Department of Internal Medicine III, Friedrich-Schiller-University Jena, Erlanger Allee 101, 07747, Jena, Germany.
Rheumatol Int. 2011 Oct;31(10):1349-54. doi: 10.1007/s00296-010-1468-4. Epub 2010 Apr 17.
The purpose of this study is to evaluate technical feasibility based on image capturing conditions (film-focus distance (FFD), film sensitivity, film brand, exposure level and tube voltage) that potentially alter radiographs and consequently may influence the semi-automated measurement of joint space distance (JSD) by computer-aided joint space analysis (CAJSA) in rheumatoid arthritis and osteoarthritis. The radiographs of a left hand (deceased man) were acquired under systematically changing image capturing conditions (exposure level: 4-8 mAs; FFD: 90-130 cm; film sensitivity: 200/400 and tube voltage: 40-52 kV with different image modalities: conventional radiographs, original digital radiographs, digital print-outs). All JSD-measurements were performed with the CAJSA-technology (Radiogrammetry Kit, Version 1.3.6; Sectra; Sweden) at the metacarpal-phalangeal articulation. JSD-analysis was not influenced by changes of FFD, exposure level, film sensitivity or film brand. JSD showed significant variation caused by tube voltage (conventional: CV = 1.913% for Agfa and CV = 2.448% for Kodak; digital: CV = 0.741% for Philips print-outs and CV = 0.620% with original digital images versus CV = 2.185% for Siemens print-outs and 0.951% with original digital images). Computer-aided joint space analysis for JSD-measurements is unaffected by the following image capturing parameters: film-focus distance, film sensitivity, film brand and exposure level. An influence of tube voltage was detected in a lesser extent for original digital images compared to the printed digital as well as conventional versions. Consequently, a standardized tube voltage is essential for accurate reproductions of CAJSA-measurements in rheumatoid arthritis and osteoarthritis.
本研究旨在评估可能改变射线照片并因此可能影响计算机辅助关节间隙分析（CAJSA）对半自动关节间隙距离（JSD）测量的图像采集条件（胶片焦点距离（FFD）、胶片感光度、胶片品牌、曝光水平和管电压）的技术可行性。在系统改变图像采集条件下（曝光水平：4-8 mAs；FFD：90-130 cm；胶片感光度：200/400 和管电压：40-52 kV，不同的图像模式：常规射线照片、原始数字射线照片、数字打印输出），获取左手（已故男子）的射线照片。使用 CAJSA 技术（Radiogrammetry Kit，版本 1.3.6；Sectra；瑞典）在掌指关节处进行所有 JSD 测量。FFD、曝光水平、胶片感光度或胶片品牌的变化不会影响 JSD 分析。JSD 显示出管电压引起的显著变化（常规：Agfa 的 CV=1.913%，Kodak 的 CV=2.448%；数字：Philips 打印输出的 CV=0.741%，原始数字图像的 CV=0.620%，而 Siemens 打印输出的 CV=2.185%，原始数字图像的 CV=0.951%）。JSD 测量的计算机辅助关节间隙分析不受以下图像采集参数的影响：胶片焦点距离、胶片感光度、胶片品牌和曝光水平。与打印数字和常规版本相比，原始数字图像中检测到管电压的影响较小。因此，对于类风湿关节炎和骨关节炎中 CAJSA 测量的准确再现，标准化管电压至关重要。
