Development of a total hip replacement phantom for the assessment of CT-image quality.

Background: The quality of computed tomography (CT) imaging is important when used to judge the success of joint replacement surgery. Metal artefacts are a known source of error, typically compensated by noise reduction software.

Purpose: To develop a transportable and stable system for the assessment of image quality of bone lesions around orthopedic implants.

Material And Methods: The design and manufacture of a bone-implant-phantom is described, which is based on a calf acetabulum with surrounding pelvic bone structures. Bone lesions of several sizes were created in the acetabulum before implanting the cup of an uncemented hip prosthesis, which was fixed with a stainless-steel bone screw. Plastic strips were placed on a cobalt-chromium stemmed femoral component, simulating typical bone lesions around loosening or infected prostheses, before embedding the stem in material similar to bone and shaped like a femur. The head of the femoral component was then placed in the acetabular cup and CT scans were produced.

Results: It was possible to construct a durable CT hip phantom for quality assurance work. The usability of different materials and the choices made for the phantom are discussed.

Conclusion: It is possible to construct a durable joint implant phantom for quality assurance and scanner hardware and software assessment with limited resources. The phantom was successfully used in the assessment of the hardware and software performance of different CT scanners.