Fluke Biomedical 07-479 - Manual (Page 14)

Victoreen 07-479
Operators Manual
4-2
A high mAs condition indicates that the beam intensity is too high and the measurement is completed with
less than 50 ms of the radiation waveform. The resulting measurements may be less accurate than those
obtained with longer sample times. This is especially true in the case of single-phase x-ray machines
where the radiation spectrum changes dramatically throughout the duration of a pulse. For example, if the
measured waveform contains less than six pulses of single-phase rectification, then a partial pulse can
have a significant contribution to the value of the average of the pulses. The effect is not as great for
three phase machines because the radiation spectrum remains relatively constant throughout the
exposure. To improve accuracy, the user should either increase distance or decrease the mA, both of
which will reduce the beam intensity.
A low mAs condition indicates that the exposure is less than the required value to make a measurement.
The user should either increase time or mA or decrease distance for the particular kVp setting. Refer to
Section 3 for a discussion of minimum mAs requirements.
The auto reset on the front panel will turn on whenever the kVp meter detects an x-ray exposure. The
LED will remain lit for 0.5 seconds or for the duration of the exposure, whichever is greater. The previous
reading is cleared when the LED lights.
Switches
The power switch and the phase switch are located on the front panel. The power switch is used to turn
the unit on or off. A phase switch allows selection for single phase and three phase applications.
4.2 Top Panel
The top panel of the kVp meter contains the following information:
• A brief set of operating instructions.
• An indication as to where to center the beam, referred to as the target.
• Display guide for A, B, C, and D decimal point indications as discussed above.
4.3 Rear Panel
The battery access panel and a BNC connector are located on the rear panel. Refer to Section 3 for
battery replacement procedures. The BNC connector allows the user to connect an oscilloscope to the
kVp meter to view the signal from the radiation detection diodes. The signal can be observed on the
oscilloscope for the duration of the exposure. A storage scope or camera is necessary to view the signal
for extended periods of time.