Quantitation of gamma and x-ray emitting isotopes
AssigneeBioTraces, Inc.
InventorAndrzey K. Drukier
Life of this patent
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Abstract
For isotopes decaying by capture of an inner shell electron by the nucleus, coincident emission of X-ray and gamma photons may occur. The X-ray results from the drop of an outer shell electron to fill the S shell. The gamma results from the transition of the excited daughter nucleus to a lower energy state. The invention disclosed is a Coincident Gamma and X-ray Detector (CGXD) which achieves extraordinary background rejection by a synergistic combination of coincident counting and other background suppression measures. Whereas the background registered by single gamma counters is of the order of 20-40 counts per minute, a CGXD optimized for the electron capture radioisotope I.sup.125 has a background of about one count per day.
Claims91
A method for quantifying a coincident gamma/x-ray (CGX) emitter in a sample, comprising:
- (a) placing the sample between separate radiation detectors and suppressing background radiation by shielding the detectors in a composite radiation shield and separating the detectors with a separator that absorbs x-rays,
- (b) and obtaining outputs from the radiation detectors comprising coincident and non-coincident output pulses, the coincident output pulses comprising pulses characteristic of coincident gamma and x-ray emissions from the CGX emitter,
- (c) analyzing the shape and height of the pulses on-line,
- (d) discriminating and rejecting non-coincident pulses,
- (e) discriminating and rejecting coincident pulses that do not match the characteristics of emissions from the CGX emitter, and
- (f) using the remaining coincident pulses to quantify the presence of as little as 100 pCi of the CGX emitter in the sample, wherein background is reduced to about one count per hour.
A method for selective quantitation of a coincident gamma/X-ray (CGX) emitter in a sample, comprising:
- (a) placing the sample between separate radiation detectors and obtaining outputs from the radiation detectors comprising coincident and non-coincident output pulses, the coincident output pulses comprising pulses characteristic of coincident gamma and x-ray emissions from the CGX emitter,
- (b) analyzing the shape and height of the output pulses from the detectors,
- (c) discriminating and rejecting non-coincident output pulses,
- (d) discriminating and rejecting coincident output pulses that are not characteristic of coincident gamma/x-ray emissions from the CGX emitter, and
- (e) using the remaining output pulses to quantify the CGX emitter in the sample.
Dependencies are inferred from the claim text.