Direct use of CT scans for hyperthermia treatment planning.

In the field of deep regional hyperthermia cancer therapy, the BSD-2000 Hyperthermia System is one of the most widely used devices. Because of the complexity of the treatment process, computer modeling has long been viewed as a desirable means of planning patient treatments. Patient-specific, three-dimensional computer modeling for treatment planning in the BSD-2000 has been in clinical use at this institution for two years. Two of the persistent problems have been the large amount of time needed to create the patient model from a computed tomography (CT) scan (one and a half days), and the lack of a way to view the large amounts of data that comprise the output of a treatment plan, i.e., the specific absorption rate (SAR) at 20,000 to 30,000 cells. Here we present a method that obtains the dielectric properties needed for hyperthermia treatment planning directly from the CT image with minimum operator interaction, a process which takes about a half day and is more accurate. Comparison is made with the previous method of drawing contours around the different tissue types. We further describe a method which displays the output as iso-SAR contours directly over the CT scan of the patient.