The invention relates generally to medical imaging systems, and more specifically to the automated alignment of patients within such systems.
Medical imaging is the process of using a specialized system to create an image of a person's internal organs, tissues, and other structures and characteristics that cannot commonly be seen with the human eye. Some medical imaging systems are large in size and require the patient to be brought within the system for imaging. For these types of systems, commonly a patient is positioned on a movable table that can advance into the medical imaging system. The patient is positioned at a specific reference point within the system, and imaging by the system occurs.
Magnetic resonance imaging (MRI) is a commonly used medical imaging technology. Within a magnetic resonance imaging (MRI) system a patient table, commonly called the patient couch, extends into the bore of the magnet, and exists to support and position the patient so the patient can lie comfortably during the imaging process. The couch houses mechanical as well as electrical components that allow the patient and the couch to be moved into the center of the magnet bore, known as the isocenter, where the optimal imaging area of the magnet is located and imaging occurs.
Cross-hair laser 20 existing on the facade of the MRI system are then turned on. Couch 14 is advanced partially into magnet 26, and RF coil 16 with anatomy of interest 18 centered inside is positioned under laser cross-hairs 20. Cross-hairs 20 of the facade laser are a pre-determined distance from isocenter 24 of magnet 26, such that when an object is centered under cross-hairs 20 and the appropriate button, which in
Attempts have been made in other medical imaging procedures with similar requirements for patient positioning to expedite and automate the patient positioning process. U.S. Pat. No. 6,662,036 (issued Dec. 9, 2003) teaches of a surgical positioning system for positioning and repositioning a portion of a patient's body for medical treatment or imaging. The patented system utilizes multiple cameras to view the body and the surgical or imaging machine, which identify index markers that are located in relationship with the portion of the patient's body that is of interest during the original imaging or surgery procedure. The positions of the index markers are used as a reference, so the position can be replicated during future surgical or imaging procedures. This system allows a portion of a patient's body to be targeted for surgery, or for exact positioning to be replicated for repeated imaging. The system of this invention differs from the Prior Art by providing for different means for obtaining the desired outcome of expediting patient positioning within a medical imaging system under a variety of circumstances and conditions, and allowing for the patient to be positioned at the desired imaging point with every imaging procedure, rather than only repeated imaging procedures. By eliminating unnecessary steps through the development of a continuous positioning procedure, this invention should improve positioning accuracy and minimize total procedure time, thus providing better quality images and improved patient comfort.
It is an object of this invention to describe a system for the automated localization of a patient in preparation for a medical imaging procedure, such as but not limited to a magnetic resonance imaging (MRI) procedure. Other applicable medical imaging techniques can include positron emission tomography (PET) procedures, optical tomography, single photon emission computed tomography (SPECT), and computerized axial tomography (CAT) procedures.
It is a further object of this invention to describe a system for patient positioning during a medical imaging procedure that operates under a process that provides for essentially continuous positioning feedback as opposed to the step process of Prior Art. After the anatomy of interest has been identified and indicated it is moved to the magnet isocenter in one step, essentially eliminating the extraneous steps currently necessary in the art of centering the anatomy of interest at a superfluous point in space that is a predetermined distance from the isocenter of the imaging system.
It is another object of this invention to describe a system of automated patient localization for medical imaging procedures that will expedite the process of medical imaging, decreasing the time necessary for an imaging session, thus effectively increasing throughput of the imaging center, as well as decreasing the time necessary from the patient to complete the imaging procedure.
It is yet another object of this invention to describe a system of automated patient localization for medical imaging procedures that will decrease the human intervention necessary for positioning and preparing the patient for the scanning procedure, thus eliminating opportunities for human error and increasing the reliability of the imaging procedure.
The invention meets these objects by providing a system consisting of an indicator for identifying the patient anatomy of interest and a controlling unit for advancing the indicated patient anatomy of interest to the desired reference point of the imaging system, for example the isocenter of an MRI system. The indicator may take on many forms, such as but not limited to a fiducial marker, acoustic sensor, touch sensor, special positioning indicator, or a software algorithm. The controlling unit will be such that it will work in conjunction with the type of indicator that is chosen.
These and other objects of the present invention will become more readily apparent from a reading of the following detailed description taken in conjunction with the accompanying drawings wherein like reference numerals indicate similar parts, and with further reference to the appended claims.
The invention may take physical form in certain parts and arrangements of parts, numerous embodiments of which will be described in detail in the specification and illustrated in the accompanying drawings that form a part hereof, and wherein:
Referring now to the drawings wherein the showings are for purposes of illustrating numerous embodiments of the invention only and not for purposes of limiting the same, the figures illustrate the novel idea of a system for the automated patient localization during medical imaging techniques.
This invention is applicable to any medical imaging system that necessitates patient localization for its proper function, such as magnetic resonance imaging (MRI) systems, positron emission tomography (PET) systems, optical tomography, single photon emission computed tomography (SPECT), and computerized aided tomography (CAT) systems.
Typically, patient 12 lies on patient table 14 that has been pulled out of MRI system 10 to allow patient 12 to be positioned thereupon. RF Coil 16 is then centered on anatomy of interest 18, which in
In a preferred embodiment, at least one location is marked with an indicator 28, as being the anatomy of interest 18. It is within the scope of the invention to incorporate the marking of more than one location as the anatomy of interest, as some imaging procedures require multi-station positioning, for example spine or contrast agent imaging procedures. The indicator is such that controlling unit 30 acting as a means of detection senses the initial position of indicator 28 and advances patient table 14 into MRI system 10 such that the anatomy of interest 18 is positioned at isocenter 24 of magnet 26, or any other predefined location within system 10. The invention does not limit the final position of the anatomy of interest to the isocenter of the magnetic field of the system, and could intend for the anatomy of interest to have a final location at any predetermined spot within the MRI system, however, the isocenter is used as the final position throughout the entirety of this description of the invention for brevity and illustrative purposes.
Indicator 28 used to mark anatomy of interest 18 can take on many forms. Some non-limiting examples of indicators utilized in certain embodiments include fiducial markers, light reflecting markers and touch sensitive markers, buttons, or indicators of any sort. A touch sensitive tape or touch sensitive screen can be placed alongside the patient for identification of the anatomy of interest. As shown in
The nature of indicator 28, shown in
The at least one indicator 28 may be positioned to mark anatomy of interest 18 in many different ways. Indicator 28 may be placed in a specific relation to the anatomy of interest 18, such as, but not limited to, on top of, below, or a specified distance away from in a specified direction from anatomy of interest 18. In certain embodiments the indicator may be inserted and fixed in its location, unable to slide or be moved to another location without being removed from the first location. In other embodiments the indicator may be movable on a slider, groove, track, or other movable device integrated with, on top of, or into the patient table that may or may not have a locking mechanism to ensure the positioning of the indicator in relation to the anatomy of interest.
Controlling unit 30 is associated with and able to read the signal or communication mode output by the type of indicator 28 being used for the particular imaging system and acts as the detection means of the indicators. For example, with a traditional MRI fiducial, a controlling unit capable of sensing MRI fiducial markers would be necessary. If a localization wand is utilized, as shown in
Controlling unit 30 may monitor indicator 28 by one of a number of different techniques, a non-limiting list including the use of sliding resistors, cable operated potentiometers, linear arrays of mechanical or electrical switches that identify different positions, or linear arrays of optical sensors. Once controlling unit 30 has received the original communication of the initial position of anatomy of interest 18 through a signal or other indication from indicator 28, it will advance patient table 14 from its original position toward reference point 24 within the system. Controlling unit 30 will determine the final position patient table 14 must advance toward by either calculating the distance between the original position of indicator 28 and reference point 24 and moving that set distance, receiving an essentially continual communication from indicator 28 and tracking its advancement toward reference point 24, or by receiving continued signals at a set interval of time or distance to track the advancement of indicator 28 toward reference point 24. The predetermined intervals of time or distance can vary depending on the type of indicator and controlling unit used, as any limitation on time between sampling position will commonly be determined by the limitations of the electronics or mechanics of the indicators and controlling units. The controlling unit may sample the location of the indicators preferably at least once per second, more preferably ten or one hundred times per second, and most preferably continuously.
The reference point, or desired final location of the anatomy, will commonly be the imaging center, or most sensitive location within the imaging system where the highest quality images are taken. The location of reference point 24 indicating the desired final position of anatomy of interest 18 may be pre-programmed in controlling unit 30 or may be identified to controller 30 by an additional indicator 28. If the distance between the original position of indicator 28 and reference point 24 is calculated, that calculation can occur by any means, including but not limited to calculating the angle between controlling unit 30, reference point 24, and current position of indicator 28. Controlling unit 30 will automatically stop patient table 14 when the calculated distance has been traveled by patient table 14 or when indicator 28 in relation to the anatomy of interest 18 has advanced to the same point as reference point 24. The controlling unit should preferably have a high degree of accuracy in calculating the movement of the patient table from the initial location to the desired final location, as a distance as small as a millimeter can affect the images produced by the imaging system. The controlling unit is preferably able to stop the patient table within 2 mm, more preferably within 1 mm, and most preferably less than 1/10 mm from the desired final location.
When more than one indicator is utilized, as in multi-station image sessions, the controlling unit will advance the patient table to the subsequent indicators using the same method as with the first indicator. Occasionally the technician may find it necessary to manually reposition the patient within the system for further imaging positions. If the table is manually repositioned by the technician after the indicated area of interest has reached the desired final position, the controlling unit will return the area of interest to the original desired final position upon the directive of the technician.
A further aspect of this invention, as shown in
Yet another embodiment of this invention, shown in
Thus, the system is essentially using the sensitivity of RF coil 16 as the indicator, and a software algorithm as the controlling unit to recognize the sensitivity of RF coil 16 from a series of quickly taken scans as the patient 12 is slowly advanced into the MRI system. When the maximum sensitivity of RF coil 16, and thus the anatomy of interest 18 is recognized by the software controlling unit, patient table 14 will be advanced to the correct position such that the anatomy of interest 18 is centered at isocenter 24 of the system. However, this method of patient localization may have less accuracy than the aforementioned methods utilizing a physical indicator and controlling unit system. Nevertheless, the accuracy of the MR signal method would be acceptable for most types of imaging studies. Pilot scans, locator scans, or other fast scans for the purpose of quickly locating the position of the body in the system would be utilized to fine tune the exact position that images should be taken.
The MR signal method for patient localization may not be appropriate in all situations, as it has inherent limitations, such as use with phased array coils. These are coils with elements that combine differently than a single element, creating numerous areas of high sensitivity within the RF coil rather than having just one area of maximum sensitivity at the center of the coil. The software algorithm will no longer be able to operate under the principle that the anatomy of interest is located at the point of highest sensitivity within the coil as there are now numerous areas of high sensitivity, not all of which are centered on the anatomy of interest. Applications that utilize only certain elements of the phased array RF coil may still be able to use this embodiment of the invention, as there would be a limited number of areas of high sensitivity, most of which would be near or on the anatomy of interest.
Complications will also arise when whole body studies, run-off studies, or other imaging protocols are used that require the patient table to move during the scan protocol. In this case, the MR signal method of the invention could still be utilized, but would not be as efficient as in other situations. The patient could be advanced into the system as the software algorithm searches for the approaching optimal sensitivity of coil 16, of
A further aspect of the invention (shown in the flowchart
For example, if the liver is the anatomy of interest of a certain patient, the patient is registered in the system, and the liver is identified on the patient's electronic profile. The patient is placed on the MRI system patient table and a torso coil (a type of RF coil) is placed around the patient's midsection. Once activated, the software algorithm instantaneously accesses its database and finds that the characteristics of the liver include that it is a predetermined distance from a certain sized black region associated with the lung. The software algorithm slowly advances the patient table with the patient on it, into the MRI system, as it searches for the sudden signal void and black region associated with the lung, and continues to advance for a predetermined distance after signal returns, indicating the lung has been passed.
The anatomy of interest identification embodiment previously described can be used by itself on any medical imaging system, or in combination with the previously mentioned MR Signal method for patient localization on MRI systems. For example, the MR Signal method can be utilized, and then the anatomy of interest identification method can be used as a secondary check to ensure the proper location was identified and centered at isocenter of the magnet, or the anatomy of interest identification method can be used and the MR Signal method can be used as the secondary assurance.
Described above is a process for patient localization in a medical imaging system that comprises of orienting the patient on the patient table and with respect to any additional necessary hardware, providing an indication of the patient anatomy of interest, and advancing the patient and the RF coil to a reference point within the medical imaging system in response to the indication, as well as a system for use with the process. The process and system can be used on any medical imaging system, such as an MRI system, PET system, and CAT system. The indication of the patient anatomy of interest and the controlling unit can take on many forms, and utilize electrical, acoustical, light sensitive, optical, touch sensitive, MR signals and other methods for proper operation.
In the foregoing description, certain terms have been used for brevity, clearness, illustration and understanding; but no unnecessary limitations are to be implied therefrom beyond the requirements of the prior art, because such terms are used for descriptive purposes and are intended to be broadly construed. Moreover, this invention has been described in detail with reference to specific embodiments thereof, including the respective best modes for carrying out each embodiment. It shall be understood that these illustrations are by way of example and not by way of limitation.