17-19 Operators’ Manual
990400 Rev C 2010 May 1
12-18
Measured Dose
The table below shows measurements performed on the detector for
a landscape mode standard scan.
Interpretation
1. The dose per frame at the detector may be calculated by:
Dose per frame at Detector = Dose at Detector / Number of
Frames
Where Number of Frames = 309 for 8.9 second scan
= 619 for 26.9 second scan
2. The tube output per mAs may be normalized to 1m using the
inverse square law for the purposes of assessing consistency of
tube output:
Tube Output (Gy/mAs) = Dose at Detector
x (Source to detector distance)
2
Displayed mAs
Where Source to detector distance = 0.68m for the system.
Tube Potential (kV) 120
Selected Scan Time (seconds) 8.9
Number of Frames 309
Approximate Exposure Time (seconds) 3.7
Displayed mAs 18.54
Measured Exposure at Detector (mR) 188
Measured Exposure at Detector / mAs (mR/mAs) 10.14
Measured Exposure at 1m (mR/mAs) 4.69
Measured Dose at 1m (Gy/mAs)
41.07
Dose at Detector per Frame (Gy/fr)
5.33
Tube Output (Gy/mAs @ 1m)
41.07
Distance Source to Detector (cm) 68
Frame Time (seconds) 0.012
Conversion Factor for Absorbed Dose (R to Gy) 0.00876
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