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February 5, 2004
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Calibrating the AEC
This chapter describes how to calibrate the AEC by generating a goal table for a
desired target/filter combination and loading it into the DirectRay Power and X-ray
Control Module (PXCM).
You use the AEC Calibration Tool to perform the calibration.
When AEC Calibration Should Be Performed
AEC calibration should be performed:
•
As part of the initial system installation.
•
Once a year.
•
If changes are made to any of the DirectRay components or the Generator (for
example, if the PXCM is replaced).
The Three Calibration-Related Procedures
The purpose of the AEC calibration is to determine a valid mAs value and, using
that value, take a series of exposures to generate goal images. The AEC Calibration
Tool averages the goal images to, in turn, generate and load a goal table into the
PXCM.
There are three calibration procedures, which are performed in sequence:
1. Determining the Half Value Layer (HVL) of the X-ray Generator for a given
target/filter combination (described in “Determining the Half Value Layer
(HVL)” on page 4-5).
2. Using the HVL, determine the Entrance Skin Exposure (ESE; described in
“Determining the Entrance Skin Exposure (ESE)” on page 4-8). The resulting
mAs value is used during the goal image exposure, in the next procedure.
3. Using the mAs value determined in the ESE procedure, generating the goal
image (described in “Generating the Goal Image” on page 4-11), which results
in a goal table being loaded into the PXCM.