MODEL 142D AND 143D FILM/SCREEN CONTACT TEST TOOLS

Focal Spot Test Tool Model 112B
The focal spot size of an X-ray tube is a key factor in determining system resolution.  The smaller the focal spot size, the sharper the image at  high geometric magnification.  The Gammex 112B Focal Spot Test Tool consists of six groups of bar patterns with spacing decreasing in 16%  steps from 0.84 lp/mm (line pairs per millimeter) to 5.66 lp/mm.  The test pattern is mounted on the top of a 16 cm acrylic cylinder.  The test tool works by forming a magnified image of the precision bar pattern.  The cylinder provides accurate and reproducible target-to-image receptor spacing.  The visually observed limiting resolution can be simply converted into an effective focal spot size.  This process is simpler than the use of an IEC slit camera and can be easier to interpret than a star pattern.
SPECIFICATIONS Gammex 112B Construction . . . . Six inch acrylic cylinder with a 12 group bar pattern target mounted on top Resolution . . . . . 0.84 to 5.66 lp/mm Size. . . . . . . . . . 16.5x7.6 cm diameter (6.5x3 in diameter) Weight. . . . . . . . 329 g (11.6 oz)