title: CT metal artifact reduction method correcting for beam hardening and missing projections.
abstract: We present and validate a computed tomography (CT) metal artifact reduction method that is effective for a wide spectrum of clinical implant materials. Projections through low-Z implants such as titanium were corrected using a novel physics correction algorithm that reduces beam hardening errors. In the case of high-Z implants (dental fillings, gold, platinum), projections through the implant were considered missing and regularized iterative reconstruction was performed. Both algorithms were combined if multiple implant materials were present. For comparison, a conventional projection interpolation method was implemented. In a blinded and randomized evaluation, ten radiation oncologists ranked the quality of patient scans on which the different methods were applied. For scans that included low-Z implants, the proposed method was ranked as the best method in 90% of the reviews. It was ranked superior to the original reconstruction (p = 0.0008), conventional projection interpolation (p < 0.0001) and regularized limited data reconstruction (p = 0.0002). All reviewers ranked the method first for scans with high-Z implants, and better as compared to the original reconstruction (p < 0.0001) and projection interpolation (p = 0.004). We conclude that effective reduction of CT metal artifacts can be achieved by combining algorithms tailored to specific types of implant materials.
authors.affiliation: Harvard Medical School and Massachusetts General Hospital, Department of Radiation Oncology, Boston, MA 02114, USA. jverburg@fas.harvard.edu
authors.forename: Joost M
authors.initials: JM
authors.lastname: Verburg
authors.forename: Joao
authors.initials: J
authors.lastname: Seco
mesh_terms: D016477:Artifacts; D003793:Dental Restoration, Permanent; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008670:Metals; D009983:Orthopedic Equipment; D019047:Phantoms, Imaging; D019736:Prostheses and Implants; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D008670:Metals