Aleksandar Zivanovic

A robotic system for blood sampling

A robotic system to take blood samples autonomously from the forearm is presented, and preliminary results are discussed which demonstrate its feasibility. Force/position profiles, while pressing a flat-headed probe against the surface of the skin, enable the determination of a veins location to within 1 mm on a phantom. When a needle is inserted, the characteristic force/position profile, on puncturing the vein wall, is distinctive enough to implement automatic needle withdrawal to prevent overshoot. Future developments of the project are presented that provide both an autonomous blood sampling robot and a force-feedback surgical trainer.

A review of magnetic resonance imaging compatible manipulators in surgery.

Abstract Developments in magnetic resonance imaging (MRI), coupled with parallel progress in the field of computer-assisted surgery, mean that an ideal environment has been created for the development of MRI-compatible robotic systems and manipulators, capable of enhancing many types of surgical procedure. However, MRI does impose severe restrictions on mechatronic devices to be used in or around the scanners. In this article a review of the developments in the field of MRI-compatible surgical manipulators over the last decade is presented. The manipulators developed make use of different methods of actuation, but they can be reduced to four main groups: actuation transmitted through hydraulics, pneumatic actuators, ultrasonic motors based on the piezoceramic principle and remote manual actuation. Progress has been made concerning material selection, position sensing, and different actuation techniques, and design strategies have been implemented to overcome the multiple restrictions imposed by the MRI environment. Most systems lack the clinical validation needed to continue on to commercial products.

The feasibility of MR-Image guided prostate biopsy using piezoceramic motors inside or near to the magnet isocentre

The excellent soft tissue contrast of Magnetic Resonance Imaging (MRI) has encouraged the development of MRI compatible systems capable of combining the advantages of robotic manipulators with high quality anatomical images. Continuing this development, a new five DOF prostate biopsy manipulator has been designed for use inside a closed 1.5T MRI scanner. Space constraints in the bore and the current trend to restrict field strength exposure for operators indicate that a master-slave configuration is ideal for controlling the robotic system from outside the bore. This system has been designed to work with piezoceramic motors and optical encoders placed inside or near the field of view of the scanner, using real time image guidance for targeting biopsies to specific lesions in the prostate. MRI tests have been performed to prove the feasibility of this concept and a one DOF proof-of-concept test rig implementing closed loop position control has been tested and is presented here. A first prototype of the slave manipulator has been designed and manufactured incorporating this new technology.

A Modular Approach to MRI-Compatible Robotics

The objective of the research described in this article is to create individual MR-compatible modules consisting of 1-DoF stages complete with actuators and position encoders for implementation of the closed-loop position control. These modules can connect together to form multi-DoF assemblies that can be located inside the scanner bore near to the patient anatomy that requires the intervention. This avoids the problems associated with remote actuation and transmission mechanisms, considerably reducing the size of the manipulator. As most robots consist of kinematic chains of 1-DoF stages, these modules would be suitable for a wide range of interventions, and their design can be optimized for the procedure for which they are applied to.

Robotic System for Transrectal Biopsy of the Prostate: Real-Time Guidance Under MRI

In this paper, to harness the possibility of real-time guidance of MRI, a robotic system has been developed to perform transrectal prostate biopsy inside a 1.5-T closed bore scanner. A specially developed MR pulse sequence is capable of tracking the needle location in real time while dynamically updating the scan planes to always include the needle and target.

Engineering requirements for a haptic simulator for knee arthroscopy training.

This paper describes the initial development of an innovative haptic device that will be integrated into an existing virtual reality training system for knee arthroscopy. The resulting system will be called WISHKATS (Warwick, Imperial, Sheffield Knee Arthroscopy Training System). This haptic device will enable the trainee to feel realistic forces on the probing tool and will work together with software, which will simulate tissue deformation. The proposed haptic system is a compact, multi-degree of freedom, motorised mechanism with force sensors, and will be used to simulate the diagnostic aspects of knee arthroscopy. There are a number of problems associated with the development of a suitable haptic system and this paper explores the engineering requirements of such a device.

A part-task approach to haptic knee arthroscopy training.

This paper describes the research behind a part-task approach to both the development of, and the training offered, by a virtual reality simulator for knee arthroscopy. An ethnographic approach has been taken to examine the nature of task performance and the current training of the arthroscopic diagnosis of the knee. This Human Factors research is used to support the development of WISHKATS. The design addresses the challenge of technically producing haptic feedback for a knee surgery simulator whilst offering sufficient fidelity to train the necessary skills and conform to traditional surgical training.

The development of a cybernetic sculptor: Edward Ihnatowicz and the senster

Edward Ihnatowicz (1926-1988) built one of the worlds first computer-controlled robotic sculptures, The Senster, in 1968-70. Rather than concentrate entirely on this groundbreaking and influential piece of work, this paper describes the stages he went through in developing his ideas, as an illustration of how a conventional artist became a cybernetic sculptor.

A magnetic-resonance-compatible limb-positioning device to facilitate magic angle experiments in vivo

Owing to their highly ordered structure, tendons and cartilage appear with low signal intensity when imaged using magnetic resonance imaging (MRI) scanners. A significant increase in signal can be observed when these structures are oriented at 55° (termed the magic angle) with respect to the static field B 0. There is a clear clinical importance in exploiting this effect as part of the diagnosis of injury. Experimental studies of this phenomenon have been made harder by the practical difficulties associated with tissue positioning and orientation in the confined environment of closed-bore scanners. An MRI-compatible mechatronic system has been developed, which is capable of positioning a number of limbs to a desired orientation inside the scanner, to be used as a diagnostic and research tool. It is actuated with a novel pneumatic motor consisting of a heavily geared-down air turbine, presenting high torques and good accuracy. The system is shown to be magnetic resonance compatible and the results of preliminary trials using the device to image the Achilles tendon of human volunteers at different orientations are presented. An increase of four fold to thirteen fold in signal intensity can be observed at the magic angle.

Ensuring the usability of a knee arthroscopy simulator.

There is limited research considering the usability of medical virtual environments. Usability evaluation is an essential validation phase that considers the extent to which a product achieves its specific goals, with effectiveness, efficiency and satisfaction. A four-stage iterative approach is adopted to enhance usability in the development of a knee arthroscopy training system. This process has drawn attention to issues that may impede system usability for example non-conformity to platform conventions, and visibility of the system status. The process highlights features that computer scientists can overlook when working closely with a system but that are essential to user acceptance and effective application.