UCSF

Cone beam computed tomography (CBCT) usage has increased dramatically over the last couple of decades. The extent to which this tool can be accurately utilized, however, remains to be seen. The purpose of this investigation is to produce a systematic, reproducible calibration of structure and mineral density, from micro X-ray computed tomography (Micro XCT) to CBCT. Three scanners were calibrated to known mineral density phantoms. Calibration curves for each scanner were built from these phantoms and hydroxyapatite specimens, which were then applied to determine the mineral density of human jaws and teeth. Systematic calibration accounting for size of the phantom (ratio of surface area to volume), and mineral density (the amount of mineral in “mg” per cubic centimeter volume “cc”) revealed that each scanner has a size and density dependence and thereby threshold – detectable size and mineral density of a specimen. Inferior resolution, enhanced bleeding, large field of view, lower mineral density, and small size of specimens all contributed to reduced accuracy and consistency of CBCT images. Based on the current calibration and quality of CBCT systems, this research has shown the accuracy of these scanners needs improvement and that screening for prevention of disease is likely beyond the current scope of its intended use. It is likely that a lesion or pathology can only be diagnosed reliably when it is of a large enough density and size to actually utilize or if it imaged under a smaller field of view with enhanced resolution. Research is warranted to reliably use CBCT imaging as an effective screening tool to improve patient care.