Surgery – Diagnostic testing – Detecting nuclear – electromagnetic – or ultrasonic radiation
Reexamination Certificate
1999-06-11
2002-07-30
Lateef, Marvin M. (Department: 3737)
Surgery
Diagnostic testing
Detecting nuclear, electromagnetic, or ultrasonic radiation
C600S111000
Reexamination Certificate
active
06425865
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a method and apparatus to perform ultrasound image acquisition for diagnostic or intervention using a robot to position the ultrasound transducer.
BACKGROUND
Ultrasound as a medical imaging modality has a number of benefits—it is inexpensive, non-invasive, real-time, etc. It is used widely for diagnosis, and also in interventions, for example, to guide needles or other instruments for anaesthesis and surgery.
Medical ultrasound examinations often require that ultrasound technicians hold the transducer probe in one hand while adjusting scanning parameters with the other hand, or hold the transducer in awkward positions for prolonged periods of time, sometimes exerting large forces for prolonged periods of time. Not surprisingly, a number of studies indicate that the technicians suffer from an unusually high incidence of musculoskeletal disorders (e.g. Vanderpool, 1993, Craig, 1985).
The use of a robot in conjunction with ultrasound imaging has been described in U.S. Pat. No. 5,817,022, Vesely et al., that discloses a system that enables the display of 2-D ultrasound images in a 3-D viewing environment. The use of a robot to position a surgical/medical intervention instrument under computer control is discussed as an option, but the ultrasound transducers described in that method are fixed. The role of the operator, position or force sensors of ultrasound image in the positioning of the instrument is not discussed.
A robot-assisted ultrasound examination system would provide other, not only ergonomic, benefits. For instance, since the location of the ultrasound transducer can be determined via the forward kinematics of the slave manipulator, three-dimensional ultrasound images can be reconstructed from a series of two-dimensional image slices. The process of creating three-dimensional ultrasound images from a series of two-dimensional slices has been suggested in lezzi et al., U.S. Pat. No. 5,551,432, which teaches a three-dimensional ultrasound imaging system that employs a motor with a screw drive to translate the ultrasound transducer in order to achieve images of the eye. U.S. Pat. No. 5,551,432 also describes an Auto-scroll feature that enables the operator to command the speed at which the transducer is translated. U.S. Pat. No. 5,810,008, Dekel et al., describes a three-dimensional ultrasound imaging system comprising position and orientation sensors that enable multiple planar computer images to be correlated to form three-dimensional ultrasound images. Another three-dimensional ultrasound imaging system that uses an actuator to move the ultrasound transducer is described in U.S. Pat. No. 5,759,153, Webler et al. Yet another three-dimensional ultrasound imaging system is described in U.S. Pat. No. 5,842,473, Fenster et al.
Remote probe positioning could also be used in teleradiology to examine patients at distant or inaccessible locations. Although a number of methods for transmitting ultrasound images have been proposed in the literature (Sublett, 1995), none allow the radiologist to view and manipulate the ultrasound transducer at the remote site. The remote positioning of an ultrasound transducer for endoscopic applications has been described in a number of patents. U.S. Pat. No. 5,842,993, Eichelberger et al., describes a navigable ultrasonic imaging probe assembly that can be positioned by the user endoscopically. Another endoscopic ultrasound transducer positioning system is described in European Patent application No. 0 514 584 A2, Solomon et al.
The computer-controlled positioning of an ultrasound probe has been described in other applications. For example, U.S. Pat. No. 5,836,880, Pratt, describes an animal tissue scanning system comprising a computer-positioned ultrasound transducer. However, such positioning has not been done as a function of sensed variables, such as ultrasound transducer position, forces or the image it acquires.
The control of multiple parameters for ultrasound image acquisition can be quite difficult. A control architecture suitable for controlling an ultrasound imager or other complex equipment is described in U.S. Pat. No. 5,853,367. The system is concerned with the efficient distribution of task loading for complex computerized systems.
The ability to position the ultrasound transducer in response to acquired ultrasound images would also be of benefit to image-guided interventions (e.g., percutaneous pericardial puncture) and registration with past examination records or images obtained with other imaging methods (e.g., MRI). The use of ultrasound imaging together with three-dimensional tracking of the transducer probe has been proposed in U.S. Pat. No. 5,797,849 as a tool for improving medical interventions.
SUMMARY OF INVENTION
A system for medical ultrasound is presented in which the ultrasound probe is positioned by a robot arm under the shared control of the ultrasound operator and the computer. The system comprises a robot arm design suitable for diagnostic ultrasound, a passive or active hand-controller, and at least one computer system to coordinate the motion and forces of the robot and hand-controller as a function of operator input, sensed parameters and ultrasound images.
While the ultrasound probe is positioned by a robot, the operator, the robot controller, and an ultrasound image processor have shared control over its motion. The motion of the robot arm and the hand controller of the proposed ultrasound are based on measured positions and forces, acquired ultrasound images, and/or taught position and force trajectories. Several modes of control are presented, including the control of the transducer using ultrasound image tracking.
An inherently safe, light, backdrivable, counterbalanced robot has been designed for carotid artery examinations but can be easily adapted for other examinations.
To operate the system, the ultrasound technician manipulates a hand-controller and enters commands via a user interface. The hand controller displacement and/or forces are sensed by appropriate sensors and read in by a computer that interprets these as a desired ultrasound transducer location or velocity or force or combination thereof (by location we mean position and orientation). A suitably designed mechanism, preferably a backdriveable, counterbalanced and light robot, positions the ultrasound transducer against the human body according to the above desired and possibly scaled values. The ultrasound transducer image is displayed on a monitor observed by the ultrasound technician, who can alter the ultrasound transducer location and force by manipulating the hand controller or entering commands via the operator interface. The operator can either control all degrees of freedom of the ultrasound transducer by manipulating the hand controller, or can control fewer degrees of freedom, with the remaining degrees of freedom being controlled by a computer. The computer-controlled degrees of freedom could specify a particular location or velocity trajectory, such as a probe translation or rotation motion, or a particular force, or the tracking of a particular feature in the ultrasound image acquired by the ultrasound machine, or a previously executed trajectory. To give the operator an intuitive way of controlling the forces the ultrasound transducer exerts on the human body, the hand controller could be active, i.e. have actuators that can exert a force on the ultrasound technician's hand. These forces could be proportional to the ultrasound transducer forces.
The invention is directed to a method of positioning an ultrasound transducer onto the surface of a human body comprising: mechanically positioning the ultrasound transducer on the surface of the human body by an operator positioned remotely from the ultrasound transducer operating a hand controller which is linked to the ultrasound transducer and which by means of a programmed computer instructs and causes the ultrasound transducer to be positioned on the surface of the human body, the ultrasound transducer then acquiring and tr
Bell Graham S.
Jameson Michael
Lawrence Peter D.
Marko Alexei
Salcudean Septimiu E.
Oyen Wiggs Green & Mutala
Patel Maulin
The University of British Columbia
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