title: THR Simulator--the software for generating radiographs of THR prosthesis.
abstract: BACKGROUND
  Measuring the orientation of acetabular cup after total hip arthroplasty is important for prognosis. The verification of these measurement methods will be easier and more feasible if we can synthesize prosthesis radiographs in each simulated condition. One reported method used an expensive mechanical device with an indeterminable precision. We thus develop a program, THR Simulator, to directly synthesize digital radiographs of prostheses for further analysis.Under Windows platform and using Borland C++ Builder programming tool, we developed the THR Simulator. We first built a mathematical model of acetabulum and femoral head. The data of the real dimension of prosthesis was adopted to generate the radiograph of hip prosthesis. Then with the ray tracing algorithm, we calculated the thickness each X-ray beam passed, and then transformed to grey scale by mapping function which was derived by fitting the exponential function from the phantom image. Finally we could generate a simulated radiograph for further analysis.
  
  
  RESULTS
  Using THR Simulator, the users can incorporate many parameters together for radiograph synthesis. These parameters include thickness, film size, tube distance, film distance, anteversion, abduction, upper wear, medial wear, and posterior wear. These parameters are adequate for any radiographic measurement research. This THR Simulator has been used in two studies, and the errors are within 2 degrees for anteversion and 0.2 mm for wearing measurement.
  
  
  CONCLUSIONS
  We design a program, THR Simulator that can synthesize prosthesis radiographs. Such a program can be applied in future studies for further analysis and validation of measurement of various parameters of pelvis after total hip arthroplasty.
authors.affiliation: Taipei City Hospital, Renai Branch, Tapei City, Taiwan. dienewu@yahoo.com.tw
authors.forename: Tai-Yin
authors.initials: TY
authors.lastname: Wu
authors.forename: Rong-Sen
authors.initials: RS
authors.lastname: Yang
authors.forename: Chiou-Shann
authors.initials: CS
authors.lastname: Fuh
authors.forename: Sheng-Mou
authors.initials: SM
authors.lastname: Hou
authors.forename: Chen-Kun
authors.initials: CK
authors.lastname: Liaw
mesh_terms: D000077:Acetabulum / Q000033:anatomy & histology / Q000000981:diagnostic imaging / Q000601:surgery; D000465:Algorithms; D019644:Arthroplasty, Replacement, Hip / Q000592:standards*; D003198:Computer Simulation; D005270:Femur Head / Q000033:anatomy & histology / Q000000981:diagnostic imaging / Q000502:physiology; D005583:Fourier Analysis; D006621:Hip Joint / Q000033:anatomy & histology / Q000000981:diagnostic imaging / Q000502:physiology; D006622:Hip Prosthesis / Q000592:standards*; D006801:Humans; D008962:Models, Theoretical; D017063:Outcome Assessment, Health Care / Q000379:methods*; D011182:Postoperative Care / Q000379:methods; D011183:Postoperative Complications / Q000517:prevention & control; D011381:Programming Languages; D011859:Radiography / Q000379:methods*; D016059:Range of Motion, Articular / Q000502:physiology; D012984:Software; D012986:Software Validation; D014025:Titanium / Q000627:therapeutic use
chemical_list: D014025:Titanium