Radiation dose reduction using a CdZnTe-based computed tomography system: Comparison to flat-panel detectors
Schematic of the CZT CT setup.
Schematic of the 2.5 cm cylindrical PMMA phantom. Embedded in the center are different concentrations of iodine and calcium.
Tube output measurements and the corresponding spectral model (a). The total aluminum filtrations were 2.6 and 2.7 mm for the tube and the model, respectively. The 80 kV spectrum with divisions of energy bin is also shown (b).
The linear attenuation coefficient of iodine, hydroxyapatite, PMMA, and 50/50 breast tissue. Also shown are the five energy bins used for CZT imaging.
Weight factors for the five energy bins are shown for HA (a) and Iodine (b). Projection-based and image-based values indicate their similarity in trend.
The reconstructed slice for the simulation experiments of the 10 cm breast (a) and the 2 cm PMMA cylinder (b). Iodine and HA contrast elements are visible. , .
Reconstructed slice of the phantom for bin 1 (a), bin 2 (b), bin 3 (c), bin 4 (d), and bin 5 (e). , .
Reconstructed slice of the phantom for different detector types: Photon counting (a), projection-based weighting HA (b), image-based weighting HA (c), and charge integrating (d). , .
Contrast-to-noise ratio vs energy bin for HA (300 mg/ml) and iodine (8 mg/ml).
CNR as a function of air kerma of the experimental 2.5 cm PMMA cylinder for 300 mg/ml HA (a) and 8 mg/ml iodine (b).
CNR improvement as a function of the energy weighting methods for HA (a) and Iodine (b). Values from both simulations and experiments are shown. integrating, counting, -based weighting, -based weighting.
Exposure reduction, compared to CNR value of the charge integrating/flat-panel detector at 2.18 mGy, as a function of the energy weighting methods for HA (a) and iodine (b). Values from both simulations and experiments are shown. integrating, counting, -based weighting, -based weighting.
Beam hardening quantification shows amount of change in for simulations (a) and measurements (b).
Energy range for bins 1–5.
Contrast-to-noise improvements for images acquired at 2.18 mGy.
Exposure reductions (in percentage) when setting the CNR of the flat-panel image acquired at 2.18 mGy as the reference.
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