GAMMA SOURCE DEVICES AND RELATED SYSTEMS AND METHODS
Methods, systems, apparatus, and computer readable program products for determining a count rate linearity of one or more gamma detectors using a single gamma radiation source, by varying the solid angle (and hence the emission rate observed by the detector(s)) between the single gamma radiation source and the one or more detector(s).
1 . A method for determining a count rate linearity of one or more gamma detectors using a single gamma radiation source, the method including, for each detector:
positioning the single gamma radiation source to create a first solid angle between the single gamma radiation source and each of the one or more gamma detectors, where the first solid angle may be different for each of the one or more gamma detectors, and the respective first solid angle for each of the one or more gamma detectors is associated with a first emission rate;
recording a first count rate of the one or more gamma detectors at the respective first solid angle;
positioning the single gamma radiation source to create a second solid angle between the single gamma radiation source and each of the one or more gamma detectors, where the second solid angle may be different for each of the one or more gamma detectors, and the respective second solid angle for each of the one or more gamma detectors is associated with a second emission rate;
recording a second count rate of the one or more gamma detectors at the respective second solid angle; and
determining the count rate linearity of each of the one or more gamma detectors based on the relationship, respectively, of the first and second recorded count rates to the respective first and second emission rates.
2 . The method of claim 1 further comprising comparing the first count rate to a first expected count rate and comparing the second count rate to a second expected count rate.
3 . The method of claim 1 further comprising, after determining the second count rate:
positioning the single gamma radiation source to create a third solid angle between the single gamma radiation source and each of the one or more gamma detectors, where the third solid angle may be different for each of the one or more gamma detectors, and the respective third solid angle for each of the one or more detectors is associated with a third emission rate; and
recording a third count rate of the one or more detectors at the respective third solid angle,
where determining the count rate linearity of each of the one or more detectors is further based on the relationship of the third recorded count rate to the respective third emission rate.
4 . The method of claim 3 further comprising comparing the third count rate to a third expected count rate.
5 . The method of claim 3 further comprising, after determining the third count rate:
positioning the single gamma radiation source to create a fourth solid angle between the single gamma radiation source and each of the one or more gamma detectors, where the fourth solid angle may be different for each of the one or more gamma detectors, and the respective fourth solid angle for each of the one or more detectors is associated with a fourth emission rate; and
recording a fourth count rate of the one or more detectors at the respective third solid angle,
where determining the count rate linearity of each of the one or more detectors is further based on the relationship of the fourth recorded count rate to the respective fourth emission rate.
6 . The method of claim 5 further comprising comparing the fourth count rate to a fourth expected count rate.
7 . The method of claim 1 wherein positioning the single gamma radiation source to create the first solid angle and/or positioning the single gamma radiation source to create the second solid angle is carried out using a positioning mechanism that may be manually manipulated to create the first solid angle and/or the second solid angle.
8 . The method of claim 1 wherein positioning the single gamma radiation source to create the first solid angle and/or positioning the single gamma radiation source to create the second solid angle is carried out using a processor with instructions to cause the single gamma radiation source to be positioned to create the first solid angle and/or the second solid angle.
9 . The method of claim 1 further comprising providing a gamma source device comprising a cylinder, a gamma source holder in the cylinder, and the single gamma radiation source connected to the gamma source holder,
wherein the gamma source holder comprises a screw that is threadingly engaged with an inner diameter of the cylinder, and wherein positioning the single gamma radiation source to create the first solid angle and/or positioning the single gamma radiation source to create the second solid angle comprises rotating the screw.
10 . The method of claim 9 wherein rotating the screw comprises rotating the screw using a hand tool.
11 . The method of claim 9 wherein rotating the screw comprises rotating the screw using a motor operatively connected to the screw.
12 . The method of claim 1 further comprising providing a gamma source device comprising a cylinder, a gamma source holder in the cylinder, and the single gamma radiation source connected to the gamma source holder,
wherein the cylinder is transparent or translucent and comprises a scale comprising a plurality of graduations, and wherein positioning the single gamma radiation source to create the first solid angle and/or positioning the single gamma radiation source to create the second solid angle comprises moving the gamma source to one of the plurality of graduations.