Source: http://www.google.com/patents/US7795590?ie=ISO-8859-1
Timestamp: 2014-12-28 08:22:41
Document Index: 382713705

Matched Legal Cases: ['art 36', 'art 36', 'art 36', 'art 36', 'art 36', 'art 36', 'art 36']

Patent US7795590 - Nuclear medical diagnosis apparatus - Google PatentsSearch Images Maps Play YouTube News Gmail Drive More »Sign inAdvanced Patent SearchPatentsA PET apparatus comprises a plurality of detector units in the circumferential direction, wherein the detector unit includes a plurality of unit substrates therein, and wherein the unit substrate includes: a plurality of detectors upon which a γ-ray is incident; and an analog ASIC and digital ASIC for...http://www.google.com/patents/US7795590?utm_source=gb-gplus-sharePatent US7795590 - Nuclear medical diagnosis apparatusAdvanced Patent SearchPublication numberUS7795590 B2Publication typeGrantApplication numberUS 11/861,977Publication dateSep 14, 2010Filing dateSep 26, 2007Priority dateSep 29, 2006Fee statusPaidAlso published asUS7964849, US8148695, US20090114826, US20100282974, US20110215254Publication number11861977, 861977, US 7795590 B2, US 7795590B2, US-B2-7795590, US7795590 B2, US7795590B2InventorsIsao Takahashi, Takafumi Ishitsu, Yuichiro Ueno, Tomoyuki SeinoOriginal AssigneeHitachi, Ltd.Export CitationBiBTeX, EndNote, RefManPatent Citations (18), Non-Patent Citations (1), Referenced by (8), Classifications (12), Legal Events (2) External Links: USPTO, USPTO Assignment, EspacenetNuclear medical diagnosis apparatusUS 7795590 B2Abstract A PET apparatus comprises a plurality of detector units in the circumferential direction, wherein the detector unit includes a plurality of unit substrates therein, and wherein the unit substrate includes: a plurality of detectors upon which a γ-ray is incident; and an analog ASIC and digital ASIC for processing a γ-ray detection signal outputted by each of the detectors. The analog ASIC includes two slow systems having mutually different time constants, each of which outputs a pulseheight value. A noise determination part of the digital ASIC determines whether a relevant detection signal is an intended γ-ray detection signal or a noise based on a correlation between the pulseheight values, and a noise counting part counts the number of times of noise determination, and a detector output signal processing control part controls the signal processing with respect to an output signal from a relevant detector based on the count.
BACKGROUND OF THE INVENTION The present invention relates to nuclear medical diagnosis apparatuses, and in particular relates to a positron emission computed tomography apparatus (hereinafter, referred to as a PET apparatus) that is one type of the nuclear medical diagnosis apparatuses using radiation detectors, a single photon emission computed tomography apparatus (hereinafter, referred to as a SPECT apparatus), and a γ-camera using γ-rays passing through a test object.
SUMMARY OF THE INVENTION The present invention has been made in view of the above problem, and it is an object of the present invention to provide a nuclear medical diagnosis apparatus that can, even without disposing multiple layers of radiation detectors, determine an abnormal radiation detector during image pickup and eliminate an adverse effect on the generated image due to a noise signal from the radiation detector.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showing the configuration of a PET apparatus as a nuclear medical diagnosis apparatus concerning a first embodiment of the present invention.
DESCRIPTION OF THE INVENTION First Embodiment Next, a nuclear medical diagnosis apparatus, which is a suitable embodiment of the present invention, will be described suitably referring to the accompanying drawings.
Incidentally, since it takes a certain amount of processing time for the slow systems 24B, 24C to calculate the pulseheight values, these are named as �slow�. A signal outputted from the detector 21 and passing through the capacitor 22 is amplified by the preamplifier 24 a, and is outputted as the γ-ray detection signal VB, and is further amplified by the waveform shaper circuits 24 d, 24 f, and is inputted to the peak hold circuits 24 e, 24 g as the signals VS1, VS2, respectively. The peak hold circuit 24 e holds a maximum value of the waveform-shaped γ-ray detection signal VS1 as described later, i.e., the pulseheight value VE1 proportional to an energy value of the detected γ-ray. The peak hold circuit 24 g holds the pulseheight value VE2 of the waveform-shaped γ-ray detection signal VS2 corresponding to the amount of electron contribution of the γ-ray detection signal VB as described later.
If a γ-ray is incident upon the detector 21 and absorbed, an electron-hole pair corresponding to the absorbed γ-ray energy will be generated, and the electron and hole are induced by an electric field applied by the high voltage power supply 27, and thereby the electron will transfer to the anode A side and the hole will transfer to the cathode C side. This transfer of the electron and the hole results in the current pulse IA occurring at the input side of the preamplifier 24 a. Since the detector 21 has a finite size, the output signal waveform of the current pulse IA varies depending on a position where a γ-ray is absorbed. This is because if a γ-ray is incident upon the vicinity of the cathode C of the detector 21, the ratio for the generated electrons to contribute to the current pulse IA (hereinafter, referred to as a �contribution of electron�) is large and on the contrary if the generated electrons are absorbed in the vicinity of the anode A, the ratio for the generated electrons to contribute to the current pulse IA is small. Since the mobility (transfer speed) of an electron is typically 10 times or more the mobility of a hole, the waveform (output signal waveform) of the current pulse IA outputted by the detector 21 will vary depending on the position where the electrons and holes are absorbed in the detector 21. If the distance between the anode A and cathode C is denoted by L0 and the distance between the anode A and a place where an electron-hole pair is generated is denoted by Lx, then in the case of Lx/L0=1, the detector 21 detects an energy approximately equal to the current resulting from the transfer of electron. Moreover, in the case of Lx/L0=0.5, the electron and the hole each half contribute to the current. Moreover, in the case of Lx/L0=0, the generated current will substantially depends on the transfer of hole.
Moreover, the noise counting part 36 f has a nonvolatile memory function to store, for eight channels of detectors 21, the number of times a relevant detection signal is determined as a noise signal. Upon input of a noise count signal from the noise determination part 36 e, the noise counting part 36 f will, based on the inputted detector ID, increment the noise count number of the relevant detector ID by one count and stores the same. Then, the noise counting part 36 f checks if the noise count number exceeds a specified reference value for each one increment, and if the noise count number exceeds the specified reference value that is set in advance, the noise counting part 36 f makes �abnormality determination� (determines as faulty) and outputs the detector ID and the abnormality determination to the control part 36 g. The noise counting part 36 f resets to zero the noise count value for the detector ID determined as abnormal, and then newly starts to count.
Effects of First Embodiment The phenomenon that the detection time delays when the position, where the energy of a γ-ray is absorbed, and the contribution of electron inside the detector 21 change as described using FIG. 12A and FIG. 12B, can be uniquely determined if the detected γ-ray energy and the contribution of electron are determined. The same applies to the case where the radiation scatters as described using FIG. 13A to FIG. 13C.
Second Embodiment Next, a nuclear medical diagnosis apparatus, which is another embodiment concerning the present invention, will be described with reference to FIG. 17 to FIG. 20. The nuclear medical diagnosis apparatus of the present embodiment is a SPECT apparatus.
Moreover, the method for determining whether the output signal from a γ-ray detector is an intended γ-ray detection signal or a noise is not limited to the comparison of the pulseheight values of the output signals from the waveform shaper circuits having mutually different time constants described in the first embodiment and second embodiment. For example, as shown in FIG. 5 of the published literature �ASTRONOMY & ASTROPHYSICS SUPPLEMENT SERIES� (122, 357-369, (1997)), the discrimination may be carried out based on a correlation between the pulseheight value of an output signal from a γ-ray detector and the waveform selection (for example, based on the rising characteristics of the waveform).
Patent CitationsCited PatentFiling datePublication dateApplicantTitleUS4670840 *Mar 26, 1986Jun 2, 1987Elscint, Inc.Ring artifact correction for computerized tomographyUS5291293 *Jun 1, 1992Mar 1, 1994Eastman Kodak CompanyElectronic imaging device with defect correctionUS5436659 *Jun 29, 1993Jul 25, 1995Eastman Kodak CompanyMethod and apparatus for determining defective pixel locationUS5473663 *Sep 12, 1994Dec 5, 1995General Electric CompanyMethod for evaluating the performance of detectors in a computed tomography systemUS6047039 *Aug 20, 1998Apr 4, 2000Siemens AktiengesellschaftMethod for post-processing of a tomogram, and computed tomography apparatus operating in accordance with the methodUS6741754 *Feb 19, 2001May 25, 2004Eastman Kodak CompanyCorrecting for defects in a digital image taken by an image sensor caused by pre-existing defects in two pixels in adjacent columns of an image sensorUS7026622 *Apr 2, 2004Apr 11, 2006Hitachi, Ltd.Radiological imaging apparatusUS7109490 *Aug 21, 2002Sep 19, 2006Siemens AktiengesellschaftMethod and medical device designed for implementing this methodUS7297958 *Oct 15, 2002Nov 20, 2007Hitachi, Ltd.Radiological imaging apparatusUS20020012417 *Mar 1, 2001Jan 31, 2002Herbert BruderMethod for reducing line artifacts in a CT image and device for implementing the methodUS20030108147 *Oct 15, 2002Jun 12, 2003Shinichi KojimaRadiological imaging apparatusUS20040135091 *Jul 9, 2003Jul 15, 2004Stefan NolewaikaMethod for exchanging detector modules in an X-ray detector in a computed tomographUS20040190676 *Apr 2, 2004Sep 30, 2004Shinichi KojimaRadiological imaging apparatusUS20060180769 *Feb 17, 2006Aug 17, 2006Siemens AgAdapter for a detector and method for carrying out faultfinding on a detector having such an adapterUS20080203309 *Aug 28, 2006Aug 28, 2008Koninklijke Philips Electronics N.V.Digital silicon photomultiplier for TOF-PETJP2002243858A Title not availableJP2003255048A Title not availableJP2006098411A Title not available* Cited by examinerNon-Patent CitationsReference1Astronomy & Astrophysics Supplement Series, 122, Apr. 1997, "The high energy instrument PDS on-board the BeppoSAX x-ray astronomy satellite", F. Frontera et al, pp. 357-369.Referenced byCiting PatentFiling datePublication dateApplicantTitleUS7964849 *Jul 16, 2010Jun 21, 2011Hitachi, Ltd.Nuclear medical diagnosis apparatusUS8024612 *Aug 6, 2007Sep 20, 2011Siemens AktiengesellschaftRemote diagnosis system for medical appliances of modular designUS8148695May 13, 2011Apr 3, 2012Hitachi, Ltd.Nuclear medical diagnosis apparatusUS8178846 *Jul 24, 2008May 15, 2012Shimadzu CorporationLight or radiation image pickup apparatusUS8520797 *Jun 3, 2011Aug 27, 2013Kabushiki Kaisha ToshibaMedical imaging apparatus, control method, and computer program productUS20110042575 *Apr 24, 2008Feb 24, 2011Sumitomo Heavy Industries, Ltd.Semiconductor Detector Block and Positron Emission Tomography Device Using the SameUS20110127441 *Jul 24, 2008Jun 2, 2011Koichi TanabeLight or radiation image pickup apparatusUS20110299656 *Jun 3, 2011Dec 8, 2011Toshiba Medical Systems CorporationMedical imaging apparatus, control method, and computer program product* Cited by examinerClassifications U.S. Classification250/363.03, 250/363.04, 250/363.02, 378/4, 378/98.8, 378/10, 250/370.09, 378/19International ClassificationG01T1/164Cooperative ClassificationG01T1/2018, G01T1/249European ClassificationG01T1/24PLegal EventsDateCodeEventDescriptionFeb 12, 2014FPAYFee paymentYear of fee payment: 4Apr 28, 2010ASAssignmentEffective date: 20071003Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:TAKAHASHI, ISAO;ISHITSU, TAKAFUMI;UENO, YUICHIRO;AND OTHERS;REEL/FRAME:024299/0290Owner name: HITACHI, LTD., JAPANRotateOriginal ImageGoogle Home - Sitemap - USPTO Bulk Downloads - Privacy Policy - Terms of Service - About Google Patents - Send FeedbackData provided by IFI CLAIMS Patent Services©2012 Google