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3.14 Collimator Assessment
Chapter 3
Performance Criteria (X-ray Field/Image Area Alignment):
X-ray
field
Cassette A
a2
Cassette B
X-ray field / Image area alignment
a2
a 2
c 2
2
d 2Chest Side
Cassette B
• Measure the deviation (a2-d2) of the coins position in relation to the exposed eld.
• If the measured area is outside the light eld that is a (+) number and if it is inside the light eld area, it is a (-).
• Enter values into the Table MP-11 (Collimator Assessment) for cassette A and cassette B. Make sure to dene cas-
sette A values as positive or negative.
• Form Table MP-11 (Collimator Assessment) calculates Pass/Fail. The deviation of the image area from the X-ray
eld must fall within 2 % of the SID.
Performance Criteria (Alignment of chest wall edges of compression paddles and image receptors):
Chest Side
lignment of chest wall edge of
compression paddles and image
Cassette A
• Measure the distance between the chest wall edge and the quarter coin.
• Enter the value into the Table MP-11 (Collimator Assessment) for cassette A. Make sure to dene cassette A val-
ues as positive or negative.
• Form Table MP-11 (Collimator Assessment) calculates Pass/Fail. The deviation of the chest wall edge of compres-
sion paddle from the image area must fall within 1 % of the SID.
Corrective Action:
If the test results fall outside of these criteria, the test should be repeated.
If the problem remains, the source of the problem should be identied and corrective action shall be taken on the
component(s) that caused the failure within 30 days of the test date. Patient examination may continue during this
period.
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