Fluke Biomedical 07-661-7662 - Manual (Page 10)

Nuclear Associates 07-661-7662
Operators Manual
1-6
Figure 1-7 Test of Viewed Field Versus Actual Field Size
This error for any given field edge must be less than 3% of the SID. If the x-ray tube is 45 cm (18”) below
the table and the image intensifier is 30 cm (12”) above the table, the allowed error is 2.25 cm (0.9”) in
any one direction.
1.6 Checking Spot Film Collimation
The spot film collimation may be checked in a similar manner. With the Beam Alignment and Collimator
Tools on the table, tape a loaded cardboard cassette (that is larger than the spot film cassettes size) onto
the face of the spot film device or grid. Record the size of the spot film cassette and make a full spot film
exposure. A loaded cassette can be placed in the spot film device for this test. If the edges of the x-ray
field are visible in the spot film, the collimation is good, and film centering with respect to the x-ray field
can be checked. If the edges of the x-ray field are not visible on the spot film, the field size shown on the
larger film from the cardboard cassette will
indicate qualitatively the size of the actual
x-ray field.
References: Regulations for the Administration and
Enforcement of the Radiation Control Health and
Safety Act of 1968. U.S. Department of Health,
Education, and Welfare. Food and Drug
Administration, July, 1980.
NOTE