Gérard Poisson

A tele-operated mobile ultrasound scanner using a light-weight robot

This paper presents a new tele-operated robotic chain for real-time ultrasound image acquisition and medical diagnosis. This system has been developed in the frame of the Mobile Tele-Echography Using an Ultralight Robot European Project. A light-weight six degrees-of-freedom serial robot, with a remote center of motion, has been specially designed for this application. It holds and moves a real probe on a distant patient according to the expert gesture and permits an image acquisition using a standard ultrasound device. The combination of mechanical structure choice for the robot and dedicated control law, particularly nearby the singular configuration allows a good path following and a robotized gesture accuracy. The choice of compression techniques for image transmission enables a compromise between flow and quality. These combined approaches, for robotics and image processing, enable the medical specialist to better control the remote ultrasound probe holder system and to receive stable and good quality ultrasound images to make a diagnosis via any type of communication link from terrestrial to satellite. Clinical tests have been performed since April 2003. They used both satellite or Integrated Services Digital Network lines with a theoretical bandwidth of 384 Kb/s. They showed the tele-echography system helped to identify 66% of lesions and 83% of symptomatic pathologies.

TER: A System for Robotic Tele-echography

The quality of ultrasound based diagnosis highly depends on the operators skills. Some healthcare centres may not have the required medical experts on hand when needed and therefore may not benefit from highly specialized ultrasound examinations. The aim of this project is to provide a reliable solution in order to perform expert ultrasound examinations in distant geographical areas and for the largest population possible. TER is a telerobotic system designed and developed by a French consortium composed of universities, hospitals and industrial companies. One originality of TER is the development of a compliant slave robot actuated by muscles. This slave robot is teleoperated by an expert clinician who remotely performs the exam. In this paper, we present the architecture of TER and describe its components.

Use of a Robotic Arm to Perform Remote Abdominal Telesonography

OBJECTIVE The purpose of this study was to design and validate a method of performing sonography between an expert center and an isolated site. A sonography probe is held on the patient by a robotic arm and remotely controlled from the experts center. The robotic arm reproduces all the movements of the experts dummy probe on the patient probe. The system was tested on 87 patients at our hospital. CONCLUSION Robotic telesonography can be used for reliable diagnosis without moving the patient. No false diagnoses were made in this study. A bandwidth of 250 Kbps via integrated services digital network or satellite is required for reliable diagnosis. Such a system can provide diagnostic information that is currently unavailable in isolated or inaccessible areas and on rescue vehicles.

ECHOGRAPHIC EXAMINATION IN ISOLATED SITES CONTROLLED FROM AN EXPERT CENTER USING A 2-D ECHOGRAPH GUIDED BY A TELEOPERATED ROBOTIC ARM

The objective of the present project was to design and validate a method for teleoperating (from an expert site) an echographic examination in an isolated site. A dedicated robotic arm holding a real ultrasound (US) probe is remotely controlled from the expert site with a fictive probe, and reproduces on the real probe all the movements of the expert hand. The isolated places, defined as areas with reduced medical facilities, could be secondary hospitals 20 to 50 km from the university hospital, or dispensaries in Africa or Amazonia, or a moving structure like a rescue vehicle or the International Space Station (ISS). These sites are linked to the expert one by ISDN (numeric) telephone or satellite lines. At the expert center, the US medical expert moves a fictive probe, connected to a computer (no. 1) that sends the coordinate changes of this probe via an ISDN or satellite line to a second computer (no. 2), located at the isolated site, that applies them to the robotic arm holding the real echographic probe. The system was tested on 20 patients. In all cases, the expert was able to perform the main views (longitudinal, transverse) of the liver, gallbladder, kidneys, aorta, pancreas, bladder, prostate and uterus as during direct examination on the patient. The heart and spleen were not visualized in 2 and 4 of the 20 cases, respectively. The mean duration of the robotized echography (27 +/- 7 min for three to four organs) was approximately 50% longer than direct echography of the patient.

The TERESA project : from space research to ground tele‐echography

Ultrasound examinations represent one of the major diagnostic modalities of future healthcare. They are currently used to support medical space research but require a high skilled operator for both probe positioning on the patients skin and image interpretation. TERESA is a tele-echography project that proposes a solution to bring astronauts and remotely located patients on ground quality ultrasound examinations despite the lack of a specialist at the location of the wanted medical act.

A new robotic mechanism for medical application

The difficulty in interpreting ultrasound images and the scarcity of trained ultrasonographers to manipulate a transducer to the optimal position are the basic premises for establishing the SYRTECH project (Tele-Scanning Robot System). The principle objective of this project is to enable an expert ultrasonographer to perform an ultrasound scan examination on a remote patient using master and slave stations. The master is the doctors post and the slave is the robotic system supporting the scan probe. The clinical expert is then able to interpret the transmitted images and move the slave arm in order to obtain the best orientation of the ultrasound beam on any anatomical part of the remotely located patient. This paper presents the master/slave system developed in our laboratory and the chosen robotic solution.

Omni-directional robot with spherical orthogonal wheels: concepts and analyses

This article addresses the omni directional mechanical architectures problematic for mobile robots using 3 motorized axles with 2 spherical orthogonal wheels. These wheels transmit a power torque according to a direction and are completely free with respect to the two others. They are used on 2 mechanical structures: SM1 and SM2. The complete kinematic study emphasizes the facility of controlling such omni-directional robots, and examines the problems involved in the transition of the wheel-to-floor contact on each axle. From this double study emerges an optimal theoretical architecture, but difficult to realize mechanically. We then present a controller which compensates for the errors related to the simplest mechanical structure; and it is validated on a mobile robot ROMNI using mechanical structure SM1

Clinical validation of a mobile patient-expert tele-echography system using ISDN lines

OTELO is an expert-patient mobile tele-echography system. It allows a medical expert, working in a hospital centre, to make an ultrasound diagnosis to a remote patient. A remotely controlled light robot holds and moves an ultrasound probe on the patients skin. It reproduces, in real-time, the motion of a fictive probe held by the expert. Ultrasound images are sent from the patients site to the experts one located at the hospital centre thanks to two ISDN communication lines. This paper presents the architecture chosen for the whole system and focuses on the mechanical and image parts. Comparable clinical ultrasound diagnoses have been obtained using classical examinations and using the tele-echography system.

Experiments with the TER Tele-echography Robot

This paper presents a master-slave system applied to the remote diagnosis from echographic data. The motion of the master manipulator is remotely controlled by a physician and reproduced by a slave robot carrying the echographic probe. The contact force between the probe and the patient is fed back to operator allowing him to have a haptic virtual environment. The innovation of this haptic control is to preserve medical expert propioception and gesture feelings, which are necessary to synchronize the ultrasound images with the motion made by the medical doctor. The slave robot is a cable-driven manipulator using pneumatic artificial muscle actuators to control the motion of the ultrasound probe. In this paper we present the architecture and the performances of the slave robot and the first experiments of the master-slave remote echography system for examinations of pregnant women.

Towards a New Tool for the Evaluation of the Quality of Ultrasound Compressed Images

This paper presents a new tool for the evaluation of ultrasound image compression. The goal is to measure the image quality as easily as with a statistical criterion, and with the same reliability as the one provided by the medical assessment. An initial experiment is proposed to medical experts and represents our reference value for the comparison of evaluation criteria. Twenty-one statistical criteria are selected from the literature. A cumulative absolute similarity measure is defined as a distance between the criterion to evaluate and the reference value. A first fusion method based on a linear combination of criteria is proposed to improve the results obtained by each of them separately. The second proposed approach combines different statistical criteria and uses the medical assessment in a training phase with a support vector machine. Some experimental results are given and show the benefit of fusion