Influence of scan mode (partial/full rotations) and FOV size in the formation of artefacts in cone beam CT

Abstract

To evaluate the influence of rotation degree and field of view (FOV) size on the amount of artefacts produced in cone beam CT (CBCT) images. methods: A cylindrical wax utility phantom, with a metallic sample in its interior, was scanned with two FOV sizes (100 x 100 and 40 x 40 mm) and in full (360°) and partial (~180°) rotations. After the acquisitions, images were objectively assessed in the ImageJ software, obtaining the standard deviation in areas around the metal sample. The influence of artefacts produced by the several FOVs and rotation degrees was compared by two-way analysis of variance (α = 0.05). results The images obtained with a large FOV presented a higher amount of noise compared to a restricted FOV, both for partial (p = 0.0037) and full (p = 0.0023) rotation degrees. For images obtained with a restricted FOV, full rotation resulted in images with less noise (p = 0.0259). For images obtained with large FOV, there was no statistically significant difference (p = 0.1494) in noise for both rotation protocols. Conclusions As there were no significant differences in the amount of artefacts in rotation protocols for large FOVs, the partial rotation can be indicated due to its lower exposure to radiation. For acquiring images with restricted FOVs, the full rotation is recommended.

Accuracy of Cone-Beam Computed Tomography in Measuring the Thickness of Radicular Dentin

“…Second by the inaccuracy of the examiner using the computer mouse; which has been previously demonstrated that the average precision error between the on-screen cursor and the mouse displacement was 0.018 mm² (16)(17)(18). This measurement error may not be suitable for precise control applications, however, this may be precise enough for a successful CBCT linear measurements, as representing less than a voxel size currently used (13,(16)(17)(18). Further studies are needed to clarify the clinical relevance of these narrow ranges, using another CBCT scanner with a smaller voxel size may allow a more accurate measurement (18).…”

“…Currently, some studies have introduced CBCT imaging to evaluate dentin thickness before and after fractured instrument removal (7,13), or before and after root canal preparation (20,21). However, no comparisons with a reference standard were reported, which prevents accuracy from being determined.…”

“…However, it may be recommended for selected cases where CR provides misleading or inadequate information for planning treatment (10,12). As a result, some recent studies have introduced the CBCT imaging to evaluate dentin thickness before or after the removal of a fractured instrument (7,13). However, an assessment…”

The Impact of Cone-Beam Computed Tomography Exposure Parameters on Peri-Implant Artifacts: A Literature Review

“…Increasing the FOV exposes more tissues to x-rays, increases scattered radiation to the surrounding tissues, decreases contrast, and increases noise and radiation dose [ 14 , 20 , 21 ]. Scatter might be reduced by reducing FOV as well as the use of an anti-scatter grid and algorithms to correct the x-ray scatter [ 22 ].…”

“…CBCT scanning with 360-degree rotation compared to the standard 180-degree scan enhances the image quality by creating more basis images. Enhancement of rotation range increases the CNR, but despite the larger amount of data, changing the device rotation range does not affect the number of artifacts (e.g., beam hardening, scatter, and ring artifacts) that occur both in 180- and 360-degree scans [ 7 , 21 , 26 ].…”