Absorbed dose and noise in intensity-modulated dental computed tomography

For a dental cone-beam computed tomography (CBCT) with a reduced patient dose, we have considered the tube-current modulation, and tube-current and voltage, or beam intensity, modulation techniques. For various modulation scenarios to the dental CBCT with various fields of view (FOVs), we assessed the absorbed dose using the Monte Carlo method. We also applied the scenarios to a laboratory bench-top CBCT system and evaluated the voxel noise. While the modulation techniques reduced the effective dose, more effectively as increasing FOV, they increased the voxel noise. The gain from their combinations was therefore none or slightly less, compared to the CBCT with the conventional uniform power scanning. We used the filtered-backprojection and the simultaneous algebraic reconstruction technique for image reconstructions, and we ignored the correction for data truncation in smaller FOVs. Therefore, there is enough room for the enhancement of image quality performance using advanced reconstruction methods. In addition, the modulation scenarios considered only the field around the cervical spine. Nevertheless we have found meaningful dose reductions in dental CBCTs in corporation with the modulation techniques.