Monte Carlo simulation of the dose distribution of ICRP adult reference computational phantoms for acquisitions with a 320 detector-row cone-beam CT scanner

A Monte Carlo simulation for the estimation of patient dose in rest and stress cardiac computed tomography with a 320-detector row CT scanner

“…A benchmarked Electron Gamma Shower V4 (EGS4) application [20] in combination with a Low Energy Photon Scattering Expansion [21] was used for the calculation of radiation transport. The program was developed and validated for the Aquilion ONE CT scanner in a previous study, comparing results from MC simulations with the actual measurements acquired under the same conditions in standard CT dose phantoms [7]. The measurements agreed with the MC results across all conditions with relative differences up to 6%.…”

“…This dose enhancement is related to the creation of secondary electrons due to photoelectric interactions in cortical bone or trabeculae, and the posterior energy release by the photoelectrons in the adjacent bone marrow. The relative uncertainties associated with the dose calculations in the MC simulations were in the range 4-5% [7,16].…”

“…The cardiac CT protocol included CT calcium scoring, CT coronary angiography and CT myocardial perfusion. For this task, Monte Carlo simulation software was used to calculate the dose distribution in two ICRP anthropomorphic voxel phantoms for this specific scanner and these acquisition protocols [7].…”

Axial or Helical? Considerations for wide collimation CT scanners capable of volumetric imaging in both modes

“…Nonuniformity occurs for two main reasons. First, the anode heel effect causes a variation in the number of photons produced by the x‐ray target along the z‐axis, which in turn affects dose and IQ in this direction . While this effect is negligible for narrow beam widths because only the central portion of the beam is used, it becomes important when using the full 16 cm collimation.…”

“…While this effect is negligible for narrow beam widths because only the central portion of the beam is used, it becomes important when using the full 16 cm collimation. Although a compensatory filter has been proposed, it has not been introduced clinically and as such the heel effect remains significant for both Toshiba and GE scanners . Second, an overlap region is present between axial sections when multiple sections are needed.…”