Fig 1.
Framework for calculating Ai values.
After selecting the CT image as in (a), we calculated the Ai value by two methods (b) Central-beam approximation and (c) actual beam shape approximation.
Fig 2.
(a) OBI CBCT and (b) XVI CBCT system. The default detector position shifted 14.8 cm using the OBI and 11.5 cm for the XVI in medium-FOV mode.
Fig 3.
The Elekta XVI-CBCT system and CIRS ATOM phantom.
Fig 4.
TCM dose per angle for simulation study.
The red line shows a conventional CBCT scan, the green-line represents a TCM scan from a center-beam approximation, and the blue-line indicates a TCM scan of an actual beam shape approximation.
Fig 5.
Reconstructed images of the XCAT phantom for central and off-center slices from conventional CBCT and TCM methods.
Table 1.
NRMSE and SSIM values are calculated for center and off-center slices.
ROIs are defined in Fig 5.
Fig 6.
Imaging dose to abdominal and pelvic organs from conventional CBCT and TCM scans using a XCAT phantom.
Fig 7.
TCM dose per angle is calculated for the abdominal and pelvic regions of the ATOM phantom.
The red line shows the results of a conventional CBCT scan; the green line represents the TCM scan of the pelvic region; and the blue line signifies the TCM scan of the abdominal region.
Fig 8.
Reconstructed images of the ATOM’s abdominal region using conventional CBCT and TCM methods.
XVI images are obtained via central and off-center slices.
Fig 9.
Line profiles from Fig 8.
A conventional CBCT image is plotted as a solid black line; the TCM images are plotted as dash-dot red lines.
Fig 10.
Reconstructed images of ATOM’s pelvic region from conventional CBCT and TCM methods.
XVI images are from the central, upper, and lower off-center regions.
Table 2.
NRMSE and SSIM are calculated for center and off-center slices.
ROIs are defined in Fig 8.
Table 3.
NRMSE and SSIM calculated for central and off-center slices.
ROIs are defined in Fig 10.