Abstract
BACKGROUND: Craniofacial disfigurements impact a person’s psychosocial well-being and can bring about anxiety, severe depression and poor self-esteem. Patients seek restorative medical interventions to improve their aesthetic appearance; these interventions, in the form of custom-made implants, require high-quality, accurate computed tomography (CT) data relating to patient anatomy. However, limited information exists about suitable parameter settings for high-quality CT images for implant design. Therefore, this study suggests CT parameter settings that should be considered when imaging patients for implant manufacturing. METHODS: From a collection of 35 stereolithography (STL) files supplied by the Centre for Rapid Prototyping and Manufacturing at Central University of Technology, Free State, 11 high-image-quality STLs were identified. Because of restricted access to original DICOM files, STLs were reverse engineered from metadata by scanning a Catphan(®) 500 phantom to create representative DICOM files. Image quality values for a range of indicators (pixel size, contrast, uniformity, slice thickness and noise) of the DICOM files were calculated with the Smári program. Index A (original value index), Index B (transformed value index), Index C (ranking index), and Index D (confirmation index) were calculated using the reports of representative files. Indexes A, B and C were used to identify the five top-ranking DICOM files for Bone and BonePlus algorithms, which were then confirmed using Index D. RESULTS: Image quality indicator values were, overall, similar for the two algorithms. The pixel sizes for the two algorithms were identical. The indicator value ranges for contrast, uniformity and slice thickness were relatively similar for the two algorithms, while the range for noise for the BonePlus algorithm was wider than for the Bone algorithm. Proposed parameter settings identified for real-world testing are 120 kV, Auto mA or manual mA selection (200–490), field of view 20–26 cm and a slice thickness range of 0.625–1.25 mm. CONCLUSION: Once tested under conditions that more closely mimic a real-world clinical setting, these CT parameter settings may result in a better-fitting implant and potentially eliminate the need for repeat imaging.