Sanfridsson J, Svahn G, Jonsson K, Ryd L
Department of Diagnostic Radiology, University Hospital, Lund, Sweden.
Acta Radiol. 1997 Jul;38(4 Pt 1):514-9. doi: 10.1080/02841859709174378.
A new method for examining and measuring the weight-bearing knee in computed radiography (CR) and picture archiving and communication systems (PACS) has recently been developed on examination equipment used in QUESTOR Precision Radiography (QPR). QPR is a method for the standardised examination of the knee, and generates 9 angles (e.g. hip-knee-ankle (HKA) angle) and 10 distances, corrected for parallax and magnification. The aim of this present study was to evaluate the reproducibility of this newly developed method and to determine intra- and interobserver variation in its measurements.
The images were generated on a CR system, archived, and transferred to a multimodality work-station that had a monitor with a resolution of 1280x1024 (1kx1k). Photostimulable phosphor plates were used to generate images with a matrix of 1760x2140 pixels (pixel size 0.2 mm, corresponding resolution 2.5 1p/mm). Ten volunteers without knee problems were examined twice, bilaterally, by 2 different radiology technologists.
The total reproducibility of the method was good, offering an HKA reproducibility of +/-2.64 degrees in slight flexion and +/-1.62 degrees in extension, at 95% confidence. The intra- and inter-observer variations were low with a reduction of the intra-observer variations in all measurements (except one) by a factor of 2.8 on average compared with the original QPR method for conventional film-screen radiography.
When QPR is modified for CR, it fulfils the requirement of reproducibility in measurements of the weight-bearing knee.
最近在QUESTOR精密放射成像（QPR）所用的检查设备上开发了一种在计算机X线摄影（CR）和图像存档与通信系统（PACS）中检查和测量负重膝关节的新方法。QPR是一种用于膝关节标准化检查的方法，可生成9个角度（如髋-膝-踝（HKA）角）和10个距离，并针对视差和放大率进行了校正。本研究的目的是评估这种新开发方法的可重复性，并确定其测量中的观察者内和观察者间差异。
图像在CR系统上生成、存档，然后传输到一个多模态工作站，该工作站有一台分辨率为1280x1024（1kx1k）的显示器。使用光激励荧光板生成矩阵为1760x2140像素（像素尺寸0.2mm，对应分辨率2.5lp/mm）的图像。10名无膝关节问题的志愿者由2名不同的放射技师进行双侧两次检查。
该方法的总体可重复性良好，在95%置信度下，轻微屈曲时HKA的可重复性为±2.64度，伸展时为±1.62度。观察者内和观察者间差异较低，与传统屏-片摄影的原始QPR方法相比，所有测量（除一项外）的观察者内差异平均降低了2.8倍。
当QPR针对CR进行改进时，它满足了负重膝关节测量中可重复性的要求。
