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P Record

Publications and source records attributed to P Record.

6 recordsLinked to original sources

Electrical impedance tomography. A sensitivity region reconstruction algorithm using adjacent drive current injection strategy.

The 'sensitivity region' method of back projection is converted from polar drive to adjacent drive current injection strategy and individual sensitivity coefficients incorporated. For each projection sensitivity coefficients for each pixel were established and pixels were grouped together into the 'sensitivity regions'. These contain all pixels that have their largest sensitivity coefficients associated with a particular measurement pair. Back projection of measurement data was performed using these coefficients as the basis of the reconstruction and less sensitive measurement pairs were ignored. Formulae for the back projection are discussed and images from computer simulated data and raw data supplied by Sheffield as part of this concerted action are presented. Comparison with polar current injection strategy is discussed.

Algorithms

Neurosurgical stimulation, impedance monitoring and data acquisition system.

We describe the design of a programmable neurosurgical stimulator with impedance monitoring facilities. The computer is used both to control a stimulator and for the storage of various parameters employed in the process. The stimulator is designed to minimize tissue damage by injecting net zero charge; its output is a current, independent of load resistance. By measuring electrode voltage, the load impedance can be calculated. Software is provided in order to log patient data, and trajectory details with reference to coordinates calculated from other imaging systems such as CAT scanners.

Computer Systems

An electronically controlled micro-welder.

An electronically controlled micro-welding apparatus has been designed and built for the manufacture of clinical electrodes. Using the principle of electrical resistance welding, the device is simple and inexpensive to construct, using readily available components. It is easy to operate and has proved to be a quick and reliable method of producing electrodes to the exact specifications of neurosurgeons.

Electrodes