AN APPARATUS FOR MONITORING THE RADIOACTIVITY OF A PLURALITY OF LIQUID SCINTILLATION SAMPLES DEPOSITED ON MULTI-WELL SAMPLE PLATES

Abstract: The present invention shows a new apparatus in the field of the liquid scintillation counting. The apparatus counts liquid scintillation or corresponding samples directly from the sample plates (10) which comprise several separate sample wells (11) or vials. The apparatus has one or several detectors for the purpose of counting one or several samples at a time. The sample plate (10) is placed manually or automatically between photomultiplier tube assembly pair (14 a, 14 b) which works in coincidence forming the detector of the apparatus. The lower photomultiplier tube assembly (14 a) is provided with a light pipe (12). The apparatus has a moving mechanism, which can move the lower photomultiplier tube assembly (14 a) with said light pipe to up and down positions. In the up position the walls of the light pipe (12) are pressed tightly against said upper photomultiplier tube assembly (14 a) in order to form an optically closed compartment around the sample well (11) which is in the counting position. In order to prevent light from travelling between the sample wells (11) through the material of the sample plate (10) one or both surfaces between the wells (18) of the sample plate (10) are painted black or this region (18) is treated in some other way which prevents light from travelling between the sample wells (11).

Description: AN APPARATUS FOR MONITORING THE RADIOACTIVITY OF A PLURALITY OF LIQUID SCINTILLATION SAMPLES DEPOSITED ON MULTI-WELL SAMPLE PLATES BACKGROUND OF THE INVENTION Multi-well sample plates which comprise several separate sample wells are widely used as test plates for in vitro analysis. Said plates can be produced for example by vacuum thermoforming (deep drawing) from a transparent plastic sheet and they have for example eight rows of wells arranged in twelve columns. These plates can be used especially for preparing typically low energy beta radiation emitting liquid scintillation samples. Unfortunately, these samples must first be transferred into liquid scintillation counting vials, because existing liquid scintillation counters cannot count samples directly from this kind of multi-well sample plates. SUMMARY OF THE INVENTION The present invention shows a new apparatus which counts one or several liquid scintillation or corresponding samples at a time directly from the multi-well sample plates which comprise several separate sample wells. BRIEF DESCRIPTION OF THE DRAWINGS Figures la and lb show a vertical section of the counting conditions of the apparatus. DESCRIPTION OF THE PREFERRED EMBODIMENTS In Figure la a sample plate (10), which has several sample wells (11) is placed manually or automatically in a position, where a liquid scintillation sample (16), which is in the sample well (11), can be counted.In order to count one or several samples (16), which are in said sample wells (11), at a time, the apparatus has one or several detectors, built of two photomultiplier tube assemblies (14 a, 14 b) which work in coincidence and are situated on the opposite sides of said sample plate (10) . The lower photomultiplier tube assembly (14 a) is provided with a light pipe (12). The inner diameter of this light pipe (12) is equal to or larger than the maximum outer diameter of the sample wells (11). The apparatus has a moving mechanism, which is not shown here, by which said lower photomultiplier tube assembly (14 a) provided with said light pipe (12) can be moved to up or down positions. In Figure la said lower photomultiplier tube assembly (14 a) provided with said light pipe (12) is in down position in order to allow free horizontal movement of said sample plate (10). In Figure lb said lower photomultiplier tube assembly (14 a) provided with said light pipe (12) has been lifted to the up position tightly against said upper photomultiplier tube assembly (14b) in order to form an optically closed compartment around said sample well (11) of the sample plate (10). In order to guide the light from the liquid scintillation samples (16) located in said sample wells (11) to said photomultiplier tubes (14 a, 14 b), the inner surfaces (17) of said light pipe (12) reflects or scatters light. In order to prevent light from travelling between the sample wells (11) inside the material of the sample plate (10), one or both of the surfaces (18) between the wells (11) of the sample plate (10) are painted black or this region (18) is treated in some other way which prevents light from travelling between the sample wells (11) inside the material of the sample plate (10). The invention is not confined to the above embodiments alone, but it may show even considerable variation within the scope of the patent claims.

Claims: WHAT IS CLAIMED IS: 1. Apparatus for counting liquid scintillation samples fro sample plates which comprise several separate sample wells o vials, characterized in that, - the sample plate is placed manually or automatically in the counting position between two photomultiplier tube assemblies which form the detector of the apparatus and which work i coincidence and are situated exactly on the opposite sides o that well of the sample plate which in that time will be counted. - the lower photomultiplier tube assembly is provided with light pipe whose inner diameter is equal to or larger than th maximum diameter of the sample wells of the sample plate. - the lower photomultiplier tube with the light pipe can be move in two positions: in the up position, the walls of the ligh pipe are pressed tightly against said upper photomultiplier tub assembly in order to form an optically closed compartment aroun said sample well which is in the counting position. The dow position of said lower photomultiplier tube assembly with sai light pipe allows free movement of said sample plate in orde to make it possible to move the next sample well to the countin position. - the inner surface of said light pipe is reflecting o scattering in order to guide the light from the liqui scintillation sample to the said photomultiplier tube pair. - the apparatus has one or several detectors in order to coun one or several samples at a time. 2. Apparatus according to claim 1, characterized in that that on or both surfaces of said sample plate between said sample well are painted black or said regions are treated in some other wa to prevent light from travelling between said sample wells insid the material of said sample plate.

Inventors: LEHTINEN KAUKO, SONNE VESA, YRJOENEN TAPIO, LEHTINEN, KAUKO, SONNE, VESA, YRJOENEN, TAPIO
Applicants: PHARMACIA AB, WALLAC OY
Application year: 1989
Main classification: G01T1
IPC codes: G01T1, G01T7