NORMI 13 (T42023)
Operating Manual - Constancy Test
20
D703.131.00/03 en
•
Set the X-ray tube voltage as follows:
– Manual setting:
70 kV (100 kV for X-ray tubes that are only
used in the voltage range of about 100 kV)
– Application device with automatic exposure
control:
100 kV (70 kV for X-ray tubes that are only
used in the voltage range of about 70 kV)
•
Generate a test image with each X-ray tube
and each application device with an automatic
exposure control function.
•
Read the measured value indicated on the
detector.
•
Document and analyze the results according
to the standard DIN 6868-13.
3.3
Verifying the Performance
Characteristics
The following performance characteristics shall
be verified in the constancy test: The per-
mitted limit deviations of the individual perfor-
mance characteristics are detailed in section
.
3.3.1 Dose
Measure the dose always in the same area (
1
,
). Mount the detector with the same ori-
entation on the radiation entrance side of the test
object. Be sure not to exceed the intended range.
It is important to keep the radiation detector of the
dosemeter clear, also when using the additional
copper plate for 100 kV.
3.3.2 Exposure Index
The exposure index is given in data relating to the
test image. Create a test image that is shown on
the image display device or on film. The image
can be taken without a structure plate and with
only the absorber.
3.3.3 Optical Density or Luminance
or Pixel Value
Determine either the optical density or the lumi-
nance. As an alternative to determining the lumi-
nance, you can analyze the pixel values of the dig-
ital test image.
