WO2017200507A1 - Multisensor digital x-ray receiver and pyramid-beam x-ray tomograph equipped with such receiver - Google Patents

Multisensor digital x-ray receiver and pyramid-beam x-ray tomograph equipped with such receiver Download PDF

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Publication number
WO2017200507A1
WO2017200507A1 PCT/UA2016/000065 UA2016000065W WO2017200507A1 WO 2017200507 A1 WO2017200507 A1 WO 2017200507A1 UA 2016000065 W UA2016000065 W UA 2016000065W WO 2017200507 A1 WO2017200507 A1 WO 2017200507A1
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Prior art keywords
ray
sections
video signals
receiver
digital
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PCT/UA2016/000065
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French (fr)
Inventor
Sergii MIROSHNYCHENKO
Andrii NEVGASYMYI
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Miroshnychenko Sergii
Nevgasymyi Andrii
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Publication of WO2017200507A1 publication Critical patent/WO2017200507A1/en

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    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B6/00—Apparatus or devices for radiation diagnosis; Apparatus or devices for radiation diagnosis combined with radiation therapy equipment
    • A61B6/42—Arrangements for detecting radiation specially adapted for radiation diagnosis
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B6/00—Apparatus or devices for radiation diagnosis; Apparatus or devices for radiation diagnosis combined with radiation therapy equipment
    • A61B6/42—Arrangements for detecting radiation specially adapted for radiation diagnosis
    • A61B6/4208—Arrangements for detecting radiation specially adapted for radiation diagnosis characterised by using a particular type of detector
    • A61B6/4225—Arrangements for detecting radiation specially adapted for radiation diagnosis characterised by using a particular type of detector using image intensifiers
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B6/00—Apparatus or devices for radiation diagnosis; Apparatus or devices for radiation diagnosis combined with radiation therapy equipment
    • A61B6/42—Arrangements for detecting radiation specially adapted for radiation diagnosis
    • A61B6/4266—Arrangements for detecting radiation specially adapted for radiation diagnosis characterised by using a plurality of detector units
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N25/00—Circuitry of solid-state image sensors [SSIS]; Control thereof
    • H04N25/40—Extracting pixel data from image sensors by controlling scanning circuits, e.g. by modifying the number of pixels sampled or to be sampled
    • H04N25/41—Extracting pixel data from a plurality of image sensors simultaneously picking up an image, e.g. for increasing the field of view by combining the outputs of a plurality of sensors
    • G—PHYSICS
    • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
    • G21K—TECHNIQUES FOR HANDLING PARTICLES OR IONISING RADIATION NOT OTHERWISE PROVIDED FOR; IRRADIATION DEVICES; GAMMA RAY OR X-RAY MICROSCOPES
    • G21K4/00—Conversion screens for the conversion of the spatial distribution of X-rays or particle radiation into visible images, e.g. fluoroscopic screens
    • G21K2004/02—Conversion screens for the conversion of the spatial distribution of X-rays or particle radiation into visible images, e.g. fluoroscopic screens characterised by the external panel structure

Definitions

  • This invention relates to a structure of multisensor digital X-ray receivers on basis of optoelectronic converters having partly overlapping visual fields, and to a structure of computer pyramid-beam X-ray tomographs equipped with such receivers. These tomographs are meant for examination of peoples and animals.
  • First phase allowed excluding irradiation of roentgenologists, and second phase ensures sharp decrease of patient radiation exposure (no less than 10, but quite often more than 20 times).
  • CCD charge-coupled devices
  • Expensive digital receivers on basis of thin layers of amorphous silicon (a-Si) shaped as lightweight flat plates are producing in USA, Germany, France, Netherlands, Japan and China. They have typical overall dimensions up to 43x43x3 cm for the sake of compatibility with usual X-ray film holders.
  • a-Si amorphous silicon
  • Multisensor digital X-ray receivers on basis of optoelectronic converters such as TV- cameras are producing in Ukraine and Japan.
  • Synchronous movement of X-ray units i.e. an X-ray emitter and an X-ray receiver
  • X-ray units i.e. an X-ray emitter and an X-ray receiver
  • the most perfect X-ray receiver of such kind disclosed in our international publication WO 2006/049589. It has a box-type lightproof housing having roentgenoparent front wall and fixed serially behind this wall a flat X-ray-to-optical converter and an unit of such formers of fragmentary video signals, which have fixed in the form of at least two-row matrix in a flat lightproof roentgenopaque partition. Enveloping surface of all these formers is a plane. Each such former comprises fastened one after another along ray path a filter of residual X- radiation (formed usually as a washer made from lead glass), a multiple-lens objective and an optoelectronic converter such as TV-camera.
  • a filter of residual X- radiation formed usually as a washer made from lead glass
  • an optoelectronic converter such as TV-camera.
  • These formers are usually equipped with blends, which are arranged in front of said washers. Visual fields of adjacent formers of fragmentary analogous video signals are partly overlapping.
  • Optical inputs of the optoelectronic converters are directed against said X-ray-to-optical converter, and their electrical outputs are connected to an ADC unit that converts fragmentary analogous video signals into fragmentary digital video signals, and further - through a multichannel corrector of geometric distortions - to a data processing unit that forms output integral digital video signals corresponding to discrete roentgenological pictures.
  • Such multisensor digital X-ray receivers are simple in construction, manufacturable, easy-to-use, reliable and inexpensive. Moreover, they ensure frequency of the integral digital video signals no less than 25 pps. This is sufficient for tomographic scanning. And, finally, structure disclosed in the said WO 2006/049589 allows substantial enlargement of active area of multisensor digital X-ray receivers that is necessary, e.g., for X-ray tomography of large parts of adult patient's body such as chest or abdominal cavity in whole.
  • US 6,940,943 disclose X-ray tomograph, comprising:
  • a controllable X-ray emitter which is placed on said carriage and equipped with a collimator meant for shaping of X-ray beam;
  • a flat digital X-ray receiver located under said table and equipped with a controllable reciprocating motion drive along it;
  • a control unit to which said controllable drives; said checker and said X-ray emitter are connected;
  • a data-processing unit connected to the X-ray receiver output and meant for generation of integral digital roentgenological pictures
  • a tomosynthesis unit connected to the said data-processing unit.
  • the X-ray emitter moves along a circle arc, and the flat digital X-ray receiver moves in the opposite direction along the straight line.
  • Cone-beam computed tomography arthrography an innovative modality for the evaluation of wrist ligament and cartilage injuries // Skeletal Radiology. 2012. V. 41 . p. 936-969; 3. A.IO. BacnnbeB, H. H. ⁇ ( ⁇ .), E.A. Eropoea. KoHycHO-Ji neBaa OMnbioTepHaa TOMorpac wH - HOBaa TexHonornfl nccneflOBamifl B TpaeiviaTonornn // MEflMJ,HHCKAfl BH3yAJll/13AH,Hfl. N°4, 2012, c.
  • the gap in said annular support of such tomographs no exceeds size of human head. Therefore they are meant usually for tomography of cartilages, bones of hands and feet, articulations of extremities and other small parts of human or animal bodies, and only on rare for tomography of brainpans (including dentitions).
  • B c is brightness of roentgenological picture in the receiver's center
  • B E is brightness of roentgenological picture at receiver's edges
  • L is distance between the aperture center of used X-ray emitter and center of used flat X-ray receiver
  • a roentgenoparent table for placing of an examined subject i.e. human or animal
  • An optical device meant for recording of roentgenological pictures (this device is usually fixed onto said annular support and can have automatic focusing device), and
  • pyramid-beam X-ray tomographs are known, in which diameter of opening of said annular support is equal 78 cm and length of said CCD detectors strip comes up to 100 cm that creates diameter of tomography region up to 60 cm, and which have 64 and more of such strips. This allows producing adequate number of tomograms during one diagnostic session (see, e.g., RAD BOOK 2015. The Radiology Guide to Technology and Information in Europe, section “Computer Tomography", pp.9-12, especially p.12).
  • a carrier of X-ray units in the form of a ⁇ -like gantry which has - horizontal cantilevered projections, on end parts of which a controllable X-ray emitter together with a collimator meant for shaping of pyramidal X-ray beam and an X-ray receiver are oppositely fastened, and
  • a horizontal roentgenoparent table which is meant for placing of an examined subject and, in operative position, is motionlessly found within a gap between said X-ray emitter and said X-ray receiver;
  • a controllable drive of reciprocating rotary motion of said ⁇ -like gantry relative to the said table is embedded in said box and coupled kinematically with said horizontal shaft;
  • Such tomograph can displace pyramidal X-ray beam only within a restricted circle sector. This reduces radiation exposure of examined subjects even if the X-ray emitter will be continuously operating during diagnostic sessions.
  • X-ray receivers based on CCD-detectors have excessive inertial mass, as it had been said above. It doesn't matter, if some tomograph equipped with easily balanceable annular support of X-ray units and with a drive of continuous uniform one-way rotation of it. However, mounting of any heavy X-ray receiver onto one cantilevered projection of such ⁇ - like gantry, which is capable to start-stop movement, is possible only under condition that said projection shaped as a massive fish-bellied girder. By-turn, it requires complicated balancing both said cantilevered projections and increase of energy consumption by said drive of reciprocating rotary motion.
  • the invention is based on the problem - Firstly, by way of improvement of form and positional relationship of components to create such multisensor digital X-ray receiver, which allows substantial equalizing brightness of roentgenological pictures in all active area of this receiver, and,
  • a multisensor digital X-ray receiver comprising - a box-type lightproof housing closed by a roentgenoparent front wall, and
  • a flat X-ray-to-optical converter and a flat lightproof roentgenopaque partition in which in the form of at least two-row matrix such formers of fragmentary analogous video signals are fixed, each of which composed of arranged one after another along ray path a filter of residual X-radiation, a multiple-lens objective and an optoelectronic converter,
  • said box-type lightproof housing is composed of at least two located at obtuse angles sections and closed by a common plano-concave roentgenoparent front wall,
  • said X-ray-to-optical converter and said lightproof roentgenopaque partition are also sectioned and mounted within the housing sections under respective planar parts of said plano-concave roentgenoparent front wall,
  • Such digital receiver allows substantial equalizing brightness of roentgenological pictures in each its discrete section and, therefore, in all its active area in spite of that the formers of fragmentary analogous video signals fixed in said each discrete section have planar enveloping surface. This equalization had achieved owing to the fact that width of discrete sections can be substantially decreased.
  • First additional feature consists in that the box-type lightproof housing is composed of two located at obtuse angle sections, in which two sections of said X-ray-to-optical converter and two sections of said partition comprising said formers of fragmentary analogous video signals are respectively mounted. These receivers are meant for equipping preferably veterinary X-ray tomographs.
  • Second additional feature consists in that the box-type lightproof housing is composed of three located at equal obtuse angles sections, in which three sections of said X-ray-to- optical converter and three sections of said partition comprising said formers of fragmentary analogous video signals are respectively mounted. These receivers are efficient for X-ray tomography even diverent peoples.
  • a pyramid-beam X-ray tomograph comprising - (1 ) A stationary vertically oriented box;
  • a carrier of X-ray units in the form of a ⁇ -like gantry which has - horizontal cantilevered projections, on end parts of which a controllable X-ray emitter together with a collimator meant for shaping of pyramidal X-ray beam and an X-ray receiver 5 are oppositely fastened, and
  • a horizontal roentgenoparent table which is meant for placing of an examined subject and, in operative position, is motionlessly found within a gap between said X-ray
  • a controllable drive of reciprocating rotary motion of said ⁇ -like gantry relative to the said table is embedded in said box and coupled kinematically with said horizontal shaft;
  • a multisensor digital X-ray receiver which has a box-type lightproof 20 housing composed of at least two located at obtuse angles sections closed by a common plano-concave roentgenoparent front wall and mounted serially within the housing sections under respective planar parts of said front wall sections of an X-ray-to-optical converter and sections of a lightproof roentgenopaque partition those serve as carriers of formers of fragmentary analogous video signals composed of arranged one after another along ray path 25 filters of residual X-radiation, multiple-lens objectives and optoelectronic converters;
  • Such pyramid-beam X-ray tomographs can be efficiently used for examination of peoples and animals. They allow substantial decrease of radiation exposure of examined subjects because the table is motionless and angular displacement of said ⁇ -like gantry is no j more than 220° during each tomographic scanning. Moreover, the proposed X-ray p5 tomographs are economical in respect of material and energy consumption because used in their structure aforesaid X-ray receivers have insignificant inertial mass. And, finally, said ⁇ - like gantries can be easy balanced during montage of said X-ray units.
  • First additional feature consists in that said roentgenoparent table is displaceable and equipped with at least one retaining device for fixation of it relative to the said stationary 40 vertically oriented box during each tomographic scanning. This allows to place said table either along or across geometrical axis of said horizontal shaft and, respectively, to form roentgenological pictures from two different directions. Comparison of tomograms synthesized on basis of two sets of roentgenological pictures can be useful in cases of differential diagnostics of many diseases (especially at examination of chest or abdominal cavity, where great number of closely spaced organs are found).
  • Second and third additional features consist, respectively, in that the pyramid-beam X- ray tomograph is equipped with two- or three-sectional multisensor digital X-ray receiver. It is sufficient for production of several families of easy-to-use and affordable computer pyramid- beam X-ray tomographs, which can be used in municipal hospitals and veterinary clinics.
  • Fig.1 shows a sample of three-sectional multisensor digital X-ray receiver (schematic longitudinal view; at that one end housing wall is removed for convenience);
  • Fig.2 shows unfolded pattern of the X-ray receiver from the Fig.1 (schematic view along the path of pyramidal X-ray beam; at that a plano-concave roentgenoparent front wall and X-ray-to-optical converter sections are removed for convenience);
  • Fig.3 shows a cross-section of one section of the X-ray receiver from the Fig.1 by plane including optical axes of one row of formers of fragmentary analogous video signals;
  • Fig.4 shows a pyramid-beam X-ray tomograph in one starting position (when a roentgenoparent table located along geometrical axis of a horizontal shaft of a ⁇ -like gantry and a traverse of this gantry is oriented horizontally);
  • Fig.5 shows the same that the Fig.4, when said traverse is oriented vertically;
  • Fig.6 shows the pyramid-beam X-ray tomograph in another starting position (the roentgenoparent table placed across geometrical axis of the horizontal shaft of the ⁇ -like gantry and the traverse of this gantry is oriented vertically).
  • Figs 5 and 6 show only mechanical and X-ray units.
  • Any proposed multisensor digital X-ray receiver has (see Fig.1 ) - A box-type lightproof housing 1 composed of some (preferably two or three) sections located at preferably equal obtuse angles,
  • a sectionalized X-ray-to-optical converter 3 composed of snap-together on each side flat sections
  • a sectionalized lightproof roentgenopaque partition 4 all flat sections of which are meant for fixation of formers 5 of fragmentary analogous video signals in the form of at least two-row matrixes (these formers 5 here and on the Fig.2 are shown as rectangles).
  • Choice of number of housing 1 sections depend on requirements to roentgenological pictures quality and acceptable production costs, which will be the more, the less width of discrete sections and more quantity of theirs. Therefore, two sections are sufficient for simple needs (e.g. for veterinary tomography), three sections are desirable for majority of cases, and more than three sections can be necessary for satisfaction of special requirements to roentgenological pictures quality.
  • plano-concave roentgenoparent front wall 2 can be wholly made from lightproof composites such as turbonit or carbon-filled plastic and so forth.
  • the flat sections of said X-ray-to-optical converter 3 can be made from cesium iodide or salts of rare earth elements, for instance, gadolinium oxysulfide.
  • the flat sections of said partition 4 are usually made from two parts (for example, a lead plate that serves as absorber of residual X-radiation, and a supporting plate from a strong material such as duralumin, sheet steel etc).
  • FIGs 1 and 2 show also that the formers 5 of fragmentary analogous video signals are connected to ADC units 8, which forms, in operative position, fragmentary digital video signals, and further to a system 9 of formation of roentgenological pictures corresponding to the specified slices and computer tomosynthesis.
  • This system 9 is equipped with softwares, which ensure correction of geometric distortions of fragmentary digital video signals, their 25 'sewing-together' into integral digital roentgenological pictures and tomosynthesis.
  • hardware implementation of the system 9 is a microcomputer or a PC.
  • the Fig.1 comprises conditional images of the X-ray emitter 10 and a collimator 1 1 belonged to a described further in detail a computer pyramid-beam X-ray 30 tomograph and some symbols, namely:
  • R that designates length of perpendicular binding the center of aperture of the X-ray emitter 10 with the center of envelope plane of a congruous section of the housing 1 , and a that designates angles between pairs of neighboring perpendiculars R.
  • R is actual length of above-mentioned perpendicular
  • jT is well-known ratio of any circle length to its diameter (approximately 3,14).
  • the schema shown on the Fig.1 reveals clearly that any obtuse angle between adjacent sections of the housing 1 can be determined as
  • Fig.2 shows that the X-ray receiver sections can be composed of several longitudinally oriented parts, which have common envelope plane and disposed within one section of the housing 1. Each such part can have own plate of the X-ray-to-optical converter 3 having above-mentioned metering raster 6 and own plate of said partition 4 having said formers 5 and said ultraviolet radiator 7.
  • Total length of such compound sections is restricted only by capability of the collimator 1 1 to form extensive pyramidal X-ray beam at the output of said X-ray emitter 10.
  • each former 5 includes serially arranged along ray path - A washer 12 that is made from roentgenopaque translucent material such as lead glass (these washers 12 in aggregate serve in each section of the X-ray receiver as main filter of residual X-radiation);
  • An objective 13 comprising at least two divided by air gap lenses 14 meant for focusing of an image fragment, and, as a rule, three (front-end, intermediate and output) diaphragms 15 meant for limitation of light flux; and
  • An optoelectronic converter 16 (usually in the form of a TV-camera), which has fixed onto own bearing within a positioner 17 for the purpose of installation on the optical axis of appropriate objective 13.
  • Electric outputs of the optoelectronic converters 16 are shaped as connectors 18, which must be connected in operative position by flexible multiple-core cable 19 - Firstly, to a not shown here energy source, and,
  • the ADC unit 8 can be divided into subunits as it shown on Figs 1 and 2. Such division facilitates montage.
  • a blend 20 can be usually mounted on said partition 4 before each objective 13. These blends 20 assure partial overlap of visual fields of adjacent formers 5 of fragmentary analogous video signals, as it is shown on Fig.3 in the form of intersection of light rays outcoming from said X-ray-to-optical converter 3 into said objectives 13. In addition, the blends 20 minimize reduction of brightness of images on the visual fields edges of said optoelectronic converters 16 in the event, if the objectives 13 have said diaphragms 9. It is desirable to apply black matt coatings onto interiors of side wall of the housing 1 and the blends 20 and onto both sides of the diaphragms 15, and to apply antireflection layers onto washers 12 and lenses 14. This allows substantially decrease flare illumination of adjacent optical channels by light that reflects from lenses 14 onto the X-ray-to-optical converter 3 and back.
  • Any pyramid-beam X-ray tomographs has (see Figs 4, 5 and 6) - A stationary vertically oriented box 21 ;
  • a carrier of X-ray units in the form of a ⁇ -like gantry 22 that is composed of:
  • a conditionally shown system 9 meant for formation of digital roentgenological pictures corresponding to specified slices and to computer tomosynthesis.
  • controller 26 has at least -
  • Detectors of actual angular position of the ⁇ -like gantry 22 relative to the table 25 e.g., in the form of photon-coupled pairs
  • the roentgenoparent table 25 is usually displaceable and equipped with at least one retaining device for fixation of it relative to the said stationary box 21 during each 65
  • the table 25 can be placed onto a wheeled frame 27 having stopper in the form of a slab 28. One end of it is turned down in order to hold in operative position one part of said frame 27, and another end has opening meant for loose fit on vertical finger 29 that is rigidly fixed in the box 21 basis.
  • This allows to arrange the table 25 either along (see Figs 4 and 5) or across (see Fig.6) geometrical axis of the horizontal shaft 24 of the ⁇ -like gantry 22.
  • the wheeled frame 27 can have a not shown especially suitable hoist of the table 25 (for example, in the form of well-known assembly 'screw - nut' having preferably self-stopping screw.
  • Region of tomographic scanning can be surrounded by not designated especially a roentgenoparent cylindrical casing, as it shown on the Fig.5.
  • the proposed tomographs can be optionally completed either with one proposed X-ray receiver or with several replaceable receivers having different number of sections and/or different total active area.
  • Each finished X-ray receiver must be calibrated.
  • a skilled craftsman or a programmable controller
  • the optoelectronic converters 16 are insensitive to the ultraviolet radiation and generate fragmentary analogous video signals only in response to fluorescence. Obtained signals come in through ADC unit(s) 8 into the system 9.
  • This system 9 memorizes position of each former 5 of fragmentary analogous video signals relative to the rasters 6 for the purpose of following use of such data during correction of geometrical distortions and 'sewing-together' of fragmentary digital video signals into integral digital roentgenological pictures during tomograph operation.
  • the described tomograph can use for the purpose of tomosynthesis as follows.
  • An attendant places the table 25 in a required position either along geometrical axis of the horizontal shaft of the 27 ⁇ -like gantry 22 (see Figs 4 and 5), or across said axis (see Fig.6). It allows tomographic scanning in the angular range up to ⁇ 1 10° at longitudinal position and no more than ⁇ 45° at perpendicular position.
  • Any subject must be placed onto the table 25 in supine position (that is preferable for peoples) or in edgewise position (that is usually used for forcedly immobilized animals). Each subject must be motionless during examination.
  • first mode at examination of any subject within a narrow (as a rule, no more than 60°) sector of tomographic scanning, because radiation exposure is, in this case, in direct proportion to duration of diagnostic session.
  • Second and third tomographic scanning modes allow extreme minimization of radiation exposure.
  • the invention can be used for the purposes of -

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Abstract

MULTISENSOR DIGITAL X-RAY RECEIVER has lightproof housing composed of some located at obtuse angles sections closed by a common plano-concave roentgenoparent front wall, and mounted serially under respective planar parts of said wall sections of an X-ray-to-optical converter and a lightproof roentgenopaque partition. The partition sections serve as carriers of formers of fragmentary analogous video signals composed of serially arranged filters of residual X-radiation, a multiple-lens objectives and an optoelectronic converters. Visual fields of adjacent formers of such signals within and along the edges of said partition sections are partly overlapping, and electrical outputs of said optoelectronic converters in operative position are connected to a former of integral digital video signals and further to the system of formation of roentgenological pictures corresponding to specified slices and computer tomosynthesis. PYRAMID-BEAM X-RAY TOMOGRAPH comprises a stationary vertically oriented box; a Π-like gantry, on horizontal cantilevered projections of which a controllable X-ray emitter together with a collimator and aforesaid X-ray receiver are oppositely fastened and a traverse of which has a horizontal shaft connected to a controllable reciprocating rotary motion drive

Description

MU LTISENSOR DIG ITAL X-RAY RECE IVER
AND PYRAMI D-BEAM X-RAY TOMOGRAPH EQU IPP ED WITH SUCH RECEIVER
Field of the In vention
This invention relates to a structure of multisensor digital X-ray receivers on basis of optoelectronic converters having partly overlapping visual fields, and to a structure of computer pyramid-beam X-ray tomographs equipped with such receivers. These tomographs are meant for examination of peoples and animals.
Background Art
History of roentgen diagnostics includes two principal phases of decrease of ill effect of X-rays for medical personnel and patients:
(1 ) Transition from fluoroscopy to roentgenography using X-ray films happened in the middle of XX century, and
(2) Transition to filmless roentgenography using digital X-ray receivers started at the end of XX century.
First phase allowed excluding irradiation of roentgenologists, and second phase ensures sharp decrease of patient radiation exposure (no less than 10, but quite often more than 20 times).
Now three principal types of digital X-ray receivers are known.
Relatively low-price digital receivers on basis of charge-coupled devices (CCD) are widespread in Canada, Switzerland, Finland, France, Russia and South Korea. Usually, they are shaped as cumbersome modules having overall dimensions up to 45x45x100 cm and mass up to 75 kg.
Expensive digital receivers on basis of thin layers of amorphous silicon (a-Si) shaped as lightweight flat plates are producing in USA, Germany, France, Netherlands, Japan and China. They have typical overall dimensions up to 43x43x3 cm for the sake of compatibility with usual X-ray film holders.
Multisensor digital X-ray receivers on basis of optoelectronic converters such as TV- cameras are producing in Ukraine and Japan.
Naturally, digital receivers have wide application in production of new and modernization of existent X-ray equipment including computer X-ray tomographs (see, for example: US 2008/0219567; EP 2308376; Suetens P. Fundamentals of medical imaging. - Cambridge University Press, second edition, 2011 ; S.N. Gurzhiev, V.P. Novikov, and S.N. Sokolov Use of the Fluoro_ProGraph_RP Digital Fluorograph for Tomosynthesis // Biomedical Engineering, Vol. 47, No. 5, January, 2014, pp. 243_246 and many other).
Computer X-ray tomographs ensure:
Synchronous movement of X-ray units (i.e. an X-ray emitter and an X-ray receiver) along predetermined trajectories relative to the patient's body,
Passing of X-rays through each examined slice of patient's body at predetermined positions on specified trajectories,
Reception of X-radiation passed through each examined slice, Formation of a roentgenological picture of each regular examined slice, and
Tomosynthesis based on the roentgenological pictures series.
Software for tomosynthesis is, as a rule, publicly available (see, for example, US 2008/0219567 A1 ). Moreover, it is no problem to program control over mechanisms, which can be used in X-ray tomographs. Therefore, designers compete generally in selection of type and development of structure of X-ray digital receivers and in enhancement of construction arrangement of X-ray tomographs in whole.
For instance, all persons skilled in the art realize that use of digital receivers on basis of CCD-detectors of X-radiation in structures of X-ray tomographs is not desirable through excessive inertial mass of said detectors. Further, intention for reduction in price and, thereafter, for accessibility of X-ray tomographs for ordinary municipal hospitals restricts use of expensive X-ray receivers based on thin amorphous silicon layers. Therefore it is preferable to equip X-ray tomographs by rather low-price and lightweight multisensor digital X-ray receivers on basis of optoelectronic converters such as TV-cameras.
Their typical structure has disclosed in many publications [see, for example, patents on the basis of PCT/UA96/00016 (WO 98/11722), and US 6,002,743; US 6,370, 225 etc.].
The most perfect X-ray receiver of such kind disclosed in our international publication WO 2006/049589. It has a box-type lightproof housing having roentgenoparent front wall and fixed serially behind this wall a flat X-ray-to-optical converter and an unit of such formers of fragmentary video signals, which have fixed in the form of at least two-row matrix in a flat lightproof roentgenopaque partition. Enveloping surface of all these formers is a plane. Each such former comprises fastened one after another along ray path a filter of residual X- radiation (formed usually as a washer made from lead glass), a multiple-lens objective and an optoelectronic converter such as TV-camera. These formers are usually equipped with blends, which are arranged in front of said washers. Visual fields of adjacent formers of fragmentary analogous video signals are partly overlapping. Optical inputs of the optoelectronic converters are directed against said X-ray-to-optical converter, and their electrical outputs are connected to an ADC unit that converts fragmentary analogous video signals into fragmentary digital video signals, and further - through a multichannel corrector of geometric distortions - to a data processing unit that forms output integral digital video signals corresponding to discrete roentgenological pictures.
The resolution of these output video signals is the higher; the more optoelectronic converters are used in said receiver. Moreover, these signals contain practically no distortions caused by unavoidable differences in the geometric shape and dimensions of individual TV cameras and their parts, and by inevitable errors at their assemblage.
Such multisensor digital X-ray receivers are simple in construction, manufacturable, easy-to-use, reliable and inexpensive. Moreover, they ensure frequency of the integral digital video signals no less than 25 pps. This is sufficient for tomographic scanning. And, finally, structure disclosed in the said WO 2006/049589 allows substantial enlargement of active area of multisensor digital X-ray receivers that is necessary, e.g., for X-ray tomography of large parts of adult patient's body such as chest or abdominal cavity in whole.
Unfortunately, quality of digital roentgenological pictures intended for computer tomosynthesis depends not only from dimensions of any flat digital X-ray receivers, but also from X-ray tomographs' structure.
For example, US 6,940,943 disclose X-ray tomograph, comprising:
A flat roentgenoparent table for placement of a patient;
A located above said table arcform guide having angular size up to 180°;
A carriage placed onto said guide and equipped with a controllable reversible drive;
A controllable X-ray emitter, which is placed on said carriage and equipped with a collimator meant for shaping of X-ray beam;
Optionally, a regulator of distance between the X-ray emitter exit aperture and the table;
A flat digital X-ray receiver located under said table and equipped with a controllable reciprocating motion drive along it;
At least one checker of location of said X-ray emitter and said X-ray receiver relative to the patient's body;
A control unit, to which said controllable drives; said checker and said X-ray emitter are connected;
A data-processing unit connected to the X-ray receiver output and meant for generation of integral digital roentgenological pictures, and
A tomosynthesis unit connected to the said data-processing unit.
When such tomograph operates, the X-ray emitter moves along a circle arc, and the flat digital X-ray receiver moves in the opposite direction along the straight line.
It is clear for each person skilled in the art that quality of generated thereby roentgenological pictures will be various on account of instability of angulations of X-ray beam geometrical axis to the envelope plane of said X-ray receiver. Really, volumes of serially examined patient's body slices will be the greater, the greater declination of said geometrical axis from perpendicular to the flat X-ray receiver's active area. Accordingly, scale of serially generated oblique roentgenological pictures will be irregularly distorted, and images of organs and tissues will be mutually collided as it occurs in usual roentgenography.
This forces to use of small digital X-ray receivers and to shrinkage of range of declination of geometrical axis of X-ray beam from perpendicular to the flat enveloping surface of such X-ray receivers active area only up to ±20° (see Table 1 in the article Tsutomu Gomi, Hiroshi Hirano, Masahiro Nakajima, Tokuo Umeda "X-ray digital linear tomosynthesis imaging" // J. Biomedical Science and Engineering, 2011 , 4, 443-453).
Acquisition of oblique roentgenological pictures can be prevented, if an X-ray emitter and an X-ray receiver will be oppositely fixed on a rotatable support, in gap of which a flat roentgenoparent table will be located. Such construction arrangement allows synchronous rotation of said X-ray units around said table and, therefore, permanent perpendicularity of geometrical axis of X-ray beams to the flat X-ray receiver. This arrangement is characteristic for many cone-beam X-ray tomographs, each of which has an annular support, wherein a controllable X-ray emitter and an X-ray receiver are fixed oppositely [see, for example: 1 . De Cock J., ermuys K., Goubau J., Van Petegem S., Houthoofd B., Casselman J.W. Cone-beam computed tomography: a new low dose, high resolution imaging technique of the wrist, presentation of three cases with technique // Skeletal Radiology. 2012. N° 41. V.1 , p.93-96; 2. Ramdhian-Wihlm R., Le Minor J. M., Schmittbuhl M., Jeantroux J., Mac Mahon P., Veillon F., Dosch J.-C, Dietemann J.-L, Bierry G. Cone-beam computed tomography arthrography: an innovative modality for the evaluation of wrist ligament and cartilage injuries // Skeletal Radiology. 2012. V. 41 . p. 936-969; 3. A.IO. BacnnbeB, H. H. ΒΠΜΗΟΒ (ΜΠ.), E.A. Eropoea. KoHycHO-Ji neBaa OMnbioTepHaa TOMorpac wH - HOBaa TexHonornfl nccneflOBamifl B TpaeiviaTonornn // MEflMJ,HHCKAfl BH3yAJll/13AH,Hfl. N°4, 2012, c. 65-68 (In English: A.Yu. Vasil'ev, N.N. Blinov (Jr.), E.A. Egorova. Cone-beam Computer Tomography - New Technology of Research in Traumatology // MEDICAL IMAGING. N°4, 2012, p.65-68) and many other].
As a rule, the gap in said annular support of such tomographs no exceeds size of human head. Therefore they are meant usually for tomography of cartilages, bones of hands and feet, articulations of extremities and other small parts of human or animal bodies, and only on rare for tomography of brainpans (including dentitions).
It can seem that X-ray tomography of a human trunk can ensure by enlargement of a flat digital X-ray receiver's active area and diameter of aforesaid annular support.
Alas, such enlargement impairs quality of roentgenological pictures the more appreciable, the greater is difference between distances from center of aperture of an X-ray emitter and optical inputs of formers of fragmentary analogous video signals. Really, intensity of X-radiation is inversely as the square of distance from its emitter to separate points on an X-ray receiver surface. Thus brightness of roentgenological pictures, which is proportional to X-radiation intensity, will atte center to its edges according to the law
Figure imgf000005_0001
Bc is brightness of roentgenological picture in the receiver's center,
BE is brightness of roentgenological picture at receiver's edges,
L is distance between the aperture center of used X-ray emitter and center of used flat X-ray receiver;
is linear dimension (especially width) of used flat X-ray receiver.
E.g., under condition that L = 80 cm and X = 80 cm attenuation of brightness Bc I BE will be equal 1.25. This is unacceptable in respect to computation of tomograms.
Brightness of roentgenological pictures can equalize, if optical inputs of all formers of fragmentary analogous video signals will be located at equal distances from the X-ray emitter aperture center. In other words, said formers must be fixed onto a substrate shaped as a circular cylinder segment. US Patent 6,574,296 discloses a pyramid-beam X-ray tomograph, in which formers of fragmentary analogous video signals of an X-ray receiver arranged exactly so (see drawings). This tomograph has:
A roentgenoparent table for placing of an examined subject (i.e. human or animal); A carrier of X-ray units in the form of an annular support, which surrounds said table and on which a controllable X-ray emitter together with a collimator meant for shaping of pyramidal X-ray beam and an X-ray receiver in the form of at least one arcwise strip composed of CCD detectors of X-radiation are oppositely fastened;
A drive of continuous rotation of said annular support around said table during each session of tomographic scanning;
A reversible drive of continuous linear displacement of said table along symmetry axis of said annular support during each session of tomographic scanning;
An optical device meant for recording of roentgenological pictures (this device is usually fixed onto said annular support and can have automatic focusing device), and
A system of tomosynthesis on the basis of said roentgenological pictures.
It is clear that continuous rotation of the annular support and synchronous continuous linear displacement of the table along said symmetry axis cause twist of pyramidal X-ray beam relative to the body of any examined subject.
At present such pyramid-beam X-ray tomographs are known, in which diameter of opening of said annular support is equal 78 cm and length of said CCD detectors strip comes up to 100 cm that creates diameter of tomography region up to 60 cm, and which have 64 and more of such strips. This allows producing adequate number of tomograms during one diagnostic session (see, e.g., RAD BOOK 2015. The Radiology Guide to Technology and Information in Europe, section "Computer Tomography", pp.9-12, especially p.12).
However, use of many CCD detectors strips complicates considerably and raises the price of production and adjustment not only X-ray receivers, but also pyramid-beam X-ray tomographs in whole. Moreover, even tomographs having great number of CCD detectors strips do not appreciably decrease radiation exposure of examined subjects, because they must be under X-radiation during quite long-term sessions of 'spiral' tomography.
Thus, it is desirable to produce pyramid-beam X-ray tomographs using such construction arrangement that allows per se restriction of radiation exposure of examined subjects [see, e.g, the tutorial « oMnbiOTepHaa ToMorpacpnfl», pucyHOK 1.1 (In English "Computed Tomography", Fig.1.1) at web-site <http://www.radioland.net.ua/contentid- 112-page1.html>]. This tomograph has:
(1) A stationary vertically oriented box;
(2) A carrier of X-ray units in the form of a Π-like gantry, which has - horizontal cantilevered projections, on end parts of which a controllable X-ray emitter together with a collimator meant for shaping of pyramidal X-ray beam and an X-ray receiver are oppositely fastened, and
a traverse that joins rigidly said cantilevered projections and is equipped with a horizontal shaft;
(3) A horizontal roentgenoparent table, which is meant for placing of an examined subject and, in operative position, is motionlessly found within a gap between said X-ray emitter and said X-ray receiver;
(4) A controllable drive of reciprocating rotary motion of said Π-like gantry relative to the said table; this drive is embedded in said box and coupled kinematically with said horizontal shaft;
(5) A controller of reciprocating rotary motion of said Π-like gantry within a presetted circle sector; and
(6) A system of formation of roentgenological pictures corresponding to specified slices and computer tomosynthesis.
Such tomograph can displace pyramidal X-ray beam only within a restricted circle sector. This reduces radiation exposure of examined subjects even if the X-ray emitter will be continuously operating during diagnostic sessions.
Unfortunately, use of said Π-like gantry restrains choice of type and structure of X-ray receivers. So, X-ray receivers based on CCD-detectors have excessive inertial mass, as it had been said above. It doesn't matter, if some tomograph equipped with easily balanceable annular support of X-ray units and with a drive of continuous uniform one-way rotation of it. However, mounting of any heavy X-ray receiver onto one cantilevered projection of such Π- like gantry, which is capable to start-stop movement, is possible only under condition that said projection shaped as a massive fish-bellied girder. By-turn, it requires complicated balancing both said cantilevered projections and increase of energy consumption by said drive of reciprocating rotary motion.
Therefore it is reasonable to equip pyramid-beam X-ray tomographs by above described simple, manufacturable, easy-to-use, reliable and inexpensive multisensor digital X-ray receivers. Unfortunately, such intention can be realized if and only if satisfactory equalization of brightness of roentgenological pictures will be ensured.
Summary of the Inven tion
The invention is based on the problem - Firstly, by way of improvement of form and positional relationship of components to create such multisensor digital X-ray receiver, which allows substantial equalizing brightness of roentgenological pictures in all active area of this receiver, and,
Secondly, by way use of improved multisensor digital X-ray receiver to create such pyramid-beam X-ray tomograph, which allows to obtain sufficiently qualitative tomograms and will be additionally economical in respect of material and energy consumption.
First part of said problem has solved in that a multisensor digital X-ray receiver, comprising - a box-type lightproof housing closed by a roentgenoparent front wall, and
fastened serially behind this wall a flat X-ray-to-optical converter and a flat lightproof roentgenopaque partition, in which in the form of at least two-row matrix such formers of fragmentary analogous video signals are fixed, each of which composed of arranged one after another along ray path a filter of residual X-radiation, a multiple-lens objective and an optoelectronic converter,
at that visual fields of adjacent formers of fragmentary analogous video signals are partly overlapping, and electrical outputs of the optoelectronic converters in operative position are connected to a former of integral digital video signals and further to the system of formation of roentgenological pictures corresponding to specified slices and computer tomosynthesis,
according to the invention
said box-type lightproof housing is composed of at least two located at obtuse angles sections and closed by a common plano-concave roentgenoparent front wall,
said X-ray-to-optical converter and said lightproof roentgenopaque partition are also sectioned and mounted within the housing sections under respective planar parts of said plano-concave roentgenoparent front wall,
at that visual fields of adjacent formers of fragmentary analogous video signals, which have located along the edges of the partition sections, are partly overlapping too.
Such digital receiver allows substantial equalizing brightness of roentgenological pictures in each its discrete section and, therefore, in all its active area in spite of that the formers of fragmentary analogous video signals fixed in said each discrete section have planar enveloping surface. This equalization had achieved owing to the fact that width of discrete sections can be substantially decreased.
So, if distance between the X-ray emitter aperture center and center of any discrete section of the proposed X-ray receiver L = 80 cm and width of this section X = 40 cm, then attenuation of brightness Bc I BE calculated according to the foregoing formula {I} will be equal only 1.0625. It is quite permissible for effective tomosynthesis. This fact allows asserting with good reason that adjustable, easy-to-use, reliable and inexpensive improved multisensor digital X-ray receivers can be used in pyramid-beam X-ray tomographs instead massive and labor-intensive X-ray receivers based on CCD-detectors.
First additional feature consists in that the box-type lightproof housing is composed of two located at obtuse angle sections, in which two sections of said X-ray-to-optical converter and two sections of said partition comprising said formers of fragmentary analogous video signals are respectively mounted. These receivers are meant for equipping preferably veterinary X-ray tomographs.
Second additional feature consists in that the box-type lightproof housing is composed of three located at equal obtuse angles sections, in which three sections of said X-ray-to- optical converter and three sections of said partition comprising said formers of fragmentary analogous video signals are respectively mounted. These receivers are efficient for X-ray tomography even corpulent peoples.
Second part of said problem has solved in that a pyramid-beam X-ray tomograph, comprising - (1 ) A stationary vertically oriented box;
(2) A carrier of X-ray units in the form of a Π-like gantry, which has - horizontal cantilevered projections, on end parts of which a controllable X-ray emitter together with a collimator meant for shaping of pyramidal X-ray beam and an X-ray receiver 5 are oppositely fastened, and
a traverse that joins rigidly said cantilevered projections and is equipped with a horizontal shaft;
(3) A horizontal roentgenoparent table, which is meant for placing of an examined subject and, in operative position, is motionlessly found within a gap between said X-ray
10 emitter and said X-ray receiver;
(4) A controllable drive of reciprocating rotary motion of said Π-like gantry relative to the said table; this drive is embedded in said box and coupled kinematically with said horizontal shaft;
(5) A controller of reciprocating rotary motion of said Π-like gantry within a presetted 15 circle sector; and
(6) A system of formation of roentgenological pictures corresponding to specified slices and computer tomosynthesis,
according to the invention
is equipped with a multisensor digital X-ray receiver, which has a box-type lightproof 20 housing composed of at least two located at obtuse angles sections closed by a common plano-concave roentgenoparent front wall and mounted serially within the housing sections under respective planar parts of said front wall sections of an X-ray-to-optical converter and sections of a lightproof roentgenopaque partition those serve as carriers of formers of fragmentary analogous video signals composed of arranged one after another along ray path 25 filters of residual X-radiation, multiple-lens objectives and optoelectronic converters;
at that visual fields of adjacent formers of fragmentary analogous video signals within and along the edges of said sections of the lightproof roentgenopaque partition are partly overlapping, and electrical outputs of said optoelectronic converters in operative position are connected to a former of integral digital video signals and further to the system of formation 30 of roentgenological pictures corresponding to specified slices and computer tomosynthesis.
Such pyramid-beam X-ray tomographs can be efficiently used for examination of peoples and animals. They allow substantial decrease of radiation exposure of examined subjects because the table is motionless and angular displacement of said Π-like gantry is no j more than 220° during each tomographic scanning. Moreover, the proposed X-ray p5 tomographs are economical in respect of material and energy consumption because used in their structure aforesaid X-ray receivers have insignificant inertial mass. And, finally, said Π- like gantries can be easy balanced during montage of said X-ray units.
First additional feature consists in that said roentgenoparent table is displaceable and equipped with at least one retaining device for fixation of it relative to the said stationary 40 vertically oriented box during each tomographic scanning. This allows to place said table either along or across geometrical axis of said horizontal shaft and, respectively, to form roentgenological pictures from two different directions. Comparison of tomograms synthesized on basis of two sets of roentgenological pictures can be useful in cases of differential diagnostics of many diseases (especially at examination of chest or abdominal cavity, where great number of closely spaced organs are found).
Second and third additional features consist, respectively, in that the pyramid-beam X- ray tomograph is equipped with two- or three-sectional multisensor digital X-ray receiver. It is sufficient for production of several families of easy-to-use and affordable computer pyramid- beam X-ray tomographs, which can be used in municipal hospitals and veterinary clinics.
Brief Description of the Drawings
The invention will now be explained by detailed description of structures and operation of the proposed devices with references to the accompanying drawings, in which:
Fig.1 shows a sample of three-sectional multisensor digital X-ray receiver (schematic longitudinal view; at that one end housing wall is removed for convenience);
Fig.2 shows unfolded pattern of the X-ray receiver from the Fig.1 (schematic view along the path of pyramidal X-ray beam; at that a plano-concave roentgenoparent front wall and X-ray-to-optical converter sections are removed for convenience);
Fig.3 shows a cross-section of one section of the X-ray receiver from the Fig.1 by plane including optical axes of one row of formers of fragmentary analogous video signals;
Fig.4 shows a pyramid-beam X-ray tomograph in one starting position (when a roentgenoparent table located along geometrical axis of a horizontal shaft of a Π-like gantry and a traverse of this gantry is oriented horizontally);
Fig.5 shows the same that the Fig.4, when said traverse is oriented vertically;
Fig.6 shows the pyramid-beam X-ray tomograph in another starting position (the roentgenoparent table placed across geometrical axis of the horizontal shaft of the Π-like gantry and the traverse of this gantry is oriented vertically).
Remark. For the sake of simplification Figs 5 and 6 show only mechanical and X-ray units.
Best Embodiments of the invention
Any proposed multisensor digital X-ray receiver has (see Fig.1 ) - A box-type lightproof housing 1 composed of some (preferably two or three) sections located at preferably equal obtuse angles,
A plano-concave roentgenoparent front wall 2 that closes said housing 1 ,
A sectionalized X-ray-to-optical converter 3 composed of snap-together on each side flat sections, and
A sectionalized lightproof roentgenopaque partition 4, all flat sections of which are meant for fixation of formers 5 of fragmentary analogous video signals in the form of at least two-row matrixes (these formers 5 here and on the Fig.2 are shown as rectangles).
Choice of number of housing 1 sections depend on requirements to roentgenological pictures quality and acceptable production costs, which will be the more, the less width of discrete sections and more quantity of theirs. Therefore, two sections are sufficient for simple needs (e.g. for veterinary tomography), three sections are desirable for majority of cases, and more than three sections can be necessary for satisfaction of special requirements to roentgenological pictures quality.
Naturally, number of planar parts of said front wall 2, sections of said X-ray-to-optical 5 converter 3 and sections of said partition 4 is equal to the number of housing 1 section.
The plano-concave roentgenoparent front wall 2 can be wholly made from lightproof composites such as turbonit or carbon-filled plastic and so forth.
The flat sections of said X-ray-to-optical converter 3 can be made from cesium iodide or salts of rare earth elements, for instance, gadolinium oxysulfide.
jl O The flat sections of said partition 4 are usually made from two parts (for example, a lead plate that serves as absorber of residual X-radiation, and a supporting plate from a strong material such as duralumin, sheet steel etc).
Visual fields of adjacent formers 5 of fragmentary analogous video signals within and on each side of the partition 4 flat sections are partly overlapping as it shown on the Fig.1 by 15 divergent dashed lines.
Surfaces of all flat sections of said converter 3, which are directed to the optical inputs of said formers 5, have a not shown especially metering raster 6 that is applied using a transparent fluorescent paint, and at least one ultraviolet radiator 7 is mounted on each sections of the partition 4. It is desirable for calibration of the proposed X-ray receiver.
20 Figs 1 and 2 show also that the formers 5 of fragmentary analogous video signals are connected to ADC units 8, which forms, in operative position, fragmentary digital video signals, and further to a system 9 of formation of roentgenological pictures corresponding to the specified slices and computer tomosynthesis. This system 9 is equipped with softwares, which ensure correction of geometric distortions of fragmentary digital video signals, their 25 'sewing-together' into integral digital roentgenological pictures and tomosynthesis. As a rule, hardware implementation of the system 9 is a microcomputer or a PC.
In order to explain a method of calculation of values of obtuse angles between the sections of the housing 1 the Fig.1 comprises conditional images of the X-ray emitter 10 and a collimator 1 1 belonged to a described further in detail a computer pyramid-beam X-ray 30 tomograph and some symbols, namely:
R that designates length of perpendicular binding the center of aperture of the X-ray emitter 10 with the center of envelope plane of a congruous section of the housing 1 , and a that designates angles between pairs of neighboring perpendiculars R.
This angle can calculate according to formula σ = 360° Wx I 2nR {II}, where 35 Wx is actual width of each section of the X-ray receiver,
R is actual length of above-mentioned perpendicular;
jT is well-known ratio of any circle length to its diameter (approximately 3,14). The schema shown on the Fig.1 reveals clearly that any obtuse angle between adjacent sections of the housing 1 can be determined as
40 0,5 (360°-2σ) {III}. For example, if Wx = 43 cm and R = 100 cm, then value a is 24,6°, and required obtuse angle is 155,4°. It is clear that use of other R and Wx values yields different values of said obtuse angles.
Fig.2 shows that the X-ray receiver sections can be composed of several longitudinally oriented parts, which have common envelope plane and disposed within one section of the housing 1. Each such part can have own plate of the X-ray-to-optical converter 3 having above-mentioned metering raster 6 and own plate of said partition 4 having said formers 5 and said ultraviolet radiator 7.
Total length of such compound sections is restricted only by capability of the collimator 1 1 to form extensive pyramidal X-ray beam at the output of said X-ray emitter 10.
Structure of discrete sections of the multisensor digital X-ray receiver corresponds usually to the WO 2006/049589. Therefore, the Fig.3 shows:
A fragment of the box-type lightproof housing 1 ,
A fragment of planar part of the plano-concave roentgenoparent front wall 2,
A fragment of the X-ray-to-optical converter 3,
A fragment of the lightproof roentgenopaque partition 4, and
Components of such formers 5 of fragmentary analogous video signals, which are fixed relative to the respective fragment of said partition 4.
Minimal configuration of each former 5 includes serially arranged along ray path - A washer 12 that is made from roentgenopaque translucent material such as lead glass (these washers 12 in aggregate serve in each section of the X-ray receiver as main filter of residual X-radiation);
An objective 13 comprising at least two divided by air gap lenses 14 meant for focusing of an image fragment, and, as a rule, three (front-end, intermediate and output) diaphragms 15 meant for limitation of light flux; and
An optoelectronic converter 16 (usually in the form of a TV-camera), which has fixed onto own bearing within a positioner 17 for the purpose of installation on the optical axis of appropriate objective 13.
Electric outputs of the optoelectronic converters 16 are shaped as connectors 18, which must be connected in operative position by flexible multiple-core cable 19 - Firstly, to a not shown here energy source, and,
Secondly, to the ADC unit 8 meant for formation of fragmentary digital video signals and further to the above-mentioned system 9. The ADC unit 8 can be divided into subunits as it shown on Figs 1 and 2. Such division facilitates montage.
A blend 20 can be usually mounted on said partition 4 before each objective 13. These blends 20 assure partial overlap of visual fields of adjacent formers 5 of fragmentary analogous video signals, as it is shown on Fig.3 in the form of intersection of light rays outcoming from said X-ray-to-optical converter 3 into said objectives 13. In addition, the blends 20 minimize reduction of brightness of images on the visual fields edges of said optoelectronic converters 16 in the event, if the objectives 13 have said diaphragms 9. It is desirable to apply black matt coatings onto interiors of side wall of the housing 1 and the blends 20 and onto both sides of the diaphragms 15, and to apply antireflection layers onto washers 12 and lenses 14. This allows substantially decrease flare illumination of adjacent optical channels by light that reflects from lenses 14 onto the X-ray-to-optical converter 3 and back.
Length A of the blends 20 must be chosen with a glance of distance D from front surface of the X-ray-to-optical converter 3 to front ends of the objectives 13 according to the known from WO 2006/049589 ratio A/D = (0,50 - 0,90).
Any pyramid-beam X-ray tomographs has (see Figs 4, 5 and 6) - A stationary vertically oriented box 21 ;
A carrier of X-ray units in the form of a Π-like gantry 22 that is composed of:
- not designated especially horizontal cantilevered projections, on end parts of which the controllable X-ray emitter 10 together with the collimator 1 1 and the multisensor digital (especially two-sectional) X-ray receiver 23 are oppositely fastened, and
- an also not designated especially a traverse that joins rigidly said cantilevered projections and is equipped with a horizontal shaft 24;
A horizontal roentgenoparent table 25, which is meant for placing of an examined subject and, in operative position, is motionlessly found within a gap between said X-ray emitter 10 and said X-ray receiver 23;
A not shown especially controllable drive of reciprocating rotary motion of said Π-like gantry 22 relative to the said table 25; this drive is embedded in the said box 21 and coupled kinematically with said horizontal shaft 24;
A conditionally shown controller 26 of stepless and/or discrete control of reciprocating rotary motion of said Π-like gantry 22 within a presetted circle sector; and
A conditionally shown system 9 meant for formation of digital roentgenological pictures corresponding to specified slices and to computer tomosynthesis.
It is clear for each person skilled in the art that controller 26 has at least -
Detectors of actual angular position of the Π-like gantry 22 relative to the table 25 (e.g., in the form of photon-coupled pairs),
Preferably adjustable masters of required values of angular position of the Π-like gantry 22 relative to the table 25,
Comparators meant for determination of values and directions [(+) or (-)] of unbalance of above-mentioned actual and required angular positions,
Controllable switches of power supply of controllable drive of reciprocating rotary motion of said Π-like gantry 22 and said X-ray emitter 10 by the horizontal shaft 24, and
Software of stepless and/or discrete control of reciprocating rotary motion of the Π-like gantry 22 relative to the table 25 within a presetted circle sector and switching-in/switching- off of the controllable X-ray emitter 10.
The roentgenoparent table 25 is usually displaceable and equipped with at least one retaining device for fixation of it relative to the said stationary box 21 during each 65
13
tomographic scanning. Particularly, the table 25 can be placed onto a wheeled frame 27 having stopper in the form of a slab 28. One end of it is turned down in order to hold in operative position one part of said frame 27, and another end has opening meant for loose fit on vertical finger 29 that is rigidly fixed in the box 21 basis. This allows to arrange the table 25 either along (see Figs 4 and 5) or across (see Fig.6) geometrical axis of the horizontal shaft 24 of the Π-like gantry 22. Moreover, the wheeled frame 27 can have a not shown especially suitable hoist of the table 25 (for example, in the form of well-known assembly 'screw - nut' having preferably self-stopping screw.
Region of tomographic scanning can be surrounded by not designated especially a roentgenoparent cylindrical casing, as it shown on the Fig.5.
It is evident that the proposed tomographs can be optionally completed either with one proposed X-ray receiver or with several replaceable receivers having different number of sections and/or different total active area.
Special feature of assemblage of sections of the proposed X-ray receiver consists in that the optoelectronic converters 16 must be installed by positioners 17 (see Fig.3) in output planes of the objectives 13 in such a manner that centers of light-sensitive surfaces of said converters 16 correspond to foci of said objectives 13, each of which is placed opposite to certain part of the surface of X-ray-to-optical converter 3 (see anew Fig.3).
Each finished X-ray receiver must be calibrated. For this purpose a skilled craftsman (or a programmable controller) switches on one after another the ultraviolet radiators 7 those activate fluorescence of said rasters 6. The optoelectronic converters 16 are insensitive to the ultraviolet radiation and generate fragmentary analogous video signals only in response to fluorescence. Obtained signals come in through ADC unit(s) 8 into the system 9.
This system 9 memorizes position of each former 5 of fragmentary analogous video signals relative to the rasters 6 for the purpose of following use of such data during correction of geometrical distortions and 'sewing-together' of fragmentary digital video signals into integral digital roentgenological pictures during tomograph operation.
The described tomograph can use for the purpose of tomosynthesis as follows.
An attendant places the table 25 in a required position either along geometrical axis of the horizontal shaft of the 27 Π-like gantry 22 (see Figs 4 and 5), or across said axis (see Fig.6). It allows tomographic scanning in the angular range up to ± 1 10° at longitudinal position and no more than ± 45° at perpendicular position.
Any subject must be placed onto the table 25 in supine position (that is preferable for peoples) or in edgewise position (that is usually used for forcedly immobilized animals). Each subject must be motionless during examination.
Further the attendant adjusts the collimator 11 to form pyramidal X-ray beam of required size.
Then he enters data about initial disposition of the X-ray emitter 10 and the X-ray receiver 23 relative to the table 25 into the controller 26 of reciprocating rotary motion of said Π-like gantry 22 and enables a required executive program. Three modes of tomographic scanning are possible:
(1) when said drive of reciprocating rotary motion of said Π-like gantry 22 and the X-ray emitter 10 operate continuously (in this case the system 9 forms digital roentgenological pictures corresponding to predetermined slices on a frequency that is conditioned by technical feasibilities of the formers 5 of fragmentary analogous video signals);
(2) when said drive of reciprocating rotary motion of said Π-like gantry 22 operates continuously, and the X-ray emitter 10 generates impulses of X-radiation at moments corresponding to presetted angular positions; and
(3) when said drive of reciprocating rotary motion of said Π-like gantry 22 operates step-by-step, and the X-ray emitter 10 generates impulses of X-radiation at moments corresponding to actual angular positions.
It is reasonable to use first mode at examination of any subject within a narrow (as a rule, no more than 60°) sector of tomographic scanning, because radiation exposure is, in this case, in direct proportion to duration of diagnostic session. Second and third tomographic scanning modes allow extreme minimization of radiation exposure.
In dus tria l Applicability
The invention can be used for the purposes of -
Serial production of inexpensive sectionalized multisensor digital X-ray receivers on the basis of readily accessible components, and
Development and production of lines of such simple and easy-to-use computer pyramid-beam X-ray tomographs equipped with said receivers, which will be affordable for any municipal hospitals and veterinary clinics.

Claims

C LAI MS
1. Multisensor digital X-ray receiver, comprising - a box-type lightproof housing closed by a roentgenoparent front wall, and
fastened serially behind this wall a flat X-ray-to-optical converter and a flat lightproof roentgenopaque partition, in which in the form of at least two-row matrix such formers of fragmentary analogous video signals are fixed, each of which composed of arranged one after another along ray path a filter of residual X-radiation, a multiple-lens objective and an optoelectronic converter,
at that visual fields of adjacent formers of fragmentary analogous video signals are partly overlapping, and electrical outputs of the optoelectronic converters in operative position are connected to a former of integral digital video signals and further to the system of formation of roentgenological pictures corresponding to specified slices and computer tomosynthesis,
characterized in that
said box-type lightproof housing is composed of at least two located at obtuse angles sections and closed by a common plano-concave roentgenoparent front wall,
said X-ray-to-optical converter and said lightproof roentgenopaque partition are also sectioned and mounted within the housing sections under respective planar parts of said plano-concave roentgenoparent front wall,
at that visual fields of adjacent formers of fragmentary analogous video signals, which have located along the edges of the partition sections, are partly overlapping too.
2. Multisensor digital X-ray receiver according to the claim 1 , characterized in that the box-type lightproof housing is composed of two located at obtuse angle sections, in which two sections of said X-ray-to-optical converter and two sections of said partition comprising said formers of fragmentary analogous video signals are respectively mounted.
3. Multisensor digital X-ray receiver according to the claim 1 , characterized in that the box-type lightproof housing is composed of three located at equal obtuse angles sections, in which three sections of said X-ray-to-optical converter and three sections of said partition comprising said formers of fragmentary analogous video signals are respectively mounted.
4. Pyramid-beam X-ray tomograph, comprising:
(1 ) A stationary vertically oriented box;
(2) A carrier of X-ray units in the form of a Π-like gantry, which has - horizontal cantilevered projections, on end parts of which a controllable X-ray emitter together with a collimator meant for shaping of pyramidal X-ray beam and an X-ray receiver are oppositely fastened, and
a traverse that joins rigidly said cantilevered projections and is equipped with a horizontal shaft;
(3) A horizontal roentgenoparent table, which is meant for placing of an examined subject and, in operative position, is motionlessly found within a gap between said X-ray emitter and said X-ray receiver; (4) A controllable drive of reciprocating rotary motion of said Π-like gantry relative to the said table; this drive is embedded in said box and coupled kinematically with said horizontal shaft;
(5) A controller of reciprocating rotary motion of said Π-like gantry within a presetted 5 circle sector; and
(6) A system of formation of roentgenological pictures corresponding to specified slices and computer tomosynthesis.
characterized in that
is equipped with a multisensor digital X-ray receiver, which has a box-type lightproof 10 housing composed of at least two located at obtuse angles sections closed by a common plano-concave roentgenoparent front wall and mounted serially within the housing sections under respective planar parts of said front wall sections of an X-ray-to-optical converter and sections of a lightproof roentgenopaque partition those serve as carriers of formers of fragmentary analogous video signals composed of arranged one after another along ray path i15 filters of residual X-radiation, multiple-lens objectives and optoelectronic converters;
at that visual fields of adjacent formers of fragmentary analogous video signals within and along the edges of said sections of the lightproof roentgenopaque partition are partly overlapping, and electrical outputs of said optoelectronic converters in operative position are connected to a former of integral digital video signals and further to the system of formation 20 of roentgenological pictures corresponding to specified slices and computer tomosynthesis.
5. Pyramid-beam X-ray tomograph according to the claim 4, characterized in that said roentgenoparent table is displaceable and equipped with at least one retaining device for fixation of it relative to the said stationary vertically oriented box during each tomographic scanning.
25 6. Pyramid-beam X-ray tomograph according to the claim 5, characterized in that it is equipped with two-sectional multisensor digital X-ray receiver.
7. Pyramid-beam X-ray tomograph according to the claim 5, characterized in that it is equipped with three-sectional multisensor digital X-ray receiver.
PCT/UA2016/000065 2016-05-20 2016-05-30 Multisensor digital x-ray receiver and pyramid-beam x-ray tomograph equipped with such receiver WO2017200507A1 (en)

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UAA201605483A UA117599C2 (en) 2016-05-20 2016-05-20 MULTI-SENSOR DIGITAL DIGITAL RECEIVER AND PYAMIDAL-X-RAY TOMOGRAPHICAL SUPPLIER

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