6 - 1
Siemens AG
SPB7-250.815.02
Page 1 of 6
MAMMOMAT
Novation
DR
Medical Solutions
Rev. 02
09.04
CS SD 24
System
X-ray tube checks
6
Tube high voltage, current and mAs values
6
This section describes how to check the X-ray tube in regard to the:
•
High voltage, tube current, mAs value with and without AEC and with a small or large
focus.
Preparation
6
•
Switch the system
OFF
.
•
Connect the oscilloscope as follows:
Channel 1 to measuring point
HV_ACT
(actual value)
(1 V= 5 kV) on the D750.
Channel 2 to measuring point
MA_ACT
(actual value)
(1 V= 40 mA) on the D750.
•
Connect the service PC to the stand.
•
Start the Service Program and check in the
anode menu
that the tungsten anode is
enabled
.
•
Switch the system
ON
.
•
Set the
cassette loaded
switch to
OFF
with the Service Program:
In the
Main menu
choose
Configuration Miscellaneous Cassette loaded check
.
Measurement method
6
•
The mAs value must be calculated as the product of the tube current and exposure time.
The tube current and the exposure time can be obtained from the oscillograms. The
diagram may have glitches, in this case you have to measure the exposure time t
1
and t
2
.
Example
:
From the figure the tube current is 150mA and the exposure time is t
1
+t
2
in seconds. The
mAs is 150mA*(t
1
+t
2
).
Be aware, that with the AEC mode on, a pre-exposure of 50 ms is
done.
Select the correct trigger on the scope, so you get the pre-expo-
sure and the all the exposure times.
t
1
t
2
MA_ACT
150mA
Fig. 1
Check X-ray tube high voltage, current and mAs values
NOTE