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3.14 Collimator Assessment
3.14.1 Test Objective
To ensure that the collimator assembly performs in such a manner that the X-ray eld coincides with the light eld
and is aligned with the image receptor.
3.14.2 Frequency
• Initially at installation of the mammography X-ray unit
• ANNUALLY
• After any service or maintenance on the X-ray tube or collimator and whenever collimation problem is suspected
3.14.3 Required Equipment
• Four REGIUS cassettes from the clinical inventory. (1) 18×24 REGIUS cassette and (3) 24×30 REGIUS cassettes
• (4) Pennies and (1) Quarter
• Metric Rule
• 2 cm of PMMA (acrylic) phantom
3.14.4 Procedure
1
Place appropriately sized REGIUS cassette into cassette holder of the mammography X-ray
unit.
2
Please select the appropriate collimator for the exposure.
3
Place the large REGIUS cassette on top of the cassette holder so that the cassette hangs over
the holder by 1cm on the chest wall side.
4
Remove the compression paddle and turn on the collimator light.
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