Data processing system employing quench simulation for enabling accurate computation of sample activity levels in liquid scintillation spectrometry

Claim 3

A method as set forth in claim 1 wherein said quench correlation parameter is measured for a plurality of standard materials having different degrees of quenching, and the value of the quench correlation parameter measured for the sample is compared with the value of the quench correlation parameter measured for a selected one of said standard materials.

Claim 4

A method as set forth in claim 1 wherein step (a) also includes determining the counting efficiency for said standard material, so that the counting efficiency is accurately known when the value of the quench correlation parameter measured for said sample is adjusted to the value of the quench correlation parameter determined for said standard material.

Claim 5

A method as set forth in claim 1 wherein said control signal is a quench simulation signal.

Claim 6

A method as set forth in claim 1 wherein the operating parameter that is adjusted in response to said control signal is a parameter that affects counting statistics.

Claim 7

A method as set forth in claim 5 wherein said operating parameter is the light input to light transducers employed for measuring said quench correlation parameter.

Claim 8

A method as set forth in claim 6 wherein said operating parameter is adjusted by incrementally moving said light transducers relative to said sample.

Claim 9

A method as set forth in claim 6 wherein said operating parameter is adjusted by interrupting the passage of light photons to said light transducers.

Claim 10

A method as set forth in claim 1 wherein said quench correlation parameter is net external standard ratio.

Claim 11

A method as set forth in claim 1 wherein said quench correlation parameter is net external standard count.

Claim 12

A method as set forth in claim 1 wherein said quench correlation parameter is channels ratio.

Claim 13

Apparatus for measuring the radioactivity of a sample containing at least one radioactive isotope disposed in a liquid scintillation medium comprising the combination of a. means for determining a selected quench correlation parameter for a standard material, b. means for measuring said selected quench correlation parameter for a quenched sample, c. means for terminating the measuring of the selected quench correlation parameter for said sample and generating an output signal representing the difference between the value of the quench correlation parameter determined for the standard material and the value of the quench correlation parameter measured for said sample, d. means for generating a control signal as a function of said output signal and representing an adjustment required of an operating parameter to make the value of the quench correlation parameter measured for said sample substantially equal to the value of the quench correlation parameter determined for the standard material, e. means for adjusting said operating parameter in response to said control signal, and f. means for measuring the activity level of said sample after said adjustment of said operating parameter.

Claim 14

Apparatus for measuring the radioactivity of a sample containing at least one radioactive isotope disposed in a liquid scintillation medium comprising the combination of a. means for determining a selected quench correlation parameter for a standard material, b. means for measuring said selected quench correlation parameter for a quenched sample, c. means for terminating the measuring of the selected quench correlation parameter for said sample and generating an output signal representing the difference between the value of the quench correlation parameter determined for the standard material and the value of the quench correlation parameter measured for said sample, d. means for generating a control signal as a function of said output signal and representing an adjustment required of an operating parameter to make the value of the quench correlation parameter measured for said sample substantially equal to the value of the quench correlation parameter determined for the standard material, e. means for adjusting said operating parameter in response to said control signal, and f. means for measuring the activity level of said sample after said adjustment of said operating parameter.

Claim 15

Apparatus as set forth in claim 12 wherein the operating parameter tHat is adjusted in response to said control signal is a parameter that affects counting statistics.

Claim 16

Apparatus as set forth in claim 12 wherein said adjusting means adjusts the light input to light transducers employed for measuring said quench correlation parameter.

Claim 17

Apparatus as set forth in claim 14 wherein said adjusting means incrementally moves said light transducers relative to said sample.

Claim 18

Apparatus as set forth in claim 14 wherein said adjusting means interrupts the passage of light photons to said light transducers.

Claim 19

Apparatus for optimizing counting conditions in test samples containing n radioactive isotopes (where n is any whole integer) disposed in a liquid scintillator with each isotope being of the type that produces an observable energy spectrum, said apparatus comprising a light transducer, means for positioning a sample adjacent said transducer in light transmissive relationship therewith, means for measuring a selected quench indicating parameter indicative of the quench level of the sample, n pulse height analyzers for analyzing pulses emanating from said transducer, said n pulse height analyzers each including means for discriminating pulses on the basis of pulse heights, and means responsive to the value of said measured quench indicating parameter for automatically adjusting the relationship between said discriminating means and the observed spectrum for each isotope to one of a plurality of predetermined, preset relationships in response to the value of said measured parameter.

Claim 20

Apparatus for optimizing counting conditions in test samples containing n radioactive isotopes (where n is any whole integer) disposed in a liquid scintillator with each isotope being of the type that produces an observable energy spectrum, said apparatus comprising a light transducer, means for positioning a sample adjacent said transducer in light transmissive relationship therewith, means for measuring a selected quench indicating parameter indicative of the quench level of the sample, n pulse height analyzers for analyzing pulses emanating from said transducer, said n pulse height analyzers each including means for discriminating pulses on the basis of pulse heights, and means responsive to the value of said measured quench indicating parameter for automatically adjusting the relationship between said discriminating means and the observed spectrum for each isotope to one of a plurality of predetermined, preset relationships in response to the value of said measured parameter.

Claim 21

Apparatus as set forth in claim 17 further characterized in that said parameter is net external standard ratio.

Claim 22

Apparatus as set forth in claim 17 further characterized in that said adjusting means includes convergence means for causing said measured quench indicating parameter to converge to a particular one of a plurality of values of said measured parameter for each of which values isotope counting efficiencies are known.

Claim 23

Apparatus as set forth in claim 19 further characterized in that said convergence means is operable in response to the value of said measured parameter to impose a simulated quench condition upon each sample sufficient to create an effective quench level for the sample identical to one of said values, so that absolute sample activity levels are computed at accurately known counting efficiencies corresponding to the particular one of said values.

Claim 26

The method as set forth in claim 21 further characterized in that said automatic adjusting step includes the step of imposing a simulated quench condition upon the test sample for the purpose of creating a preselected effective quench level for which counting efficiencies are accurately known.

Claim 27

The method as set forth in claim 22 further characterized in that the degree of simulated quench imposed upon the sample is controlled as a function of the value of said measured parameter.