Metal artifacts correction in cone-beam CT bone imaging

Cone-beam CT (CBCT) technique is needed by orthopaedists in their new studies([1,2]) to monitor bone volume growth and blood vessel growth of structural bone grafts used in reconstruction surgery. However, titanium plate and screws, which are commonly used to connect bone grafts to host bones, can cause severe streaking artifacts and shading artifact in the reconstructed images due to their high attenuation of x-rays. These metal artifacts will distort the information of the bone and cause difficulties when measuring bone volume growth and the inside; blood vessel growth. To solve this problem and help orthopaedists quantitatively record the growth of bone grafts we present a three-dimensional metal artifact correction technique to correct the streaking artifacts generated by titanium implants. In this project not only the artifacts need to be corrected but also the correct information of the bone is required in the image for the quantitative measurements. Both phantom studies and animal studies were conducted to test this correction method. Images without metal correction and images with metal correction were compared together, as well as the reference bone images acquired without metal. It's shown the streaking and shading artifacts were greatly reduced after metal correction. The accuracy of bone volume measurements was also greatly increased by 79% for phantom studies and 53% for animal studies.