Radiant energy – Automatic/serial detection of similar sources
Patent
1990-02-01
1991-10-29
Fields, Carolyn E.
Radiant energy
Automatic/serial detection of similar sources
250364, 250368, G01T 1204
Patent
active
050618539
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
Liquid scintillation counters are mainly used for measuring low energy beta radiation emitting samples, which are of, for example, biological or medical interest. The conventional liquid scintillation counters are designed to count samples which are in the sample vials with the scintillation liquid. The volume of the sample vial is typically 6 or 20 milliliters. The sample vials are placed into sample racks, which have separate compartments for individual sample vials. The sample racks are placed on the conveyor of the automatic sample changer system of the counter.
Because the above mentioned liquid scintillation counter is designed to count vials whose volume is up to 20 milliliters, serious difficulties are encountered when the sample volume is a only few hundred microliters or less. Typically, these kind of samples are prepared in small vials, which are inserted into normal vials. In addition, the handling of separate sample vials is very time consuming and includes potential risk of setting the sample vials in incorrect order into the sample racks. The sample changing mechanism of such an instrument is also rather complicated, because the vial must be removed from the sample rack and must be positioned into a light tight radiation detection chamber, and after counting it must be returned back into the sample rack.
In addition to the above mentioned conventional liquid scintillation counters, one special purpose liquid scintillation counter exists, namely 1205 Betaplate, which is manufactured by Wallac Oy, Finland. This instrument is designed to count liquid scintillation samples directly from a filter mat, which is sealed into a plastic bag with a small amount of scintillation liquid. On the same filter mat there can be up to 96 samples, and six samples are counted at a time.
SUMMARY OF THE INVENTION
The present invention shows a new apparatus which counts liquid scintillation or corresponding samples directly from the sample plates which comprise several separate sample wells or vials. A typical plate of this kind is produced by a vacuum thermoforming process (deep drawing) from transparent material) and has eight rows of wells arranged in twelve columns. The typical volume of the sample wells of such a 96-well sample plate is 200-400 microliters. Another type of plate has four rows of wells arranged in six columns. The volume of the wells of such a 24-well sample plate exceeds one milliliter. In addition, sample plates with two rows of wells arranged in three columns are available. The volume of the wells of such a 6-well sample plate is about 10 milliliters. Thus the apparatus according to the present invention is designed to count samples (including liquid scintillant), the volume of which is from a few microliters up to ten milliliters.
BRIEF DESCRIPTION OF THE DRAWINGS
The apparatus according to the present invention will be described in detail with reference to the attached drawings, wherein
FIG. 1 is a perspective view showing the general principle of the apparatus according to the present invention.
FIG. 2 shows a vertical section of the counting conditions.
FIG. 3a shows a vertical section of the counting conditions, where the plate holder is equipped with gamma radiation sensitive detectors.
FIG. 3b shows a section along the line A--A in FIG. 3a.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
In FIG. 1 a sample plate (10), which has several sample wells (11), is placed in the counting position or before the counting position manually or automatically on a rigid plate holder (12) made of photon attenuating material and having holes (13) for the wells of the sample plate. In order to count one or several samples at a time, the apparatus has one or several detectors, built of two photomultiplier tubes (14) working in cooperation and are situated on the opposite sides of the plate holder (12). The apparatus has a mechanism, (which is not shown here), which presses said photomultiplier tubes in the down position tightly against said sample plate in order to form a
REFERENCES:
patent: 3898460 (1975-08-01), Noakes et al.
patent: 4298796 (1981-11-01), Warner et al.
patent: 4659222 (1987-04-01), Ekholm
patent: 4933554 (1990-06-01), Lehtinen et al.
Lehtinen Kauko
Sonne Vesa
Yrjonen Tapio
Fields Carolyn E.
Philpitt Fred
Wallac Oy
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