Hyperthermia treatment provides for the heating of living tissue for therapeutic purposes, most typically the treatment of malignant tumors. Hyperthermia has been used as a method of treating cancer by raising the temperature of a malignant tumor locally since it has been proven that relatively high heat can contribute to the natural regression and/or remission of tumors Hyperthermia treatment can be used as an independent therapy or it may be used in conjunction with other cancer therapies such as radiation, surgery, chemotherapy, and immunotherapy to enhance the effectiveness of the other therapeutic treatments.
Typically, in hyperthermia treatment a tumor is heated to a temperature slightly below that which would injure normal cells in order to thermally destroy it. The treatment is believed to be effective because many types of malignant cell masses have been found to have less heat dissipation capability than normal tissues do, due apparently, to reduced blood flow characteristics. The most common types of hyperthermia modality used presently are radiofrequency, microwave and ultrasound treatment. Radiofrequency and microwave equipment can be used for local, regional and whole body heating. Ultrasound can be used for local and regional heating.
Hyperthermia is presently in an early stage of dose quantification which is similar to that of conventional ionizing radiotherapy of the early twentieth century. Development of dosimetric indices with therapeutic significance strongly depends on the few temperature measurements which are made interstitially. However, problems of scanning thermometers in tissues include choices of measurement dwell times and inter-measurement spacing. With present hyperthermia heat delivery systems, manual scanning of thermometric probes within tissues is awkward. Also, slippage of thermometry catheters and other difficulties limit the extent and accuracy of manual probe temperature scanning. Nevertheless, detailed and strategic temperature measurements are vital to hyperthermia treatment planning. Thus, an improved temperature scanning system for use in hyperthermia treatment is greatly needed at this time.
An automated device presently utilized for thermal mapping is the BSD-1000 manufactured by BSD Medical Corporation of Salt Lake City. This computer controlled apparatus is adapted to move from one to eight thermometric probes within stationary catheters which have been inserted into the tissue volume of interest. The probes are moved at fixed distance intervals through the catheters during conditions approximating thermal stability and are allowed to remain long enough at each position for sufficient thermal equilibration. The temperature is then recorded and the probe withdrawn or moved to the next position. The apparatus utilizes only one stepper motor and therefore the eight thermometric probes are all forced to move within catheters for the same scan length and all utilize the same measurement spacing and dwell time. Moreover, the device utilizes a friction drive and a probe translation mechanism which can result in bending of one or more of the thermometric probes with the resulting problems and inaccuracies which can result therefrom. Because of the relatively large size and rigidity of BSD thermometry tubes, it is difficult to position multiple probes at varying angles to each other and it is not possible to use these tubes for translation of widely used thermometers that are more fragile than BSD thermometers.
Therefore, a need exists for an automated system which will allow for more efficient, accurate and versatile thermal mapping by the movement of thermometric probes within stationary catheters which have been inserted into tissue volume of interest. The new system should overcome the shortcomings presently existing in both manual and automated apparatus now available for use in thermal mapping associated with hyperthermia treatment.