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WO2001010019A2 - Dispositif pour amplifier un signal emis par un detecteur de rayons - Google Patents

Dispositif pour amplifier un signal emis par un detecteur de rayons Download PDF

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Publication number
WO2001010019A2
WO2001010019A2 PCT/DE2000/002572 DE0002572W WO0110019A2 WO 2001010019 A2 WO2001010019 A2 WO 2001010019A2 DE 0002572 W DE0002572 W DE 0002572W WO 0110019 A2 WO0110019 A2 WO 0110019A2
Authority
WO
WIPO (PCT)
Prior art keywords
signal
amplification
gain
amplifier
signals
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/DE2000/002572
Other languages
German (de)
English (en)
Other versions
WO2001010019A3 (fr
Inventor
Clemens Doubrava
Dieter Gallein
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Siemens AG
Siemens Corp
Original Assignee
Siemens AG
Siemens Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Siemens AG, Siemens Corp filed Critical Siemens AG
Priority to JP2001514536A priority Critical patent/JP2003506945A/ja
Publication of WO2001010019A2 publication Critical patent/WO2001010019A2/fr
Publication of WO2001010019A3 publication Critical patent/WO2001010019A3/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01T—MEASUREMENT OF NUCLEAR OR X-RADIATION
    • G01T1/00—Measuring X-radiation, gamma radiation, corpuscular radiation, or cosmic radiation
    • G01T1/16—Measuring radiation intensity
    • G01T1/17—Circuit arrangements not adapted to a particular type of detector

Definitions

  • Such devices are used for example in computer tomographs.
  • the electrical analog signals that can be derived from a radiation receiver when a radiation object is scanned are amplified by a floating point amplifier and fed to an analog / digital converter, the output signals of which are fed to a signal processing device, which generates signals from these signals for visual display on a display device.
  • the analog signals can vary greatly depending on the radiation absorption of the examination subject, the gain of the amplifier must be adjusted.
  • a comparator is therefore assigned to the amplifier, to which the analog signal is likewise fed and which generates an output signal as a function of this signal, via which the amplification of the amplifier is set in an analog manner.
  • the amplification of the amplifier is consequently set directly via the analog signal that can currently be derived at the radiation detector.
  • Such comparators are sensitive analog components that are also severely limited in their working frequency.
  • the amplifier is often overloaded, so that the images obtained on the basis of the output signals of the amplifier contain artifacts.
  • the object of the invention is therefore to design a device for amplifying a signal emanating from a radiation detector in such a way that it does without these analog components, allows fast signal processing and permits the acquisition of artifact-poor images.
  • the object is achieved by the subject matter of claim 1.
  • the advantage of the invention is that the amplification of a current signal is set as a function of the signal level of a previous signal.
  • the sensitive analog components can thus be dispensed with.
  • the avoidance of analog components also enables fast signal processing.
  • the risk of overdriving the amplifier due to the fact that the gain is set as a function of the signal level of a previous signal is reduced compared to the prior art, so that images with fewer artifacts can be obtained on the basis of the output signals of the amplifier.
  • the amplification is set as a function of an expected range for the current signal, since the expected range is considerably smaller than the entire possible amplification range and thus an optimal amplification for the current signal can be set in a simple manner.
  • the amplification of the current signal is set as a function of the signal level of at least two previous signals, in particular as a function of the mean value of two previous signals.
  • the gain setting is thus less sensitive to incorrect or disturbed signals.
  • the two signals are weighted, which depends, for example, on the distance of the detector elements from which these signals are derived from the detector element whose current signal is to be amplified.
  • the signal of one detector element can preferably also be used to set the gain of another detector element.
  • the previous signal is digitized and the amplification is set on the basis of the digitized signal. Analog components can therefore also be dispensed with.
  • the radiation detector d is, for example, a detector element of a row or flat detector arrangement.
  • the radiation detector d as shown in the figure, is one of the detector elements of a one-dimensional or multidimensional detector array D known per se of a computer tomograph.
  • Each detector element d forms a so-called channel of the detector array D, and a device according to the invention can be connected downstream of each of the detector elements of the detector array D.
  • the signal of the radiation detector d depends on the radiation absorption of the examination area and thus on the radiation intensity impinging on the radiation detector d.
  • This analog signal is amplified in amplifier 1 in accordance with a set amplification factor V x and fed to a downstream analog / digital converter 2.
  • the amplifier 1 can have various predetermined gain factors V x , each of which is assigned a gain sub-range V b .
  • the output signal of the analog / digital converter 2 is used as a digital signal from a downstream signal processing unit. direction, for example an image computer C. Based on all signals from the radiation detectors d of the detector array D, the latter calculates, for example, a transmission silhouette or a sectional image of the examination area in a manner known per se, which can be displayed on a display device, for example a monitor M, connected to the image computer C.
  • the output signal of the analog / digital converter 2 is, however, also fed to a computer 3 which, on the basis of this digital signal, calculates the amplification factor V x for a next signal, for example the next signal which can be read / read by the radiation detector d, and the amplification factor V x thus calculated on the amplifier 1 sets.
  • a previous signal for example the immediately previous signal, is consequently used to set the gain factor V x for the current signal.
  • the device according to the invention thus does not require sensitive analog components which are also severely limited in their working frequency. Due to the digital design, the device according to the invention is faster and particularly suitable for the signal processing of signals from detector arrays with a multiplicity of channels. In addition, the risk of overdriving the amplifier is reduced due to the fact that the gain is set as a function of the signal level of a previous signal, so that the image computer C can obtain images with fewer artefacts on the basis of the output signals of the amplifier 1 or the amplifier 1.
  • an expectation range for the current signal S r can be calculated. This range of expectations lies between l / fS r - ⁇ and f'S r _ ⁇ . If the signal to be expected in extreme cases is no longer in the amplification sub-range V b of the currently selected amplification with the amplification factor V x with regard to the signal level, a corresponding amplification factor V x is set on the amplifier 1 via the computer 3 and covers the full expected range , Each gain sub-range V b of the amplifier 1 covers, for example, at least the gain range ff, where f is the uncertainty factor of the gain prediction. It has also proven to be advantageous if the gain subregions V b do not connect to one another, but rather overlap in a certain region.
  • a practical division of the reinforcement sub-areas V b is given below.
  • FS fill size
  • a first amplification sub-area V bi can then include signals whose signal level is between FS and FS "2 ⁇ 12.
  • a second amplification sub-area V bi can then include signals whose signal level is between FS and FS "2 ⁇ 12.
  • Amplification sub-area V b2 can then comprise signals whose signal level lies between FS '2 ⁇ 3 and FS' 2 "15.
  • a third amplification sub-area V b3 can then comprise signals whose signal level lies between FS '2 ⁇ 6 and FS" 2 ⁇ 18 .
  • the reinforcement sub-region V b ⁇ can be arranged with a gain of 1, the reinforcement sub-region V b2 with a gain of 8 and the reinforcement sub-region V b3 with a gain of 64.
  • an amplification sub-range V b can always be selected which covers the entire expected range of the signal S r .
  • only the reinforcement sub-areas V b i and V b3 can be used, which results in an overlap area U with a dynamic range of 64.
  • the invention also encompasses variants with regard to the factor f, the reinforcement sub-areas V b and the overlap areas U, although the information mentioned has proven to be advantageous.
  • a device according to the invention can be connected downstream of each of the radiation detectors of the detector array D.
  • a radiation detector d there is also the possibility, based on the signal of a radiation detector d, to also set the amplification factor V x of some radiation detectors adjacent to the respective radiation detector d, so that the memories 4 and 5 and the computer 3 can be omitted with respect to these radiation detectors.
  • the signals of the radiation detector d used to set the amplification factor V x of adjacent radiation detectors can be weighted, for example depending on the distance between the relevant radiation detector d and the respective neighboring radiation detector.
  • the computer 3 which can also be designed as logic, is assigned a memory 4 for storing the previous signal or signals.
  • the amplification sub-areas V b and the overlap areas U can be stored in the form of a look-up table in a further memory 5 alternatively connected downstream of the computer 3, the output signal of the memory 3 occurring after a corresponding supply of a signal from the computer 3 having the amplification factor V x on the amplifier 1.

Landscapes

  • Physics & Mathematics (AREA)
  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • High Energy & Nuclear Physics (AREA)
  • Molecular Biology (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Measurement Of Radiation (AREA)
  • Analysing Materials By The Use Of Radiation (AREA)
  • Control Of Amplification And Gain Control (AREA)
  • Apparatus For Radiation Diagnosis (AREA)

Abstract

L'invention concerne un dispositif servant à amplifier un signal émis par un détecteur de rayons. Ce dispositif comporte un amplificateur (1) et des moyens pour régler l'amplification de l'amplificateur (1) en fonction d'un signal (Sr). Selon l'invention, l'amplification du signal (Sr) du moment est réglée en fonction de la hauteur d'un signal précédent (Sr-1).
PCT/DE2000/002572 1999-08-03 2000-08-02 Dispositif pour amplifier un signal emis par un detecteur de rayons Ceased WO2001010019A2 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP2001514536A JP2003506945A (ja) 1999-08-03 2000-08-02 放射線検出器から出た信号の増幅装置

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE19936362 1999-08-03
DE19936362.5 1999-08-03

Publications (2)

Publication Number Publication Date
WO2001010019A2 true WO2001010019A2 (fr) 2001-02-08
WO2001010019A3 WO2001010019A3 (fr) 2001-06-07

Family

ID=7916924

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/DE2000/002572 Ceased WO2001010019A2 (fr) 1999-08-03 2000-08-02 Dispositif pour amplifier un signal emis par un detecteur de rayons

Country Status (2)

Country Link
JP (1) JP2003506945A (fr)
WO (1) WO2001010019A2 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US10041830B2 (en) 2016-02-26 2018-08-07 Kabushiki Kaisha Toshiba Radiation detection apparatus

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4739307A (en) * 1984-01-31 1988-04-19 Analogic Corporation Multichannel predictive gain amplifier system
DE69917229T2 (de) * 1998-12-22 2005-05-04 Koninklijke Philips Electronics N.V. Computertomograph mit mehrstufigem integriertem ladungsleseverstärker

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US10041830B2 (en) 2016-02-26 2018-08-07 Kabushiki Kaisha Toshiba Radiation detection apparatus

Also Published As

Publication number Publication date
JP2003506945A (ja) 2003-02-18
WO2001010019A3 (fr) 2001-06-07

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