基于美国放射学会标准的MRI放射治疗模拟定位系统长期稳定性检测

Detection on the long term stability of simulation positioning system of MRI radiotherapy based on ACR standard

目的:基于美国放射学会(ACR)模体检测MRI定位系统的稳定性和图像质量,并将该方法纳入质量控制流程,以保证临床扫描数据的可靠性。方法:收集2019-2020年(每月1次,共12次)内在德国西门子3.0T Skyra大孔径MRI定位机上的T_(1)、T_(2)序列扫描ACR Large Phantom模体图像数据。根据ACR模体指南,分析比较ACR Large Phantom模体图像数据与MRI定位系统扫描图像的几何精度(误差±2 mm)、高对比度空间分辨率(≥1 mm)、图像均匀性(≥82%)、信号伪影率(≤0.025)和低对比度分辨率[可观测总轮辐数T_(1)加权成像(T_(1)WI)≥35,T_(2)WI≥31]。结果:矢状位、T_(1)WI和T_(2)WI图像的几何精度差异均<±1.5 mm;T_(1)WI和T_(2)WI图像的高对比度空间分辨率为1.0 mm,图像均匀度百分比(PIU)平均值分别为88.86%和85.00%,平均信号伪影分别为0.0014和0.0035,测量低对比度分辨率的可观测总轮辐数均值分别为39和37。各评价指标均满足临床图像质量需求和ACR模体指南处置限值。结论:基于ACR模体掌握MRI图像质量检测方法,并定期进行图像质量检测,是保证MRI系统稳定和图像质量的重要质量控制手段,可用于长期检测MRI系统和成像质量,不断提高临床诊疗水平。

Objective:To detect the stability and image quality of magnetic resonance imaging(MRI)positioning system based on the phantom of American College of Radiology(ACR),and bring this method into the process of quality control so as to ensure the reliability of clinical scanning data.Methods:The image data of ACR Large Phantom with T_(1) and T_(2) sequence scan on Siemens 3.0T Skyra large aperture MRI positioning machine were collected during 2019 and 2020(once a month,total of 12 times).According to the guideline of ACR phantom to analyze and compare the geometric accuracy(error±2 mm),high-contrast spatial resolution(≥1 mm),image homogeneity(≥82%),percent-signal ghosting(≤0.025)and low-contrast resolution(the number of observable total spokes T_(1)WI≥35,T_(2)WI≥31).Results:The differences of geometric accuracies among sagittal view and the images of T_(1)WI and T_(2)WI were less than±1.5 mm.The high-contrast spatial resolutions of T_(1)WI and T_(2)WI images were 1.0 mm respectively,and the means of the percentage of image uniformity(PIU)of them were 88.86% and 85.00% respectively,and the average presents-signal ghosting of them were 0.0014 and 0.0035 respectively.The average number of observable total spokes were 39 and 37 respectively in detecting low-contrast resolution.The results indicated that each evaluation indicator could meet the requirement of clinical image quality and the limiting value of ACR phantom guideline.Conclusion:The grasped detection method of MRI image quality on the basis of ACR phantom and the regular detection of image quality are an important measure of quality control in ensuring the stability of MRI system and image quality,which can be used in long term detection of MRI system and imaging quality so as to improve continually the clinical level of diagnosis and treatment.