Del Medical DynaRad Phantom-8000, Installation, Operation & Service Manual

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Phantom Installation, Operation & Service Manual
5-8 Calibration
5.2.6 Exposure time
Remove the phone plug from the mA jack. Measure the time base of the
kVp waveform at the 50% level.
5.2.7 X-ray to light field alignment
1
Ensure that the collimator is level in both the front-to-back and the
side-to-side directions.
2
Place a fluorescent screen, marked with a 5” square, on top of an
empty cassette making sure that the surface of the screen is 40” from
the tube focal spot and is level in both directions.
3
Press the collimator lamp button and collimate the light field to the 5”
square marked on the fluorescent screen. Note: be sure to use the
actual contrast edge of the light field, not the outside of the shadow.
4
Rotate the collimator to the following positions; left 90°, right 90°, and
then back to center. The collimator light field should rotate about the
center of the 5” square with minimal deviation.
5
Re-check the level of the collimator and shoot a 2 to 3 second exposure
at 60 to 70 kV noting the position of the x-ray field in relation to the 5”
square on the screen.
6
If required, adjust the collimator position using the (4) ring
adjustment set screws. Note: Move the collimator in the opposite
direction that the X-ray field is off.
7
Re-center the fluorescent screen and repeat as required to ensure the
X-ray field is aligned with the 5” square.
8
Remove the empty cassette and screen and place a loaded casette in
the chamber. Place a collimator test tool on top of the cassette and
position both so that the center of the light field is centered to the
collimator test tool.
9
Place four coins around the perimeter of the light field to indicate light
field position. Remember to use the contrast edge not the outside edge
of the light field.
10
Take an exposure at approximately 60kVp and 2 mAs. Develop the
film and place onto a light box. Mark the film to indicate collimator
position (“0”) and to identify front.
11
Measure the light field to X-ray field deviation (on all four sides) and
record it on the film. Note: The total deviation front-to-back or left
side-to-right side must be within 1% of SID (0.4” maximum).
12
Measure the overall X-ray field and record it on the film. Note: The
size of the X-ray field must be within the indicated size on the