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Energy deposition portions in the paired air slabs for the mammography X-ray beams
| Location of the paired air slabs | Energy deposition portion (%) | ||||||||
|---|---|---|---|---|---|---|---|---|---|
| Upper slab (mm) |
Lower slab (mm) | Beam code | |||||||
| M20 | M23 | M25 | M28 | M30 | M35 | M40 | |||
| 35–40 | 30–35 | 94.39 | 93.34 | 92.78 | 92.11 | 91.70 | 90.93 | 90.35 | |
| 40–45 | 25–30 | 5.56 | 6.61 | 7.16 | 7.82 | 8.20 | 8.89 | 9.34 | |
| 45–50 | 20–25 | 0.02 | 0.03 | 0.03 | 0.05 | 0.07 | 0.15 | 0.25 | |
| 50–55 | 15–20 | 0.01 | 0.01 | 0.01 | 0.01 | 0.01 | 0.02 | 0.04 | |
| 55–60 | 10–15 | 0.01 | 0.01 | 0.01 | 0.01 | 0.01 | 0.01 | 0.01 | |
| 60–65 | 5–10 | 0.00 | 0.00 | 0.01 | 0.00 | 0.00 | 0.00 | 0.00 | |
| 65–70 | 0–5 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | |
The air slabs were piled symmetrically with the beam axis plane placed 35-mm-high from the collector electrode as a symmetry plane. The low-energy mammography X-ray beams were incident on the front face of the air box (see Fig. 4). The number appearing in the beam code indicated the high voltage loaded on the X-ray tube with a molybdenum anode. The added filtration was 0.03 mm molybdenum, and the inherent filtration was 1 mm beryllium.