Abstract:
A dental fluoroscopic imaging system includes a flat panel detector comprising a converter, a plate, a collector, a processing unit, and a transmitter suitable for 2D, intraoral dental fluoroscopy and for 3D extraoral dental fluoroscopy. The converter contains a material capable of transforming low dose radiation received from an emitter after going through the dental examination area into electrical signals. The plate transmits the electric signals to a collector, which amplifies the signals. The processing unit processes the signals into digital images, and the transmitter transfers digital images sequentially to a host computer having software that acquires, processes, transforms, records, freezes, and enhances 2D and 3D images, and compiles videos having video frame rates of between 3 and 100 frames per second. Two dimensional images and video are obtained using a single flat panel detector, while three dimensional images and video are obtained using two flat panel detectors.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    The present application is a U.S. continuation application of, and claims priority under 35 U.S.C. to, U.S. nonprovisional patent application Ser. No. 12/653,964, filed Dec. 22, 2009, which published as U.S. patent application publication no. 2011/0150185, which application and publication are incorporated by reference herein. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    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. 
         [0003]    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 intraoral, i.e., they can be placed inside the mouth. Others are larger in size and are extraoral, i.e., they are used outside the mouth in order to obtain a dental image. 
         [0004]    The first intraoral X-rays imaging sensor available on the market was introduced following the principles described in U.S. Pat. No. 4,593,400 and U.S. Pat. No. 5,382,798 and were based on a scintillating material and a charged coupled device (CCD) technology. Other inventions in the field used similar CCD sensors such as disclosed, for example, in U.S. Pat. No. 5,434,418; U.S. Pat. No. 5,510,623; U.S. Pat. No. 5,693,948; and U.S. Pat. No. 5,519,751. 
         [0005]    Another particular type of digital system which uses a memory phosphor plate in place of the film was introduced in U.S. Pat. No. 4,965,455. In this system, the digitized images are stored, scanned and then displayed on a 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. 
         [0006]    The complementary metal-oxide-semiconductor (CMOS) active pixel sensor technology was proposed to dentistry in U.S. Pat. No. 5,912,942, which provides advantages over the CCD technology, including competitive wafer processing pricing, and on-chip timing, control and processing electronics. Other inventions in the field utilizing similar CMOS technology are disclosed in U.S. Pat. No. 6,404,854; U.S. Pat. No. 7,211,817; U.S. Pat. No. 7,615,754; and U.S. Pat. No. 7,608,834, which introduced some improvements through the description of the biCMOS technology combining bipolar transistors and CMOS devices. 
         [0007]    Due to the rigidity of the CMOS intraoral sensors, which translated into patient discomfort while placed inside the mouth, a flexible sensor using thin film transistors technology was devised in 2009, as disclosed in U.S. Pat. No. 7,563,026, with a goal of trying to reproduce the comfort of conventional film. 
         [0008]    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, as illustrated in U.S. Pat. No. 5,834,782; U.S. Pat. No. 7,016,461; U.S. Pat. No. 7,197,109; U.S. Pat. No. 7,319,736; U.S. Pat. No. 7,136,452; U.S. Pat. No. 7,336,763; and U.S. Pat. No. 7,322,746. 
         [0009]    A perceived disadvantage of these foregoing dental digital intraoral and extraoral radiography technologies is that the final result is either a 2D or 3D still image. 
         [0010]    Fluoroscopy is a dynamic x-ray, or x-ray movie showing images at video frame rates. It differs from dental digital radiography in that dental digital radiography is a static x-ray picture. An analogy is that of a movie compared to a snapshot. The beginning of fluoroscopy can be traced back to 8 Nov. 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. 
         [0011]    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. 
         [0012]    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&#39; filtration correctly sensitized the physician&#39;s eyes prior to the procedure while still allowing the physician to receive enough light to function normally. The invention of X-ray image intensifiers 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. 
         [0013]    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. 
         [0014]    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, i.e., the image intensifiers which have diameters greater than six inches. However, recent breakthroughs in imaging and night vision technologies have made possible the miniaturization of the medical fluoroscope for dental use by using small image intensifiers, as disclosed in U.S. Pat. No. 6,543,936. Night vision image intensifiers (18-40 mm diameter)—like those used for military purposes)—can convert fluoroscopy&#39;s low-radiation beam to a vivid video image after going through the patient&#39;s dental area. This image can be captured by a digital video camera chip and then displayed as a real-time video on a monitor. Consequently, this breakthrough has allowed the fluoroscopy technology to fit in a dental operatory. 
         [0015]    Another attempt to reduce the medical fluoroscope size is disclosed in WO/2004/110277; WO/2005/072615; and WO/2005/110234. 
         [0016]    Despite these efforts, the image receptor configuration using the image intensifier and camera is still too bulky to be used inside the mouth and the image receptor configuration is not sufficiently ergonomic for the dentist so as to be placed extraorally while performing treatments on patients. Moreover, the proposed configurations in previous inventions only disclose the use of fluoroscopy in a 2D approach using image intensifiers. 
         [0017]    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 doses. The introduction of flat-panel detectors in for 2D fluoroscopy in medicine allows for the replacement of the image intensifier in the medical fluoroscope design. This is illustrated, for example, in U.S. Pat. Nos. 5,262,649; 5,610,404; 5,648,654; 5,773,832; 5,949,848; 5,962,856; 6,566,809; 6,717,174; 7,231,014; 7,323,692; 7,426,258; and 7,629,587. 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 are disclosed in U.S. Pat. No. 5,049,987, wherein a plurality of image capture devices are arranged in a predetermined pattern; in U.S. Pat. No. 5,841,830, wherein a motor is used to rotate the emitter and detector around the patient body; and in U.S. Pat. No. 7,596,205, wherein 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. In view of the foregoing, it will be apparent that such current technologies are designed to be used in a medical setting and generally are too large to be used in a dental setting. 
       BRIEF SUMMARY OF THE INVENTION 
       [0018]    The present invention relates generally to the field of diagnostic radiology and, more particularly, to dental fluoroscopic imaging. The present invention also includes many aspects and features. 
         [0019]    In a first aspect, a dental fluoroscopic imaging apparatus comprise flat panel detectors and emitters for two dimensional (2D) and three dimensional (3D) dental fluoroscopy. The emitters may be, for example, in a C-shaped arm configuration, U-shaped arm configuration, or O-shaped arm configuration. 
         [0020]    In another aspect, a dental fluoroscopic imaging system using flat panel detectors comprises a housing containing a converter material, a plate, a collector, a processing unit, and a transmitter capable of reading out, and transferring to a host, digital images at video frame rates. 
         [0021]    In a feature of this aspect, an intraoral flat panel detector is sized to fit within a patient&#39;s mouth. 
         [0022]    In another feature, an extraoral flat panel detector is sized to be placed outside patient&#39;s mouth. 
         [0023]    In another feature, the converter comprises a semiconductor of amorphous selenium (a-se), or a material such as NaI, NaI(TI); higher-Z bismuth germinate (BGO); BaF 2 ; CaF 2 (EuI); high-purity germanium HPGe; Cesium Iodide (CsI); CsI(TI); CsI(Na); LaCl 3 (Ce); LaBr 3 (Ce); LuI 3 ; Lu 2 SiO 5 ; Gadolinium Oxysulphide (GSO); Lu 1.8 Y 0.2 SiO 5 (Ce); amorphous silicon (a-si); poly-si; metal ceramic; CdWO 4 ; CaWO 4 ; linear photodiode array (PDA); Si(Li); CdTe; CdZnTe; CZT; CdSe; CdS; Se; PbI 2 ; PbTe; HgTe; HgI 2 ; ZnS; ZnTe; ZnWO 4 ; GaP; AlSb; YAG(Ce); Gd 2 O 2 S; or Kodak Lanex as a material to transform the low dose gamma rays or x-rays received from an emitter, after going through the dental examination area, into electrical signals or a light image consequent with the radiographed image. 
         [0024]    In another feature, the system further comprises 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 amorphous silicon for electrical signals or light image transmission. 
         [0025]    In another feature, the system further comprises 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 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. 
         [0026]    In another feature, the system further comprises a processing unit and a transmitter such as an analog to digital converter unit in order to sequentially convert and sequentially transfer digital images. 
         [0027]    In another feature, system further comprises a host computer and software which acquires, processes, transforms, records, freezes and enhances 2D and 3D images at video frame rates ranging from 1 to 100 fps. 
         [0028]    In another aspect of the invention, a method of producing dental fluoroscopy comprises receiving with a flat panel detector electromagnetic radiation in the form of low dose gamma rays or x-ray beams from an emitter, after going through an dental examination area, and processing the received electromagnetic radiation into electrical signals or a light image consequent with the radiographed image. 
         [0029]    In a feature, the emitter operates with direct current. 
         [0030]    In another feature, the emitter utilizes a focal spot size within the range from 0.005 to 0.8 mm. 
         [0031]    In another feature, the method further comprises operating the emitter with a target angle range from 0 to 30 degrees. 
         [0032]    In another feature, the method further comprises operating the emitter at voltage peaks within the range from 35 to 95 kVp. 
         [0033]    In another feature, the method further comprises operating the emitter at current peaks between 0.0001 to 10 mA. 
         [0034]    In another feature, the method further comprises operating the emitter to cause 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. 
         [0035]    In another aspect, a method includes producing 2D and 3 D dental fluoroscopy. 
         [0036]    In a feature relating to producing 2D dental fluoroscopy, the method comprises utilizing a single emitter and a single extraoral flat panel detector positioned in parallel relation facing each other. They may be attached to a C-arm configuration or U-arm configuration. 
         [0037]    In a feature relating to producing 3D dental fluoroscopy, the method comprises utilizing two emitters and two extraoral flat panel detectors attached to an O-arm configuration, and facing each other in a cross approach and emitting x-rays beams which intercepts in a perpendicular point. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0038]      FIG. 1   a  is a schematic illustration pertaining to an embodiment of the present invention. 
           [0039]      FIG. 1   b  is a schematic illustration pertaining to another embodiment of the present invention. 
           [0040]      FIG. 2   a  is a schematic illustration pertaining to an embodiment of the present invention. 
           [0041]      FIG. 2   b  is a schematic illustration pertaining to another embodiment of the present invention. 
           [0042]      FIG. 3  is a schematic illustration of a preferred flat panel detector used in one or more embodiments of the present invention. 
           [0043]      FIG. 4  is a schematic illustration of an embodiment of the present invention. 
           [0044]      FIG. 5  is a schematic illustration of another embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0045]    In accordance with one or more preferred embodiments of the present invention, a dental fluoroscopic imaging apparatus comprises an intraoral flat panel detector  1 , and in accordance with one or more preferred embodiments of the present invention, a dental fluoroscopic imaging apparatus comprises an extraoral flat panel detector  2 . An intraoral flat panel detector  1  is shown in  FIG. 1 , and an extraoral flat panel detector  2  is shown in  FIG. 2 . Whether intraoral or extraoral, each flat panel detector utilizes a converter  3  as illustrated in each of  FIGS. 1 and 2 . As additionally illustrated in each of  FIGS. 1 and 2 , systems in accordance with preferred embodiments of the invention include a high frequency direct current (DC) emitter  5  that generates a beam  4  of electromagnetic radiation. The electromagnetic radiation may comprise low dose gamma rays or x-rays. 
         [0046]    With reference to  FIG. 2   a , the flat panel detector is positioned so that the converter  3  receives the beam  4  after the beam  4  passes through a dental examination area. The converter  3  transforms the electromagnetic radiation of the beam  4  that is received into electrical signals or a light image  6  consequent with a radiographed image. The converter  3  is coupled to a plate  7 . The electrical signals or light image  6  are transmitted to a collector  8 . When the collector  8  is activated by address signals from the high speed processing unit  9 , the electrical signals that are read out in response to the address signals are amplified and sent to a transmitter  10 , where the electrical signals received from the high speed processing unit  9  are converted to digital images and transferred, sequentially, to a host computer  11 . The host computer  11  preferably runs software that enables the computer  11  to acquire, process, transform, record, freeze and enhance the digital images transferred from the transmitter  10 . The software also preferably generates 2D and 3D images as well as compiles the images into videos having a video frame rate ranging from 3 to 100 frames per second (fps). In this respect, the transmitter  10  preferably transmits digital images at a rate of 3 to 100 images per second. Moreover, the transmitter  10  may transmit video frames at the rate of 3 to 100 frames per second, which video frames are received, processed, and stored or played by the software. 
         [0047]    Preferably, the converter  3  comprises a semiconductor of amorphous selenium (a-se), or a material such as NaI, NaI(TI), higher-Z bismuth germinate (BGO), BaF 2 , CaF 2  (Eu), high-purity germanium HPGe, Cesium Iodide (CsI), CsI(TI), CsI(Na), LaCl 3 (Ce), LaBr 3 (Ce), LuI 3 , Lu 2 SiO 5 , Gadolinium Oxysulphide (GSO), Lu 1.8 Y 0.2 SiO 5 (Ce), amorphous silicon (a-si), poly-si, metal ceramic, CdWO 4 , CaWO 4 , linear photodiode array (PDA), Si(Li), CdTe, CdZnTe, CZT, CdSe, CdS, Se, PbI 2 , PbTe, HgTe, HgI 2 , ZnS, ZnTe, ZnWO 4 , GaP, AlSb, YAG(Ce), Gd 2 O 2 S or Kodak Lanex. 
         [0048]    The plate  7  comprises, for example, a dielectric and top electrode layers material, fiber optic, aluminum, metal ceramic, glass and amorphous carbon or by a photodiode array of amorphous selenium or amorphous silicon. 
         [0049]    The collector  8  comprises, for example, 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 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 
         [0050]    The transmitter  10  preferably comprises an analog-to-digital converter unit. 
         [0051]    The emitter  5  may contain a radioactive source, a radiation generator, a gamma rays source, a charged particles radiation, a neutral particles radiation, a Marx generator, a device based on bremsstrahlung radiation, a tape on a vacuum system, an X-ray tube or a Cold Cathode X-ray tube. 
         [0052]    The emitter focal spot size preferably is within the range from 0.005 to 0.8 mm with a target angle range from 0 to 30 degrees. Also, the voltage peaks preferably are within the range from 35 to 95 kVp and while the current peaks preferably are between 0.0001 to 10 mA. 
         [0053]    The emitter  5  preferably generates an x-ray beam with a continuous rate from 1 to 50 ms or with a pulse width range from 1 to 100 pulses per second. 
         [0054]    It is believed that preferred embodiments of the invention provide dental fluoroscopy images with a better spatial resolution, high quantum efficiency, high gain, and low noise, a high image signal-to-noise ratios, high dynamic range and high speed on the same detector. Moreover, it is believed that preferred embodiments of the invention enable use of intraoral and extraoral flat panel detectors without such detectors being coupled to an image intensifier unit, lenses, and fiber optic taper. Consequently, size and the costs are considerably reduced. Following these principles, dental procedures can be observed at the same time that they are being performed. 
         [0055]    The intraoral and extraoral flat panel detectors preferably are included in a biocompatible housing  12  that fulfills the EN30993-1 Biological Testing of Dental and Medical Devices and with the ISO standards that have a feature of not allowing light to pass through its surface, but allowing gamma rays or x-rays to pass through its surface. As set forth elsewhere, the housing contains the converter  3 , plate  7  if included, collector  8 , processing unit  9 , and transmitter  10 . Moreover, the interior face of an internal wall on the backside of the detector preferably is covered by a thin sheet  13  made of lead, x-rays attenuating plastic, or other material, which functions as a shield to inhibit gamma rays or x-rays and to minimize scattered radiation, as shown in  FIG. 3 . 
         [0056]    The intraoral flat panel detector  1  preferably encompasses three different types which correspond with the conventional film sizes available in dentistry, i.e., Type 1—Periapical; Type 2—Bite Wing; and Type 3—Occlusal in sizes 0, 1, 2, 3 and 4, ranging from 22×35 millimeters to 57×76 millimeters of overall dimension. The thickness of the intraoral flat panel detector  1  preferably is sufficiently small such that the intraoral flat panel detector  1  can be placed inside the patient&#39;s mouth and be maintained by any x-ray intraoral sensor positioning system. 
         [0057]    The extraoral flat panel detector  2  preferably has an active area ranging from 40×40 to 60×60 millimeters and can be attached, along with the emitter  5 , to a C-shaped arm support assembly, U-shaped arm support assembly, or O-shaped arm support assembly.  FIGS. 4 and 5  show the emitter  5  attached to mechanical arms  16 , which are able to extend, fold, go up and down, and to move to the left and to the right. These mechanical arms  16  can be fixed through an attachment  17  on the dental office&#39;s wall, roof and/or any dental unit. In addition, if it is desirable, the attachment  17  can be used to couple the system with a mobile unit making the apparatus portable. 
         [0058]    Between the mechanical arms  16  and the posterior side of the emitter  5  there is a spin attachment  18 , which allows the movement up, down, left and right of the emitter  5 . 
         [0059]    When using the intraoral flat panel detector  1 , it is placed inside the patient&#39;s mouth in the selected place with a film positioning device in order to place the collimator cone  19  aiming to the direction to the area to be radiographed with the desired angulation. For this purposes, the arm support assembly is provided with a hinge  20  which allows folding back the extraoral flat panel detector. 
         [0060]    The activation of for the dental fluoroscopic imaging system is based on a wireless or cable-based pedal control  21 . 
         [0061]    When using the extraoral flat panel detector  2 , arm  14  interlocks at  22  which allows the distance between the emitter  5  and the extraoral flat panel detector  2  to be fixed. Thereby, the arm support assembly can be adjusted to take into consideration the patient&#39;s size and the angle of the beam  4 . In addition, the emitter  5  is attached to the mechanical arms  16  by means of a rotational axis  23  which allows the arm support assembly to rotate up to 360 degrees around the emitter  5 . 
         [0062]    The single emitter  5  and single extraoral flat panel detector  2  positioned parallel facing each other and attached to a the C-shaped or U-shaped arm support assembly  14 , as shown in  FIG. 4 , preferably are used to obtain a 2D fluoroscopic image. 
         [0063]    The arm support assembly  14  shown in  FIG. 4  can be upgraded to an O-shaped arm support assembly  15  with two emitters  5  and detectors  2 , as shown in  FIG. 5 , by connecting the arm support assembly portion  24  which is not attached to the mechanical arms  16 , through attachments  25  and an extraoral flat panel detector  2  through the flat panel attachment  26 . 
         [0064]    The two emitters  5  and two extraoral flat panel detectors  2  attached to the O-shaped arm support assembly  15 , as shown in  FIG. 5 , preferably are used to obtain a 3D dental fluoroscopic image. In this arrangement, beams  4  are emitted so as to intersect orthogonally at a point within the patient examination area, as illustrated in  FIG. 5 . As a result, two beams  4  from two the different emitters  5 , after going through the dental examination area in orthogonal directions, are received by the two different extraoral flat panel detectors  2 . There, the images consequent with the patient radiographed area are converted into light or electrical signals, collected, amplified and processed as described above with reference to  FIGS. 2   a  and  2   b . Resulting digital images are transmitted, preferably at the same time, to the host computer  11 , where at the software processes the received images and generates a 3D video. 
         [0065]    These improved dental fluoroscopic imaging system enhanced productivity capabilities are because they fulfill the Digital Imaging and Communication in Medicine (DICOM) and Picture Archiving and Communication System (PACS) digital image format standards for x-rays image capture. With these digital image capture systems the image data sent to workstations, printers and files is always identical to the original. 
         [0066]    In order to reduce the level of the exposure to radiation of the patient and the operator, it is normally required to use mechanical barriers of radiological protection and to fulfill the requirements of the Federal Food and Drug Administration Regulations (FDA), that include the warnings as hearing alarms that indicate when the exposure levels of the skin exceed the 5 R/min for fluoroscopy. According to the Dose Rate Guidance Levels for Fluoroscopy for a Typical Adult Patient of the IAEA, 2004, the doses allowed in the normal fluoroscopic operation mode are up to 25 mGy per min. 
         [0067]    It is to be understood that the above-described arrangements are only illustrative of the application of the principles of the present invention. Numerous modifications and alternative arrangements may be devised by those skilled in the art without departing from the spirit and scope of the present invention.