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Monte Carlo performance on the x-ray converter thickness in digital mammography using software breast models
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10.1118/1.4757919
/content/aapm/journal/medphys/39/11/10.1118/1.4757919
http://aip.metastore.ingenta.com/content/aapm/journal/medphys/39/11/10.1118/1.4757919

Figures

Image of FIG. 1.
FIG. 1.

The main components and processes of the present study. Radiation is produced from an x-ray source (e.g., anode/filter combination), transmitted through the simulated breast model and thereafter is detected by an x-ray converter.

Image of FIG. 2.
FIG. 2.

Breast models and simulated mammography images. (a) illustrates 3D fatty breast model used in the study. (b) and (c) correspond to simulated projections of uncompressed and compressed phantom configuration, respectively.

Image of FIG. 3.
FIG. 3.

Geometry of the simulated x-ray converter models: (a) the granular gadolinium oxysulphide: Gd2O2S:Tb, (b) the columnar structured cesium iodide: CsI:Tl, and (c) the amorphous selenium: a-Se.

Image of FIG. 4.
FIG. 4.

Energy and angular distributions of x-rays incident on the x-ray converters after the irradiation of dense and fatty breast models: (a) Energy distributions before and after the irradiation of both phantoms (dense and fatty) with (Mo/Mo) x-ray spectrum, (b) energy distributions before and after the irradiation of both phantoms (dense and fatty) with (W/Rh) x-ray spectrum, (c) angle distributions after the irradiation of both phantoms (dense and fatty) with (Mo/Mo) x-ray spectrum, and (d) angle distributions after the irradiation of both phantoms (dense and fatty) with (W/Rh) x-ray spectrum.

Image of FIG. 5.
FIG. 5.

The variation of the statistical factor I x as a function of x-ray energy. Data are provided for: a 140 mg/cm2 Gd2O2S:Tb x-ray layer [line corresponds to values taken from Chan and Doi (Ref. 38)], a 100 mg/cm2 CsI:Tl x-ray layer (line corresponds to values taken from Chan and Doi (Ref. 38), a 43 mg/cm2 a-Se x-ray layer [line corresponds to values taken from Blevis et al. (Ref. 49)]. Dots correspond to Monte Carlo values obtained from the present model.

Image of FIG. 6.
FIG. 6.

The variation of sensitivity (a) and (b) and zero-frequency DQE (c) and (d) as a function of material thickness (50–150 mg/cm2). Data are provided for Gd2O2S:Tb, CsI:Tl, and a-Se x-ray converters for two different x-ray spectra (Mo/Mo, W/Rh) after the irradiation of dense (a) and (c) and fatty (b) and (d) breast phantoms.

Image of FIG. 7.
FIG. 7.

The variation of zero-frequency DQE as a function of x-ray energy (20–30 keV). Data are provided for a 150 μm converter layer. Dots correspond to Monte Carlo values obtained from the present model. Monte Carlo data were compared with other published data taken from Zhao et al. (Ref. 40) for the CsI converter and Fang et al. (Ref. 51) for the a-Se converter.

Image of FIG. 8.
FIG. 8.

The variation of CTH (%) as a function of material thickness (50–150 mg/cm2). Data are provided for Gd2O2S:Tb, CsI:Tl, and a-Se x-ray converters for different x-ray spectra (Mo/Mo, W/Rh) after the irradiation of dense (a) and (c) and fatty breast phantoms (b) and (d).

Image of FIG. 9.
FIG. 9.

The variation of CTH (%) as a function of material thickness (50–150 mg/cm2). Data are provided for the a-Se x-ray converter and two different x-ray spectra (Mo/Mo, W/Rh) after the irradiation of dense (a) and fatty (b) breast phantoms. CTH values are provided for different incident ESAK values on the breast phantoms (3 mGy, 5 mGy, and 7 mGy).

Image of FIG. 10.
FIG. 10.

The variation of CTH improvement as a function of material thickness (50–150 mg/cm2). Data are provided for Gd2O2S:Tb, CsI:Tl, and a-Se x-ray converters for different x-ray spectra (Mo/Mo, W/Rh) after the irradiation of dense (a) and (b) and fatty breast phantoms (c) and (d).

Tables

Generic image for table
TABLE I.

ESAK values (mean values with relative standard deviation less than 1%) at converter. Table considers incident ESAK values 3 mGy, 5 mGy, and 7 mGy on breast models: (i) Dense and (ii) fatty, using two different x-ray spectra: (a) 28 kV Mo, 0.030 mm Mo and (b) 32 kV W, 0.050 mm Rh.

Generic image for table
TABLE II.

The variation of A Q (mean values with relative standard deviation less than 1%) as a function of thickness (50–150 mg/cm2). Data are provided for: (i) two breast models, dense and fatty, (ii) two different x-ray spectra: (a) 28 kV Mo, 0.030 mm Mo and (b) 32 kV W, 0.050 mm Rh, incident on the simulated phantom, and (iii) three x-ray converter materials: Gd2O2S:Tb, CsI:Tl, and a-Se.

Generic image for table
TABLE III.

The variation of the statistical factor of the signal (light) distribution I s (mean values with relative standard deviation less than 1%) as a function of phosphor thickness for Gd2O2S:Tb phosphor material. Data are provided for two different x-ray spectra 28 kV Mo, 0.030 mm Mo and 32 kV W, 0.050 mm Rh used with the dense breast model.

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/content/aapm/journal/medphys/39/11/10.1118/1.4757919
2012-10-12
2014-04-21
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752b84549af89a08dbdd7fdb8b9568b5 journal.articlezxybnytfddd
Scitation: Monte Carlo performance on the x-ray converter thickness in digital mammography using software breast models
http://aip.metastore.ingenta.com/content/aapm/journal/medphys/39/11/10.1118/1.4757919
10.1118/1.4757919
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