Activity meter
An activimeter (also out of date Curiemeter , after the outdated unit Curie ) is a calibrated measuring device that can display the activity of a measurement sample .
The activimeter is a regular part of the hot laboratory in nuclear medicine facilities. If radionuclides from a generator system are used in diagnostics - for example a technetium-99m generator or a gallium-68 generator - the presence of an activimeter is required in Germany.
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From left to right: test source , glass bottle for radionuclide in aqueous solution, syringe and sample insert.
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View from above into an activimeter bore (embedded in a work surface); left sample insert.
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Activimeters are usually equipped with a bore into which the sample to be measured - for example in a closed syringe - is introduced. This hole represents the anode of a coaxially arranged, cylindrical , gas-filled ionization chamber . An activimeter with such a structure is characterized by constant measuring sensitivity and a large measuring range . Active meters approved in Germany must have at least a measuring range between 370 k Bq and 11 GBq.
Measurement accuracy
Because of the potential use of the measured nuclides on humans, activimeters must have a particularly high measurement accuracy . For all nuclides to be measured, the device must have been calibrated by the manufacturer; the measurement conditions to which the calibration applies must be defined. There must be good linearity and proportionality between sample activity and the displayed measurement result. Deviations of a maximum of 5% are tolerated. The presence of a long-life test source is mandatory. This must be able to be brought into the measuring shaft in a reproducible manner and cause an evaluable display in the measuring range for each selectable radionuclide.
It is important that a suitable, constant measurement geometry is maintained with regard to the volume of the sample and the type of sample container. The device must be able to be operated easily and clearly, for example using preprogrammed buttons, so that the wrong radionuclide cannot be selected.
Quality control
In Germany, DIN 6855 (Part 11) and the “Radiation Protection in Medicine” guideline require constancy tests on working days with regard to the background effect and responsiveness. A recalibration must be carried out by the manufacturer every six years.
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- BO Knoop, SI Ziegler. Radiation physics and measurement technology, quality control. in: Torsten Kuwert, Frank Grünwald , Uwe Haberkorn , Thomas Krause (Eds.) Nuclear Medicine. Stuttgart 2008 ISBN 978-3-13-118504-4
Individual evidence
- ↑ Guideline "Radiation Protection in Medicine" (administrative regulations-im-internet.de); accessed on March 25, 2018.