X-ray image calibration and its application to clinical orthopedics.
X-ray imaging is one of the most commonly used medical imaging modality. Albeit X-ray radiographs provide important clinical information for diagnosis, planning and post-operative follow-up, the challenging interpretation due to its 2D projection characteristics and the unknown magnification factor constrain the full benefit of X-ray imaging. In order to overcome these drawbacks, we proposed here an easy-to-use X-ray calibration object and developed an optimization method to robustly find correspondences between the 3D fiducials of the calibration object and their 2D projections. In this work we present all the details of this outlined concept. Moreover, we demonstrate the potential of using such a method to precisely extract information from calibrated X-ray radiographs for two different orthopedic applications: post-operative acetabular cup implant orientation measurement and 3D vertebral body displacement measurement during preoperative traction tests. In the first application, we have achieved a clinically acceptable accuracy of below 1° for both anteversion and inclination angles, where in the second application an average displacement of 8.06±3.71 mm was measured. The results of both applications indicate the importance of using X-ray calibration in the clinical routine.
Institute for Surgical Technology and Biomechanics (ISTB), University of Bern, Switzerland. Electronic address: steffen.schumann@ieee.org.
Steffen
S
Schumann
Institute for Surgical Technology and Biomechanics (ISTB), University of Bern, Switzerland.
Benedikt
B
Thelen
Institute for Surgical Technology and Biomechanics (ISTB), University of Bern, Switzerland.
Steven
S
Ballestra
Institute for Surgical Technology and Biomechanics (ISTB), University of Bern, Switzerland.
Lutz-P
LP
Nolte
Institute for Surgical Technology and Biomechanics (ISTB), University of Bern, Switzerland.
Philippe
P
Büchler
Institute for Surgical Technology and Biomechanics (ISTB), University of Bern, Switzerland. Electronic address: guoyan.zheng@ieee.org.
Guoyan
G
Zheng
D002138:Calibration / Q000592:standards; D004867:Equipment Design; D019544:Equipment Failure Analysis; D057918:Fiducial Markers / Q000592:standards*; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000295:instrumentation* / Q000592:standards*; D009985:Orthopedics / Q000592:standards*; D011856:Radiographic Image Enhancement / Q000295:instrumentation* / Q000592:standards*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013557:Switzerland
3D reconstruction; Calibration; Orthopedics; Pelvis; Spine; X-ray radiograph