The primary objective is to quantify the distribution of temperature, perfusion and oxygen in normal and tumor tissue during and in the absence of hyperthermia. This research and development effort combines a unique, microminiature probe integrating 10 oxygen electrodes and 10 temperature sensors with a powerful but inexpensive computer providing graphic displays. Continually present is a picture of oxygen tension and temperature as it is actually distributed in the tissue. The display features high spatial resolution (2 mm) and excellent accuracy (PO2 to 1 mm Hg and temperature to 0.005 C). Its sophisticated computational ability solves three dimensional second order differential equations and derives parameters such as the local distribution of absorbed power and perfusion (plus or minus 15%). The high temporal resolution of the temperature measurement (1msec sampling rate) allows assessment of pulse phenomena and derivation of local power absorption and perfusion. A unique feature of the development is a multisensor array using state-of-the-art techniques developed for fabricating integrated circuits. Using well characterized platinum electrodes for oxygen sensing and well understood, commercially available doped oxide thermistor material with high temperature sensitivity, the unique, combined transducer will provide superior sensitivity without fundamental technological development. The individual sensor measures 0.010"""""""" x 0.010"""""""" with 10 pairs of sensors distributed one every 2 mm. An unusual feature of the design is the use of a single thin film conductor joining each sensor pair to the translation electronics. Thus only a single bond to the micro-ribbon cables results in a tremendous increase in yield and decrease in cost. Both the design of the proposed structure and the choice of materials and components can result in a temperature probe thermally matched to tissue. The computer provides an excellent interface for the human user and features continual calibration without human intervention for reliable, accurate measurements. This ambitious project involves the integrated effort of four separate but interdependent tasks--microelectronics, instrumentation, thermal and perfusion, and oxygen tension measurements. Logical extension of this work will lead to probes of reduced size incorporating distributed pH sensors.
