Introduction: Quality control is important because it contributes to gather a sufficient amount of diagnostic information, with the lowest exposure of the patient. The European Commission has recommended six parameters that should be included in the quality control program for CBCT images: display of low-contrast elements, homogeneity and the presence of artefacts, noise, spatial resolution, geometric resolution and grayscale. Purpose: The purpose is to assess the acceptability of the PRO-DENT CT mk II phantom for quality control of images of CBCT machine. Methods: We assessed the quality of the images on the Vatech, Sirona and Instrumentarium apparatus with the Pro-Dent CT mk II phantom, which consists of PMMA 1.19 g/cm3 and has inserted objects of different specifications. After the quality control measurements were performed, we analysed the homogeneity and noise, artefacts, geometric distortion, contrast and spatial resolution. We analysed the images with the ImageJ program. Results and discussion: In our homogeneity research, we discovered that CBCT images are highly non-homogeneous. The peripheral values vary greatly from the values in the centre. Due to the presence of metals, artefacts are more visible under higher exposition conditions. That is why some manufacturers use filters to reduce this effect. We did not detect any issues in determining geometric distortion. For contrast resolution, we found that the smallest implants visible were of 1 or 2 mm. The appliances were not calibrated on the Hounsfield scale. The CNR ratio was low for most materials. Spatial resolution was between 1 and 1,7 lp/mm, or in Endo program 2,5 lp/mm. Conclusion: Based on all the findings we can conclude that the phantom and tests would be aplicable for annual QC tests, because we could use the PRO-DENT CT mk II phantom on all three different apparatus, and it allowed us to carry out all the recommended image quality control tests.
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