User Manual

37
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121030
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 8 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
3 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 5 6 7 8
Median Value
[LSB]
500 ~
1500
4500~
5500
9500 ~
10500
14500 ~
15500
19500~
20500
24500 ~
25500
29500 ~
30500
34500~
35500
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 ‘20000’ in this
case the level is
contained in Bright
point of ‘4’(refer
‘Table 5 : Median
value’). The meaning
is you don’t have to
make bright point
for ‘5’ and ‘6’(In this
case, it will be does
not working if you
get image on higher
level than maximum
bright point.)