116
3.14 Collimator Assessment
11
Repeat steps 1 through 10 for all routinely used collimator/bucky/compression paddle com-
binations and target materials. When testing the large image receptor, the top anode may be
positioned diagonally to capture all four edges of the X-ray eld, or, two large cassettes may
be used on top of the image receptor.
Place the 24×30 cassette
diagonally across the
breast support table so that
the cassette corner extends
beyond the chest wall.
3.14.5 Performance Criteria and Corrective Action
Performance Criteria (X-ray Field/Light Field Alignment)
• Measure the deviation (a1-d1) of the coins position in relation to the exposed eld. Enter values into the Table
MP-11 (Collimator Assessment). It is not necessary to dene whether it is a negative or positive number.
a
1
c
1
d
1
b
1
Light
Field
X-ray field/Light field alignment
Cassette A
Chest Side
• Form Table MP-11 (Collimator Assessment) calculates Pass/Fail. The deviation of the light eld from the X-ray eld
must fall within 2 % of the SID.
To Next Page
Loading...
Need help?
General
