The effect of calibration and detector temperature on the reconstructed cone beam computed tomography image quality: a study for the workflow of the iCAT Classic equipment.

OBJECTIVE: The image quality of the reconstructed dental cone beam computed tomography (CBCT) acquisition is strongly dependent on the characteristics of the applied detector. Some flat panel detector (FPD) types require a warming-up period (WUP) to achieve a steady-state temperature; and some of them, those that have a cesium iodide detector, may require a calibration process (CP) after each WUP. STUDY DESIGN: Quality-assurance phantom was used for the evaluation of image quality, including spatial accuracy and density response with and without WUP and CP using iCAT Classic equipment. RESULTS: The correlation between the measured gray values and the multidetector computed tomography (MDCT) values deviated slightly from linearity (defined by the 45-degree line). There was no detectable difference in the spatial accuracy of the four different scanning modes. CONCLUSIONS: Although the WUP is important to reach the required steady-state temperature, the CP has a greater effect on the image quality.

High-quality image acquisition by double exposure overlap in dental cone beam computed tomography.

OBJECTIVE: With a double exposure overlapping cone beam computed tomography (CBCT) scan technique, using CBCT acquisition radiation dose, the objective was to obtain apparent density similar to that of multidetector computed tomography (MDCT). STUDY DESIGN: Factory quality-assurance phantom and water phantom were used for the evaluation of apparent density fidelity of iCAT scans in different modes. Each scan's apparent density was analyzed for identical regions using ImageJ, version 1.42q. RESULTS: The iCAT Classic extended height acquisition with 4-cm central overlap and reconstruction of 2 groups of 300 projections per rotation for the water and quality-assurance CBCT phantoms resulted in improved apparent density fidelity. This apparent density accuracy was superior to that of iCAT scan at high resolution (600 projections during 1 rotation). CONCLUSIONS: Using double exposure overlapping CBCT scans allows the analysis quality to be comparable with that of MDCT.

Intraosseous territory of the facial artery in the maxilla and anterior mandible: implications for allotransplantation.

AIM: The aim of this anatomical study was to define the intraosseous vascular territory of the facial artery. The clinical issue is whether ipsilateral facial artery anastomosis will guarantee blood supply to the ipsi- and contralateral mandibular symphyses and maxillae in allotransplantation. MATERIAL AND METHODS: Of 10 human cadaveric heads, the left facial artery was injected with a positive contrast agent. The maxillae and mandibular symphyses were investigated with cone-beam computed tomography (CBCT). RESULTS: Each ipsilateral maxilla and mandibular bone segment showed contrast medium in the intraosseous vessels. In 50% of cases, this was also the case on the contralateral side of the maxilla and anterior mandible. CONCLUSIONS: The maxillae and the mandibular symphyses receive ipsilateral blood supply from the facial artery and, in 50% of cases, also from the contralateral facial artery. Internal maxillary artery anastomosis is not required for a vascularized maxillary bone flap. Additionally, involvement of the submental artery is not needed for a mandibular symphyseal bone flap.