[Evaluation of gantry tilt correction in multi detector-row CT: effect on multi-planar reconstruction images]

In multi-slice CT, the scanning center of each line multiple-row detector array is shifted in the Y-axis direction by the tilting of the gantry. Correction of this effect is necessary when CT images are reconstructed. Correction of table feed is necessary as well. These corrections are possible with the Somatom Plus4 Volume Zoom. The use of multi-planar reconstruction (MPR) images has been increasing rapidly in the area of clinical diagnosis. Therefore, we examined the influence of MPR images according to gantry tilt. For each gantry tilt, the spatial resolution of MPR images was almost the same even though scanning pitch was changed. When the gantry was tilted, the full width at half maximum (FWHM) of the section sensitivity profile (SSP) was about 10% to 20% wider than that when the gantry was not tilted. The spatial resolution of MPR images is more affected by whether or not the gantry is tilted than by the angle of tilt. Gantry tilt correction is useful to obtain images without artifact for metal and artificial teeth; however, deterioration in spiral resolution cannot be avoided.