Fluke Biomedical 07-600 - Manual (Page 5)

General Information
Introduction
1
1-1
Section 1
General Information
1.1 Introduction
In misaligned fluoroscopic image intensifier systems, part of the x-ray field may fall outside the visible
area of the image receptor. This portion of the field does not contribute to the useful fluoroscopic image
and may result in unnecessary exposure to the patient.
The Fluoroscopic Beam Alignment Device will determine the alignment of the x-ray field and the image
receptor. If corrective measures are required, the device provides a measure of optimum beam alignment
within the limits of the equipment’s design.
This device consists of a plate into which channels have been cut to accept four sliding brass strips. The
strips define the visible area of the image receptor, and they are adjustable with respect to the center of
the device. The holes drilled at ½” intervals on a line through the center of each channel are filled with
radiopaque plugs. The clear visibility of the plugs in the fluoroscopic image permits their use as a means
of centering the device. The size of the field can be determined by counting the number of visible plugs
from one edge of the field to the opposite edge, and multiplying that number by one-half to give the value
in inches. A transparent plastic overlay on the aluminum plate prevents the vertical displacement of the
brass strips.
1.2 Operation
1. Place the device on the table so that one set of brass strips lies along the centerline of the table.
Push all four strips fully towards the center of the device.
2. With the shield curtain in place, advance the imaging (or x-ray) head to the center lock position and
lock it. Place the head at its lower limit of vertical travel, and adjust the beam-limiting system to the
full open position.
3. Advance the unit to the appropriate center of the alignment device, and fluoroscope to ascertain the
exact center.
4. Lock the head in this center position.
5. With the fluoroscopy system on automatic and the user wearing shielding gloves, withdraw the four
brass strips so that the inner end of each strip corresponds to one of the four edges of the visual
field.
6. Record the spacing distribution of the four brass strips to yield the visual field size. The plugs are
½” apart.
7. Place a piece of film on top of the Beam Alignment Device and expose.
8. Develop of the film and observe. The ends of the brass strips should correspond with the edges of
the field as defined by the beam limiter. If not, the system is out of alignment.
If the image taken on the spot film (or seen on the image amplifier) appears rotated, this also
indicates a misalignment.
9. Repeat steps 1 through 8 for the upper limit of the head’s vertical travel.