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Scatter radiation in digital tomosynthesis of the breast
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10.1118/1.2428404
/content/aapm/journal/medphys/34/2/10.1118/1.2428404
http://aip.metastore.ingenta.com/content/aapm/journal/medphys/34/2/10.1118/1.2428404

Figures

Image of FIG. 1.
FIG. 1.

Diagram of a tomosynthesis acquisition depicting the moving x-ray source and the stationary detector.

Image of FIG. 2.
FIG. 2.

Diagram of the simulated CC and MLO views: (a) CC top view, (b) MLO top view, and (c) side view (in the CC view breast, the pectoralis muscle is not present). The pectoralis muscle’s thickness decreases towards the caudal side.

Image of FIG. 3.
FIG. 3.

Comparison of a scatter PSF computed with and without the variance reduction scheme. The validity of the results computed with the variance reduction scheme is apparent.

Image of FIG. 4.
FIG. 4.

Comparison of the scatter PSF computed by the Geant4 program (lines) against those previously reported by Boone and Cooper (symbols) (Ref. 24). Excellent agreement can be seen for all cases.

Image of FIG. 5.
FIG. 5.

Images of the scatter PSF for a compressed breast in the CC view for projection angles from 0° to 30°, in 6° steps. The loss of circular symmetry with increasing projection angle is apparent. The x-ray tube moves towards the top of the page with increasing projection angle.

Image of FIG. 6.
FIG. 6.

Vertical profile through the center of the scatter PSF of breasts of thickness 2, 5, and . The loss of symmetry with increasing projection angle is apparent.

Image of FIG. 7.
FIG. 7.

Sample graphs showing the variation of the 0° and 30° scatter PSF with varying (a) breast glandular fraction and (b) x-ray spectrum. Both graphs are for a breast with , , , and Rh/Rh x-ray spectrum, unless specified otherwise.

Image of FIG. 8.
FIG. 8.

Images of the SPR for a CC view breast showing the effect of the breast support plate and the detector cover plate. The increases in SPR near the edges of the breast for the 5 and thick breast are apparent for both the 0° and the 30° projections. The breast has a , , and the x-ray spectrum is Rh/Rh .

Image of FIG. 9.
FIG. 9.

Images of the SPR for a MLO view breast showing the effect of the breast support plate and the detector cover plate. The increases in SPR near the edges of the breast for the 5 and thick breast are apparent for both the 0° and the 30° projections. The breast has a , , and the x-ray spectrum is Rh/Rh .

Image of FIG. 10.
FIG. 10.

Images of the SPR for a CC view breast showing the absence of the increase in SPR when the breast support plate and the detector cover plate are not present. The simulation parameters are the same as those depicted in Fig. 8.

Image of FIG. 11.
FIG. 11.

Images of the SPR for a MLO view breast showing the absence of the increase in SPR when the breast support plate and the detector cover plate are not present. The simulation parameters are the same as those depicted in Fig. 9.

Image of FIG. 12.
FIG. 12.

Horizontal profiles through the center of mass of the breast of the SPR maps depicted in Figs. 8 and 10.

Image of FIG. 13.
FIG. 13.

Horizontal profiles through the center of mass of the breast of the SPR maps depicted in Figs. 9 and 11.

Image of FIG. 14.
FIG. 14.

Diagram showing the cause of the SPR increase due to the presence of the breast support plate and the detector cover plate. The straight downward arrows depict the primary x rays. The diagonal arrows depict the scattered x rays. Although the plates are very thin, the much higher x ray fluence entering the breast support plate results in a considerable amount of scattered x rays. The portion of these x rays that is detected under the shadow of the breast is divided by the much lower number of primary x rays that travel through the breast, resulting in a high scatter to primary ratio.

Image of FIG. 15.
FIG. 15.

Surface and contour plots of the SPR for a CC view breast with , , , and projection angles 0° to 30° in 6° steps. The spectrum is Rh/Rh . The increase in SPR, widening tail, and loss of symmetry with increasing projection angle is apparent. The x-ray tube’s motion is towards the negative side with increasing projection angle.

Image of FIG. 16.
FIG. 16.

Profiles parallel to the chest-wall, through the center of mass, of the CC view breast with a thickness of 2, 5, and .

Image of FIG. 17.
FIG. 17.

Sample graphs of SPR variation with varying (a) breast glandular fraction, (b) x-ray spectrum, (c) chest wall to nipple distance, and (d) compressed breast thickness. All four graphs are for CC view, , , , and Rh/Rh x-ray spectrum, unless specified otherwise.

Image of FIG. 18.
FIG. 18.

Sample graphs of SPR variation with varying (a) breast glandular fraction, (b) x-ray spectrum, (c) chest wall to nipple distance, and (d) compressed breast thickness. All four graphs are for MLO view, , , , and Rh/Rh x-ray spectrum, unless specified otherwise. Positive angle projections are defined as when the x-ray tube swings towards the cranial side of the patient.

Tables

Generic image for table
TABLE I.

Values of the geometric parameters used in the Monte Carlo simulations for the scatter to primary ratio studies.

Generic image for table
TABLE II.

First half-value layer values of the x-ray spectra used to combine the mono-energetic Monte Carlo results. The mono-energetic results were combined using the computed HVL above the breast compression plate due to the inclusion of the breast compression plate in the simulation.

Generic image for table
TABLE III.

Coefficients for the fit equations (1) and (2) to compute scatter to primary ratios at the center of mass, for both the MLO and CC views.

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/content/aapm/journal/medphys/34/2/10.1118/1.2428404
2007-01-19
2014-04-17
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752b84549af89a08dbdd7fdb8b9568b5 journal.articlezxybnytfddd
Scitation: Scatter radiation in digital tomosynthesis of the breast
http://aip.metastore.ingenta.com/content/aapm/journal/medphys/34/2/10.1118/1.2428404
10.1118/1.2428404
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