Patent Application
20130182829
This application generally relates to alignment systems. In particular, this application relates to alignment systems for x-ray devices that help position an x-ray source so that it is aimed at an x-ray detector.
Alignment systems have been used for many types of alignment. One of their uses has been to assist an operator of an x-ray device to align an x-ray source with an x-ray detector in the device. These have been especially useful in x-ray devices that are used in dental radiography.
In film based dental radiography, a cartridge containing a radiographic film is placed in the patient's mouth, (i.e., behind a patient's tooth), and an x-ray beam is projected through the tooth and onto the film. The film is developed in a dark room or a closed processor using special chemicals to obtain a radiographic image of the tooth. In filmless dental radiography, an x-ray beam is projected through the patient's tooth, but instead an electronic sensor is placed in the patient's mouth behind the tooth to be examined. The electronic sensor may include a charge-coupled device (CCD), a complementary metal oxide semi-conductor (CMOS), or any other filmless radiation sensor. The x-rays pass through the tooth and impinge on the electronic sensor, which converts the x-rays into an electrical signal. The electrical signal is often transmitted to a computer, either directly or through a module containing intermediate processing circuitry. The computer then processes the signal to produce an image on an associated output device, such as a monitor or a printer.
When a dentist or dental technician takes an x-ray of a patient's tooth, though, the x-ray source and the electromagnetic sensor (or x-ray detector) are often not properly aligned, thereby causing geometric distortion of the radiographic image and potential loss of diagnostic value. In addition, if the imaging system is misaligned there is a possibility that the area of interest is missed in the image, and the dentist or technician may need to repeat the x-ray imaging, causing unnecessary additional radiation exposure to the patient
This application relates to alignment systems and associated methods of using such systems to help aim an x-ray source at an x-ray detector. The alignment systems can contain an electromagnetic radiation transmitter (or receiver) that is associated with the x-ray detector and an electromagnetic radiation receiver (or transmitter) that is associated with the x-ray source. The electromagnetic radiation produced by the electromagnetic radiation transmitter can be detected by the receiver and used to align the x-ray source and the x-ray detector in the x-ray device. In some configurations, the electromagnetic radiation transmitter contains a radio-frequency (RF) antenna (or antenna array) that is attached in a fixed position relative to the x-ray detector and the electromagnetic radiation receiver also contains an RF antenna (or antenna array) that is in a fixed position relative to the x-ray source.
The following description of the alignment systems can be understood in light of the Figures, in which:
The Figures illustrate specific aspects of the described systems and methods for alignment systems and methods for using such systems. Together with the following description, the Figures demonstrate and explain the principles of the methods and structures produced through these methods. In the drawings, the thickness of layers and regions are exaggerated for clarity. The same reference numerals in different drawings represent the same element, and thus their descriptions will not be repeated. As the terms on, attached to, or coupled to are used herein, one object (e.g., a material, a layer, a substrate, etc.) can be on, attached to, or coupled to another object regardless of whether the one object is directly on, attached, or coupled to the other object or there are one or more intervening objects between the one object and the other object. Also, directions (e.g., above, below, top, bottom, side, up, down, under, over, upper, lower, horizontal, vertical, “x,” “y,” “z,” etc.), if provided, are relative and provided solely by way of example and for ease of illustration and discussion and not by way of limitation. In addition, where reference is made to a list of elements (e.g., elements a, b, c), such reference is intended to include any one of the listed elements by itself, any combination of less than all of the listed elements, and/or a combination of all of the listed elements.
The following description provides specific details in order to provide a thorough understanding. The skilled artisan, however, would understand that the x-ray devices can be practiced without employing these specific details. Indeed, the x-ray devices can be practiced by modifying the description herein and can be used in conjunction with apparatus and techniques conventionally used in the industry. While the devices are described for alignment in x-ray imaging for dental purposes, they could be used in medical applications such as ultrasound imaging, determination of the location of catheters inside the body, or accurate positioning of surgical instruments where visual indication of the location of the instrument is obstructed by body tissue or other obstructions. As well, these alignment systems could be used for alignment in other industries, such as determination of locations of pipes inside walls in the construction industry or to determine the location and motion of a free-floating stylus or pointing device.
The alignment systems and methods for using the same in dental radiography are described herein and illustrated in the Figures. Generally, the alignment systems contain an electromagnetic transmitter (sometimes referred to as an electromagnetic generator) and an electromagnetic receiver. The electromagnetic transmitter and electromagnetic receiver are associated with the components of a device which need to be aligned (such as an x-ray source and an x-ray detector of an x-ray device). The electromagnetic field produced by the electromagnetic transmitter and can then be detected by the electromagnetic receiver. The electromagnetic transmitter and electromagnetic receiver can be aligned with each other and this alignment can then be used to help align such components of that device (i.e., the x-ray source and the x-ray detector in the x-ray device). Using multiple transmitters and/or receivers, the relative location of the transmitter(s) to the receiver(s) can be determined and the information relayed to the operator of the device.
One example of an alignment system is illustrated in
In some embodiments, the electromagnetic transmitter may include one or more coils of an electrically conductive material to which a current can be applied for producing a variable electromagnetic field. The current may be modulated or may be an alternating current. The electromagnetic receiver may also contain one or more coils of an electrically conductive material for detecting the variable electromagnetic field generated by the transmitter.
The transmitter and/or receiver may also include at least two coils in different orientations for detecting at least two vector components of the variable electromagnetic field. In some configurations, the transmitter and/or receiver contains multiple sets of at least two coils, with each set of the at least two coils having a similar or the same orientation, for emitting or detecting a vector component of the variable electromagnetic field.
In some configurations, the coil assemblies 50 may contain a three-axis dipole coil transmitter or a three-axis dipole coil receiver. Each three-axis transmitter or receiver can be built so that the three coils exhibit the same effective area, are oriented orthogonally to one another, and are centered at the same point.
In these configurations, the mutual inductances between each of the three coils in the coil assembly of receiver 20 and each of the three coils in the coil assembly of the transmitter 10 can be measured. The position and orientation of the transmitter 10 with respect to the receiver 20 may then be calculated from the nine resulting mutual inductances of each of those coils and the knowledge of the coil characteristics. Thus, the position and orientation of the transmitter 10 with respect to the receiver 20 may be calculated by sensing the magnetic field generated by the transmitter 10.
In the embodiments shown in
The transmitter and the receiver may be powered using any power source. In some embodiments, both the transmitter and the receiver are powered from the same source, while in other embodiments they are powered from different sources. In some configurations, the power source could be a local battery.
In other embodiments, the alignment system can contain one or more RF transmitters that contain at least one antenna and one or more RF receivers that contain at least one antenna. In these embodiments, an RF signal is produced by the RF transmitter using its antenna, producing an RF field that can be detected by the receiving antenna(s). In some configurations, the RF transmitter and/or the RF receiver can contain 4 antennas. For example, in the case of dental radiography the 4 transmitting antennas could be located at the 4 corners of a rectangular intra-oral sensor. A similar arrangement of 4 receiving antennas located at the end of the x-ray source collimator would provide the closest coupling of receivers to transmitters for the most accurate positioning. The four receiving (or transmitting) antennas can be utilized to provide relative signal strengths to a control unit that interprets the received (or transmitted) signals and provides information to the operator of the alignment system. Since the signal strength of the signal detected by the four antennas is directly proportional to the distance from the RF transmitter, it can be used to help determine the position and orientation needed for alignment. In some configurations, the antennas can be located in known positions relative to each other while being as far apart as allowed by the signal strength. In these configurations, the position accuracy can improve by adding more antennae. One receiver (or transmitter) can provide the relative position to each other, but not an overall location in 3-dimensional space. Having at least 3 antennae will provide the position in all 3 dimensions, and the accuracy improves with each additional antenna.
A first configuration of these embodiments is illustrated in
In this configuration, the RF transmitter 115 contains a loop antennae 150, oscillator 110, frequency reference 120, filter 130, amplifier 140, and power source 160. The oscillator 110 can be used to provide the basic frequency required to generate the RF signal. Any oscillator providing the desired RF frequency can be used. The frequency reference 120 can be used to provide frequency stability under varying operating conditions of temperature and voltage. In some embodiments, the frequency reference 120/220 may comprise a crystal device, a ceramic resonator, and/or other RF generators. The frequency filter 130 removes any unwanted harmonics that could cause erroneous operation or spurious RF emissions that could interfere with other electronic equipment with which the alignment system is used. The amplifier 140 can be used to boost the RF signal to a level that will provide a sufficient RF signal that matches the impedance of the receiver antenna 150. The power source 160 can be used to provide sufficient power to operate all of these components.
A second configuration of these embodiments is illustrated in
In this configuration, the RF transmitter 215 contains an antenna array 250 (of up to four antennae or even more) oscillator 210, frequency reference 220, filter 230, amplifier 240, and power source 260. All of these components operate substantially similar to the same named components described with reference to
A third configuration of these embodiments is illustrated in
The filtered radio frequency energy is then amplified. While a logarithmic amplifier can be utilized as the amplifier 330 in
In these configurations, an algorithm can followed to calculate the position of the transmitting antenna with respect to the receiving antenna array. When utilizing the RF transmitter configuration illustrated in
The configuration in
In yet other configurations, the antenna sequencer and antenna distributor illustrated in
The alignment systems described herein can be used with many devices that need aligning, such as ultrasound devices or x-ray devices, including those x-ray devices used in dental radiography. The alignment systems can be used with these devices by incorporating the transmitter in one portion of the device and the receiver to another location of the device or another location that contains the object to be analyzed. For example, when used to align ultrasound equipment, the transmitter (or receiver) could be attached to the ultrasound emitter that is used to analyze the patient. The receiver (or transmitter) could then be attached to a location on the opposite side of the patient. For example, in a pregnancy examination, the receiver could be located on a pad placed on the table where the patient is laying down to be examined.
When used with the x-ray devices, the electromagnetic transmitter can be associated with the x-ray detector and the electromagnetic detector can be associated with the x-ray source. Alternatively, the electromagnetic transmitter can be associated with the x-ray source and the electromagnetic detector can be associated with the x-ray detector. In some embodiments, the transmitter and/or the receiver can be associated with the x-ray detector and/or the x-ray source by being removably attached to that component. In other embodiments, the transmitter and/or the receiver can be associated with the x-ray detector and/or the x-ray source by being permanently attached to that component.
The electromagnetic field can be detected by the receiver and analyzed using the processor (or processing system) to determine the relative position and orientation of the transmitter and receiver. Since the transmitter is attached in a fixed spatial relationship to the x-ray detector and the receiver is attached in fixed spatial relationship to the x-ray source, or vice versa, the relative position and orientation of the x-ray detector and the x-ray source can be determined. Any deviation from the desired relative position and/or orientation may be corrected by moving either the x-ray source or the x-ray detector. The relative position and orientation of the x-ray detector and the x-ray source may be moved and any alignment can be corrected until a desired alignment is achieved. In this manner, once the operator has detected the correct orientation, the x-ray source can be move to maximize the measured signal strength.
When the x-ray device is used in dental radiography to take x-rays of a tooth a patient, the transmitter can be removably or permanently connected to the x-ray detector. The x-ray detector can then be placed inside the mouth of the patient, such as behind a tooth to be examined. In some configurations, to maintain the desired position in the mouth, the combination of transmitter/x-ray detector can be configured with a projecting tab on which the patient can bite to secure their position.
In those embodiments using electromagnetic coils, the position of the x-ray source and x-ray detector can be based on the acquisition of the output signals from the coils and their relevant spatial geometry. These signals can be used to reconstruct a complete model of the generated electromagnetic field and identify the relative position and orientation of the transmitter and receiver. A complete simulation of the generated electromagnetic field may be realized using finite elements analysis (FEA) tools, such as available in standard mathematic libraries, and the output signals from the detection coils. In other embodiments, the position of the x-ray source and x-ray detector can be determined based on the acquisition of the output signals from the transmitter antenna relative to the receiver antenna.
When used for dental radiography, the alignment system and/or the x-ray device may further include a display to indicate to an operator of the x-ray device any misalignment of the x-ray detector and the x-ray source. The display can indicate to an operator the appropriate directions and/or orientations to move the x-ray detector or x-ray source to achieve the desired alignment. The display can also indicate to the operator when the x-ray source is located sufficiently close to the x-ray detector so that the electromagnetic field generated by the electromagnetic transmitter is detected by the electromagnetic receiver. The display may have one or more arrays of LEDs indicating to an operator the directions or orientations to move an x-ray detector or an x-ray source to achieve the desired alignment. The display can be external to the x-ray device or integrated into the x-ray device.
In some embodiments, the alignment system can be used with the x-ray devices shown in
The RF receiving antenna can be integrated into any desired location of the device 410. In some configurations, the RF receiving antenna can be incorporated into collimating cone 495. In other configurations, the RF receiving antenna can be incorporated into shielding 480 as shown in
The x-ray device 410 also contains a mechanism for displaying the x-rays detected by the x-ray detector. Examples of displays that can be used include film, imaging plates, and digital image displays such as cathode ray tubes (CRT) or liquid crystal display (LCD) screens. In some configurations, and as illustrated in
The radiographic image of the tooth 490 detected by the x-ray detector (CCD sensor 450) is transmitted to the x-ray device 410 and then viewed via the display 460. This communication can take place using a wire or a cable 455, as shown in
With such a configuration, the x-ray device 410 can be especially useful for dental radiography. The x-ray device 410 can be used to analyze a tooth 490 (or multiple teeth) of a patient by placing the tooth 490 between the x-ray device 410 and the CCD sensor 450 and then operating the device.
In other embodiments, the alignment systems can be used with the x-ray devices shown in
The RF receiving antenna has been integrated into any desired location of the device 510. In some configurations, the RF receiving antenna can be incorporated into collimating cone 595. In other configurations, the RF receiving antenna can be incorporated into shielding 580 as shown in
In
In both types of devices illustrated in
In the devices illustrated in
In other embodiments, the housing 610 can be replaced with a disposable container. In these embodiments, as illustrated in
In these embodiments, the RF antenna and associated electronics described herein can be printed onto a surface of the sleeve 710 using thin film technology. In these embodiments, the alignment systems could operate at any approved frequency for low-power communications, including those in the ISM bands. Thus, the alignments systems do not interfere with other equipment and the other equipment is kept from interfering with the alignment systems.
These x-ray devices can be used for dental radiography in the following manner. The RF transmitter may be associated with the CCD sensor using either the housing 610 or the sleeve 710. The housing (or sleeve) is placed in the desired position in the mouth of the patient behind a tooth to be examined. The patient can bite on the tab to lock the housing (or sleeve) in place. Then, the x-ray handheld device shown in
In some configurations, these alignment systems could be used as a safety feature. The x-ray source could be configured so that it would not operate unless the alignment was achieved within a certain range of accuracy. Thus, the x-ray dose to the patient can be minimized by only taking the radiographic image when the desired alignment is obtained.
With respect to the use of substantially any plural and/or singular terms herein, those having skill in the art can translate from the plural to the singular and/or from the singular to the plural as is appropriate to the context and/or application. The various singular/plural permutations may be expressly set forth herein for sake of clarity.
In addition to any previously indicated modification, numerous other variations and alternative arrangements may be devised by those skilled in the art without departing from the spirit and scope of this description, and appended claims are intended to cover such modifications and arrangements. Thus, while the information has been described above with particularity and detail in connection with what is presently deemed to be the most practical and preferred aspects, it will be apparent to those of ordinary skill in the art that numerous modifications, including, but not limited to, form, function, manner of operation and use may be made without departing from the principles and concepts set forth herein. Also, as used herein, the examples and embodiments, in all respects, are meant to be illustrative only and should not be construed to be limiting in any manner.
This application claims priority of U.S. Provisional Application Ser. No. 61/587,268 filed Jan. 17, 2012, the entire disclosure of which is incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 61587268 | Jan 2012 | US |
