EP2434955A1

EP2434955A1 - Dental fluoroscopic imaging system

Info

Publication number: EP2434955A1
Application number: EP09833773A
Authority: EP
Inventors: Daniel Uzbelger Feldman
Original assignee: Individual
Current assignee: Individual
Priority date: 2008-12-16
Filing date: 2009-12-22
Publication date: 2012-04-04
Also published as: WO2010071680A1; EP2434955A4; WO2010071680A4

Abstract

The dental fluoroscopic imaging system includes a flat panel detector comprised by a gamma-rays or x-rays converter, a plate, a collector, a processing unit and a transmitter suitable for 2D intraoral/extraoral and 3D extraoral dental fluoroscopy. The x-ray converter contains a material capable of transforming the low dose gamma rays or x-rays beam received from an emitter after going through the dental examination area into electrical signals or a light image consequent with the radiographed image. The plate transmits the electric signals or light image to a collector which amplifies it and sends it to a processing unit and then to transmitter designed to transfer digital images sequentially to a host computer and software which can acquire, process, transform, record, freeze and enhance 2D and 3D images of video frame rates. Two dimensional images are obtained while using a C-arm/U-arm configuration while 3D images are obtained while using the O-arm configuration.

Description

Dental Fluoroscopic Imaging System

(0001) 1. Technical field and industrial applicability of the invention

(0002) The present invention relates generally to the field of diagnostic radiology, and specifically to a dental fluoroscopic imaging system apparatus using flat panel detectors and emitters in C-arm/U-arm, O-arm configurations suitable for two dimensional (2D) and three dimensional (3D) dental fluoroscopy and the method of producing the same.

(0003) 2. Background of the invention

(0004) Before the discovery of electromagnetic radiation known as x-rays, techniques and procedures in the field of dentistry were based on purely empirical knowledge. On Nov. 8, 1895, William Conrad Roentgen announced the discovery of this new kind of radiation. Within fourteen days, Otto Walkhoff, a German dentist, took the first dental radiograph of his own mouth. Dr. William James had completed several dental radiographs five months later. In 1913, Coolidge improved the manufacturing techniques of the x-ray tube, which allowed for better control of the quality and quantity of radiographs. The panoramic x-ray device was invented in 1950. During many decades, the use of film-based radiography dominated these trends in dentistry.

(0005) Dental digital radiography is a form of x-ray imaging, where digital X-ray sensors are used instead of traditional photographic film. Advantages include time efficiency through bypassing chemical processing and the ability to digitally transfer and enhance images. Also less radiation can be used to produce a 2D still image of similar contrast to conventional film-based radiography. Some types of digital dental radiography sensors are small and thin enough that they can be placed intraorally or inside the mouth. Others are larger in size and are used extraorally or outside the mouth in order to obtain a dental image. The first intraoral X-rays imaging sensor available on the market was introduced following the principles described in US Patent No. 4,593,400 and 5,382,798 of Mouyen, 1986 and 1995 respectively based on a scintillating material and a charged coupled device (CCD) technology. Other inventions in the field used similar CCD sensors such as in US Patent No. 5,434,418 of Schick, 1995, US Patent No. 5,510,623 and 5,693,948 of Sayed et al., 1996 and 1997 respectively and US Patent No. 5,519,751 of Yamamoto et al., 1996. Another particular type of digital system which uses a memory phosphor plate in place of the film is introduced in US Patent No. 4,965,455 of Schneider et al., 1990. The digitized images are stored, scanned and then displayed on the computer screen. This method is halfway between old film-based technology and current direct digital imaging technology. It is similar to the film process because it involves the same image support handling but differs because the chemical development process is replaced by the scanning process. The complementary metal-oxide-semiconductor (CMOS) active pixel sensor technology was proposed to dentistry in US Patent No. 5,912,942 of Schick et al., 1999 which provided advantages such as competitive wafer processing pricing, and on chip timing, control and processing electronics when compared to the CCD technology. Other inventions in the field utilizing similar CMOS technology are included in US Patent No. 6,404,854 of Carrol et al., 2002, US Patent No. 7,211,817 of Moody, 2007, US Patent No. 7,615,754 of Liu et al., 2009, and in US Patent No. 7,608,834 Boucly et al., 2009 which introduced some improvements through the description of the biCMOS technology combining bipolar transistors and CMOS devices. Due to the rigidity of these intraoral sensors which translated in patient's discomfort while placed inside the mouth, a flexible sensor using thin film transistors technology was devised in US Patent No. 7,563,026 of Mandelkern et al., 2009 trying to reproduce the comfort of conventional film.

(0006) On the other hand, the use of flat panel detectors in dentistry has been focused in the cephalometric, orthopantomographic, scannographic, linear tomographic, tomosynthetic and tomographic fields for 2D and 3D extraoral radiography. These principles are illustrated in the US Patent No. 5,834,782 of Schick et al., 1998, US Patent No. 7,016,461, 7,197,109 and 7,319,736 of Rotondo et al, 2006, 2007 and 2008 respectively, US Patent No. 7,136,452 and 7,336,763 of Spartiotis et al., 2006 and 2008 respectively and US Patent No. 7,322,746 of Beckhaus et al., 2008. The problem with all these existing dental digital intraoral and extraoral radiography technologies is that their final outcome is either 2D or a 3D still image.

(0007) Fluoroscopy is a dynamic x-ray, or x-ray movie showing images of video frame rates. It differs from dental digital radiography in that dental digital radiography is static x-ray, or an x-ray picture. An analogy is that of a movie compared to a snapshot. The beginning of fluoroscopy can be traced back to 8 November 1895 when Wilhelm Roentgen noticed a barium platinocyanide screen fluorescing as a result of being exposed to what he would later call x-rays. The fluoroscopic image obtained in this way was rather faint. Thomas Edison quickly discovered that calcium tungstate screens produced brighter images and is credited with designing and producing the first commercially available fluoroscope. The first fluoroscope for dental use was described by William Herbert Rollins in 1896. Due to the limited light produced from the fluorescent screens, early radiologists were required to sit in a darkened room in which the procedure was to be performed, getting their eyes accustomed to the dark and thereby increasing their sensitivity to the light. The placement of the radiologist behind the screen resulted in significant radiation doses to the radiologist. Red adaptation goggles were developed by Wilhelm Trendelenburg in 1916 to address the problem of dark adaptation of the eyes, The resulting red light from the goggles' filtration correctly sensitized the physician's eyes prior to the procedure while still allowing him to receive enough light to function normally. The invention of X-ray image intensifϊers in the 1950s allowed the image on the screen to be visible under normal lighting conditions, as well as providing the option of recording the images with a conventional camera. Subsequent improvements included the coupling of, at first, video cameras and, later, video CCD cameras to permit recording of moving images and electronic storage of still images. Medical fluoroscopes also known as C- arms or mini C-arms are too large to fit in a dental operatory. The main reason is the size of one of their main components: > 6 inches diameter image intensifϊers. However, recent breakthroughs in imaging and night vision technologies made possible the miniaturization of the medical fluoroscope for dental use as disclosed in the Patent No. 6,543,936 of Feldman, 2003 by using small image intensifiers. Night vision image intensifiers (18-40 mm diameter) — like those used for military purposes - can convert fluoroscopy's low-radiation beam — after going through the patient's dental area - on a vivid video image. This image can be captured by a video digital camera chip and then displayed in real-time video on a monitor. Consequently, this breakthrough has allowed the fluoroscopy technology to fit in a dental operatory. Another attempt to reduce the medical fluoroscope size is seen in foreign Patents No. WO/2004/110277, WO/2005/072615 and WO/2005/110234 of Kim, 2004, 2005 and 2005 respectively. Despite these efforts, the image receptor configuration using the image intensifier and camera is still too bulky to be used inside the mouth and not ergonomic for the dentist to be placed extraorally while performing treatments on patients. Also, the proposed configurations in previous inventions only disclose the use of fluoroscopy in a 2D approach using image intensifiers.

(0008) However, more modern medical technology improvements in flat panel detectors have allowed for increased sensitivity to X-rays, and therefore the potential to reduce patient radiation dose. The introduction of flat-panel detectors in for 2D fluoroscopy in medicine as illustrated in the US Patent No. 5,262,649 of Antonuk et al., 1993, US Patent No. 5,610,404 and 5,648,654 of Possin, 1997 respectively, US Patent No. 5,773,832 of Sayed et al., 1998, US Patent No. 5,949,848 of Giblom, 1999, US Patent No. 5,962,856 of Zhao et al., 1999, US Patent No. 6,566,809 of Fuchs et al., 2003, US Patent No. 6,717,174 of Karellas, 2004, US Patent No. 7,231,014 of Levi, 2007, US Patent No. 7,323,692 of Rowlands et al., 2008, US Patent No. 7,426,258 of Zweig, 2008, US Patent No. 7,629,587 of Yagi, 2009 allows for the replacement of the image intensifier in the medical fluoroscope design. Temporal resolution is also improved over image intensifiers, reducing motion blurring. Contrast ratio is also improved over image intensifiers: flat-panel detectors are linear over very wide latitude, whereas image intensifiers have a maximum contrast ratio. Medical fluoroscopy 3D approaches have been described in the US Patent No. 5,049,987 of Hoppenstein, 1991 utilizing a plurality of image capture devices arranged in a predetermined pattern, in the US Patent No. 5,841,830 of Barni et al., 1998 where a motor is used to rotate the emitter and detector around the patient body and in the US Patent No. 7,596,205 of Zhang et al., 2009 in which the X-ray radiography unit irradiates a subject with X-rays from first X-ray tube to obtain an X- ray radiographic image. The X-ray CT unit irradiates the subject with X-rays from the second X-ray tube and acquires projection data from a beam of the X-rays that has passed through the subject, to reconstruct an image using the acquired projection data, and to obtain a tomographic image.

(0009) As has been shown, all these inventions are designed to be used on a medical setting. They are too large to be used for dental purposes. Consequently, none of these dental and medical technologies offer a flat panel, an emitter in a C-arm/U-arm and an O-arm configuration suitable for 2D and 3D dental fluoroscopy.

Claims

What is Claimed is:

1. A dental fluoroscopic imaging system using flat panel detectors, comprising: a housing which contains a converter material, a plate, a collector, a

5 processing unit and a transmitter capable of reading out and transferring to a host digital images of video frame rates.

2. An intraoral flat panel detector according to claim 1 is sized to fit within a patient's mouth.

3. An extraoral flat panel detector according to claim 1 is sized to be placed 10 outside patient's mouth.

4. A flat panel detector according to claim 1, wherein the converter includes a semiconductor of amorphous selenium (a-se), or a material such as NaI, NaI(TI), higher-Z bismuth germinate (BGO), BaF₂, CaF₂(Eu), high-purity germanium HPGe, Cesium Iodide (CsI), CsI(TI), CsI(Na), LaCl₃(Ce), LaBr₁(Ce), LuI_3, Lu₂SiO₅,

15 Gadolinium Oxysulphide (GSO)_, Lui g Y(_USiOs(Ce), amorphous silicon (a-si), poly-si, metal ceramic, CdWO₄, CaWO₄, linear photodiode array (PDA), Si(Li), CdTe, CdZnTe, CZT, CdSe, CdS, Se, PbI₂, PbTe, HgTe, HgI₂, ZnS, ZnTe, ZnWO₄, GaP, AlSb, YAG(Ce), Gd₂O₂S or Kodak Lanex as a material to transform the low dose / gamma rays or x-rays beam received from an emitter after going through the

20 examination dental area into electrical signals or a light image consequent with the radiographed image.

5. A flat panel detector according to claim 1, further comprising: a plate such as a dielectric and top electrode layers material, or fiber optic, aluminum, metal ceramic, glass and amorphous carbon or a photodiode array of amorphous selenium or

25 amorphous silicon for electrical signals or light image transmission.

6. A flat panel detector according to claim 1, further comprising: a collector made of an active matrix array or an amplified pixel detector array (APDA) of amorphous selenium or amorphous silicon thin film transistor and storage capacitor (TFT), or Electrometer Probes, a Charged Coupled Device type (CCD) such as the

30 Electron Multiplied CCD (EMCCD) chip and the Thinned Back Illuminated (BICCD) chip, an active pixel sensor Complementary Metal Oxide Semiconductor (CMOS) array or a biCMOS based on silicon-germanium-carbon (SiGe:C) technology in order to amplify and read out the electrical signals or light image.

7. A flat panel detector according to claim 1, further comprising: a processing unit and a transmitter such as an analog to digital converter unit in order to sequentially convert and sequentially transfer digital images.

8. A flat panel detector according to claim 1, further comprising: a host computer and software which can acquire, process, transform, record, freeze and enhance 2D and 3D images of video frame rates ranging from 1 to 100 fps.

9. A method of producing dental fluoroscopy wherein the flat panel detector receives and processes the low dose gamma rays or x-rays beam from an emitter after going through the examination dental area into electrical signals or a light image consequent with the radiographed image.

10. The method as claimed in claim 9, wherein said emitter operating with direct current.

11. The method as claimed in claim 9, comprising said emitter utilizing a focal spot size within the range from 0.005 to 0.8 mm.

12. The method as claimed in claim 9, comprising operating said emitter with a target angle range from 0 to 30 degrees.

13. The method as claimed in claim 9, comprising operating said emitter at voltage peaks within the range from 35 to 95 kVp.

14. The method as claimed in claim 9, comprising operating said emitter at current peaks between 0.0001 to 10 mA.

15. The method as claimed in claim 9, comprising operating said emitter allowing an x-ray beam with a continuous rate from 1 to 50 ms or with a pulse width range from 1 to 100 pulses/sec. (0043)

16. A method of producing 2D and 3 D dental fluoroscopy.

17. A method according to claim 16, of producing 2D dental fluoroscopy wherein said method utilizes a single emitter and a single extraoral flat panel detector positioned parallel facing each other and attached to a C-arm/U-arm configuration.

18. A method according to claim 16, of producing 3D dental fluoroscopy wherein said method utilizes two emitters and two extraoral flat panel detectors attached to an O-arm facing each other in a cross approach and emitting x-rays beams which intercepts in a perpendicular point.