Specifications

3.0 OPERATIONAL CHECK-OUT PROCEDURE
3.1 Operational Check - After the Collimator, Power Chassis and cabling have been
installed, apply 24 VAC power and observe the collimator.
3.1.1 Push the LAMP button and check that the light field lamp remains on for
approximately 25 seconds.
3.1.2 While the field lamp is on, be sure the light field can be collimated to required
size with the control knobs.
3.2 LIGHT FIELD/X-RAY FIELD CONGRUENCE TEST
The following operational check is performed with the collimator located in a single fixed
position above a test pattern located on the table top.
Any required adjustments are made while observing the light-field edges, therefore it is
necessary to confirm that the light-field is representing the X-Ray field. By establishing
a defined light-field and exposing a film to a density of 1.0, the X-Ray field (image) can
be compared to the light-field.
The Performance Standards 1020.30 (b)(22) and (45) define the edges of the light-field
as the locus of points at which the illumination is one-fourth of the maximum and the
edges of the X-Ray field as the locus of points at which the exposure rate is one- fourth
of the maximum.
The X-Ray field should be determined by exposing film to a density of 1.0 on the
developed image, and observing the point at which the density is just visibly increased
above the fog background of the film.
In a similar manner, the light-field edges should be determined by observing the
lightfield on a white background. By observing the point at which the light-field is just
visibly in increased over the background illumination, and comparing this to the X-Ray
field (and to the tolerance marks on the pattern), comparisons may be made.
EQUIPMENT REQUIRED:
A. LINEAR collimator test pattern (contained in this manual)
B. Measuring tape (ruler)
C. 14” X 17” (35.5 cm x 43 cm) X-Ray film cassette
D. Densitometer (or a 1.0 density neutral density filter for a density comparison).
November 2005 ( 3-3 ) Linear MC150-C Collimator