Title page
Contents
About Public Health England 2
About PHE Screening 2
Executive summary 4
1. Introduction 5
1.1. Testing procedures and performance standards for digital mammography 5
1.2. Objectives 5
2. Methods 6
2.1. System tested 6
2.2. Dose and contrast-to-noise ratio using AEC 8
2.3. Image quality measurements 9
2.4. Geometric distortion and reconstruction artefacts 9
2.5. Alignment 11
2.6. Image uniformity and repeatability 11
2.7. Detector response 11
2.8. Timings 11
2.9. Modulation transfer function 12
2.10. Local dense area 12
3. Results 14
3.1. Dose and contrast-to-noise ratio using AEC 14
3.2. Image quality measurements 16
3.3. Geometric distortion and resolution between focal planes 17
3.4. Alignment 19
3.5. Image uniformity and repeatability 19
3.6. Detector response 20
3.7. Timings 20
3.8. Modulation Transfer Function 21
3.9. Local dense area 22
4. Discussion 24
4.1. Dose and contrast-to-noise ratio 24
4.2. Image quality 24
4.3. Geometric distortion and reconstruction artefacts 24
4.4. Alignment 25
4.5. Image uniformity and repeatability 25
4.6. Modulation transfer function 25
4.7. Local dense area 25
5. Conclusions 26
References 27
Table 1. System description 6
Table 2. Image file sizes for 60mm CBT, 24cm x 30cm field size 7
Table 3. HVL and tube output measurement in tomosynthesis mode 14
Table 4/Table 5. MGD for tomosynthesis images acquired using AEC 15
Table 5/Table 6. CNR for tomosynthesis images acquired using AEC 16
Table 6/Table 7. Threshold gold thickness for reconstructed focal plane 26 of the image of the CDMAM phantom (automatically predicted data) 17
Table 7/Table 8. z-FWHM measurements of 1mm diameter aluminium balls 19
Table 8/Table 9. Scan and reconstruction timings 21
Table 9/Table 10. MTF for central projections in the directions parallel (u) and perpendicular (v) to the tube axis 22
Table 10/Table 11. MTF50 for central projection 22
Table 11/Table 12. AEC performance for local dense areas, measured on the midline and 50mm from the CWE 23
Figure 1. The Siemens Revelation digital breast tomosynthesis system 7
Figure 2. The position of 5mm x 5mm ROIs for assessment of CNR. (The CWE is to the left) 9
Figure 3. Setup to measure AEC performance for local dense areas 12
Figure 4. MGD for tomosynthesis exposures acquired using AEC for different equivalent breast thickness. Error bars indicate 95% confidence limits 14
Figure 5. CNR for tomosynthesis images acquired using AEC for different equivalent breast thickness. Error bars indicate 95% confidence limits 15
Figure 6. Variation of projection CNR with angle for images of 45mm PMMA. Error bars indicate 95% confidence limits 16
Figure 7. Threshold gold thickness for plane 26, at 3 dose levels. Error bars indicate 95% confidence limits 17
Figure 8/Figure 9. Appearance of 1mm aluminium balls in reconstructed focal planes at 1mm intervals, from 4mm below to 3mm above the plane of best focus 18
Figure 9/Figure 10. Extracts from planes showing 1mm aluminium ball in (i) single focal plane, (ii) Maximum Image Projection (MIP) through all focal planes, and through re-sliced vertical planes in the directions... 19
Figure 10/Figure 12. Detector response in tomosynthesis mode 20
Figure 11/Figure 13. MTF for tomosynthesis central projections 21
Figure 12/Figure 14. AEC performance in projection images for local dense areas 23