Figure 16.

Use of residual volume measurements to assess the CT radiation dose reduction process for 3D printing of bone. A, The residual volume is used to compare the effect of reducing the CT radiation dose with iterative reconstruction (IR) versus filtered back-projection (FBP) reconstruction for 3D printing of the maxillofacial bone. Top: The residual volume is the red shell around the bone on the reference-standard model derived from 155-mAs IR images (left), and on each test STL model derived from images acquired with a reduced radiation dose (middle and right). Bottom: A small portion of the mandible is shown in pink to aid in visualizing the residual volume. S.D. = standard deviation. B, C, Despite the higher signal-to-noise ratio of the IR images, B, calculated from the mean and standard deviation of the muscle attenuation (in Hounsfield units), the IR and FBP reconstruction performed quite similarly in terms of residual volume at all given reduced doses, C. D, The average thickness of the residual volume was calculated to quantify the average difference in the dimensions of the bone derived from each image dataset.