Radiant energy – Automatic/serial detection of similar sources
Patent
1991-09-23
1993-12-07
Hannaher, Constantine
Radiant energy
Automatic/serial detection of similar sources
G01T 708, G01T 702
Patent
active
052685748
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to a transfer device for cassettes containing radioactive samples in a gamma counter provided with at least one well-type detector, the transfer device for the cassettes comprising a transfer unit or a path, which is a table provided with at least one conveyor, by which the cassettes of different widths, containing sample containers of different sizes, can be moved one at a time to a lifting position wherefrom the sample containers can be lifted into the measuring unit for measuring.
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 and 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. No. 4,029,961 and 4,035,642. In these devices the sample containers to be measured have been placed in cassettes of ten containers and the measuring device takes one cassette at a time for measuring. As there are ten gamma detectors in the device, all samples in the cassette can be measured simultaneously. However, this kind of device is only suitable for use in RIA measurements because it would become too large and expensive for use in research if manufactured using known technique. 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.
SUMMARY OF THE INVENTION
The object of this invention is to provide a new transfer device for cassettes, being of different sizes and containing radioactive samples. The invention is characterized in that, at the lifting position, one vertical long side of the cassette is locked in place against the edge of the table so that the distance of the center of the sample container in the cassette from the edge of the table is principally directly proportional to the radius of the sample container.
The object of the invention is also a cassette system for use in the transfer device presented above. The cassette system comprises at least two different cassettes, being of the same length but differing from each other principally in that cassettes can take a different number of adjacent sample containers depending on their size, the sample containers in the same cassette being of the same size with each other.
The invention is characterized in that the width of the cassette is principally directly proportional to the width of the sample c
REFERENCES:
patent: 4122936 (1978-10-01), Johnson
patent: 4454939 (1984-06-01), Kampf et al.
patent: 4924093 (1990-05-01), Johnson et al.
Aalto Juhani
Hakala Olli
Glick Edward J.
Hannaher Constantine
Wallac Oy
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