Fluke Biomedical 18-222 - Manual (Page 13)

2-5
Table 2-3. Attenuation Comparison (
µ
x) for Uses in the Well Known Relationship Various
Phantom Densities and Sizes
Tissue: Acrylic Acrylic Acrylic BR-12 50/50 30/70 50/50 30/70 50/50 20/80
Thickness: 4.4 cm 5.0 cm 4.55 cm 4.5 cm 4.0 cm 4.5 cm 4.5 cm 5.0 cm 5.0 cm 6.0 cm
MFGR: ACR MFR #1 MFR #2 NAD NAD NAD NAD NAD NAD NAD
Fat Layer: No No No No Yes Yes Yes Yes Yes Yes
keV
10 15.542 17.769 16.995 15.942 13.703 14.257 15.514 15.889 17.325 18.294
15 5.127 5.891 5.608 5.298 4.601 4.803 5.207 5.352 5.814 6.175
20 (28 kVp) 2.705 3.103 2.936 2.728 2.392 2.523 2.706 2.811 3.021 3.251
30 1.477 1.691 1.582 1.402 1.251 1.346 1.412 1.498 1.573 1.758
40 1.162 1.328 1.236 1.062 .956 1.042 1.078 1.159 1.201 1.371
50 1.033 1.179 1.095 .925 .836 .918 .944 1.021 1.051 1.211
This chart compares the composite attenuation for various phantom size/density compositions.
The linear attenuation coefficient (
µ) for each type of material (wax/lucite/gland/fat/etc.) applied to the thickness of
the material in each phantom design permits calculation of total attenuation for each phantom design.
Actual Breast Tissue per Hammerstein
Tissue 70/30 50/50 50/50 50/50 30/70 20/80
Thickness: 4.0 cm 4.0 cm 4.5 cm 5.0 cm 5.0 cm 6.0 cm
MFGR: Actual Actual Actual Actual Actual Actual
Fat Layer: Yes Yes Yes Yes Yes Yes
keV
10 15.689 14.411 16.317 18.223 16.578 18.996
15 5.066 4.697 5.314 5.931 5.446 6.271
20 (28 kVp) 2.571 2.411 2.725 3.038 2.829 3.279
30 1.307 1.254 1.414 1.574 1.502 1.762
40 .989 .961 1.082 1.204 1.165 1.375
50 .862 .843 .949 1.055 1.028 1.217
I -
µx
I
O
= e