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WO1991011959A1 - Analyse d'images sur ecran - Google Patents

Analyse d'images sur ecran Download PDF

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Publication number
WO1991011959A1
WO1991011959A1 PCT/EP1991/000203 EP9100203W WO9111959A1 WO 1991011959 A1 WO1991011959 A1 WO 1991011959A1 EP 9100203 W EP9100203 W EP 9100203W WO 9111959 A1 WO9111959 A1 WO 9111959A1
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WO
WIPO (PCT)
Prior art keywords
reference points
interest
screen
area
image
Prior art date
Application number
PCT/EP1991/000203
Other languages
English (en)
Inventor
Douglas Benn
Original Assignee
Benn Computer Consultants
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Benn Computer Consultants filed Critical Benn Computer Consultants
Publication of WO1991011959A1 publication Critical patent/WO1991011959A1/fr

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Classifications

    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61C—DENTISTRY; APPARATUS OR METHODS FOR ORAL OR DENTAL HYGIENE
    • A61C19/00—Dental auxiliary appliances
    • A61C19/04—Measuring instruments specially adapted for dentistry
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61C—DENTISTRY; APPARATUS OR METHODS FOR ORAL OR DENTAL HYGIENE
    • A61C9/00—Impression cups, i.e. impression trays; Impression methods
    • A61C9/004—Means or methods for taking digitized impressions
    • A61C9/0046—Data acquisition means or methods

Definitions

  • This invention relates to a method of analysing a screen-displayed image of a part or structure, e.g. of a human or animal body part, for locating any changes in the part or structure, e.g. diagnosing disease in a body part.
  • the invention has application in dentistry for diagnosing caries and/or periodontal diseases from images derived from an X-ray image of a person's teeth and jaws.
  • the invention may find application in other fields involving the interpretation of either radiographically produced records of other body parts of a human or animal, or of non-biological imaging systems where subjective identification of reference points for making measurements is required, e.g. for detecting or monitoring the progression of cracks in a metal structure.
  • the invention also relates to a system of image analysis. Conventionally dentists use radiography to diagnose and monitor on X-ray film any abnormalities in a patient's teeth or jaw bone. Such radiographic methods are particularly helpful in enabling dentists to locate teeth, gum and bone disorders which are not normally readily visible.
  • intraoral X-ray films are typically used for the location of unerupted or impacted teeth, the detection of retained broken tooth roots, the detection of small carious lesions at approximal surfaces, the detection of resorption of the bone from the necks of teeth and the detection of subgingival deposits of salivary calculus.
  • the object of the present invention is to provide a more accurate method of analysing and measuring screen-displayed images of a part or structure.
  • the invention When applied to the analysis and measurement of screen-displayed images of human or animal body parts the invention assists in the diagnosis of disease and the monitoring of its progress in the body part by reducing intra- and inter-examiner variability. Accordingly the present invention comprises a method of comparing an earlier- and a later-acquired screen-displayed image of a part or structure and determining any significant changes in at least one selected area of interest therein in which the method of selecting includes selecting on the screen the area of interest while a corresponding previous selection is displayed elsewhere on the screen to facilitate more accurate selection.
  • the invention comprises identifying at least one area of interest on the earlier screen-displayed image, selecting on the screen-displayed image at least two reference points associated with the or each area of interest, recording information to enable subsequent display of the or each area of interest and the said selected reference points associated therewith, and comparing, for the or each area of interest, at least one reference measurement, which is a function of at least some of the said selected reference points for the area of interest in question, with either at least one preset value or at least one equivalent reference measurement, the or each of which is a function of further selected similarly positioned reference points created from the later- acquired, screen-displayed image of the part or structure for the area of interest in question, any significant differences in these comparison(s) indicating a change in the said part or structure.
  • the invention is concerned with the analysis of screen-displayed images of anatomical body parts and the reference points selected are anatomical reference points.
  • the selection of reference points for the or each area of interest comprises positioning under human control a first set of reference points on the earlier screen-displayed image defining an area of interest and storing their positions, distance(s) between the points and the associated image window, reproducing on the screen from the stored information a display window showing the area of interest with the first set of reference points displayed thereon superimposed on the first display but not covering the area of interest, positioning under human control a second set of reference points on the first display in positions corresponding as closely as possible to the positions of the first set of reference points and averaging the distances between the corresponding points of said first and second sets of reference points to derive an average distance in each case.
  • the later selected reference points for the or each area of interest are each chosen so as to be positioned as closely as possible to the corresponding originally selected reference point but with regard to the particular region or boundary of the part or structure under investigation for example, in diagnosis of dental problems particular original anatomical reference points would typically be positioned at least on the alveolar bone crest margin and the cemento-enamel junction.
  • the corresponding further selected anatomical reference points must also be selected to be positioned on the parts of the alveolar bone crest margin and the cemento-enamel junction which are positioned nearest to the positions of the original anatomical reference points even if the outline of the alveolar bone crest margin has changed (e.g. as a result of recession of the bone).
  • the later selected reference points are averaged, e.g. as described with regard to the originally selected reference points.
  • an error estimation is conveniently also obtained with regard to the accuracy with which the reference points for the later-produced screen-displayed image are positioned under human control.
  • the method is designed to be put into effect in a computerised diagnostic system
  • a computer e.g. an IBM PC-AT
  • a computer e.g. an IBM PC-AT
  • a screen means for transferring the image to the computer, eg a video camera and frame store or any other image acquisition device or stored image, and means for displaying the image(s) to be viewed, e.g. an X-ray film, on the screen
  • storage means e.g, disc storage, for storing information regarding the screen-displayed image and said selected reference points and a computer program controlling operation of the various features of the method.
  • the computer has a "mouse" or the like for enabling a cursor to be moved on the screen to effect selection of the said reference points.
  • a screen displayed image derived from an X-ray film it may be desirable when analysing different images of the same area of interest of a person, to select at least two anatomical reference points associated with a part of the image showing overlapping regions of the body part in order to check that the different images have been taken from the same angle.
  • adjacent three dimensional teeth may show up as overlapping approximal surface shadow regions on the two-dimensional X-ray film and the dimensions of these shadow regions would change with alteration of the angle and position of the X-ray beam from the X-ray generator relative to the patient.
  • the corresponding shadow regions for two differently produced images have substantially the same dimensions, it can be assumed that the angle and position of the X- ray beams from the generator or generators in the two instances are substantially the same and thus the anatomical reference measurements for the two images can be validly compared.
  • a warning can be produced alerting a human operator that measured differences between separate films are likely to suffer from artificial changes.
  • Figure 1 is a schematic view of an exposed intraoral X-ray film depicting a person's teeth
  • Figure 2 is a schematic view of an image of part of the X-ray film shown in Figure 1 displayed on a computer screen
  • Figure 3 is a schematic view on an enlarged scale of part of the image shown in Figure 2 with selected anatomical reference points located thereon
  • Figure 4 is a schematic view of part of a screen displayed image of an X-ray film depicting two overlapping teeth.
  • Figure 5 is a schematic diagram showing the relationship between distance measurements made on a primary image, the generation of stored areas of interest and their use in selecting further reference points for the same and subsequent images.
  • Figure 1 illustrates a conventional exposed intraoral radiograph or X-ray film 1 (typically having a size of 4cm by 3cm) showing a person's upper and lower posterior teeth biting upon a bite part 2.
  • X-ray film 1 typically having a size of 4cm by 3cm
  • FIG. 1 illustrates a conventional exposed intraoral radiograph or X-ray film 1 (typically having a size of 4cm by 3cm) showing a person's upper and lower posterior teeth biting upon a bite part 2.
  • a screen 10 e.g. forming part of a monitor
  • a video camera for displaying at least part of an X-ray film on the screen 10
  • a memory e.g. in the form of disk memory associated with the computer and a computer program.
  • the screen 10 may be of any size but will typically comprise a high resolution monitor having a diagonal dimension of at least 25cm.
  • the area of interest 11 chosen shows the crest margin of the alveolar bone part 4b and the facing surfaces of adjacent teeth 3a and 3b. Each of these teeth surfaces incorporates the cemento-enamel junction. Other "types" of area of interest could be chosen, e.g. areas of interest showing occlusal teeth surfaces.
  • the present invention is concerned with diagnosing problems not readily apparent by means of a direct visual inspection but which are present on X-ray films.
  • a computer operator Under the control of the computer program, a computer operator is prompted to identify anatomical reference points associated with each area of interest. Typically the operator will use a "mouse" or similar device to position a cursor at the selected location, but other forms of cursor control, e.g. keyboard keys or joystick, could be employed.
  • cursor control e.g. keyboard keys or joystick
  • reference points 12a and 12b correspond to the location of the cemento-enamel junction on the teeth 3a and 3b, respectively; reference point 12c corresponds to the lowest point (as viewed in Figure 3) on the alveolar bone crest margin 13; reference points 12d and 12e correspond to opposite ends of the generally flat lower edge of the crest margin 13; reference joints 12f and 12g correspond to points on the dentine surface of the teeth 3a and 3b, respectively, opposite the reference points 12d and 12e, respectively; and reference 12h represents where a cut-away corner portion (indicating alveolar bone recession, base of vertical bone loss where periodontal ligament space is of "normal" width) of the crest margin 13 meets a flank of the alveolar bone.
  • the next stage involves assessing the degree of operator error associated with the placement of the anatomical reference points 12.
  • This error assessment can be performed at any period of time after the initial placement and storage of the reference points 12 - e.g. it could be performed immediately after the initial placement and storage or several days or even weeks later.
  • the error assessment involves firstly accessing the memory in order to display on the screen 10 a first display and a second display 15.
  • the first display is either an exact digital copy of the original image or the original intraoral radiograph re-entered into the system and comprises at least one area of interest 11 (see Figure 2).
  • the second display 15, positioned, for example, immediately below the first display, consists of the same area or areas of interest but containing the initially positioned reference points 12.
  • the computer operator is then prompted to enter on the area of interest 11 of the first display, e.g. with the aid of a mouse-controlled cursor, ref rence points 12' cprresponding as closely as possible in position to the initially positioned reference points 12 shown on the second display 15. This procedure is repeated for each of the stored areas of interest.
  • Fig 5 The procedure for using a previously stored image window to assist in the selection of the equivalent area in a subsequent selection is shown schematically in Fig 5 wherein a method involving two images is illustrated.
  • R represents a reading
  • AOI represents a stored image window of the area of interest
  • Image 1 is the earlier image
  • Image 2 is the later image.
  • the image window associated with the first reading R ⁇ is displayed to assist in selecting the equivalent reference points.
  • the computer In making readings R3 and R4 the stored image windows from readings R2 and R3 respectively are used. This greatly improves the accuracy with which the operator can select the same area at each reading.
  • the computer is programmed to calculate the operator reproducibility error involved in placing reference points at known locations. Furthermore, it is possible to average the position of each reference point, or to average a distance between two reference points or reference lines to provide an averaged reference measurement. For example, with reference to Figure 3, there is shown a first reference measurement Dl which is the shortest distance between the reference point 12c and a line passing through reference points 12a,
  • the program controls the computer to obtain an average first reference measurement Dlav which is the average of the initial first reference measurement Dl ⁇
  • the program also enables the computer to calculate the operator error involved in the initial and final reference measurements.
  • the operator measurement errors Dl ⁇ ff and D2,*jiff in the first and second reference measurements are given by D1 diff * D1 l " D1 2 and
  • the computerised diagnostic system is primarily concerned with building up a time-displaced series of records of one or more person's teeth - e.g. a series of records taken at 6-monthly or yearly intervals.
  • the procedure at a subsequent dental inspection is to take a similar intraoral X-ray of the patient's teeth to produce a similarly sized X-ray film of the same teeth as previously on record.
  • Each area of interest originally recorded, after error assessment, in the memory is recalled on the screen 10 with the last recorded reference points positioned thereon.
  • the newly produced X-ray film (or a part or parts corresponding to the area of interest(s) displayed) is also displayed on the screen 10 using a video camera/frame store or other image acquisition device and ensuring that the new screen-displayed image is of the same size and scale as the recalled areas of interest.
  • the computer operator is prompted by the program to enter new reference points on the new screen-displayed image corresponding to those of the originally recorded reference points.
  • the aim when the operator positions the new reference points is to identify similar zones or intersections as in the reference image block 15. For example, the aim is to identify the cemento-enamel junctions corresponding to reference points 12a and 12b the lowest point 12c of the crest margin 13 etc..
  • a procedure for assessing the degree of operator error associated with reference point location is initiated in precisely the ML
  • D2 ⁇ and D2 2 are the initial and final first reference measurements for the new screen-displayed image and d2 ⁇ and d2 are the initial and final second reference measurements for the new screen-displayed image.
  • the computer is able to determine changes in reference measurements, namely Dl av - D2 av and dl av - d2 av for the first and second reference measurements, and changes in operator error measurement, namely Dl ⁇ ff, D2 ( jiff and dl ⁇ iff, d 2 ⁇ aiff for the first and second reference measurements, in respect of the two time-displaced recorded images.
  • jaws can be built up over a period of time. In this manner a particular area of interest of a patient's teeth can be compared over a period of time from the recorded information on that area of interest compiled over the period of time. In particular the manner in which the positions of the reference points change or the manner in which the reference measurements change are recorded.
  • a warning can be issued automatically by the computer that even though reference changes may have been measured reliably by the system, the image distortion produced by the irradiation geometry changes could invalidate the reference distance changes.
  • a pre-set value can be stored in the computer regarding approximal surface shadow overlap or periodontal ligament space distance changes which, if exceeded, could initiate the irradiation geometry change warning.
  • the degree of overlap 23 is normally calculated by the computer by obtaining two reference points at the two extremes of the overlap. AH -
  • the program may be able to automatically detect or diagnose a problem from an averaged reference measurement if that measurement is greater than a pre-set stored measurement distance by a significant amount. For example a problem may be diagnosed if Dl av significantly exceeds a pre-set value for this distance in a "normal" tooth.

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  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Biomedical Technology (AREA)
  • Biophysics (AREA)
  • Oral & Maxillofacial Surgery (AREA)
  • Dentistry (AREA)
  • Epidemiology (AREA)
  • Animal Behavior & Ethology (AREA)
  • General Health & Medical Sciences (AREA)
  • Public Health (AREA)
  • Veterinary Medicine (AREA)
  • Apparatus For Radiation Diagnosis (AREA)

Abstract

Méthode permettant la comparaison d'images sur écran acquises à des moments différents d'une partie du corps ou d'une structure et détermination des modifications importantes d'au moins une zone sélectionnée, la méthode comprenant la sélection sur écran de la zone d'intérêt tandis qu'une sélection précédente correspondante est représentée ailleurs sur l'écran pour faciliter une sélection plus précise.
PCT/EP1991/000203 1990-02-13 1991-02-04 Analyse d'images sur ecran WO1991011959A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB9003172.5 1990-02-13
GB909003172A GB9003172D0 (en) 1990-02-13 1990-02-13 Analysing screen-displayed images

Publications (1)

Publication Number Publication Date
WO1991011959A1 true WO1991011959A1 (fr) 1991-08-22

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PCT/EP1991/000203 WO1991011959A1 (fr) 1990-02-13 1991-02-04 Analyse d'images sur ecran

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WO (1) WO1991011959A1 (fr)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2003011165A1 (fr) * 2001-07-30 2003-02-13 3M Innovative Properties Company Procede et appareil permettant de selectionner une prescription pour un appareil orthodontique
US8386061B2 (en) 2008-06-02 2013-02-26 Dentsply International Inc. Methods for designing a customized dental prosthesis using digital images of a patient
CN108463172A (zh) * 2015-11-13 2018-08-28 新泽西州立拉特格斯大学 基于图像分析结果对根尖周疾病的鉴别诊断

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4528627A (en) * 1982-11-12 1985-07-09 Coben Eugene S Method for cephalometric quantitation and expression of growth
GB2159943A (en) * 1984-06-06 1985-12-11 Oreal Monitoring variations in time of characteristics of a zone of or the whole of a person
EP0245098A2 (fr) * 1986-05-07 1987-11-11 Teijin Limited Méthode et appareil pour juger la déformation d'une colonne vertébrale
US4764012A (en) * 1981-07-28 1988-08-16 Hans Ryden Device for determining the displacement of a tooth between two different examinations made on separate occasions
EP0314506A1 (fr) * 1987-10-29 1989-05-03 The Governors of the University of Alberta Méthode et appareil pour aligner des images radiographiques

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4764012A (en) * 1981-07-28 1988-08-16 Hans Ryden Device for determining the displacement of a tooth between two different examinations made on separate occasions
US4528627A (en) * 1982-11-12 1985-07-09 Coben Eugene S Method for cephalometric quantitation and expression of growth
GB2159943A (en) * 1984-06-06 1985-12-11 Oreal Monitoring variations in time of characteristics of a zone of or the whole of a person
EP0245098A2 (fr) * 1986-05-07 1987-11-11 Teijin Limited Méthode et appareil pour juger la déformation d'une colonne vertébrale
EP0314506A1 (fr) * 1987-10-29 1989-05-03 The Governors of the University of Alberta Méthode et appareil pour aligner des images radiographiques

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2003011165A1 (fr) * 2001-07-30 2003-02-13 3M Innovative Properties Company Procede et appareil permettant de selectionner une prescription pour un appareil orthodontique
US6733289B2 (en) 2001-07-30 2004-05-11 3M Innovative Properties Company Method and apparatus for selecting a prescription for an orthodontic brace
EP1658821A1 (fr) * 2001-07-30 2006-05-24 3M Innovative Properties Company Procédé et appareil permettant de sélectionner une prescription pour un appareil orthodontique
US7766653B2 (en) 2001-07-30 2010-08-03 3M Innovative Properties Co Method and apparatus for selecting a prescription for an orthodontic brace
US8386061B2 (en) 2008-06-02 2013-02-26 Dentsply International Inc. Methods for designing a customized dental prosthesis using digital images of a patient
CN108463172A (zh) * 2015-11-13 2018-08-28 新泽西州立拉特格斯大学 基于图像分析结果对根尖周疾病的鉴别诊断
EP3374964A4 (fr) * 2015-11-13 2019-09-11 Rutgers, The State University of New Jersey Diagnostic différentiel de maladies périapicales en fonction de résultats d'analyse d'image
US10792004B2 (en) 2015-11-13 2020-10-06 Rutgers, The State University Of New Jersey Differential diagnosis of periapical diseases based on results of image analysis

Also Published As

Publication number Publication date
GB9003172D0 (en) 1990-04-11

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