Checking the radiation field limitation
17 - 3
Siemens-Elema AB
Register 3
SP B7-230.033.07
Page 3 of 4
Mammomat 1000/3000
Solna, Sweden
Rev. 03
11.99
SPS-UD
Installation and Start-Up
Evaluation
17
Alignment radiation field/light field
17
1.
On the film that was placed in the film bag, mark the light field limit with guidance
of the coin marks as shown in (Fig. 2) above.
The maximum divergence between radiation field and light field of 6.5 mm must
not be exceeded on any side.
Radiation field limitation
17
1.
Measured from the chest wall side of the object table, the radiation field must be
within -4 and +5 on the chest wall side and must not exceed 188 mm (18x24 film)
and 248 mm (24x30 film) on the nipple side.
2.
The radiation field must under no circumstances extend beyond the side edges of
the object table. The margins to the edges must at least be 7 mm. Compare the
side values read off on film-bag film with the corresponding values written down in
point 6 above.
Correction, see Service Instructions.
3.
Finally check the radiation field on a film exposed inside the object table.
18x24 film must be completely exposed on all sides. 24x30 film might have up to
3 mm white edge on the nipple side
1
. The other sides must be completely
exposed
Repeat this check with all object tables and both "wings" (base plates).
Fig. 2
Field limitation
Values for evaluation are defined in the plane of the film bag.
1. adjust within the given tolerance in point 1 above if necessary
-4 mm
+5 mm
Allowed overradiation vs. object table
Radiation field
Light field
*
left: +/- 6.5 mm
*
right: +/- 6.5 mm
*
front: +/- 6.5 mm
*
back: +/- 6.5 mm
MAM00648
Chest-wall side
Cassette film
left
*
right
*
Centering cross
back
*
front
*
Object table
188/248
NOTICE
