PTW NORMI 13 - 2 Preparing the Constancy Test

NORMI 13 (T42023)
Operating Manual - Preparing the Constancy Test
D703.131.00/03 en 15
2 Preparing the Constancy Test
2.1 Required Test Equipment
The following test equipment is needed for per-
forming the constancy test:
– NORMI 13 test object
– PMMA or aluminum absorber
– CONNY II diagnostic dosemeter (T11007) or
NOMEX Dosemeter (L981816) or NOMEX
Multimeter (L981815)
additional equipment for documentation on film:
– densitometer
– ruler
– magnifying lens with a magnification of 4 times
or more
for diagnosis on a clinical review monitor:
– luminance meter
2.2 Test Conditions
To allow the constancy of the X-ray system to be
assessed by comparison with the reference val-
ues, it is mandatory to perform all tests under the
same conditions, which are specified below:
– use of the same test equipment
– identical radiographic or fluoroscopic, image
processing, documentation, and viewing con-
ditions
– test object positioned in the same place with
the same spatial orientation and the same
beam geometry; the maximum permitted devi-
ation of the distance between focus and image
receptor compared with the initial state is 1%
max.
– for imaging plate systems:
use of the same plate
– for units with removable anti-scatter grid:
use of the same grid with the same orientation
and the same distance
– for X-ray equipment with light field indicator:
test object positioned such that the edges of
the light field (center of the penumbra region)
coincide with the four line marks of the test
object
These conditions must be defined and recorded
during the acceptance test.