mm criteria) images was performed. The film measurements in phantom for two metal beads were conducted for evaluating the calculated dose on both OMAR and non-OMAR images.
RESULTS
In the OMAR images, noise values were generally reduced, and the mean HU became closer to the reference value (measured from patients without metal implants) in both patient and phantom cases. Although dosimetric difference was insignificant for the eight closed-mouth patients (γ = 99.4 ± 0.5%), there was a large discrepancy in dosimetric calculation between OMAR and non-OMAR images for the three opened-mouth patients (γ = 91.1%, 94.8% and 96.6%). Moreover, the calculated dose on the OMAR image is closer to the real delivered dose on a radiochromic film than was the dose from the non-OMAR image.
CONCLUSION
The OMAR algorithm increases the accuracy of CT HU and reduces the noise such that the entire radiation treatment planning process can be improved, especially for contouring and segmentation.
ADVANCES IN KNOWLEDGE
OMAR reconstruction is appropriate for the radiotherapy planning process of H&N patients, particularly of patients who use a bite block.
目的
评估飞利浦骨科金属伪影减少（OMAR）（飞利浦医疗系统，俄亥俄州克利夫兰）功能对减少头颈部（H&N）患者CT图像上金属伪影的图像质量和剂量学影响。
方法
对11名患者和一个带有金属珠插入物（氧化铝、钛、氧化锆和铬）的定制体模进行扫描。图像以两种方式重建：使用OMAR和不使用OMAR（OMAR图像和非OMAR图像）。对每种情况下选定感兴趣区域的CT亨氏单位（HU）的平均值和标准差进行了研究。为所有病例生成容积调强弧形治疗计划。对患者（1%/1毫米标准）和体模（分别为2%/2毫米和3%/3毫米标准）图像中的每对剂量分布进行伽马分析。对体模中的两个金属珠进行胶片测量，以评估OMAR图像和非OMAR图像上的计算剂量。
结果
在OMAR图像中，噪声值普遍降低，在患者和体模病例中，平均HU都更接近参考值（从未植入金属的患者测量）。虽然对于8名闭口患者剂量学差异不显著（γ = 99.4 ± 0.5%），但对于3名开口患者，OMAR图像和非OMAR图像之间的剂量学计算存在较大差异（γ分别为91.1%、94.8%和96.6%）。此外，与非OMAR图像的剂量相比，OMAR图像上的计算剂量更接近放射变色胶片上的实际传递剂量。
结论
OMAR算法提高了CT HU的准确性并降低了噪声，从而可以改进整个放射治疗计划过程，特别是在轮廓勾画和分割方面。
知识进展
OMAR重建适用于H&N患者的放射治疗计划过程，特别是使用咬块的患者。
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