Radiant energy – Automatic/serial detection of similar sources
Patent
1991-09-23
1993-03-16
Hannaher, Constantine
Radiant energy
Automatic/serial detection of similar sources
G01T 708
Patent
active
051947331
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a multipurpose gamma counter enabling measurement of one sample at a time or alternatively two or more samples at a time.
Gamma counter measurements of radioactive samples are commonly conducted using either RIA (Radio Immuno Assay) devices, then the question usually being of a mass survey, or research devices, the question being of a single research of a small series only. RIA devices must be fast and therefore they handle several samples simultaneously. A research device need not be so fast but samples may, instead, be in containers or cassettes of different sizes. The radioactive isotope of the samples may also emit high energy radiation and therefore the detector of a research device must be larger and the lead shield must be much better than in a RIA device.
Either well-type or diametrically through hole-type detectors are generally used in counters. Well-type detectors are provided with a hollow, formed in the detector material, in which the sample is inserted. In hole-type detectors a hole goes through the detector material into which the sample is lifted. A well-type detector is easier to manufacture. It also has better efficiency and it is easier to shield than a hole-type detector.
Known gamma counters have been disclosed e.g. in the U.S. Pat. publications 4 029 961 and 4 035,642. In these devices, the sample vials to be measured have been placed in cassettes of ten vials and the measuring device takes one cassette at a time for measuring. As there are ten gamma detectors in the device, all samples vials in the cassette can be measured simultaneously. However, this kind of device is only suitable for use in RIA measurements because it would because too large and expensive for use in research if manufactured using know techniques. Moreover, one cannot use a well-type detector in this kind of device because the sample is lifted into the detector.
For economical reasons, research devices have only one large and well shielded detector. Since it has not been possible to combine RIA devices and research devices, those isotope laboratories which want to do both RIA counting and actual gamma research have been forced to purchase two separate counters. Therefore, for economical reasons, counters are also manufactured with 1, 2, or 4 detectors. They are larger and better shielded than necessary in actual RIA work and therefore they can, to a certain extent, be also used in research work. However, the drawback in RIA work is lower speed compared to actual RIA devices and limited efficiency in research work. Furthermore, the volume of samples cannot exceed that of RIA samples.
The object of this invention is to provide a new gamma counter which does not have the above mentioned drawbacks. The gamma counter according to the invention is characterized in that the measuring unit and/or the grip unit of the sample containers are fully or partly formed of replaceable modules so that one or more necessary modular units can be fitted on the gamma counter depending on the measuring method in use at each time.
The object of the invention is also to provide a new method for sample handling in gamma measuring. The method is characterized in that samples are moved to such a gamma counter which has at least two measuring chamber modules (51, 52), at least one of which is a research measuring chamber module (51) and at least one is a RIA measuring chamber module (52), that every sample in the gamma counter is identified whether the sample in question is a research sample or a RIA sample, that samples identified as research samples are moved one at a time into the detector of the research measuring chamber module (51) for measuring, and that samples identified as RIA samples are moved many at a time into the detector of the RIA measuring chamber module (52) for measuring.
Thus the best method can always be chosen depending on the situation. The sample containers for research samples can be in cassettes of different sizes, but sample containers for RIA samples can be only in cassettes of the same si
REFERENCES:
patent: 3855473 (1974-12-01), Burgess et al.
patent: 4005292 (1977-01-01), Oesterlin et al.
patent: 4057148 (1977-11-01), Meyer et al.
Glick Edward J.
Hannaher Constantine
Wallac Oy
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