X-ray or gamma ray systems or devices – Source support – Including movable source
Reexamination Certificate
2000-12-28
2003-12-23
Bruce, David V. (Department: 2882)
X-ray or gamma ray systems or devices
Source support
Including movable source
C378S062000
Reexamination Certificate
active
06666579
ABSTRACT:
CROSS REFERENCE TO RELATED APPLICATIONS (IF APPLICABLE)
Not applicable.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH & DEVELOPMENT (if applicable)
Not applicable
BACKGROUND OF THE INVENTION
The preferred embodiments of the present invention generally relate to a mobile C-arm based x-ray system for constructing three dimensional (3-D) volumetric data sets and using the data sets in diagnostic and interventional medical procedures. More specifically, at least one preferred embodiment of the present invention relates to a mobile C-arm based x-ray medical imaging system that constructs three-dimensional volumetric data sets of digital x-ray images, based, in part, on coordinate information for patients and the x-ray receptor, and uses the data sets for diagnostic and interventional procedures to be carried out.
Conventional medical imaging modalities, such as computed tomography (CT) and magnetic resonance imaging (MRI), use sophisticated mechanical gantry structures to support patients and equipment used to construct patient imaging data sets. The CT and MRI data sets are formed from a plurality of scans in which the exact position of the patient is known from the relation between the mechanical gantry and the patient table formed integral with the gantry. For instance, CT systems use a circular gantry that supports a continuously rotating fan beam x-ray source and an opposed arcuate detector array. The fan beam x-ray source and detector array continuously rotate within the gantry. The CT system also includes a patient table integral with the gantry. The table moves the patient through the gantry at predefined incremental steps while the fan beam x-ray source continuously rotates. The mechanical interconnection of the gantry and table in the CT system maintain a known relationship between the position of the patient and of the x-ray source and detector array at all times, and thus is able to construct a set of 2-D images aligned in a known relationship to one another in order to construct a 3-D volumetric data set of the images. Once the 3-D volume is constructed, individual slices of the patient may be obtained to present to the doctor desired views, such as the sagittal, coronal and axial views; or segmented or rendered image views. MRI systems maintain a similar mechanical interconnection between the gantry holding the magnet coils and patient table.
However, CT and MR systems are extremely complex, large and expensive. In the more recent history, intraoperative MR and mobile CT systems have been proposed. However, these intraoperative MR and mobile CT systems still require a configuration comprising a patient table formed integrally with the gantry. Many intraoperative and diagnostic procedures do not justify or warrant the cost of MR and CT systems, mobile or otherwise. Further, intraoperative MR and mobile CT systems are still quite large and take up a significant portion of an operating room.
Today, many diagnostic and surgical procedures are carried out using a mobile C-arm type x-ray system in a fluoroscopy or digital spot mode. Mobile C-arm x-ray systems are more commonly found in an OR or interoperative hospital and clinical facilities as such systems are much smaller, less complex and less expensive than CT and MR systems. Conventional mobile C-arm systems have been used during surgical procedures by performing standard fluoroscopic x-ray imaging to acquire one or more x-ray images of the patient during the procedure. The most common x-ray images obtained using the mobile C-arm include the AP and lateral views. By way of an example, during a surgical planning phase, the doctor may obtain two exposures/shots, namely one AP view and one lateral view to initially observe and study the region of interest. In a spinal procedure, the doctor next will resect tissue from the region of interest (ROI) to expose a bony portion of interest. Next, the doctor places the surgical instrument or tool near the bony portion of interest, with the instrument or tool located at a desired position and orientation at which the doctor desires to carry out the surgical procedure. The doctor next typically obtains two new exposures/shots (AP and lateral) of the ROI and instrument to view the position and orientation of the instrument/tool relative to the bony portion of interest. Then the doctor begins the surgical procedure, such as drilling a hole in the bone or the like. At various stages along the surgical procedure, the doctor obtains new pairs of exposures/shots (AP and lateral) to determine the progress of the procedure. This process is repeated until the tool reaches a desired destination. The foregoing process requires several exposures to be taken of the patient, thereby causing the patient to receive a large x-ray dose, even though it is preferable to minimize the radiation dosage required to complete a procedure.
C-arm based systems have a configuration of joints and interconnects that permit the doctor to move and rotate the C-arm through several directions of movement, such as an orbital tracking direction, longitudinal tracking direction, lateral tracking direction, transverse tracking direction, pivotal tracking direction, and “wig-wag” tracking direction. The C-arm may be moved through each of the foregoing tracking directions by releasing mechanical locks at the appropriate joints and interconnects.
At least one C-arm type system has been proposed that includes a mechanical motor to drive the C-arm (and thus the x-ray source and image intensifier) in the orbital tracking direction, namely in an arcuate path within the plane defined by the C-arm frame. As the motor moves the C-arm in the orbital tracking direction, a series of exposures are taken. The series of exposures are combined into a data set for display as a three-dimensional volume. However, the motor driven C-arm system is only useful for diagnostic procedures, not interventional operations, since the image frames are not correlated to the patient location and alignment.
A need remains for an improved C-arm based system capable of constructing 3-D volumetric data sets of patient and instrument information and capable of displaying slices, segments or rendered volumes of data at any desired viewing angle for use during diagnostic and interventional procedures.
BRIEF SUMMARY OF THE INVENTION
According to one aspect of a preferred embodiment, a medical imaging system is provided having a C-arm with an x-ray source for generating x-rays and a receptor device for receiving x-rays and deriving a fluoroscopic image from the x-rays received. The C-arm moves the x-ray source and receptor device along an image acquisition path between at least first and second image acquisition positions. An acquisition module obtains a series of 2-D fluoroscopic images, wherein first and second fluoroscopic images are obtained when the x-ray source and receptor are located at the first and second image acquisition positions, respectively. An image processor constructs a 3-D volume of object voxels based on the series of fluoroscopic images. A monitor displays images based on the 3-D volume, such as 3D renderings, patient slices and the like. A position tracker monitors the position of the C-arm and patient at each of the positions through the series of exposures and provides position information for the patient and the receptor for fluoroscopic images. The C-arm may be manually, mechanically or automatically moved along the image acquisition path.
According to at least one alternative embodiment, an image processor constructs a computed tomography volume from a series of 2-D fluoroscopic images. The image processor transforms multiple 2-D fluoroscopic images into 3-D volumetric data sets. The image processor may perform an iterative reconstruction technique to construct the 3-D volume. Alternatively, the image processor may perform a back projection technique to construct the 3-D volume.
According to at least one alternative embodiment, the C-arm is rotatably mounted to a base that moves the C-arm along an orbital rotation path to cause t
Bruce David V.
Dellapenna Michael A.
GE Medical Systems Global Technology Company LLC
McAndrews Held & Malloy Ltd.
Thomas Courtney
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