Fluke Biomedical 8000 Victoreen - Manual (Page 59)

Calibration
General
3
3-1
Section 3
Calibration
3.1 General
The serial numbers of the NERO mAx control console unit, detector and filter slides must be matched in
order to obtain accurate results. Since the control console unit, detector and filter slides are calibrated
together, they must be used together for accurate measurements.
The NERO mAx is factory calibrated for kV with reference to calibrated voltage dividers. The voltage
dividers used in the calibration of the NERO mAx are calibrated on a routine basis and the calibrations
are N.I.S.T. traceable.
The NERO mAx’s internal ion chamber is factory calibrated to provide accurate exposure and rate
measurements over the entire kVp range of the NERO mAx. These exposure and rate measurements
are adjusted by applying energy dependent correction factors that are determined by comparison to
applicable N.I.S.T. techniques. In addition to the factory calibration, a user entered multiplier is available
for exposure and rate measurements made with the NERO mAx’s internal ion chamber. The application
of calibration factors to an individual measurement is the responsibility of the user and care must be
exercised in interpolation or extrapolation of the calibration factors.
The NERO mAx is factory calibrated for mA with reference to a calibrated current source. Equipment
used to calibrate the current source is calibrated on a routine basis and the calibrations are N.I.S.T.
traceable.
A calibration report is provided with each NERO mAx. This calibration report contains the NERO mAx’s
calibration data as well as the recommended re-calibration date. Copies of calibration reports can be
obtained by contacting Fluke Biomedical at 440.248.9300
The NERO mAx must be returned to an authorized calibration facility for re-calibration
3.2 Calibration Check
Radio mode is used to make routine kV calibration constancy checks of the NERO mAx. In this mode,
the detector ratios are displayed instead of kVp. Several exposures should be made and the results
averaged to eliminate variations in the readings. These detector ratios should be recorded and used for
comparison to determine the constancy of the NERO mAx’s calibration.
At 80 kVp, a 2% change in detector ratio corresponds to approximately a 1% change in measured kVp.
Therefore, the NERO mAx can experience a change in detector ratio of up to 2% at 80 kVp and remain
within its specified accuracy.
Before assuming that the NERO mAx detectors response has changed, proper generator performance
should be verified. Changes in an x-ray machines output waveform can contribute to erroneous results.
For this calibration check to provide valid results, it should be performed routinely on the same x-ray
generator, using the same generator settings.