Fluke Biomedical 18-222 - Manual (Page 6)

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The basic phantom (Model 18-222) matches the composition of an average firm breast consisting of 50% adipose
tissue and 50% glandular tissue and is realistically shaped. The phantom is suitable for evaluating the mammographic
process in the laboratory as well as for monitoring system performance in the clinic. The phantom may be used for
screen-film mammography or xeromammography. Each molded breast is surrounded with a .5 cm adipose-
equivalent tissue. Thus, the glandular portion of the standard phantom is 3.5 cm in thickness.
The materials used in this phantom have been formulated for optimum response in the film-screen mammographic
range of x-ray exposure (24 to 34 kVp), but will generally provide similar results at higher (xeromammographic)
exposure ranges.
The resin materials mimic the photon attenuation coefficients of a range of breast tissues. The average elemental
composition of the human breast being mimicked is based on the individual elemental compositions of adipose and
glandular tissues as reported by Hammerstein (11). See Tables 2-1 and 2-2 for comparative data.
The attenuation coefficients are calculated using the "mixture rule" and the photon mass attenuation and energy
absorption coefficients table of J.H. Hubbell (16).
Optional Size Phantoms
The Model 18-222 Phantom is 4.5 cm in compressed thickness. Other sizes available are 4 cm, 5 cm, and 6 cm
thickness.
Optional Tissue Densities
Densities ranging from 20% glandular/80% adipose to 70% glandular/30% adipose are available on request.
Details
The Standard Phantom (Model 18-222) has embedded details (Figure 2-2) consisting of:
• Seven masses that are 75% glandular and hemispherical in shape.
• A wax insert with embedded nylon fibers.
• The Model 18-222 has an optical density reference zone. This allows OD measurements, which are position
dependent, to be taken from the same area each time. This helps factor out OD variances.
• The Model 18-222 has two edges of beam targets. This enables precise localization of the x-ray beam's edge - for
example, is the machine penetrating the chest wall, or is it not close enough to the chest wall such that
something may be missed in a clinical setting?
• One line pair test target with line pair tests between 5 and 20 line pair/mm.
The Physicist Research Model (Model 18-223) includes:
• Three tissue equivalent phantoms with removable outer fat layer and with embedded details similar to Model
18-222
- 4 cm - 50/50 (dense)
- 5 cm – 30/70 (normal) (or 4.5 cm - 50/50)
- 6 cm - 20/80 (fatty)
• Three tissue equivalent slab combinations of plates ranging from .5 cm thickness to 2 cm. This permits test
imaging in .5 cm increments from a thickness of .5 cm to 7 cm.
- 30% glandular/70% adipose
- 50% glandular/50% adipose
- 70% glandular/30% adipose