Wolf Orthopaedic Biomechanics Lab, Fowler Kennedy Sport Medicine Clinic, The University of Western Ontario, London, Ontario, Canada.
J Biomech. 2011 Nov 10;44(16):2847-50. doi: 10.1016/j.jbiomech.2011.08.009. Epub 2011 Sep 29.
Standard, beaded radiostereometric analysis (RSA) and markerless RSA often use computed tomography (CT) scans to create three-dimensional (3D) bone models. However, ethical concerns exist due to risks associated with CT radiation exposure. Therefore, the aim of this study was to investigate the effect of decreasing CT dosage on RSA accuracy. Four cadaveric shoulder specimens were scanned using a normal-dose CT protocol and two low-dose protocols, where the dosage was decreased by 89% and 98%. 3D computer models of the humerus and scapula were created using each CT protocol. Bi-planar fluoroscopy was used to image five different static glenohumeral positions and two dynamic glenohumeral movements, of which a total of five static and four dynamic poses were selected for analysis. For standard RSA, negligible differences were found in bead (0.21±0.31mm) and bony landmark (2.31±1.90mm) locations when the CT dosage was decreased by 98% (p-values>0.167). For markerless RSA kinematic results, excellent agreement was found between the normal-dose and lowest-dose protocol, with all Spearman rank correlation coefficients greater than 0.95. Average root mean squared errors of 1.04±0.68mm and 2.42±0.81° were also found at this reduced dosage for static positions. In summary, CT dosage can be markedly reduced when performing shoulder RSA to minimize the risks of radiation exposure. Standard RSA accuracy was negligibly affected by the 98% CT dose reduction and for markerless RSA, the benefits of decreasing CT dosage to the subject outweigh the introduced errors.
标准的、珠状的放射立体定位分析（RSA）和无标记 RSA 通常使用计算机断层扫描（CT）扫描来创建三维（3D）骨骼模型。然而，由于与 CT 辐射暴露相关的风险，存在伦理问题。因此，本研究旨在探讨降低 RSA 准确性的 CT 剂量。使用正常剂量 CT 方案和两种低剂量方案对四个尸体肩部标本进行扫描，剂量分别降低 89%和 98%。使用每个 CT 方案创建肱骨和肩胛骨的 3D 计算机模型。使用双平面荧光透视术对五个不同的静态盂肱关节位置和两个动态盂肱关节运动进行成像，其中总共选择了五个静态和四个动态姿势进行分析。对于标准 RSA，当 CT 剂量降低 98%时，珠（0.21±0.31mm）和骨性标志（2.31±1.90mm）位置的差异可以忽略不计（p 值>0.167）。对于无标记 RSA 运动学结果，在正常剂量和最低剂量方案之间发现了极好的一致性，所有 Spearman 等级相关系数均大于 0.95。在这种降低的剂量下，对于静态位置，还发现平均均方根误差为 1.04±0.68mm 和 2.42±0.81°。总之，当进行肩部 RSA 时，可以显著降低 CT 剂量，以最大程度地降低辐射暴露的风险。标准 RSA 的准确性几乎不受 98%CT 剂量减少的影响，对于无标记 RSA，降低 CT 剂量对受试者的好处超过了引入的误差。
