US3675027A - System for continuously varying the size of the field of an x-ray image intensifier tube - Google Patents

System for continuously varying the size of the field of an x-ray image intensifier tube Download PDF

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Publication number
US3675027A
US3675027A US74454A US3675027DA US3675027A US 3675027 A US3675027 A US 3675027A US 74454 A US74454 A US 74454A US 3675027D A US3675027D A US 3675027DA US 3675027 A US3675027 A US 3675027A
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Prior art keywords
field
size
voltage
annode
electrodes
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Expired - Lifetime
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US74454A
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English (en)
Inventor
Motohisa Tsuda
Masao Yoshimura
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Shimadzu Corp
Shimadzu Seisakusho Ltd
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Shimadzu Corp
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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
    • H05G1/64—Circuit arrangements for X-ray apparatus incorporating image intensifiers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J31/00—Cathode ray tubes; Electron beam tubes
    • H01J31/08—Cathode ray tubes; Electron beam tubes having a screen on or from which an image or pattern is formed, picked up, converted, or stored
    • H01J31/50—Image-conversion or image-amplification tubes, i.e. having optical, X-ray, or analogous input, and optical output
    • H01J31/501—Image-conversion or image-amplification tubes, i.e. having optical, X-ray, or analogous input, and optical output with an electrostatic electron optic system
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N5/00—Details of television systems
    • H04N5/30—Transforming light or analogous information into electric information
    • H04N5/32—Transforming X-rays
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N23/00—Cameras or camera modules comprising electronic image sensors; Control thereof
    • H04N23/30—Cameras or camera modules comprising electronic image sensors; Control thereof for generating image signals from X-rays

Definitions

  • X-ray image intensifier tubes generally comprise a vacuum envelope and an input and an output screen at the opposite ends thereof, with several control electrodes therebetween for focussing an X-ray image formed on'the input screen onto the output screen as a visible image.
  • the output screen is far smaller in size than the input screen, the latter being for example eleven inches in diameter while the former is only one inch in diameter. If the entire image on the input screen is reproduced on the output screen, the image is demagnified to one-eleventh but much intensified in brightness. If only a portion of the input image is reproduced on the entire area of the output screen, the output image is less demagnified or enlarged but less intensified.
  • the size of that portion of the input image which is reproduced as an output image is called the field of view (or simply the field) of the tube, and the ratio of the input image size to the output image size is called the demagnification ratio, which will be designed by M. Since the size of the output screen is fixed in a particular tube, the demagnification ratio is determined by the size of the field of view.
  • zooming is a very effective technique in observation through the X-ray image intensifier tube.
  • an examiner is viewing the entire area of an object, for example, a patient's chest cavity on the output screen. If he wishes to closely examine a small portion of the chest cavity, he may zoom up the image on the output screen by increasing the demagnification ratio.
  • zooming is effected by varying the voltages impressed on the electrodes of the intensifier tube.
  • the voltage to be applied to the annode and the subsidiary annode is very high, sometimes as high as kV, so that in order to regulate the high voltage it is practically impossible to insert a potentiometer in the high direct current voltage output circuit connected to the electrodes.
  • a smoothing condenser having a large capacity is usually provided at the output side of a direct current power source to smooth the output voltage thereof to be applied to the subsidiary annode.
  • the size of the image on the output screen changes in inverse proportion to the change of the demagnification ratio M.
  • the size of the output image changes at a lower speed in the larger field with a larger demagnification ratio than in the small field with a small demagnification ratio.
  • a point in an image on the output screen radially moves more slowly in a large field than in a smaller field. This not only causes irritation to the observer but also detriorates the tracing observation effect.
  • Another object of the invention is to provide a system for zooming the output image of an Xray image intensifier tube, wherein when any change for zooming in the voltages impressed on the electrodes of the tube results in a corresponding change in the size of the output image without substantial delay, so that no reduction of the resolving power occurs during the course of zooming operation.
  • FIG. 1 is a schematic, longitudinal section of an image intensifier tube incorporated into the system of the invention
  • FIG. 2 is a graph illustrating the relation between the size of the field of view of the tube and the voltages impressed on the electrodes thereof;
  • FIG. 3 is an electrical circuit diagram of the control circuit showing the intensifier tube.
  • FIG. 4 is a diagram of a portion of FIG. 3 showing the detailed construction of the voltage regulators.
  • X-ray image intensifier tube generally designated by 10 and comprising a vacuum tube 11, an input screen 12 at one end of the tube, a first electrode or grid 13 connected to a terminal G1, a second electrode or grid 14 connected to a terminal G2, a subsidiary annode 15 connected to a terminal SA, an annode 16 connected to a tem'iinal A and an output screen 17 at the opposite end of the tube 11.
  • the input screen 12 has a diameter of, say, 1 1 inches, which is far greater than the output screen 17 having a diameter of, say, only one inch.
  • the X-ray image of an object, not shown, formed on the input screen is changed into a beam of electrons carrying the image thereon, and the beam is condensed and focussed by the electrodes 13 -16 onto the output screen 17 so as to display thereon a visible image corresponding to the input image, demagnified insize but intensified in brightness.
  • that portion of the image on the input screen 12 which is reproduced on the output screen 17 is called the field of view (or simply the field), and the ratio of the size of the input image to that of the output image is called the demagnification ratio M.
  • the size of the field or the ratio M can be changed by changing the voltages applied to the terminals of the electrodes of the tube in a correlated manner as shown in FIG. 2, wherein the diameter of the field inches is taken along the abscissa and the voltages on the terminals G1, G2 and SA, along the ordinate, with the SA voltage being scaled at the left-hand side and the grid voltages G1 and G2, at the right-hand side of the graph.
  • a circuit for varying the voltages applied to the electrodes is shown by way of example in FIG. 3.
  • the reference symbols A, SA, G1 and G2 designate the terminals designated by the same reference symbols, respectively, in FIG. 1.
  • a voltage regulator 18 has its slider 19 connected to the terminal G1 and its opposite ends, to the secondary side of a transformer 20, with a rectifying diode 21, a smoothing condenser 22 and a grounding resister 23 connected therebetween.
  • a voltage regulator 24 has its slider 25 connected to the terminal G2 and its opposite ends, to the secondary side of a transformer 26, with a rectifying diode 27, a smoothing condenser 28 and a grounding resister 29 connected therebetween.
  • the voltage regulators l8 and 24 regulate the voltages to be applied to the grids l3 and 14, respectively.
  • the transformers and 26 have their respective primary windings connected to an alternating current source L.
  • a constant speed motor 30 is provided, which mechanically mOves the sliders l9 and of the voltage regulators to regulate the level of the output voltages therefrom.
  • the construction of the regulators constitutes an essential portion of this invention and will be described in detail later.
  • a transfer switch 31 is inserted between the alternating current source L and the motor to determine the direction of rotation of the motor.
  • the voltages to be applied to the annode A and the subsidiary annode SA are very much higher than those applied to the grids G1 and G2 and therefore it is practically impossible to have a voltage regulator inserted in the output circuitof the transformer connected between the source and the electrodes A and SA, as in the case with the grids G1 and G2. Therefore, the terminal SA of the subsidiary annode 15 is connected to the secondary side of a transformer 32 through a series combination of a protective resistor 33 and a rectifying diode 34, with a parallel smoothing condenser 35.
  • the primary side of the transformer 32 is connected to the source L, with variable transformer 36 inserted therebetween, the slider 37 of which is controlled by a servo-motor 38.
  • a servo-amplifier 39 includes voltage regulators 40 and 48 similar to the previously mentioned regulators 18 and 24.
  • the amplifier 39 amplifies the difference voltage between the sliders 41 and 49 and controls the operating voltage to be applied to the servo-motor 38.
  • the slider 41 of the regulator 40 is controlled by the motor 30 which controls the sliders 19 and 25 of the regulators 18 and 24.
  • a voltage corresponding to the resistance set by the regulator 40 is applied to the terminal SA, as will be described in detail later.
  • the terminal A of the annode 16 is connected to the secondary side of a transformer 42 through a protective resistor 43, a rectifying diode 44 and a smoothing condenser 45.
  • the primary sidelof the transformer 42 is connected to a variable transformer 46, which is in turn connected to the source L.
  • the slider 47 of the variable transformer 46 is manually mova-- ble to set the annode voltage to a predetermined fixed value.
  • FIG. 4 shows the detailed structure of the voltage regulator 18,
  • the other voltage regulators are of a similar structure to the regulator 18, so that the structure of the regulator 18 alone will sufficiently be described as a representative of the others.
  • the regulator 18 comprises a plurality of serial section resistors r-l r2, r-3, r-n having different predetermined resistance values, with the slider 18 movable along the series combination, so that the voltage taken out therefrom is applied to the control grid G1.
  • the resistance values of these section resistors are so selected that as the slider is moved, the voltage taken out of each of the regulators changes in a correlated manner to those from the other regulators so as to provide different sizes of the field as shown in FIG. 2. Strictly speaking, so long as the slider moves along one of the section resistors, the voltage taken out therefrom varies linearly, and when the slider moves intO the adjacent one of the resistors,
  • the voltage changes linearly but with a difierent inclination.
  • the resistance values of the resistors are so selected that these short section lines having different inclinations or slopes approximately correspond to the curves G1, G2 and SA, and as 5 will be easily seen, the more section resistors there are provided, the closer approximation to the curves is attained.
  • the resistance values are also so predetermined that the change in the voltages applied to the electrodes causes each and every point of the output image to move at a substantially constant speed as the size of the field changes.
  • the maximum field size is 1 1 inches; the minimum field size is 5 inches; and the time required for the field to change from the maximum to minimum sizes is T,
  • the resistance values of the section resistors are so selected that for the same moving speed of the slider, the voltage taken out from those of the resistors which effect smaller fields changes at a smaller rate and the voltage taken out from those of the resistors which effect larger fields changes at a greater rate.
  • said voltage regulator comprises a series combination of section resistors with a slider adapted to be moved by said motor along the length of said combination, the resistance values of said resistors being so selected that the rate of field change increases as the size of field goes from minimum to maximum.
  • each said voltage regulators comprises a series combination of section resistors with a slider adapted to be moved by said motor along the length of said combination, the resistance values of said resistors being so selected that the rate of field change increases as the size of field goes from minimum to maximum.

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  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • X-Ray Techniques (AREA)
  • Image-Pickup Tubes, Image-Amplification Tubes, And Storage Tubes (AREA)
US74454A 1969-10-03 1970-09-22 System for continuously varying the size of the field of an x-ray image intensifier tube Expired - Lifetime US3675027A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP44079463A JPS4915898B1 (de) 1969-10-03 1969-10-03

Publications (1)

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US3675027A true US3675027A (en) 1972-07-04

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US74454A Expired - Lifetime US3675027A (en) 1969-10-03 1970-09-22 System for continuously varying the size of the field of an x-ray image intensifier tube

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US (1) US3675027A (de)
JP (1) JPS4915898B1 (de)
DE (1) DE2048553C3 (de)
FR (1) FR2064920A5 (de)
NL (1) NL167275C (de)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3835314A (en) * 1973-03-05 1974-09-10 Machlett Lab Inc Intensifier radiographic imaging system
EP0526921A1 (de) * 1991-06-17 1993-02-10 Koninklijke Philips Electronics N.V. Röntgenbildsystem
US5563407A (en) * 1993-09-20 1996-10-08 Kabushiki Kaisha Toshiba X-ray image intensifier tube with an ion pump to maintain a high vacuum in the tube
US6301331B1 (en) * 1990-11-16 2001-10-09 Hitachi Medical Corporation Digital radiography system having an X-ray image intensifier tube

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3225204A (en) * 1960-10-28 1965-12-21 Philips Corp Electron-optical image intensifier system
US3303345A (en) * 1962-12-20 1967-02-07 Philips Corp Image amplifier with magnification grid
US3417242A (en) * 1965-09-20 1968-12-17 Machlett Lab Inc Image intensification system comprising remote control means for varying the size of the output image

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3225204A (en) * 1960-10-28 1965-12-21 Philips Corp Electron-optical image intensifier system
US3303345A (en) * 1962-12-20 1967-02-07 Philips Corp Image amplifier with magnification grid
US3417242A (en) * 1965-09-20 1968-12-17 Machlett Lab Inc Image intensification system comprising remote control means for varying the size of the output image

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3835314A (en) * 1973-03-05 1974-09-10 Machlett Lab Inc Intensifier radiographic imaging system
US6301331B1 (en) * 1990-11-16 2001-10-09 Hitachi Medical Corporation Digital radiography system having an X-ray image intensifier tube
US6351518B2 (en) 1990-11-16 2002-02-26 Hitachi Medical Corporation Digital radiography system having an X-ray image intensifier tube
EP0526921A1 (de) * 1991-06-17 1993-02-10 Koninklijke Philips Electronics N.V. Röntgenbildsystem
US5563407A (en) * 1993-09-20 1996-10-08 Kabushiki Kaisha Toshiba X-ray image intensifier tube with an ion pump to maintain a high vacuum in the tube

Also Published As

Publication number Publication date
FR2064920A5 (de) 1971-07-23
NL7014415A (de) 1971-04-06
DE2048553B2 (de) 1973-10-18
DE2048553A1 (de) 1971-05-13
JPS4915898B1 (de) 1974-04-18
NL167275B (nl) 1981-06-16
DE2048553C3 (de) 1974-05-09
NL167275C (nl) 1981-11-16

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