Fluke Biomedical 8000 Victoreen - Manual (Page 24)

Victoreen 8000
Operators Manual
2-12
2.5.1 Radio Mode
Radio mode is primarily used to make measurements on tungsten target, aluminum filtered radiographic
x-ray machines. Radio mode simultaneously measures kVp, exposure, exposure time and mAs from a
single radiographic exposure. A measurement delay of up to 999 milliseconds may be used to delay the
start of kV data acquisition in order to skip over waveform anomalies at the beginning of an exposure.
See "Using a Measurement Delay" (at the end of this section) for more information on using a
measurement delay. The percentage of peak kV over which exposure time is measured may be selected
from 90%, 80%, or 75% of the kV peak. In addition, exposure time may be measured between zero
crossings or x-ray pulses may be counted (for single-phase generators). See "Using %kV and Exposure
Time Measurements" (at the end of this section) for more information about using %kV.
Generally, to measure radiographic exposures, choose a filter card (kV) setting such that the measured
(or expected) kV is in the upper end of the filter range. For instance, use the 50 - 100 kVp range instead
of the 80 - 160 kVp range to make measurements at 80 kVp. Staying in the upper end of the filter's kVp
range improves the signal to noise performance of the NERO mAx and allows the NERO mAx to "receive"
more of the radiation output that improves its measurements accuracy. Also, start out in low sensitivity, if
a channel A or B overrange occurs, switch to the next kVp filter range. If the NERO mAx does not
respond to an exposure and displays "MAKE EXPOSURE", switch to high sensitivity.
Radio mode may also be used to make measurements on dental x-ray generators. When using the
NERO mAx with dental x-ray machines, follow the instructions in section "Positioning the Detector" to
properly locate the detector. Generally, low sensitivity should be used, however if the NERO mAx does
not respond to an exposure, switch to high sensitivity. Select the proper %kV for the type of generator
being tested, generally ZERO or 1ØPULSE modes are needed for self-rectified generators, 75%, 80%, or
90% may be needed for three phase and medium to high frequency generators. If necessary, use a
measurement delay in order to disregard any filament preheat effects at the beginning of an exposure.
See "Using a Measurement Delay" and "Using %kV and Exposure Time Measurements" at the end of this
section for more information about using the %kV and measurement delay functions.
To make a radiographic measurement
Make sure that the Model 8000 is turned off. Plug one end of the Model 8000's detector cable into the
Model 8000 detector. Plug the other end of the detector cable into the Model 8000's detector connector.
Insert the W/Al filter card into the detector and place the filter card in the correct position for the kV range
to be measured. Place the Model 8000 detector on the x-ray table with the top of the detector facing the
x-ray tube. Position the detector so that the detector is centered in the beam and is aligned with the x-ray
tube axis. If mAs measurements are to be made, plug the mAs cable into the 8000 detector's mAs input
and connect the mAs leads to the generators mAs terminals. For more information on positioning the
Model 8000 detector, see section "Positioning the Detector".
WARNING
Extreme caution should be used when making
connections to the mAs terminals of the X-ray
generator or detector. Improper connections may
result in injury, damage to the NERO mAx, and/or
damage to the x-ray generator.
If results are to be printed, plug the printer cable into the printer port at the rear of the Model 8000 then
plug the other end of the printer cable into the printer and turn the printer on (see Section 1.5--Printing).
Plug the AC adapter into the 8000 if needed (see Section 1.4--Battery Operation and Charging) and turn
the instrument on.