Siemens MAMMOMAT NovationDR, Installation Instructions Manual, Page: 80 / 95

February 5, 2004
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Maintaining Image Quality
This chapter contains information to help maintain acceptable image quality.
DirectRay Detector Calibration
While calibration is typically performed by the customer as part of normal system
operation, calibration information is provided in the event that you are required to
perform a system calibration.
What Calibration Does
The DirectRay 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 adjustments to the output data to compensate for these differences.
When to Calibrate the DirectRay Detector
Calibration of the DirectRay Detector must be done:
•
Once a week.
•
When the Detector has been powered off.
NOTE: Calibration must not be performed for at least one hour after the Detector has been powered
on to allow it to warm up.
•
When the room temperature has varied more than ±3°C (±5.4°F) from the last
calibration.
NOTE: Calibration must always be performed according to Siemens Calibration Instructions.