MAMMOMAT
Novation
DR
SPB7-250.815.02
Page 8 of 20
Siemens AG
System
Rev. 02
09.04
CS SD 24
Medical Solutions
9 - 8
Image Quality
Checking Image Quality
9
While calibration is typically performed by the customer as part of normal system opera-
tion, calibration information is provided in the event that you are required to perform a sys-
tem calibration.
To calibrate the system proceed as follows:
•
First perform a
calibration of the detector
and check the images for bad pixels.
•
If you observe any bad pixels, perform a
creation of the pixel map
and do a
calibration
of the detector
afterwards.
If you have to troubleshoot an image quality problems, please see the chapter "Trouble-
shooting Image Quality" on Page 12 - 1.
Calibration of detector
9
The detector captures charge in its TFT, which is then carried as an electronic signal
through charge amplifiers and analog-to-digital conversion to generate a digital signal.
While the charge amplifiers are matched, small differences in their performance can result
in differences in the X-ray densities detected for the same amount of X-ray.
Performing calibration allows the system to detect these small differences, along with
other variables that can affect the digital signal output. The system can then apply adjust-
ments to the output data to compensate for these differences.
When to Calibrate the detector
Calibration of the detector must be done:
•
Once every two weeks.
•
When the Detector has been powered off.
•
When the room temperature has varied more than
±3°C
(±5.4°F) from the last
calibration.
Proceed as follows:
1.
Log into local service
Options -> Service -> Local Service.
Calibration must not be performed for at least one hour "after" the
Detector has been powered on to allow it to warm up.
Make sure that no patient is registered before you start the Gain
Calibration.
The Service Level 1 or higher is necessary to do the Gain Calibra-
tion.
NOTE
NOTE
NOTE