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Chapter 3
3.4 Beam Quality
3.4.1 Test Objective
To measure half value layer of the device.
3.4.2 Frequency
• Initially at installation of the mammography X-ray unit
• ANNUALLY
• As part of an MEE
• After any service or maintenance on the mammography X-ray unit which may aect beam quality
3.4.3 Required Equipment
• Calibrated dose meter
• Al sheets for ltration (The purity of the Al ≥99.9% is required.)
3.4.4 Procedure
1
Set the exposure device to the most common clinical kVp used at the site.
2
Adjust the mAs on the mammography X-ray unit to achieve 500mR. (exposure should be as
close as possible +/- 20%)
3
Position the detector of the dose meter 4.5cm above the breast support table and centered
4cm in from the chest wall.