Mammo Phototimer

Consistency Test Tools

A mammographic unit's Automatic Exposure Control should be capable of maintaining optical density within ±0.15 OD as the voltage is varied from 25 to 35 kVp, and as breast thickness is varied from 2 to 8 cm for each technique.  Test images taken of uniform phantoms of varying thicknesses should not differ by more than ±0.30 OD from each other.  These tests should be carried out over the kVp range customarily used by the mammography center.

The phototimer consistency test tools are available in two materials:  acrylic and, for more accurate results, breast tissue equivalent BR-12 material.

BR-12 is a designation (D.R. White et al.) of certain epoxy resin formulations that react to X-rays in the mammographic energy range (15-30 keV) in the same manner as the human tissue.  The tissue simulation properties for these slabs are maximized at 20 keV (28kVp±).  The glandular equivalency of this material is 45% in the mammographic range.

Close Window