Hologic QDR 4500 - X-RAY BEAM ALIGNMENT (C and W Only)

QDR

4500 Technical Manual
4-8
4. Turn off X-rays.
5. Remove the block and pin.
6. Turn off SUSQ.
X-RAY BEAM ALIGNMENT (C and W only)
It is crucial that the X-ray beam be precisely aligned with the detector, because improper
alignment will directly affect the repeatability (coefficient of variation, or CV) of the QDR 4500.
Therefore this alignment must be verified at the time of installation or whenever any work is
performed that may affect it.
To check the beam alignment:
1. Insert the alignment test fixture into the detector opening.
2. Turn on X-rays (using SUSQ)
WARNING:
X-rays are being generated during this procedure. Keep hands, head and other
body parts out of beam.
a) use gain of “2” for high and “1” for low
b) use X-ray mode “3”
3. Look at the monitor screen. The display should be flat and have an amplitude of about
six (6) volts.
4. If the X-ray beam alignment is not correct, continue this procedure.
5. If the tank cover is on, remove it.
6. Remove the C-arm cover.
7. Set the machine in the Center Table position.
8. At the Filter Drum assembly, loosen the jam nuts, and insert Allen wrenches (3/32"), in
both Filter Drum Allen alignment screws (Figure 4-7 shows location of front alignment
screw and jam nuts). Ensure that the Filter Drum is running.
9. Type SUSQ <Enter>, set high gain = 2, low gain = 1. Set X-ray mode to 3.
10. Press <Ctrl> <Page Down> to get the bar graph.
11. Verify that the screen shows Pulse 1 (high air). If it doesn't, press <Alt><P> until it
does.
12. Set X-ray mode to 3, and make sure the screen still shows pulse 1. Press <Ctrl><Page
Down>.
13. Press F1 to turn on X-rays.
The next 3 steps adjust the beam side to side.
1. Move the
front
Filter Drum Allen alignment screw until the X-ray signal peaks.