[With post-doctoral fellow Wen-Hong Zhu, graduate student Purang Abolmaesumi, research engineer Simon Bachmann. In collaboration with Prof. PD.Lawrence. Project supported by IRIS/PRECARN ].

The use of teleoperation to provide a more ergonomic and useful interface to diagnostic ultrasound machines is being presently pursued. We intend to use a robot to position the ultrasound probe against the patient,  with the ultrasound technician operating a force-feedback joystick to control the probe location and the force applied to the patient. Control of the ultrasound probe will be shared between the operator, the robot control computer, and an ultrasound image processing computer. This approach offers several advantages. For example:

• The operator can be seated in a comfortable position, and would be required to provide only small motions and forces to the master joystick,  the range of such forces and motions being programmable.
• Repetitive precise motions could be done with some of the motion axes being under computer control, depending on the ultrasound image.
• Position information from the robot sensors during a scan and ultrasound imaging information can be combined to form 3-D ultrasound images.
• The system could be used for distance ultrasound examinations and training, with several users being able to access the same ultrasound machine from a distance, across the web, for example.

The prototype problem addressed first is that of examination of the carotid artery. This examination is carried out to detect occlusive disease in the left and right common carotid arteries - a major cause of strokes.

Ultrasound image of the carotid artery.

A significant effort to date has been dedicated to the design of a light, safe robot capable of accurate motions and force control. The robot can be positioned not only by the sonographer through an input/output device such as the SpaceMouse, but also by the patient by directly pushing against the robot linkage. The fully counterbalanced mechanical design allows the robot to remain its in its position/orientation in case of power failure.

Block diagram of the control system.

Ultrasound examination with the ultrasound robot

Contour extraction of the carotid artery, using the discrete snake method.