EP0165850A1 - Verfahren zur Steuerung der Position des Brennflecks einer Röntgenröhre und Steuervorrichtung zur Durchführung dieses Verfahrens - Google Patents

Verfahren zur Steuerung der Position des Brennflecks einer Röntgenröhre und Steuervorrichtung zur Durchführung dieses Verfahrens Download PDF

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Publication number
EP0165850A1
EP0165850A1 EP85401034A EP85401034A EP0165850A1 EP 0165850 A1 EP0165850 A1 EP 0165850A1 EP 85401034 A EP85401034 A EP 85401034A EP 85401034 A EP85401034 A EP 85401034A EP 0165850 A1 EP0165850 A1 EP 0165850A1
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EP
European Patent Office
Prior art keywords
pinhole
axis
displacement
image
focal point
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
EP85401034A
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English (en)
French (fr)
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EP0165850B1 (de
Inventor
André Plessis
Guy-Henri Seite
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General Electric CGR SA
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Thomson CGR
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Publication of EP0165850A1 publication Critical patent/EP0165850A1/de
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    • 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
    • H05G1/52—Target size or shape; Direction of electron beam, e.g. in tubes with one anode and more than one cathode
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J35/00—X-ray tubes
    • H01J35/24—Tubes wherein the point of impact of the cathode ray on the anode or anticathode is movable relative to the surface thereof
    • 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

Definitions

  • the invention relates to a method for controlling the position of the focal point of an X-ray tube, applicable to the monitoring of radiological equipment provided with X-ray tubes and to the mounting of the latter in sheaths.
  • the invention also relates to a control device allowing the implementation of this method.
  • An X-ray assembly conventionally comprises an X-ray tube provided with a target called an anode, and with an electron emitter called a cathode.
  • the cathode emits electrons in a directive manner, to form a beam of electrons which strike very locally the target in a very small zone, called focal point of X-ray radiation.
  • the anode and cathode electrodes are contained in an envelope where a clean vacuum prevails to favor thermoelectronic emission.
  • the envelope and the electrodes together constitute the X-ray tube.
  • An essential condition for obtaining the required geometric qualities of the X-ray beam lies in the centering of the focal point with respect to this window.
  • the hearth is centered with respect to the exit window, so that the geometric axis of this window passes through the hearth; this geometric axis of the exit window, thus constituting the axis of the useful beam of X-rays.
  • the sheath equipped with the X-ray tube is commonly associated, to form an X-ray assembly, with a device such as a locator or a beam limiter.
  • a device such as a locator or a beam limiter.
  • the geometric shapes of the duct outlet window are such that they serve as a reference for the mechanical assembly of the fitted duct and, for example of the beam limiter; the alignment of the axis of the beam limiter opening, on the planned axis of the X-ray beam, is thus very simplified thanks to the prior centering of the focus.
  • a receiver or detector means sensitive to X-ray radiation is used, such as a camera, for example, which is fixed on the exit window, bearing on the reference faces of the latter; this camera also comprising elements making it possible to produce the image of the hearth, on a film or on a screen on which is materialized, by means of wires or engravings, the theoretical axis of the exit window.
  • the focus of the focal point image makes it possible to calculate the focus of the focal point relative to the axis of the window, according to the geometric characteristics of the camera.
  • the present invention relates to a method of controlling the position of the focal point of an X-ray tube, allowing instantaneous control of the position of the focal point with great precision, as well in the context of a control in the factory or in the laboratory, as in part of the actual operation of a radiological installation.
  • a method of controlling the position of the focal point of an X-ray tube in which an image of said focal point is produced using a pinhole camera and makes it possible to carry out said position control according to at least a first given axis, said X-ray tube being contained in a sheath and producing an X-ray beam leaving said sheath by an exit window, is characterized in that it consists in centering said pinhole on a reference axis cutting said first axis at a point constituting a reference position with respect to which said control is carried out, then in producing said image on the input planes of at least two adjoining detector means, sensitive to X-radiation, said input planes constituting a useful measurement length and being separated by a median line through which said reference axis passes and on either side of which said image is distributed, then comparing the output signals generated by each of said means s detectors as a function of the distribution of said image, so as to obtain a difference signal having a zero value when said focal point occupies said reference position
  • Figure 1 shows a first version of a control device 15 according to the invention, allowing the implementation of the method according to the invention for controlling, in a sheath 1 containing an X-ray tube 2, the position of a focus f relative to an outlet window 10 with which the sheath 1 is provided.
  • the X-ray tube 2 comprises an anode 3, of the rotary anode type in the nonlimiting example described, this anode 3 being secured to a rotor 4 by means of a shaft 5.
  • a cathode 6 is arranged in a way conventional opposite anode 3 and delivers in operation electrons (not shown) which determine on anode 3 the focus f.
  • the focal point f constitutes the source of an X-ray radiation beam 9 which leaves the sheath 1 through the outlet window 10.
  • the exit window 10 has a geometric axis 11 which, when the focal point f is centered relative to the exit window 10 as in the example shown in FIG. 1, also constitutes the axis of the X-ray radiation beam 9.
  • the outlet window 10 has reference faces 34, which are particularly intended, during the assembly of the sheath 1 and of a beam limiting device (not shown), for centering these elements, one with respect to the other.
  • the control of the position of the focus f takes place along at least a first axis 8, this first axis 8 being in the nonlimiting example described parallel to the shaft 5.
  • This control of the position of the focus f is also carried out with respect to a reference position P r , determined on the first axis 8 by the control device 15, as explained in the following description.
  • the focal point f being shown centered with respect to the outlet window 10, it occupies a theoretical position T, constituted by the intersection between the geometric axis 11 and the first axis 8; the reference position P being confused with this theoretical position T in the nonlimiting example of FIG. 1.
  • the control device 15 comprises a support structure 16, essentially containing a pinhole 18 and a first and a second detector means 20, 21, contiguous, sensitive to X-radiation, on which the pinhole 18 is intended to produce an image I of the focus f.
  • pinhole camera we mean any means comprising an opening allowing the image of the focal point f to be produced, this opening also being able to have the form of a slit.
  • the first and second detector means 20, 21 each have an entry plane, respectively 22, 23 arranged symmetrically with respect to a center line 12 of separation.
  • This median line 12 being perpendicular to the plane of FIG. 1, it is visible on the latter in the form of a point, which symbolizes the center of an area on which the image I is produced.
  • the center line 12 or center of the imaging zone determines with the pinhole 18 a reference axis 24, the position of which relative to an axis of symmetry 14 of the structure 16 is defined by construction; the axis of symmetry 14 and the reference axis 24 being combined in the nonlimiting example described.
  • the pinhole 18 is carried by means of a calibrated displacement means, constituted in the nonlimiting example described by a micrometric screw 13 where "palmer” making it possible to move the pinhole 18 on either side of the axis 24, along a second axis 25 parallel to the first axis 8.
  • the pinhole 18 is thus movable in one or other of the directions shown by the first and the second arrow 17, 19, the value of its displacement being known to 1/100 of mm for example by means of graduations 7 which comprises in a conventional manner the micrometric screw 13; a reference (not shown) making it possible to keep the positioning of the reference axis 24, relative to the axis of symmetry 14.
  • One end 15 of the support structure 16 comprises centering means, formed in the nonlimiting example described by a flange 26 and a second reference face 27; this end is fixed to the sheath bearing on the first reference faces 34 of the outlet window 10 in which the centering collar 26 is engaged.
  • the method according to the invention consists in producing, using the pinhole camera 18, an image 1 of the focal point f on the input planes 22,23 of the two detector means 20,21, so as to link the position of the focal point f along the first axis 8, to the distribution of the image 1 on each of the input planes 22, 23.
  • This distribution of image 1 is equal on each of the input planes 22, 23 on either side of the center line 12, when the reference axis 24, passing through this center line and the pinhole 18, passes also through the home f.
  • the intersection of the reference axis 24 with the first axis 8 determines the reference position P r , with respect to which the control of the position of the focus f takes place. Given the application, the reference position P coincides with the theoretical position T of the focus f.
  • the geometric axis 11 and the reference axis 24 are combined, but this condition is not necessary, these two axes being able to form between them an angle (not shown), the essential being, for the envisaged position control, that the reference axis 24 intersects the first axis 8 at the theoretical position T, that is to say at the same point as the geometric axis 11; this being obtained with the control device 15 according to the invention, of construction, for a given mark of the graduations 7 that the micrometric screw 13 includes.
  • the entry planes 22, 23 respectively comprise, on either side of the center line 12, a length L 1 , L 2 , which constitute a useful measurement length L, substantially parallel to the second axis 25 along which is movable pinhole 18; this useful measurement length constituting a first dimension of the previously mentioned area on which the image is produced and of which another dimension, perpendicular to the plane of FIG. 1, is not visible on the latter.
  • Image 1 includes, along the useful measurement length L, a dimension 1 less than this useful length L. It should be noted that when image 1 is equally distributed over the two input planes 22, 23, these entry planes are each illuminated by the image 1 of the focal point f over a distance l 1 , 1 2 less than their length L 1 , L 2 .
  • Each detector means 20, 21 delivers an output signal S 1 , S 21 of which a characteristic, the amplitude for example, is a function of the illumination of its input plane 22,23 by the image I.
  • the latter deliver an output signal S 1 , S 2 of the same amplitude when the image I is also distributed over the two input planes 22, 23.
  • This configuration is that shown in FIG. 1 where, the focal point f being centered with respect to the outlet window 10, its position coincides with the reference position P, the image I then being formed equally on the two planes d input 22, 23.
  • a comparison of the output signals S 1 , S 2 makes it possible to obtain a difference signal SD of zero value, which indicates that the focus f is correctly positioned.
  • a position P 1 represented in FIG. 1 by a line in dotted lines, its image (not shown) produced by the pinhole camera 18 is then unevenly distributed over the entry planes 22, 23; in this case, the distance 1 1 along which the first plane 22 is illuminated by the image is less than the distance 1 2 according to which the second input plane 23 is illuminated.
  • the output signals S 1 , S 2 then have a different amplitude, and their comparison makes it possible to obtain the difference signal SD having a non-zero value, which can constitute a reference signal and whose polarity indicates the direction of the center of focus f.
  • the comparison of the output signals S 1 , 5 2 can be carried out in different ways, known to those skilled in the art, as for example in the example described where the output signals S 1 , S 2 are respectively applied to the input + and at input - of a differential amplifier 30; an output s of the latter delivering the previously mentioned difference signal SD, which can be displayed on a conventional display means 31.
  • the difference signal SD constitutes a reference signal usable for controlling the position of the focus f, this difference signal SD or reference signal being able to be used in configurations different from those which have just been described, such as it will be explained in a continuation of the description.
  • the position of the focus f can also be checked along an axis (not shown) different from the first axis 8, perpendicular to the latter for example. It then suffices to orient the useful measurement length L of the input planes 22, 23 along an axis (not shown) corresponding to the expected direction of displacement of the image I; it is also possible to use a number of detectors 20, 21 greater than two, so as to simultaneously control the position of the focus f along the first axis 8 and along this different axis.
  • control of the position of the focus f we mean both the verification or the enslavement of this position, as well as the measurement of a difference in position ⁇ f between a position of the focus f such as the position P 1 for example, and the reference position PR along the first axis 8; this difference in position ⁇ f originating either from an original positioning of the hearth f or from a displacement of the latter during the operation of the X-ray tube 2.
  • the method and the control device 15 according to the invention make it possible to express the position difference ⁇ f either as a function of a movement of the pinhole 18, or by the value of the difference signal SD according to a linear relationship.
  • the method also consists in placing the pinhole 18 at a first known distance Y from the reference position P, and in placing the detector means 20, 21 at a second known distance Z in the pinhole 18.
  • the difference signal SD generated by the differential amplifier 30 shows variations (not shown in FIG. 1) which correspond to the difference in illumination between each input plane 22, 23 or difference in distribution of the image 1 on these input planes.
  • the first and second positions P 2 , P 3 between which the pinhole 18 is moved correspond to positions where the pinhole produces an image (not shown) of the focal point f outside the entry planes 22, 23; third and fourth positions P 49 P 5 corresponding to positions between which the pinhole 18 produces the image I simultaneously on the two input planes.
  • FIG. 2 shows a curve 32 representing variations in amplitude in volts of the difference signal SD as a function of the displacement A p of the pinhole 18 along the second axis 25, in the direction 19, that is to say of the first detector means 20 to the second detector means 21; this displacement at p of the pinhole 18 being effected by means of the micrometric screw 13 (shown in FIG. 1) which makes it possible to control this displacement in a very fine manner.
  • Zone 1 corresponds to a formation of the image of the focal point f on the input pland 22 of the first detector means 20, and on it alone.
  • the second zone Z 2 corresponds to a simultaneous illumination of the first and second detector means 20, 21.
  • the third zone Z 3 corresponds to the illumination of the second detector means 21, and to it alone.
  • the second zone Z 2 constitutes the zone of interest in which the variation of the difference signal SD is comparable to a straight line 33 passing through 0 at a point C, where the illumination of the input plane 22 of the first detector means 20 is equal to the illumination of the input plane 23 of the second detector means 21; this straight part 33 of the curve originating in particular from the fact that an increase in a given quantity of the illumination of one of the detector means 20 or 21, linked to the displacement of the image I, is accompanied by a reduction, of the same amount of the illumination of the other detector means, considering that the illumination distribution on the axis of movement 25 is a constant.
  • This slope or first constant a corresponds to the ratio of the voltage variation ⁇ v I to the position variation ⁇ p 1 having generated this voltage variation:
  • This determination of the slope a constitutes a calibration of the control device 15.
  • FIG. 3 is a geometric construction which makes it possible to illustrate the correlation between displacements ⁇ f of the focus f and ⁇ p of the pinhole 18, which generate the same displacement d 1 of the image I.
  • the reference axis 24 passes through the focal point f merged with the reference position P r , the pinhole 18 and, by the image I of this focal point f, which image I is in FIG. 3 symbolized by a point constituting its center.
  • the pinhole 18 is arranged at a first known distance Y from the focal point f, at a point D, and the entry planes 22, 23 on which the image I is formed, are arranged at a second known distance Z from the pinhole 18; a known displacement ⁇ P of the pinhole 18 thus causing a known displacement ⁇ 1 of the image.
  • a displacement ⁇ 1 of the image, causing the latter to occupy a position G can be generated either by a displacement ⁇ p of the pinhole 18 bringing the latter to a position E, or by a displacement ⁇ f of the focus f bringing the latter at position B.
  • the expression A contains only one unknown, the first constant or slope a.
  • the slope a is determined according to the first relation: by means of a calibration which consists in moving the pinhole 18 by a known value, using the micrometric screw 13, and in measuring the corresponding variation ⁇ v l of the difference signal SD.
  • the values of the displacements ⁇ p 1 of the pinhole camera 18 are preferably large in front of possible displacements of the focal point f during this calibration.
  • the control device 15 constitutes a highly sensitive device, suitable for use in the laboratory, the displacements A f of focus f which can be discerned being of the order of a micrometer .
  • the support structure 16 comprises centering means 26, 27 intended to cooperate with the reference faces 34 of the outlet window 10, so as to reference mechanically with respect to the latter, the control device 15; the reference axis 24 being positioned in construction and passing through the theoretical position T of the focus f.
  • Another version of the invention consists in mechanically referencing the control device 15, with respect to an element of a radiological installation in relation to which the position of the focus f must be carried out.
  • the method of the invention makes it possible to control the position of the focal point of the X-ray tube, during the normal operation of a radiological installation; that is to say without closing the exit window 10.
  • the position of the focal point can be of paramount importance for the quality of the image, in particular in the field of computed tomography and particularly CT scan; position variations at f with focus f, which may arise, for example, from mechanical play or expansion.
  • FIG. 4 schematically shows a radiological installation 40, partially represented by elements essential for understanding the invention.
  • the sheath 1 is arranged in a conventional manner above an irradiation plane 41 constituted by a patient-carrying panel (represented by a line in dotted lines), under which is disposed a means X-ray receiver 42.
  • the sheath 1 is assembled with a beam limiting device 43, and it is conventionally supported by a rail 44, by means of a motorized carriage 45.
  • the rail 44 is disposed parallel to the first axis 8 along which s checks the position of the focal point f; the sheath 1 thus being capable of displacement along the rail 44 in one or the other of the directions shown by the third and fourth arrows 46, 47.
  • the X-ray tube 2 (not shown in FIG. 4) is contained in the sheath 1, and produces from the focal point f the X-ray radiation beam 9.
  • the projection of the X-ray radiation beam 9 determines on the irradiation plane 41 a irradiation field inscribed in first limits 48, within which there is a useful field called useful radiological field, inscribed in second limits 49 and in which the differences in illumination and definition are acceptable.
  • the control device 15 is arranged, the support structure 16 of which is secured to the receiving means 42 by conventional fixing means, such as beams 81 for example.
  • the structure 16 is of the one-piece type as previously described, but it can also be produced so as to allow separate mounting of the pinhole camera 18 and the detector means 20, 21; the essential being in this version of the invention that it is mechanically independent of the sheath 1, but dependent on the reference means chosen, that is to say in the example described the receiving means 42.
  • the control of the position of the focal point f can be carried out by linking a displacement ⁇ f to a displacement A p of the pinhole 18 as has already been explained, by applying the relation 3:
  • the slope a can have different values depending on the intensity of the X-ray produced, that is to say the intensity of the illumination by the image I of the focal point f to which are subjected. the first and second detector means 20, 21.
  • an X-ray tube is subjected to different regimes (acceleration voltage, electronic flow), the intensity of the illumination of the detector means 20, 21 then being different for each regime, consequently bringing about a variation in the slope of the straight line which constitutes the calibration slope; this slope being all the steeper the higher the operating regime of the X-ray tube.
  • This particular aspect is used in the method according to the invention to produce a control of the position in space of the hearth f.
  • the method according to the invention then consists in orienting the reference axis 24 so as to pass it through the focal point f, so as to make the latter coincide with the reference position P and, obtain an equal illumination on each detector means 20 , 21 and a zero value of the difference signal SD generated by the differential amplifier 30.
  • the difference output signal SD thus constitutes an error signal which, depending on whether it is positive or negative, controls the movement of the carriage 45 along the rail 44 in one or other of the directions shown by the arrows 46,47 .
  • Figure 5 shows the block diagram of a control loop formed in the control device 15 (shown in a frame in dotted lines), allowing the implementation of this last part of the method according to the invention. This last part of the method is also applicable to a radiological installation, not shown in FIG. 5, where only the focal point f is shown for clarity of the figure.
  • This part of the process consists, for an initial position of the focal point F, in making the latter coincide with the reference position P by acting on the micrometric screw 13 for example, in order to pro evoke a movement of the pinhole 18 and obtain an equal illumination on each detector means 20, 21, so that the output signal SD delivered by the differential amplifier 30 is zero; this difference signal SD being applied to control means 50 of a motor 51.
  • This motor 51 is mechanically coupled in rotation on the one hand to the micrometric screw 13 which it drives in rotation according to the sixth arrow 70 around the 'axis of movement 25 of the pinhole 18, and on the other hand to a feedback means constituted in the nonlimiting example described by a feedback potentiometer 52; these mechanical couplings being carried out by traditional means, symbolized in FIG.
  • the feedback potentiometer 52 is supplied with a voltage between -V and + V applied respectively to its first and second ends 56, 57; the cursor 58 of this feedback potentiometer 52 being connected to a display means 31 such as a voltometer for example, to which it delivers information V 3 .
  • the difference signal SD which constitutes an error signal passes from a zero value to a negative or positive value according to the direction, shown by the fifth arrow 60, of this displacement A f of the focus F.
  • This positive or negative value of the difference signal SD constitutes a error signal used to activate the motor 51, the latter causing the pinhole 18 to move dp in the direction shown by the fifth arrow 60.
  • This control of the motor 50 is continued until the pinhole 18 reaches a position P 4 where it restores the balance of the illuminations of the first and second detector means 20, 21; this position being that where the reference axis 24, displaced by the movement of the pinhole 18, passes through the position P occupied by the focus f.
  • the motor 51 having simultaneously caused the displacement ⁇ p of the pinhole 18 and, the displacement of the cursor 58 as shown by the eighth arrow 80, the latter determines a variation V 3 of the information v 3 which it delivers to the voltmeter 31; this variation ⁇ v 3 being positive or negative depending on the direction of movement of the pinhole 18, and proportional to this movement.
  • variation ⁇ v 3 of the information v 3 represents the displacement ⁇ p of the pinhole 18, after a calibration for example with respect to the graduations (not shown in FIG. 5) of the micrometric screw 13, and makes it possible to determine the value displacement ⁇ f of the corresponding focal point f according to the relation: where Y is the first distance between the reference position P and the pinhole 18, and Z is the second distance between the pinhole 18 and the detector means 20,21.
EP85401034A 1984-05-30 1985-05-28 Verfahren zur Steuerung der Position des Brennflecks einer Röntgenröhre und Steuervorrichtung zur Durchführung dieses Verfahrens Expired EP0165850B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8408489A FR2565451B1 (fr) 1984-05-30 1984-05-30 Procede de controle de la position du foyer d'un tube radiogene et dispositif de controle mettant en oeuvre ce procede
FR8408489 1984-05-30

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EP0165850A1 true EP0165850A1 (de) 1985-12-27
EP0165850B1 EP0165850B1 (de) 1988-10-26

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US (1) US4675892A (de)
EP (1) EP0165850B1 (de)
DE (1) DE3565924D1 (de)
FR (1) FR2565451B1 (de)

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EP0793902A1 (de) * 1994-11-22 1997-09-10 Analogic Corporation Kompensationsvorrichtung für röntgenstrahlen-brennpunktbewegungen
NL1004633C2 (nl) * 1995-11-28 1997-09-26 Analogic Corp Inrichting voor het regelbaar prekalibreren van de positie van het brandpunt van een röntgenbuis voor gebruik in een CT scannerstelsel.

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DE102004025119B4 (de) * 2004-05-21 2012-08-02 Siemens Ag Röntgenstrahler
JP2009517828A (ja) * 2005-12-01 2009-04-30 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 Ｘ線管および焦点スポット特性を定める方法
CN101410928B (zh) * 2006-03-29 2010-11-03 皇家飞利浦电子股份有限公司 X射线焦斑温度的双色高温测量
CN102224557B (zh) * 2008-11-25 2014-03-05 皇家飞利浦电子股份有限公司 具有靶标温度传感器的x射线管
CN103959423B (zh) 2011-11-23 2017-09-29 皇家飞利浦有限公司 X射线强度的周期性调制
US9405021B2 (en) * 2013-06-03 2016-08-02 Unfors Raysafe Ab Detector for detecting x-ray radiation parameters
US9417194B2 (en) 2013-08-16 2016-08-16 General Electric Company Assessment of focal spot characteristics
US10386313B2 (en) 2016-09-29 2019-08-20 Bruker Jv Israel Ltd. Closed-loop control of X-ray knife edge
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EP0306081A2 (de) * 1987-08-29 1989-03-08 Philips Patentverwaltung GmbH Röntgengerät für Schlitzradiographie
EP0306081A3 (en) * 1987-08-29 1990-12-12 Philips Patentverwaltung Gmbh Apparatus for slit radiography
EP0793902A1 (de) * 1994-11-22 1997-09-10 Analogic Corporation Kompensationsvorrichtung für röntgenstrahlen-brennpunktbewegungen
EP0793902A4 (de) * 1994-11-22 1998-04-08 Analogic Corp Kompensationsvorrichtung für röntgenstrahlen-brennpunktbewegungen
NL1004633C2 (nl) * 1995-11-28 1997-09-26 Analogic Corp Inrichting voor het regelbaar prekalibreren van de positie van het brandpunt van een röntgenbuis voor gebruik in een CT scannerstelsel.
US5745548A (en) * 1995-11-28 1998-04-28 Analogic Corporation Apparatus for and method of adjustably precalibrating the position of the focal spot of an X-ray tube for use in a CT scanner system

Also Published As

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FR2565451B1 (fr) 1986-08-22
DE3565924D1 (en) 1988-12-01
EP0165850B1 (de) 1988-10-26
US4675892A (en) 1987-06-23
FR2565451A1 (fr) 1985-12-06

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