4-52 P/N 9-500-0255
Service Manual
Chapter 4: Calibrations and Performance Checks
X-ray and Light Field Check and Alignment Procedures
F. Lateral Position: alignment of left and right edges - Loosen the screws (Fig-
ure 4-14, Item 2) and move the lamp toward the left to move the light field
to the right; move the lamp toward the right to move the light field to the
left.
G. Overall Size: overall area of pattern (combined length and width) - loosen
the screws securing the bracket to the C-arm frame (Figure 4-14, Item 3) and
move the entire bracket forward (toward patient) to expand the Light Field
area; move it back to contract the Light Field area.
3. Remove the template and screen, then install a loaded 24 x 30 cm cassette in a Bucky
device and mount it onto the image receptor support. Press the Light field button to
project the lighted area onto the Bucky.
4. Accurately mark the edges of the light field on the Bucky surface using the Alignment
Bars (PN 9-060-0173). Mark the front edge with a paper clip for orientation.
5. Set the unit for a Manual mode exposure at 22 kV, 48 mAs, Large focal spot. Step behind
the radiation shield, then conduct an exposure. Remove the cassette and develop the
film.
6. Compare the edges of the image area with the white marks made by the pieces of wire
or solder. The total mis-alignment of the edges of the light field with respect to the expo-
sure field, (along either the length or the width) shall not exceed 2% of SID (1.3 cm).
Note… Inability to accurately align the Light Field with the x-ray image area may
indicate aperture plate mis-alignment.
7. Remove the auto aperture and the Bucky device. Install the 18 x 24 cm Small Focal Spot
Aperture (refer to Figure 4-12), then position the X-ray Beam alignment template (Figure
4-10) on the IRSD. Select the Small focal spot, then press the light field lamp button.
Compare the edges of the light field (18 x 24 cm Small Spot) to the markings on the tem-
plate.
8. Make lamp adjustments per steps 2 (A = longitudinal, B = lateral & C = overall) to make
the light field congruent to the x-ray field.
9. Remove the template and screen, then block the outermost (left side) accessory detector
on the IRSD using reflective material (to simulate the smaller film format). Install a
loaded 24 x 30 cm cassette in a Bucky device and mount it onto the image receptor sup-
port. Press the Light field button to project the lighted area onto the Bucky.
10. Accurately mark the edges of the light field on the Bucky surface using the Alignment
Bars (PN 9-060-0173). Mark the front edge with a paper clip for orientation.
11. Set the unit for a Manual mode exposure at 22 kV, 48 mAs, Small focal spot. Step behind
the radiation shield, then conduct an exposure. Remove the cassette and develop the
film.
12. Compare the edges of the image area with the marks made by the Alignment Bars (PN 9-
060-0173). The total mis-alignment of the edges of the light field with respect to the
exposure field, (along either the length or the width) shall not exceed 2% of SID (1.3
cm).
13. Make light field size adjustments (see Figure 4-14) as necessary for both the large and
small focal spots, then repeat the exposures. Continue the checks and adjustments until
the light field is congruent with the x-ray field for both focal spots.
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