EP0234603A2 - Générateur de rayons X avec asservissement de la dose d'exposition - Google Patents

Générateur de rayons X avec asservissement de la dose d'exposition Download PDF

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Publication number
EP0234603A2
EP0234603A2 EP87200013A EP87200013A EP0234603A2 EP 0234603 A2 EP0234603 A2 EP 0234603A2 EP 87200013 A EP87200013 A EP 87200013A EP 87200013 A EP87200013 A EP 87200013A EP 0234603 A2 EP0234603 A2 EP 0234603A2
Authority
EP
European Patent Office
Prior art keywords
examination
value
sampling
dose rate
controller
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.)
Granted
Application number
EP87200013A
Other languages
German (de)
English (en)
Other versions
EP0234603A3 (en
EP0234603B1 (fr
Inventor
Rudolf Ochmann
Robert Zimmermann
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.)
Philips Intellectual Property and Standards GmbH
Koninklijke Philips NV
Original Assignee
Philips Patentverwaltung GmbH
Philips Gloeilampenfabrieken NV
Koninklijke Philips Electronics NV
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 Philips Patentverwaltung GmbH, Philips Gloeilampenfabrieken NV, Koninklijke Philips Electronics NV filed Critical Philips Patentverwaltung GmbH
Publication of EP0234603A2 publication Critical patent/EP0234603A2/fr
Publication of EP0234603A3 publication Critical patent/EP0234603A3/de
Application granted granted Critical
Publication of EP0234603B1 publication Critical patent/EP0234603B1/fr
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05G—X-RAY TECHNIQUE
    • H05G1/00—X-ray apparatus involving X-ray tubes; Circuits therefor
    • H05G1/08—Electrical details
    • H05G1/26—Measuring, controlling or protecting
    • H05G1/30—Controlling
    • H05G1/38—Exposure time
    • H05G1/42—Exposure time using arrangements for switching when a predetermined dose of radiation has been applied, e.g. in which the switching instant is determined by measuring the electrical energy supplied to the tube
    • H05G1/44—Exposure time using arrangements for switching when a predetermined dose of radiation has been applied, e.g. in which the switching instant is determined by measuring the electrical energy supplied to the tube in which the switching instant is determined by measuring the amount of radiation directly
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05G—X-RAY TECHNIQUE
    • H05G1/00—X-ray apparatus involving X-ray tubes; Circuits therefor
    • H05G1/08—Electrical details
    • H05G1/26—Measuring, controlling or protecting
    • H05G1/30—Controlling
    • H05G1/36—Temperature of anode; Brightness of image power
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05G—X-RAY TECHNIQUE
    • H05G1/00—X-ray apparatus involving X-ray tubes; Circuits therefor
    • H05G1/08—Electrical details
    • H05G1/26—Measuring, controlling or protecting
    • H05G1/30—Controlling
    • H05G1/46—Combined control of different quantities, e.g. exposure time as well as voltage or current

Definitions

  • the invention relates to an X-ray generator with actuators at least for the tube current and the tube voltage, a controller which acts on the actuators as a function of the actual value and the target value of the dose rate, at least one measuring device for measuring the actual value of the dose rate, and with one by the user operable selection device which determines the type of examination and the target value of the dose rate.
  • Such an X-ray generator is known from DE-OS 26 53 252.
  • slice pictures can be taken and on the other hand bucky pictures in which the recording time does not exceed an upper and a lower limit.
  • the controller is a sampling controller formed by a microprocessor system, in that a memory is provided in which the sampling frequency and the actuating function are stored for the various types of examination, and in that the sampling controller corresponds to the actuating function and after another
  • the stored program calculates the manipulated variables for the next sampling interval and controls the actuators accordingly.
  • the sampling frequency of the sampling regulator and thus the control speed can be determined by means of a programmable counter contained in the microprocessor system, which is loaded from the memory with a value corresponding to the sampling interval and assigned to the respective type of examination.
  • the implementation of these control functions and the control behavior (proportional behavior or integral behavior) of the dose rate control in the respective type of examination are determined by the program, according to which the manipulated variables for the next sampling interval are determined in the sampling controller.
  • the dose rate in the different types of examination is not determined with the same measuring organ.
  • the dose rate in a slice image can be determined, for example, with an ionization chamber, while it is determined in operation with a cinema camera by means of a photomultiplier and is derived from the video signal in fluoroscopic mode.
  • a further development of the invention provides that several measuring devices are provided, one of which is effective for each type of examination, that matching amplifiers are provided which bring the output signal of the measuring device to a predetermined level at a predetermined dose rate, and that a switchover device is provided which couples the measuring device intended for the respective examination to the sampling controller.
  • the scanning frequency has a first value in a first section of an X-ray image and a second value in a subsequent section, and that the first value is significantly larger than the second value.
  • a favorable transient response can be achieved if the first section is ended with a high sampling frequency as soon as, for example, the tube voltage has reached a predeterminable fraction of its starting value.
  • simpler and shorter control algorithms must be used because of the increased sampling frequency, which ensure that an evaluable dose rate signal is available sufficiently quickly as long as the tube voltage does not yet deviate significantly from its starting value.
  • FIG. 1 shows a schematic representation of an x-ray system with an x-ray generator 1 and an x-ray tube 2, the radiation of which passes through an examination area symbolized by the body l3 and generates an x-ray silhouette either on a film positioned in a cassette holder 4 or on the output screen of an x-ray image intensifier 5.
  • the dose or the dose rate is measured by means of an ionization chamber 3 and fed to a unit 30 for dose evaluation.
  • the output image of the image intensifier 5 can be recorded by means of a cinema camera 7, a sheet or roll film camera 8 or a television camera 9 or a television chain 90 connected to it with a monitor 91.
  • An adjustable iris diaphragm 11 is located in the optical beam path.
  • the X-ray generator 1 contains, among other things. Actuators with which the tube voltage, the tube current and the focal spot size can be set.
  • the tube voltage actuator l00 can contain, for example, a medium frequency converter with a high voltage generator and a rectifier combination.
  • a lattice control unit or an electronically controlled heating circuit can serve as the tube current actuator ll0, and the focal spot actuator 120 can also be designed such that only the focal spot size can be switched between two values.
  • the actuators l00, ll0 and l20 receive their control signals via lines l43, l4l and l42 from a sampling controller l40.
  • This receives its setpoints and control functions from a central control unit and its actual values either from the ionization chamber 3, the photomultiplier l2 or the television chain 90 via matching amplifiers l7l, l72 and l73, which provide the output signals bring these measuring processes to a normalized level and via the switching device l70, which is controlled via line l75 in such a way that the output signal of one of the three matching amplifiers l7l ... l73 is fed to the sampling controller l40 via line l44.
  • the central control unit l60 is coupled via a bidirectional connection l62 to a selection device in the form of a control panel l80.
  • the user selects the type of examination, for example, by pressing a button, whereupon the associated sampling frequency and the actuating function are called up in a memory of the central control unit 160 and loaded into a memory of the sampling controller 140 via the connection 159.
  • sampling controller l40 and the central control unit l60 results from FIG. 2. Both contain a microprocessor l47 or l65 as well as read-only and read / write memories l48 or l66 and input / output units l49 or l64, l67. Both units contain a programmable counter l50 or l69.
  • the sampling controller l40 also contains an analog-digital converter l46 for converting the analog signals representing the actual values on the line l44 into digital values and digital-analog converter l45, which convert the digital control signals generated by the microprocessor l47 into analog signals, which are transmitted via the Carry lines l4l, l42 and l43 to the associated actuators.
  • the optimal actuating function, the required sampling frequency and further parameters, for example the image frequency, the minimum and the maximum recording time (in the case of cinema recording technology) etc., are stored in the memory l66 of the central control unit l60 for each type of examination.
  • These programs can be bidirectional Connection l62 can be called up from the control panel l80. Before the start of the recording, they are transmitted via the input / output interface l67 of the central control unit l60 and the connection l59 to the input / output interface l49 of the scanning controller l40.
  • the recording time is set by means of the programmable counter l69, which is started by the recording start signal and generates a signal at the end of the recording, which switches off the tube voltage and thus the X-ray radiation via the line l6l connected to the high-voltage actuator l00, among other things, and that via the Interrupt line l58 acts on microprocessor l47 in sampling controller l40.
  • the memory l48 which is called up depending on the respective type of examination, the latter calculates the actuating signals for the next sampling interval within a sampling interval.
  • x-ray images are generated with the cinema camera, generally between 50 and 300 images per second, x-ray images being generated. It is necessary to regulate the dose per image. Dose deviations occurring due to disturbance variables do not have to be corrected within a picture, but after a few ten pictures, since otherwise a restless picture impression (flickering) would result. The dose is therefore a scanning signal that is available after each image. The sampling frequency thus corresponds to the frame rate.
  • U i is the tube voltage set during the last image and a is the exponent with which the dose rate changes when the tube voltage changes.
  • the voltage U x calculated in this way represents the value that would be required in the case of a control with proportional behavior, in which the dose or the dose rate is regulated exclusively by changing the tube voltage.
  • the tube current I x associated with U x is then determined as a function of the actuating function loaded for this type of examination.
  • An actuating function suitable for cinema operation is shown in FIG. 3a.
  • the curve entered in the tube current / tube voltage diagram indicates the manner in which tube voltage and tube current are to be changed in order to achieve a change in the dose rate.
  • the curve begins with the smallest possible tube voltage and the smallest possible tube current with a horizontal section, ie only the voltage is changed in this area to change the dose rate.
  • This section is followed by a second section in which tube current and tube voltage are changed in the same direction in order to change the dose rate.
  • This second Section is followed by a third section, again horizontal, which is determined by the maximum tube current.
  • This third section is followed by a fourth section, which is predetermined by the resilience of the focal spot of the X-ray tube and which has a hyperbolic shape.
  • tube voltage and tube current are changed in opposite directions to one another so that their product remains constant.
  • the actuating function shown in Fig. 3a is stored in that the values of tube current and tube voltage are stored at the start and end points of the individual sections.
  • the description of the characteristic curve using the start and end points may not be sufficient. In this case, a large number of points are stored on the characteristic.
  • h is a factor that determines the proportional behavior of the control, while the factor k defines the integral behavior of the control.
  • the value I il is the tube current during the penultimate picture.
  • the values of tube current and tube voltage calculated in this way are given to the actuators l00 and ll0 as control signals via lines l43 and l4l.
  • the resulting dose is measured again, after which the control signals are calculated again, etc.
  • the regulation in the case of pulsed fluoroscopy in which the actual value is derived from the signals of the television chain 90, can be carried out in a similar manner. However, a different sampling frequency and a different actuating function can be specified.
  • each image should be correctly exposed, whereby the recording time should not exceed a lower and an upper limit frequency.
  • the imaging dose rate In order not to exceed the limit of the exposure time for no single exposure, the imaging dose rate must be regulated.
  • An adapted sampling frequency results from the shortest recording time. If this is 10 to 20 ms, the sampling frequency should be about 1 kHz.
  • the end of admission takes place when the target dose required for admission has been reached.
  • the value is set to a value at the start of an image in the period from switching on until approximately 95% of the starting value of the tube voltage which is much higher, e.g. 5 kHz.
  • the sampling frequency is set to the above-mentioned value (1 kHz).

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  • Health & Medical Sciences (AREA)
  • General Health & Medical Sciences (AREA)
  • Toxicology (AREA)
  • X-Ray Techniques (AREA)
  • Apparatus For Radiation Diagnosis (AREA)
EP87200013A 1986-01-10 1987-01-07 Générateur de rayons X avec asservissement de la dose d'exposition Expired - Lifetime EP0234603B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE19863600464 DE3600464A1 (de) 1986-01-10 1986-01-10 Roentgengenerator mit dosisleistungsregelung
DE3600464 1986-01-10

Publications (3)

Publication Number Publication Date
EP0234603A2 true EP0234603A2 (fr) 1987-09-02
EP0234603A3 EP0234603A3 (en) 1988-08-17
EP0234603B1 EP0234603B1 (fr) 1992-07-08

Family

ID=6291589

Family Applications (1)

Application Number Title Priority Date Filing Date
EP87200013A Expired - Lifetime EP0234603B1 (fr) 1986-01-10 1987-01-07 Générateur de rayons X avec asservissement de la dose d'exposition

Country Status (4)

Country Link
US (1) US4797905A (fr)
EP (1) EP0234603B1 (fr)
JP (1) JP2591739B2 (fr)
DE (2) DE3600464A1 (fr)

Families Citing this family (25)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3732634A1 (de) * 1987-09-28 1989-04-06 Siemens Ag Roentgendiagnostikeinrichtung
DE3801027A1 (de) * 1988-01-15 1989-07-27 Saunalux Gmbh Products & Co Kg Verfahren und geraet zur grossflaechigen bestrahlung des menschlichen koerpers
US4980905A (en) * 1989-02-16 1990-12-25 General Electric Company X-ray imaging apparatus dose calibration method
US5012504A (en) * 1989-12-26 1991-04-30 General Electric Company Automatic brightness compensation for fluorography systems
US5003572A (en) * 1990-04-06 1991-03-26 General Electric Company Automatic brightness compensation for x-ray imaging systems
DE4013703C2 (de) * 1990-04-28 1999-04-01 Bork Klaus Peter Schaltungsanordnung für insbesondere für Diagnosezwecke eingesetzte Röntgengeneratoren
DE4235010A1 (de) * 1992-10-16 1994-04-21 Siemens Ag Röntgendiagnostikanlage mit einer Bildverstärker-Fernsehkette
JP2634369B2 (ja) * 1993-07-15 1997-07-23 浜松ホトニクス株式会社 Ｘ線装置
JP2002528851A (ja) * 1998-10-19 2002-09-03 コーニンクレッカ フィリップス エレクトロニクス エヌ ヴィ 照射量制御を備えたｘ線検査装置
WO2001028298A1 (fr) 1999-10-08 2001-04-19 Dentsply International Inc. Commande automatique de l'exposition pour un appareil de radiographie dentaire panoramique et de cephalographie
JP4549462B2 (ja) * 1999-10-14 2010-09-22 ジーイー・メディカル・システムズ・エス アー 蛍光透視画像の画質改善方法及び、蛍光透視画像の画質を改善するシステム
EP1252762B1 (fr) * 2000-02-02 2005-04-20 Dentsply International, Inc. Detection automatique de rayons x pour appareil d'imagerie dentaire intraorale par rayons x
US6795528B2 (en) * 2001-01-12 2004-09-21 Canon Kabushiki Kaisha Radiographic apparatus, radiographic method, and computer-readable storage medium
US6810109B2 (en) * 2001-07-13 2004-10-26 Medtronic Ave, Inc. X-ray emitting system and method
WO2003010556A2 (fr) * 2001-07-25 2003-02-06 Dentsply International Inc. Imageur radiologique numerique en temps reel
JP2003142294A (ja) * 2001-10-31 2003-05-16 Ge Medical Systems Global Technology Co Llc 高電圧発生回路およびｘ線発生装置
DE10163583A1 (de) * 2001-12-21 2003-07-03 Philips Intellectual Property Verfahren und Vorrichtung zur Belichtung von Röntgenaufnahmen
WO2003086028A1 (fr) * 2002-04-05 2003-10-16 Hamamatsu Photonics K.K. Procede et appareil de controle de tube a rayons x
AU2003261200A1 (en) * 2002-07-25 2004-02-25 Dentsply International Inc. Real-time digital x-ray imaging apparatus and method
US7431500B2 (en) * 2003-04-01 2008-10-07 Analogic Corporation Dynamic exposure control in radiography
DE102004017180B4 (de) * 2004-04-07 2007-08-02 Siemens Ag Röntgendiagnostikeinrichtung zur digitalen Radiographie
US7274771B2 (en) * 2005-05-03 2007-09-25 General Electric Company Methods and systems for controlling exposure for medical imaging devices
WO2010128416A2 (fr) * 2009-05-05 2010-11-11 Koninklijke Philips Electronics N.V. Procédé et dispositif de re-dimensionnement dépendant de la charge d'un point focal d'un dispositif de génération de rayons x
US9168010B2 (en) * 2012-04-11 2015-10-27 Kabushiki Kaisha Toshiba X-ray imaging apparatus and medical image processing apparatus
JP6009799B2 (ja) * 2012-04-11 2016-10-19 東芝メディカルシステムズ株式会社 Ｘ線画像撮影装置

Citations (5)

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Publication number Priority date Publication date Assignee Title
DE2207280A1 (de) * 1972-02-16 1973-08-23 Siemens Ag Roentgendiagnostikapparat zur anfertigung von roentgenaufnahmen mit einem zeitschalter zur bestimmung der aufnahmedauer
FR2372570A1 (fr) * 1976-11-24 1978-06-23 Philips Nv Generateur utilise pour le radiodiagnostic et muni d'un dispositif pour mesurer le debit de rayonnement
GB1600220A (en) * 1977-06-23 1981-10-14 Gen Electric Programmers for diagnostic x-ray apparatus
EP0063644A1 (fr) * 1981-04-23 1982-11-03 VEB Transformatoren- und Röntgenwerk "Hermann Matern" Procédé de prises de vues radiographiques
DE3303150A1 (de) * 1983-01-31 1984-08-02 Siemens AG, 1000 Berlin und 8000 München Roentgendiagnostikanlage mit stellmitteln fuer die dosisleistung der roentgenroehre

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US3783286A (en) * 1970-12-23 1974-01-01 Picker Corp X-ray image brightness stabilizer
US4035649A (en) * 1973-10-08 1977-07-12 U.S. Philips Corporation X-ray generator for a tomography apparatus
US4158138A (en) * 1977-10-25 1979-06-12 Cgr Medical Corporation Microprocessor controlled X-ray generator
JPS56159097A (en) * 1980-05-08 1981-12-08 Shimadzu Corp X-ray tube current compensator circuit
JPS6010600A (ja) * 1983-06-30 1985-01-19 Toshiba Corp Ｘ線動態画像診断装置

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2207280A1 (de) * 1972-02-16 1973-08-23 Siemens Ag Roentgendiagnostikapparat zur anfertigung von roentgenaufnahmen mit einem zeitschalter zur bestimmung der aufnahmedauer
FR2372570A1 (fr) * 1976-11-24 1978-06-23 Philips Nv Generateur utilise pour le radiodiagnostic et muni d'un dispositif pour mesurer le debit de rayonnement
GB1600220A (en) * 1977-06-23 1981-10-14 Gen Electric Programmers for diagnostic x-ray apparatus
EP0063644A1 (fr) * 1981-04-23 1982-11-03 VEB Transformatoren- und Röntgenwerk "Hermann Matern" Procédé de prises de vues radiographiques
DE3303150A1 (de) * 1983-01-31 1984-08-02 Siemens AG, 1000 Berlin und 8000 München Roentgendiagnostikanlage mit stellmitteln fuer die dosisleistung der roentgenroehre

Also Published As

Publication number Publication date
JP2591739B2 (ja) 1997-03-19
US4797905A (en) 1989-01-10
DE3780187D1 (de) 1992-08-13
EP0234603A3 (en) 1988-08-17
EP0234603B1 (fr) 1992-07-08
DE3600464A1 (de) 1987-07-16
JPS62222600A (ja) 1987-09-30

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