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WO1993015436A1 - Procede pour la lecture d'une plaque phosphore de radiographie dentaire - Google Patents

Procede pour la lecture d'une plaque phosphore de radiographie dentaire Download PDF

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Publication number
WO1993015436A1
WO1993015436A1 PCT/FI1993/000029 FI9300029W WO9315436A1 WO 1993015436 A1 WO1993015436 A1 WO 1993015436A1 FI 9300029 W FI9300029 W FI 9300029W WO 9315436 A1 WO9315436 A1 WO 9315436A1
Authority
WO
WIPO (PCT)
Prior art keywords
read
image
plate
final
preliminary
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/FI1993/000029
Other languages
English (en)
Inventor
Lauri Koivulehto
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Orion Oyj
Original Assignee
Orion Yhtyma Oy
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 Orion Yhtyma Oy filed Critical Orion Yhtyma Oy
Priority to JP5512957A priority Critical patent/JPH07503155A/ja
Priority to EP93914541A priority patent/EP0624259A1/fr
Priority to DE0624259T priority patent/DE624259T1/de
Publication of WO1993015436A1 publication Critical patent/WO1993015436A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01T—MEASUREMENT OF NUCLEAR OR X-RADIATION
    • G01T1/00—Measuring X-radiation, gamma radiation, corpuscular radiation, or cosmic radiation
    • G01T1/16—Measuring radiation intensity
    • G01T1/20—Measuring radiation intensity with scintillation detectors
    • G01T1/2012—Measuring radiation intensity with scintillation detectors using stimulable phosphors, e.g. stimulable phosphor sheets
    • G01T1/2014—Reading out of stimulable sheets, e.g. latent image
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
    • G03B42/00—Obtaining records using waves other than optical waves; Visualisation of such records by using optical means
    • G03B42/02—Obtaining records using waves other than optical waves; Visualisation of such records by using optical means using X-rays

Definitions

  • the present invention relates to a method in dental X-ray pho ⁇ tography for the read-out of an image, stored on a phosphor plate, by means of a beam directed at the surface of the plate, the method comprising a preliminary read-out step and, there ⁇ after, the final read-out step which will yield the desired information and in which setting values determined on the basis of the preliminary read-out will be used.
  • the purpose of the preliminary read-out is to determine the radiation dose received by the phosphor plate in the exposure, and on the basis of this dose the optimal amplification by the read-out amplifier is adjusted for the final read-out step.
  • the purpose is to find the gain level which makes maximal use of the conversion range of the analog/digital converter used in the read-out.
  • the gain can be adjusted to the correct level if the signal intensity of those regions of the image which have received the largest amount of X-radiation is known.
  • these regions are the interdental spaces, which are shown black in the radiograph. The denture and the interdental spaces will usually be in the central region of the radiograph, but the exact locations of the interdental spaces cannot be anticipated.
  • Regions which have received the largest amount of X-radiation can be sought by adjusting the amplification during the image read-out. However, in this case the gain in the middle of the image may change, whereupon the read-out result will not be optimal. Since part of the latent image on the phosphor plate will disappear during the image read-out, there is also no sense in reading out the image a second time using the amplifi ⁇ cation which could be set on the basis of the first read-out.
  • US patent publication 4,527,060 discloses a method of prelim- inary read-out using a mechanism by which the intensity of the laser beam used for the read-out is lowered and/or the laser dot is enlarged, whereupon the intensity of the radiation im ⁇ pinging on the phosphor plate will lower to a level at which the latent image on the phosphor plate will substantially be retained.
  • the preliminary read-out is carried out using this lowered-intensity laser dot, and on the basis of this read-out the necessary read-out amplifier parameters are set for the final full-intensity read-out of the image.
  • the preliminary read-out is targeted on the entire image surface, or at least on those regions of the image sur ⁇ face which contain essential information. A laser dot with its intensity lowered in the said manner is used in each case.
  • the object of the present invention is to provide a new read ⁇ out method suitable for dental X-ray photography, wherein the preliminary image read-out can be carried out without lowering the intensity of the laser beam used and, thus, without the auxiliary devices required for that procedure.
  • the invention is characterized in that the preliminary read-out is carried out on the marginal regions of the image, which in the main include the jawbone or the like, and the final read-out is carried out on the central region of the image, which includes the informa ⁇ tion desired from the image, such as the denture and the inter ⁇ dental spaces.
  • the invention is based on the fact that, regardless of how well the photographed denture with its interdental spaces has coin ⁇ cided with the central region of the image, in the marginal regions of a normal dental radiograph there is always jawbone or some other non-dark region which can be taken as the basis for the adjustment of the amplification in the final read-out step.
  • a preliminary read-out without lowering the intensity of the laser beam will destroy some of the latent image on the phosphor plate, but this is not of significance, since in terms of the information desired from the image the marginal regions of the image are in general not of interest.
  • the final read-o is limited to the central region of the image, in which the denture and the interdental spaces can be made visible and which has been retained intact in the preliminary read-out.
  • the amplification can adjusted by taking as the basis for the adjustment the degree of darkness, corresponding to the jawbone, prevalent in the marginal regio of the image.
  • the highest degree of image darkness, corresponding to the interdental spaces is adjusted to a level substantially darker than it, for example, three times its darkness, in which case the interdental spaces will be shown black in the radiograph.
  • the degree of darkness of the image will be correct also if, for some reason, interdental spaces are not shown in the image.
  • the amplification can be based directly on the image darkness preliminarily read out a corresponding to the interdental spaces.
  • the image read-out according to the invention is most prefer ⁇ ably carried out so that the preliminary read-out takes place during a mutual linear movement of the phosphor plate and the read-out device, and the final read-out during a mutual linear movement of the phosphor plate and the read-out device in the direction reverse to that of the preliminary read-out.
  • the sa read-out device can thus be used for both the preliminary rea out and the final read-out.
  • the read-out can advantageously be performed so that the phosphor plate is drawn out of the protective casing and is read out preliminarily in connection with the drawing out, in a read-out station outside the protective casing, whereafter the final read-out is carried out in the same read ⁇ out station during the return of the phosphor plate into the protective casing.
  • the apparatus described in FI application 903796 which according to the said application reads out the image stored on a sliding exposed plate while the sheet is being drawn out of an RIM cas ⁇ sette serving as a protective casing and, after the read-out, deletes the information from the plate while the plate is being returned into the cassette.
  • the apparatus is used so that a preliminary read-out is carried out in connection with the drawing out of the plate and the final read-out in connection with the return movement of the plate. Thereafter the plate may make a new movement out of and into the cassette for deletion by means of an intense ray of light aimed at the surface of the plate.
  • the image read-out may, according to the invention, take place advantageously so that in the preliminary read-out step those regions of the image are read out which frame one side and the two opposite ends of the image, and the rest of the image is read out in the final read-out step.
  • the read-out device may be made up of, for example, a scanner equipped with a pivotable mirror, the scanner guiding the laser beam which carries out the read-out back and forth across the phosphor plate, which is in steady linear motion, and the said read-out steps will in this case require only the control of the direction and extent of the transverse movement of the scanner in the different steps of the read-out.
  • Figure la shows a phosphor plate 1, which has been exposed in dental X-ray photography and has been placed in a protective casing 2 after the exposure.
  • the protective casing may be an RIM cassette according to FI application 903796, and the phos ⁇ phor plate may be a sliding plate which can be drawn out of th cassette in accordance with the said patent application, al ⁇ though the present invention is by no means limited to merely these embodiments.
  • the preliminary read-out of the image produced by exposure on the phosphor plate 1 takes place while the plate is being draw out of the protective casing 2 in accordance with Figure lb.
  • the phosphor plate 1 is brought into steady linear motion, and a laser beam 4 scanning the plate surface reciprocally in the lateral direction is directed at it in a read-out station 3.
  • the laser beam 4 is directed so that it initially reads the phosphor plate preliminarily over its entire width, thereafter over a rather narrow region limited to one side of the plate, and finally again over the entire width of the plate.
  • Figure l depicts a step in which the preliminary read-out has been com ⁇ pleted.
  • the preliminary read-out thus covers the marginal regions 5 of the plate 1, which surround as a rather narrow zone one side 6 and the two opposite ends 7 of the plate.
  • the central region 8 of the plate has been lef intact in the preliminary read-out.
  • the final image read-out using setting values determined on th basis of the preliminary read-out is carried out by using the same read-out station 3 and laser beam 4 during the return of the phosphor plate 1 into the protective casing 2.
  • the read-ou is now directed only at the central region 8 of the phosphor plate 1, left intact in the preliminary read-out, and the lase beam 4 reads it out with reciprocal scans in accordance with Figure Id.
  • Figure le shows a step in which the final read-out has been completed, whereafter the plate can be returned into the protective casing 2 ( Figure la).
  • the phosphor plate 1 may make a new movement out of and into the protective casing 2, during which the information is deleted from the plate by means of a delet ⁇ ing light directed at the surface. After the deletion the phos phor plate is ready for a second round of use.
  • the apparatus depicted in Figures 2a-2c, by means of which th plate 1 read-out and deletion steps described above can be im ⁇ plemented, comprises a frame 9, a space 10 receiving a phospho plate in a protective casing 2, a cover 11 closing the said space, and a drawing device 13 which moves reciprocally on a shaft 12 turning about its own axis and being driven by a step motor (not shown) . Furthermore, the apparatus is equipped with a read-out station 3 for the preliminary read-out and the fina read-out of the image on the phosphor plate 1 drawn out of the protective casing 2, as well as with a deleting station 14 for the deletion step subsequent to the read-out step.
  • a spring-loaded pin 16 belonging to the cover 11 is at this time in alignment with an opening 17 i the frame and the end of a rod 18 belonging to the drawing de ⁇ vice 13, and the cover will prevent the access of outside ligh into the space below the cover and to the read-out and deletio stations 3, 14 behind it.
  • the drawing device 13 When the drawing device 13 begins to move from the initial po ⁇ sition according to Figure 2b, the rod 18 of the drawing devic will withdraw from the opening 17 in the frame, and the pin 16 belonging to the cover 11 will, pressed by the spring, push into the said opening, thereby locking the cover in place.
  • the magnet of the drawing device 13 will draw the phosphor plate 1 out of the protective casing 2, and the preliminary read-out o the plate will be carried out by a laser beam 4 in the read-ou station, as described above.
  • the phosphor plate 1, drawn by the drawing device 13, will make a new reciprocal movement, during which the information is deleted from the plate by means of light directed at its surface in the deletion station 14. Afte the deletion, the phosphor plate 1 will return into the protec tive casing 2, the cover 11 will be opened ( Figure 2a), and th protective casing with its phosphor plate, ready for a new ex ⁇ posure, will be removed from the apparatus.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • High Energy & Nuclear Physics (AREA)
  • Molecular Biology (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Apparatus For Radiation Diagnosis (AREA)
  • Conversion Of X-Rays Into Visible Images (AREA)
  • Radiography Using Non-Light Waves (AREA)

Abstract

L'invention concerne un procédé pour la lecture d'une image stockée sur une plaque phosphore (1) de radiographie dentaire, au moyen d'un rayon laser (4) dirigé sur la surface de la plaque. Le procédé comprend une étape préliminaire de lecture et ensuite une étape finale de lecture qui fournit l'information désirée et dans laquelle les valeurs de réglage déterminées sur la base de la lecture préliminaire sont utilisées. Selon l'invention, la lecture préliminaire est effectuée sur une zone marginale (5) de l'image, comprenant principalement la mâchoire, et la lecture finale est effectuée sur la région centrale de l'image (8) comprenant la denture et les espaces interdentaires. L'agrandissement utilisé pour la lecture finale peut, dans ce cas, être ajusté sur la base de la lecture préliminaire de sorte que les zones les plus sombres de l'image, c'est-à-dire les espaces interdentaires, soient noires. La lecture préliminaire et la lecture finale peuvent être reliées à un mouvement de va-et-vient d'une plaque phosphore (1) extraite d'un étui de protection (2) puis rentrée dans cet étui, et l'effacement de l'information de la plaque, suivant la lecture, peut être relié à un second mouvement de va-et-vient de la plaque.
PCT/FI1993/000029 1992-01-30 1993-01-29 Procede pour la lecture d'une plaque phosphore de radiographie dentaire Ceased WO1993015436A1 (fr)

Priority Applications (3)

Application Number Priority Date Filing Date Title
JP5512957A JPH07503155A (ja) 1992-01-30 1993-01-29 歯科用ｘ線写真撮影において露光された蛍光板の読み出し方法
EP93914541A EP0624259A1 (fr) 1992-01-30 1993-01-29 Procede pour la lecture d'une plaque phosphore de radiographie dentaire
DE0624259T DE624259T1 (de) 1992-01-30 1993-01-29 Ausleseverfahren von belichtete phosphorplatten in zahnärztliche röntgenaufnahmen.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FI920427A FI90147C (fi) 1992-01-30 1992-01-30 Foerfarande foer laesning av en exponerad bildplatta vid tandroentgenfotografering
FI920427 1992-01-30

Publications (1)

Publication Number Publication Date
WO1993015436A1 true WO1993015436A1 (fr) 1993-08-05

Family

ID=8534340

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/FI1993/000029 Ceased WO1993015436A1 (fr) 1992-01-30 1993-01-29 Procede pour la lecture d'une plaque phosphore de radiographie dentaire

Country Status (5)

Country Link
EP (1) EP0624259A1 (fr)
JP (1) JPH07503155A (fr)
DE (1) DE624259T1 (fr)
FI (1) FI90147C (fr)
WO (1) WO1993015436A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US10599030B2 (en) * 2015-03-27 2020-03-24 Duerr Dental Ag Imaging plate scanner

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4527060A (en) * 1981-10-16 1985-07-02 Fuji Photo Film Co., Ltd. Radiation image read-out method and apparatus
EP0154880A2 (fr) * 1984-02-28 1985-09-18 Fuji Photo Film Co., Ltd. Méthode pour l'ajustement des conditions de lecture d'une image de radiation et/ou des conditions de traitement d'image
JPS63106642A (ja) * 1986-06-13 1988-05-11 Fuji Photo Film Co Ltd 放射線画像情報読取方法
JPS63106641A (ja) * 1986-06-13 1988-05-11 Fuji Photo Film Co Ltd 放射線画像情報読取方法
US4804841A (en) * 1985-06-13 1989-02-14 Fuji Photo Film Co., Ltd. Radiation image read-out method
US4864133A (en) * 1985-08-28 1989-09-05 Fuji Photo Film Co., Ltd. Method of adjusting radiation image read-out conditions
WO1992002849A1 (fr) * 1990-07-30 1992-02-20 Orion-Yhtymä Oy Procede et appareil servant a enregistrer des informations a partir d'une feuille coulissante d'une cassette rim

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4527060A (en) * 1981-10-16 1985-07-02 Fuji Photo Film Co., Ltd. Radiation image read-out method and apparatus
EP0154880A2 (fr) * 1984-02-28 1985-09-18 Fuji Photo Film Co., Ltd. Méthode pour l'ajustement des conditions de lecture d'une image de radiation et/ou des conditions de traitement d'image
US4804841A (en) * 1985-06-13 1989-02-14 Fuji Photo Film Co., Ltd. Radiation image read-out method
US4864133A (en) * 1985-08-28 1989-09-05 Fuji Photo Film Co., Ltd. Method of adjusting radiation image read-out conditions
JPS63106642A (ja) * 1986-06-13 1988-05-11 Fuji Photo Film Co Ltd 放射線画像情報読取方法
JPS63106641A (ja) * 1986-06-13 1988-05-11 Fuji Photo Film Co Ltd 放射線画像情報読取方法
WO1992002849A1 (fr) * 1990-07-30 1992-02-20 Orion-Yhtymä Oy Procede et appareil servant a enregistrer des informations a partir d'une feuille coulissante d'une cassette rim

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN, Vol. 12, No. 354, P-761; & JP,A,63 106 641 (FUJI PHOTO FILM CO LTD), 11 May 1988. *
PATENT ABSTRACTS OF JAPAN, Vol. 12, No. 354, P-761; & JP,A,63 106 642 (FUJI PHOTO FILM CO LTD), 11 May 1988. *

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US10599030B2 (en) * 2015-03-27 2020-03-24 Duerr Dental Ag Imaging plate scanner

Also Published As

Publication number Publication date
FI90147C (fi) 1993-12-27
FI90147B (fi) 1993-09-15
JPH07503155A (ja) 1995-04-06
DE624259T1 (de) 1995-08-03
EP0624259A1 (fr) 1994-11-17
FI920427A0 (fi) 1992-01-30
FI920427A7 (fi) 1993-07-31

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