Fluke Biomedical 18-201 - Manual (Page 5)

Introduction
Purpose
1
1-1
Section 1
Introduction
1.1 Purpose
To assure that optimum screen-film contact is obtained in mammographic cassettes.
Mammographic screen-film systems have much
higher resolution than conventional systems.
Consequently, good screen-film contact is
extremely important. Copper meshes used for
conventional screen-film cassettes are not
adequate for mammographic screen-film systems.
A 40 mesh (40 wires per inch) copper screen must
be used to test the contact of mammographic
cassettes.
ACR recommendations state that acrylic sheets (sufficient to provide 4 cm thickness) are required.
The plastic material in the 18-201 and 18-207 has the equivalent density of 4 cm thickness of acrylic.
1.2 Equipment Required
1. Mammographic Screen-Film Contact Test Tool (18-201 8 ½” x 10” 21 x 25 cm or 18-207 in white 11
¼” x 13 ¼” 28.5 x 33.5 cm copper screen laminated in plastic)
2. Cassettes (with film) to be tested
3. Lead numbers
4. Densitometer
1.3 Frequency
This test should be carried out when new cassettes and screens are purchased or initially (at the start of
the quality control program) and every six months. In addition, the test should be repeated whenever
reduced image sharpness is suspected.
1.4 Procedures
1. Place the cassette to be tested on edge of the cassette holder, i.e., without any grid between the x-
ray tube and the cassette.
2. Place the mesh on top of the cassette, and move the compression device as close as possible to
the x-ray tube.
NOTE