A schematic overview of the subsequent steps involved in simulation of a 2D projection image at a specific camera angle from a 3D source distribution with UMCS. E and μ represent E central and μ eff, respectively.
Profiles through the measured and simulated projection images of a line source centered in 40 × 40 × 2 cm3 scatter material (a) and in 40 × 40 × 20 cm3 scatter material (b). Measured, MCNPX-simulated and UMCS-simulated LSFs in (a) and (b) were normalized to the maximum intensity of the respective LSF in (a). MCNPX-simulated photopeak gamma (PP), high energy gamma (HE) and bremsstrahlung photon (BS) contributions were shown in addition to the total MCNPX-simulated LSF.
Image contrast (QH) and the residual count error in the lung insert (ΔC lung) plotted as a function of image noise (CV) for SPECT-DSW (a), SPECT-ppMC+DSW (b), and SPECT-fMC (c) with varying numbers of iterations. The number of iterations chosen as “optimal” for activity quantification is illustrated by the vertical dashed line.
The left column shows the center slices through the SPECT-DSW (top), SPECT-ppMC+DSW (middle), and SPECT-fMC (bottom) reconstructed images, overlaid with the boundaries of the hot sphere, lung insert, and background ROIs (a). All images are linearly window-leveled from zero to six times the mean background intensity. The hot sphere contrast (QH) is plotted as a function of sphere diameter (b). The residual count error in the lung insert (ΔC lung) and image noise (CV) are plotted in (c). Images were reconstructed with the optimal reconstruction settings.
ARCs as a function of sphere volume. The error bars indicate the estimated uncertainties (standard deviations) of the ARCs.
The activity recovered in the whole-body ROIs (Aest) on the SPECT-DSW (a), SPECT-ppMC+DSW (b), and SPECT-fMC images (c), plotted as a function of the administered activity at time of scanning (A). The scout dose data points are depicted by circles and the treatment data points by squares. The solid lines represent the best linear fit (Aest = a × A + b) through the data points and the dashed lines represent the 95% confidence intervals (C.I.).
Bar plots of the SPECT-DSW, SPECT-ppMC+DSW, and SPECT-fMC estimated mean absorbed doses in the nontumor and tumor ROIs of each patient. The standard deviations of the means are depicted by the error bars. Data points represent the peak absorbed doses in the tumor ROIs in accordance with PERCIST criteria.
Transversal slices through the SPECT-DSW (top), SPECT-ppMC+DSW (middle), and SPECT-fMC (bottom) dose images of patient 5, fused with CT and overlaid with the tumor ROI boundaries (a). Cumulative dose-volume-histograms of the nontumor and tumor ROIs are shown in panel (b) to illustrate the dose distributions.
Energies and intensities of the betas (ß) and gamma photons (γ) of 166Ho decay. Data were obtained from the website of the National Nuclear Data Center (NNDC, Brookhaven National Laboratory, NY, http://www.nndc.bnl.gov).
Characteristics of the reconstruction algorithms.
Patient and treatment characteristics.
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