Chapter 7
Page no. 690
JC-ELE-A-028.fm
GE Healthcare
Senographe DS
Revision 1
Service Information and Procedures Class A 2385072-16-8EN
Job Card ELE A028 - Collimation Checks
7-3
Action Limit
The results from the Mo/Mo and Rh/Rh tests above must adhere to the following three action limits:
1. Congruence of the light field with the X-ray field must be such that the total misalignment (sum of
misalignments on opposite sides) is within 2% of the SID. As required by
21 CFR chapter I, Subchap-
ter J, 1020.31(d)(2)(i)
.
Enter measured deviations between the X-ray field and light field on the data form as follows (i.e. Y
f
for each XR-M film strip determined in step
of
for film
positions):
If both | Y
d
A| + |Y
d
D| and | Y
d
B| + |Y
d
C| are less than 13.2 mm
then this action limit has passed.
If either | Y
d
A| + |Y
d
D| or | Y
d
B| + |Y
d
C| is more than or equal to 13.2 mm
then this action limit has
failed.
Note:
If either | Y
d
A| + |Y
d
D| or | Y
d
B| + |Y
d
C| is more than or equal to 10 mm
,
it is recommended to adjust
the position of the Collimator Lamp according to
Adjusting a Newly Installed Lamp
then re-perform the Collimator Checks.
Mo/Mo
-
The magnitudes of deviations at the left edge and right edge (ig or – signs) are entered
on the data form and added together.
-
Similarly, the deviations at the anterior and posterior (chest wall) edges are entered (without
regard to sign) and the magnitudes added together.
Rh/Rh
-
The magnitudes of deviations at the left edge and right edge (ig or – signs) are entered
on the data form and added together.
-
Similarly, the deviations at the anterior and posterior (chest wall) edges are entered (without
regard to sign) and the magnitudes added together.
Film
Edge
Y
f
| Y
f
A| + |Y
f
D|
Is | Y
f
A| + |Y
f
D| less
than 13.2 mm?
A
Left
D
Right
Film
Edge
Y
f
| Y
f
B| + |Y
f
C|
Is | Y
f
B| + |Y
f
C| less
than 13.2 mm?
B
Anterior
C
Posterior (chest wall)
Film
Edge
Y
f
| Y
f
A| + |Y
f
D|
Is | Y
f
A| + |Y
f
D| less
than 13.2 mm?
A
Left
D
Right
Film
Edge
Y
f
| Y
f
B| + |Y
f
C|
Is | Y
f
B| + |Y
f
C| less
than 13.2 mm?
B
Anterior
C
Posterior (chest wall)
