WARNING
It is necessary to make exposures in the following procedure.
Therefore, take all precautions needed to protect personnel against
unnecessary radiation.
NOTE:
The potentiometer adjustments referred to are those found in the Eureka
EXT-950 (DPSC) spot-film device.
(2) Collimator centering alignment. Loosen the four collimator-mounting
screws. Activate a very low-level fluoro exposure (such as .5ma at 50kvp) and adjust
the shutter controls to just display the four shutter blades on the fluoro image.
Determine the direction of movement required and shift the collimator (without X-ray) to
center all four shutters on the image. Refer to figure 1-5. Tighten the four mounting
screws.
NOTE:
Some tube carriages provide additional centering adjustments than those
mentioned here. Refer to the table manufacturer's manual for any additional
adjustments which may be required.
Figure 1-5. Collimator centering.
(3) Fluoroscopic image size (I.I.) adjustment. Select the fluoro mode on the
generator and open the collimator shutter blades to their maximum, using the shutter
controls on the SFD.
(a) Lower the SFD to its minimum surface-to-image distance (SID).
Depress the X-ray switch on the SFD and observe the fluoroscopic image. The
collimator blades should be evenly visible at the edges of the display. If they are not,
adjust the "NORM" potentiometer, R18, on the SFD interface board until they are.
NOTE:
If you are unable to obtain a square image on the image tube, the collimator
shutter calibration procedure may need to be performed or leveling of the
image intensifier/spot device may need to be checked. Refer to the
manufacturer's service manual for shutter calibration procedures.
MD0351
1-31
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