Oral Presentation at the European Congress of Radiology, Vienna, 2019

Purpose

Many dental patients have root-canal filled teeth which cause artefacts on a Cone Beam CT (CBCT) scan. We studied the effect of voxel size on image quality of CBCT scans in presence and absence of root-canal filling material.

Methods and Materials

CBCT scans of 30 patients, 15 with (group-1) and 15 without (group-2) root-canal filling,having both 90u and 180u voxel size were obtained. In group-1, patient scans had root canal filling material & no other artefact causing material in field of view. In group-2, patient scans had no artefact causing material. In all scans, CNR (contrast-to-noise ratio) was calculated by determining the mean and standard deviation of grey values on DICOM data, adjacent to root canal filling material(group-1)/central region of scan volume (group-2) and also determing the grey values at edge of the scan volume (both groups). CNRs of the scans were analysed by Student t-test.

Result

Significant difference (paired t-test, p=0.018) was seen in CNR between the 90u and 180u scans of the same patient in group-1. Significant difference (p=0.135) was not seen in CNR between the 90 and 180u scans of the same patient in group-2.

Conclusion

In presence of root-canal filling material, the image quality of 90 microns scan is significantly better than that of 180 microns scan. However, in absence of artefact causing material, the image quality is not affected significantly by voxel size, even though it is better in 90 microns scan.