User's Manual

50
Bright Calibration Point
To gain correction, bright frame and dark frame should be
acquired. The dark frame is needed only one frame. The bright
frame is recommended to be acquired more than 2 different
levels of median values of bright frames. The X-ray source
condition will be recommended the tube energy level of 70kVp
with variable tube current and exposure time. To acquire at least
2 frames at same condition will be recommended. The median
values of bright frames are below.
(Additional 21mm Al filter is recommended for calibration)
The Purpose of Bright Calibration
The center of the non calibrated image is brighter than the edge
due to hill effect of X-ray exposure. Generally, the intensity of X-
ray flux at center region of exposed area is higher than
surroundings due to the X-ray expose like cone shape. A
calibration process is used to compensate for this effect.
Generally, called it ‘Flat Field Correction’(Bright calibration).
Point
1
2
3
4
Median Value [LSB
500 ~
1000
2900 ~
3400
6200~
6700
9500 ~
10000
Table 5 : Median value
The
calibration
range of
bright is can be
select by which
exposure level is
maximum level that
user want to use. If
the maximum level
of user want to use
is ‘6500’ in this case
the level is
contained in Bright
point of ‘3’(refer
‘Table 5 : Median
value’). The meaning
is you don’t have to
make bright point
for ‘4’(In this case, it
will be does not
working if you get
image on higher
level than maximum
bright point.)