The top right four-digit LED Activity Display always
indicates activity in the Detector's Chamber Well, no matter
which keys are pressed. (There are momentary exceptions:
when you press the TEST key, for example.)
To the right of the Activity Display are the units of measure,
e.g., microcuries (µCi). At this time, the display will indicate
some numeric value and the µCi symbol. Also lit is a LED
associated with one of the Isotope Selection keys. When an
isotope is selected, the Atomlab Dose Calibrator is automat-
ically calibrated to display the activity of that isotope. Press
the Tc-99m (or any other Isotope Selection key) and
observe the LED on the key come on (the Tc-99m key may
already be selected). If there is no activity in the Detector,
the displayed value should be about 1.00 µCi or less. This
value may get lower after "warm-up".
The Mo-99 key has a special function for the Moly
Breakthrough test, which is described in Chapters 4 and 5.
The activity reading when you first power up your
dose calibrator may be any value, even negative, as you
have not yet corrected for the background radiation in your
work area. After you use the BKGND key as described below,
and after the dose calibrator has warmed-up, the activity
level should be close to zero (<0.1µCi).
Before activity measurements are normally made, a dose
calibrator requires a background adjustment to assure there
are no errors in the displayed value. The Atomlab Dose
Calibrator automatically stores and subtracts the
Background Value before displaying the activity reading.
With nothing in the Detector but the Chamber Well Liner
and empty Sample Holder, press the BKGND key. The LED
on the key will come ON while background measurements
are made. The LED will go OFF automatically when com-
pleted and the displayed value should be less than 0.1 µCi.
The activity value will remain in memory until the BKGND key
is pressed again or the system is turned OFF.
ATOMLAB Dose Calibrator Operation Manual Chapter 3
Biodex Medical Systems 3-3 Release 2.0
Read the Display
Background
Adjustment
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