Fluke Biomedical 18-216 - Manual (Page 5)

General Information
Objective
1
1-1
Section 1
General Information
1.1 Objective
Focal spot performance may be evaluated by determining limiting resolution using a high-contrast
resolution pattern providing a test up to 16 lp/mm and preferably 20 Ip/mm (either a bar pattern, a star
pattern, or a wedge pattern marked to identify the number of Ip/mm in the image at the appropriate
points).
1.2 Description Of Phantom
The Single-Exposure High Contrast Resolution Phantom
incorporates two 17.5 micron thick gold-nickel alloy bar
patterns positioned at 90 degrees. This allows assessment
of resolution perpendicular and parallel to anode-cathode
axis in just one exposure. Each pattern has 17 segments
from 5 Ip to 20 Ip/mm and is equivalent to 25 microns of
lead or 2.6 mm of aluminum at 20 keV.
The bar patterns are permanently embedded in a thin
acrylic wafer to protect them from wear or damage.
The phantom body is available in BR12 (Model 18-216) or
BR50/50 (Model 18-216-1000). It enables consistent,
reproducible positioning of the bar pattern at 4.5 cm above
the breast support plate and 1 cm from the chest wall,
centered laterally (as recommended by the American
College of Radiology). The bar pattern can also be
positioned at a variety of heights for more thorough
evaluations. The Single-Exposure High Contrast Resolution
Phantom includes a 30X hand-held microscope.