Fluke Biomedical 35080B - Manual (Page 32)

35080B
Operators Manual
6-2
The reading from the Linear Mammo Filter Pack (37351) is compared to that taken with the Cadmium K-
edge Mammo Filter Pack (37355) and a kV correction value for the Linear Mammo Filter Pack (37351) is
computed. This correction value is applied uniformly to all readings taken with the Linear. The K-edge
measurement should be performed each time a generator is tested. Part of the correction factor for the
Linear Mammo Filter Pack (37351) is due to variations in tube filtration and part is due to positional
dependence. Therefore when using the Linear Mammo Filter Pack (37351), if the Model 35080B kVp
Divider is moved, a new measurement at the K-edge comparison kVp point must be made with the Linear
Mammo Filter Pack (37351) and a new correction factor computed.
6.4 Corrections
If the amount of molybdenum filtration were known, the correction could be made with the correction
curves in Figures 6-1 and 6-2. Figure 6-1 shows the correction required for total molybdenum filtration of
12 microns, 24 microns, and 35 microns (no correction is required for 24 microns). Figure 6-2 shows the
effect of adding 0.25 mm Al to the 24 microns of molybdenum.
Figure 6-1.
Correction Curves for 12, 24, and 35 Microns Molybdenum Filtrations
A machine with 35 microns of molybdenum and a reading of 29.0, add 1.0 kV; the corrected reading is
30.0 kVp (Refer to Figure 6-1). For 12 microns and a reading of 28.0 kVp, subtract 1.5 kV for a corrected
reading of 26.5 kV.
Indicated kVp
kV C
o
rrection
Linear Mammo Filter Pack (37351)
Correction for Molybdenum Filtration