Lisa McDaid, Abigael Clough, Rebecca K Benson, Claire Nelder, John McMahon, Steven Jackson, Marianne Aznar, Ananya C Choudhury, Marcel van Herk, Cynthia L Eccles
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引用次数: 0
摘要
目的:金属植入物会导致磁共振成像出现伪影和失真。为确保在磁共振成像仪上进行准确的剂量投放和计划调整,有必要对造成的失真进行评估:参试者在磁共振成像仪(Elekta Unity™)上进行成像。对三个序列进行了评估。两个供应商提供的序列(T2W TSE 3D 序列)和一个为减少金属伪影失真而优化的 T2W TSE 3D 序列。图像由一名观察者利用骨骼解剖学原理与 CT 图像进行严格配准。选取三张冠状和三张轴向图像,在每张切片上确定六个成对、相邻的骨性地标。包括与治疗等中心一分为二的图像。测量结果:结果:共有五名观察者参与。共确定了 36 对骨性地标。地标位置差异的中位数为≤3毫米(范围为0.3-4.4毫米)。观察者平均值之间的单因子方差分析显示,序列或患者之间无明显差异(平面内 p = 1.26,穿过平面 p = 0.11)。观察者间平面内 ICC 为 0.70,平面外 ICC 为 0.78。三位观察者的观察者内ICC分别为0.76、0.81和0.83,在这一小型群体中显示出中等至良好的可靠性:这项体内可行性研究表明,金属髋关节假体的变形并不妨碍在磁共振Linac上进行盆腔放疗。对计划质量影响的研究是有必要的:这项研究支持在磁共振Linac上治疗金属髋关节假体患者的可行性。
Geometric distortion caused by metallic femoral head prosthesis in prostate cancer imaging on an MR Linac: in-vivo measurements of spatial deformation.
Objectives: Metallic implants cause artefacts and distortion on MRI. To ensure accurate dose delivery and plan adaptation on an MR Linac, there is a need to evaluate distortion caused.
Methods: Participants were imaged on an MR Linac (Elekta Unity, Elekta AB Stockholm). Three sequences were evaluated. Two vendor supplied (T2W TSE 3D), and one T2W TSE 3D optimized to reduce metal artefact distortions. Images were rigidly registered to CT images by a single observer, using bony anatomy. Three coronal and three axial images were selected, and six paired, adjacent, bony landmarks were identified on each slice. Images bisecting treatment isocentre were included. Difference between landmark coordinates was taken to be measure of distortion.
Results: Five observers participated. Thirty six pairs of bony landmarks were identified. Median difference in position of landmarks was ≤3 mm (range 0.3-4.4 mm). One-way analysis of variance (ANOVA) between observer means showed no significant variation between sequences or patients (P = 1.26 in plane, P = 0.11 through plane). Interobserver intra class correlation (ICC) was 0.70 in-plane and 0.78 through-plane. Intra-observer ICC for three observers was 0.76, 0.81, 0.83, showing moderate to good reliability on this small cohort.
Conclusions: This in-vivo feasibility study suggests distortion due to metallic hip prosthesis is not an obstacle for pelvic radiotherapy on an MR Linac. Research on the impact on plan quality is warranted.
Advances in knowledge: This work supports feasibility of treating patients with metallic hip prosthesis on an MR Linac.
期刊介绍:
BJR is the international research journal of the British Institute of Radiology and is the oldest scientific journal in the field of radiology and related sciences.
Dating back to 1896, BJR’s history is radiology’s history, and the journal has featured some landmark papers such as the first description of Computed Tomography "Computerized transverse axial tomography" by Godfrey Hounsfield in 1973. A valuable historical resource, the complete BJR archive has been digitized from 1896.
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- ISSN: 0007-1285
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