Abstract
Introduction:
Conventional radiographic images are the gold standard method for postoperative evaluation of uncemented cups in patients with total hip arthroplasty. A conventional radiographic image of the pelvis gives a radiation dose of 0.7 mSv. Normally two images are needed. At present, dual energy CT is becoming more accessible in clinical practice and could allow lower radiation dose.
Aim:
We wanted to assess what radiation dose was possible without sacrificing image resolution.
Materials and methods:
We used a pig cadaver to assess a wide variety of radiation doses. A 13 mm “osteolysis” was drilled into the acetabulum dorsally-apically of the cup. A two mm wear was made on the apical part of the liner. There were bilateral uncemented hip replacements inserted into the pelvis to imitate a case with metal artefacts.
Radiation doses for human adults were estimated from scans of Kyoto Kagaku PBU-60 with extra attenuation (prosthesis) with parameters from the cadaver.
We used dual energy CT with 50% reduction of radiation dose. The images were enhanced using a software package called SAFIRE (Siemens). Similar softwares are available on all CT machines.
Results:
The image quality was surprisingly good. Both wear and osteolysis were easy to detect without much disturbing metal artefact.
Conclusion:
Dual energy computed tomography can produce high resulotion images with a radiation dose equivalent to two conventional radiographs of the pelvis.
