Radiant energy – Invisible radiant energy responsive electric signalling – With or including a luminophor
Patent
1989-08-07
1990-12-04
Fields, Carolyn E.
Radiant energy
Invisible radiant energy responsive electric signalling
With or including a luminophor
250368, G01T 120
Patent
active
049755838
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
The present invention relate$ to the detection of radioisotopes in fluids and is applicable, for example, to any requirement for measuring the time of arrival of a radioactively labelled slug of fluid at a fixed point in a system.
Such a requirement exists in the field of gas/liquid chromatography and FIG. 1 schematically illustrates a conventional radioisotope detection technique employed in known chromatography columns. Such columns are widely used to analyse radioisotope-labelled molecules (such as proteins) contained in a liquid carrier flow on the basis of their time of transit down a long narrow conduit 2. After transit down the conduit 2 the different molecular species arrive at a detector zone 4 at different times where they are monitored by a scintillation counting technique. In known columns the detector zone 4 comprises a packed powder of crystalline phosphor (commonly P47 Ce.sup.3+ doped yttrium silicate) or powdered scintillating glass (i.e. glass doped with scintillating material). The light output from the detector zone 4 is monitored through the glass wall of the conduit 2 by a photomultiplier 6 or the like. Disadvantages associated with this technique are, firstly, that the powder packing density and powder particle size distribution are limited by the need to avoid clogging up the column or creating a back pressure and, secondly, that much of the emitted light from the detector zone 4 is lost by internal scatter and self-absorption within the powder or glass grains, so reducing the sensitivity of the apparatus.
It is an object of the present invention to obviate or mitigate the aforesaid disadvantages.
According to a first aspect, the invention provides a method of detecting radioisotopes contained within a fluid, wherein at least one scintillating optical fibre is immersed within said fluid and the light emitted from at least one end of said fibre is monitored by light detecting means.
Preferably, a plurality of fibres is used and the light emitted from each end of the fibres is monitored.
Preferably also, the diameter of the fibres is selected according to the type and energy of radiation emitted from the radioisotope being used and the scintillating material with which the fibres are doped is selected to suit the spectral characteristics of the light detecting means. The fibres are preferably also unclad.
The fluid is preferably also flowed past the fibres and fibres are preferably oriented either substantially along the direction of flow of the fluid or transversely to said direction of flow.
Preferably also, light detecting means are provided at either end of the fibres. The outputs from the light detecting means may be summed to give an output of amplitude proportional to the amount of radioactivity in contact with the fibres, or, in the case where the fibres are oriented transversely to the direction of fluid flow, the outputs from the light detecting means are used to determine the transverse position from which a pulse of light is emitted.
According to a second aspect, the invention provides an apparatus for detecting radioisotopes contained within a fluid comprising at least one scintillating optical fibre having at least one end thereof coupled to light detecting means.
Preferably, said apparatus includes a plurality of fibres coupled to said light detecting means.
Preferably also, both ends of said fibres are coupled to light detecting means.
Alternatively, one end of said fibres is coupled to light detecting means and the other end thereof is mirrored.
Preferably also, said fibres are unclad and the ends thereof are fused together.
Preferably also, the outputs from said light-detecting means are connected to summing means.
Preferably also, said fibres are located within a conduit along which said fluid is flowed, the ends of said fibres passing through the walls of the conduit and coupled to said light detecting means externally thereof.
Preferably also, the fibres within said conduit are oriented substantially along the direction of fluid flow. Alternatively, th
REFERENCES:
patent: 3169187 (1965-02-01), Stone et al.
patent: 4598202 (1986-07-01), Koechner
Engstrom,"Improvements in Photomultiplier and TV Camera Tubes for Nuclear Medicine", IEEE Trans. Nucl. Sci, NS-24 (2), Apr. 1977, pp. 900-903.
Sansom et al, "A Simple Device for the Scintillation Counting of Aqueous Solutions of Calcium-45 and Other .beta.-Emitting Isotopes", Nature, vol. 211, Aug. 6, 1966, p. 626.
Vol. 16, No. 9 of IBM Technical Disclosure Bulletin of Feb. 1974, entitled "Image Intensifier", R. W. Dreyfus.
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