STEP 2 : Dose verication (mGy)
The dose in air is measured with a “non invasive” instrument, by positioning the detector at a source-skin distance
= 31cm (12”) (SSD) or 20cm (8”) (SSD)
SET TECHNICAL FACTORS
NOMINAL VOLTAGE Vn ± 10%
MAXIMUM VOLTAGE DROP 3%
NOMINAL HIGH VOLTAGE 60 / 70 kV
NOMINAL CURRENT 4 / 8 mA
SET EXPOSURE TIME 1 s
Dose in air is:
SOURCE-SKIN DISTANCE
31 cm = 12”
60kVp - 4mA = 2,2mGy/s ± 30%
70 kVp – 4mA = 3mGy/s ± 30%
60kVp - 8mA = 4,5mGy/s ± 30%
70kVp - 8mA = 5,5mGy/s ± 30%
20 cm = 8”
60kVp - 4mA = 4,5mGy/s ± 30%
70 kVp – 4mA = 6mGy/s ± 30%
60kVp - 8mA = 9mGy/s ± 30%
70kVp - 8mA = 12mGy/s ± 30%
STEP 3 : Checking the exposure time (s)
The exposure time is measured with a “non invasive” instruments.
SET TECHNICAL FACTORS
NOMINAL VOLTAGE Vn ± 10%
MAXIMUM VOLTAGE DROP 3%
NOMINAL HIGH VOLTAGE 60 / 70 kV
NOMINAL CURRENT 4 / 8 mA
SET EXPOSURE TIME 3,2 s
The exposure time measured is 3,2s ±5% or ±20ms, whichever is larger.
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