HF Series Generators
Calibration
CA-1036R2
42
2.6.5 PHOTOMULTIPLIER RAD--AEC (DIGITAL RAD) ADJUSTMENT (OPTIONAL)
The Photomultiplier RAD--AEC adjustment can be performed in two ways: one
is the value stored in E23 Memory Location and the other is the high voltage
applied to the Photomultiplier Tube.
The recommended procedure for this adjustment is to store a constant value
in E23 Memory Location and adjust the high voltage applied to the
Photomultiplier Tube.
Value in E23 Memory Location is a common data used for
Photomultiplier AEC Calibration or used for the Fourth Ion
Chamber Calibration (AEC-4).
Perform the following procedure:
1. Enter in “Manual Calibration” mode selecting a Workstation configured
for DSI. Select E23 Memory Location and set a value of “127”. Then enter
in user mode by pressing the “Go to User Mode” button.
2. Set up a Dosimeter as close as possible to the Image Intensifier
Radiation Input to measure the Entrance Image Intensifier Exposure
Dose Rate. Position the Probe at the center of the primary beam with the
entire active volume within the primary beam. Select the Field of View
for the Image Intensifier to have 9” FOV.
Place the Tube-Collimator Assembly at the normal SID (1 meter).
Collimate the X-ray beam so it completely covers the Image Intensifier
field but does not extend beyond limits of the phantom.
3. Place 2 mm of Copper (or equivalent homogeneous phantom) in the
Collimator Filter Holder. (1 mm Copper
≃
10 cm Plexiglass or Water).
4. Select on the Console:
G RAD Menu: 70 kV, 200 mA Large Focus (or the first mA station for
Large Focus if 200 mA station is set for Small Focus) and 1 second
back-up time.
G AEC Menu: “Central Area”,“Density 0” and “Medium
Film/Screen”.
Note .
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