P/N 9-500-0255 4-53
Service Manual
Chapter 4: Calibrations and Performance Checks
X-ray and Light Field Check and Alignment Procedures
Legend for Figure 4-14
1. Longitudinal Adjustment
2. Lateral Adjustment
3. Overall Adjustment
Figure 4-14: Light Field Size Adjustment
7.11 Light Field Edge Contrast Check
This check ensures the contrast of the lighted x-ray field complies to the performance
standard set forth by FDA 21CFR. Always perform this test with the ambient light reduced
(darken the room).
The following equipment is required for this test:
• Light Detector Model 268P
• Light Meter (UDT Instruments, Model 351)
• Aluminum Aperture, 1.0 mm diameter (or equivalent)
1. Place the probe of a light detector on the IRSD and center it. Place the aluminum aper-
ture directly on the probe. Position it so that the aperture is centered on the probe’s sen-
sor. Turn the room lights OFF and record the ambient light reading as IA.
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