Unattenuated beam (in front of the phantom) – Fluke Biomedical TNT 12000 User Manual
Page 100
TNT 12000
Users Manual
A-6
measurements in an attenuated beam not similar to a DN series point, the user may
calculate the actual first HVL and locate the proper correction value on the curve.
Unattenuated Beam (In Front of the Phantom)
The energy correction factors for the 96020C are determined for the unattenuated
diagnostic beam using the PTB defined DV series of beam qualities given in Table A-2.
Table A-2. Specifications for PTB Defined Unattenuated Beam Qualities
PTB
Denomination
kVp
Added Filtration
in mm AI
First HVL in mm
AI
First HVL in mm
Cu
DN40 40
2.5 1.05
0.031
DN50 50
2.5 1.42
0.045
DN60 60
2.5 1.82
0.059
DN70 70
2.5 2.45
0.081
DN80 80
2.5 3.10
0.112
DN90 90
2.5 3.60
0.126
DN100 100
2.5 4.30
0.165
DN120 120
2.5 5.40
0.231
DN150 150
2.5 1.05
0.031
Typical energy correction factor curves are obtained by dividing the calibration factor at
each beam quality by the calibration factor at a reference point and plotting the result
versus first HVL.
The typical correction factor curves for the unattenuated beam are shown below
normalized to L100 in Figure A-5 and DV70 in Figure A-6.
Typical Correction Factors - Unattenuated Beam
Normalized to L100
First HVL (mm A1)
Colrrection Factor
1
1.5
2
2.5
3
3.5
4
4.5
5
5.5
1.05
1.04
1.03
1.02
1.01
1
0.99
0.98
0.97
0.96
0.95
40
30
50
70
120
150
90
100
fct35.eps
Figure A-5. Energy Correction Factors for Model 96020C in Unattenuated Beam Normalized to L100