Voltage measurements are made periodically. The time peri-
od between measurements is accurately calibrated. The
second of two successive values is subtracted from the first
by the microprocessor, which yields the net voltage change
on the capacitor. Because the time interval between meas-
urements is so small, any offset arising from fluctuations in
the electronics is the same for both measurements, and is
automatically compensated for during the subtraction.
DISPLAY UNITS
When you set your dose calibrator to display Activity Values
in Ci (Curies), the conventional system of units, either µCi
or mCi will be indicated next to the numeric display. The
prefix micro or µ (10
-
6
), or milli or m (10
-
3
) is automatically
selected by the system's microprocessor.
For example, if the numeric value displayed is 12.03, and
µCi is indicated, the activity will be 12.03x10
-6
Ci or
0.00001203 Curies; if 63.9 is displayed and mCi indicated,
the activity is 63.9x10
-
3
Ci or 0.0639 Curies.
In the same manner, when you set the dose calibrator to
the international system of units, Becquerels, either MBq or
GBq will be indicated, where the prefix M represents Mega
(10
6
) and G represents Giga (10
9
).
The absolute measurement range of the Atomlab Dose
Calibrator is from 0.01 µCi to 9.999 Ci of Tc-99m (and the
equivalent in Becquerels).
For example, 12.03 µCi = .445 MBq and 63.9 mCi = 2.36
GBq. If the numeric display reads 0.445 and MBq is indicat-
ed, the activity value is 445,000 Becquerels; if 2.36 is dis-
played and GBq indicated, the activity is 2,360,000,000
Becquerels.
ATOMLAB Dose Calibrator Operation Manual Chapter 4
Biodex Medical Systems 4-4 Release 2.0
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