Manual

If the radiation has a pulsed characteristic, the time is measured until the last pulse ends. The dead time
interval between pulses must, however, be less than the Calc. Delay time (0.5, 2, 4, 6 or 7 s). The R/F low
sensor has an electrical bandwidth of 0.1 kHz (slower rising and falling slopes), causing the displayed exposure
time to be a few milliseconds longer than for the R/F high sensor, which has a bandwidth of 2.5 kHz.
Figure 5. 75 % trig level activated (figure also applies to 25 and 50 % trig level settings). Please note that
the trig level setting aects the dose measurement.
Single phase generators (normally dental applications) may have slowly increasing amplitude characteristics for
approximately 100 ms. It is then recommended to activate a higher trig level in the SETUP MENU after the first
exposure.
PULSE
The RaySafe Xi counts pulses from 1 to 9999. The trigger to increment the pulse counter occurs when the dose
rate has a negative slope and the amplitude falls below 25 % of the peak amplitude for the exposure. At peak
dose rates of approximately < 3 µGy/s (for R/F low) the signal to noise ratio is too low to count pulses and “---”
will be displayed. If possible, increase the mA and/or kVp to increase the radiation output or decrease the FDD.
Pulse is available for the R/F and mA/mAs detectors.
FRAME RATE
The RaySafe Xi calculates frame rate as: (number of pulses -1)/(exposure time in seconds). If pulses can not be
counted, the frame rate can not be calculated (see Pulse section above).
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RaySafe Xi User Manual – Measurement definitions