The National Aeronautics and Space Administration (NASA) seeks interested parties for the commercial application of a microwave treatment system for prostate cancer and benign prostate hyperplasia that was developed by engineers at the Johnson Space Center. In theory, this technology provides precise control within the treatment area, thus allowing for necrosis of only the targeted treatment zone. Current prostate treatment methods, including chemotherapy, cryotherapy, radiation therapy and prostatectomy, often damage the healthy cells surrounding the targeted treatment zone causing undesirable risks and side effects.
This microwave catheter design, which was developed for commercial use in treating ventricular tachycardia, can be modified to treat prostate cancer and benign prostatic hyperplasia (BPH).Why it was Developed
Considering that the occurrence of BPH is increasing—currently 350,000 operations per year are performed in the United States alone to treat this condition—this microwave catheter has significant commercial potential.How it Works
The self-advancing, step-tap drill bit uses a cutting edge to simultaneously enlarge a hole and cut threads. The drill bit is stepped, enabling an increase in the diameter of the hole with each step. To prevent the threads from stripping caused by the required cutting forces between the drill bit and the work material, the thread pitch (number of threads per inch) and diameter increase for each step are adjusted for the material type and thickness. The diameters of the steps are in increments of 0.030-0.060 inch (0.8-1.5 mm). The tip typically has a diameter of 1/8-3/16 inch (3.2-4.8 mm).
The microwave operating frequency affects the heating depth. An electrophysiologist will be able to take advantage of the physics of depth of penetration (in particular, the variations of conductivity and permittivity of tissue with frequency) to focus the microwave beam. The power level and delivery time also affect the balance between the increase in heat (due to the absorption of microwave energy) and the loss of heat (due to conduction away from targeted cells). A computer program that simulates the heating profile has been written to assist in determining the balance needed to necrose targeted cells while saving non-targeted cells. There are several variations of microwave radiators suitable for treating specific regions of the prostate or the prostate as a whole.Single Antenna Within the Urethra
A single antenna radiates within the urethra. A urethra catheter can be made to include a phase-change material surrounding the radiation tip to prevent a significant temperature rise without need for a water cooling system. The phase-change material must, of course, be nearly transparent to the microwave radiation. This material provides localized cooling to protect the urethra from damage, but permits microwave heating to occur beyond the urethra, into the prostate. For treatment over the entire prostate, or over large regions of the prostate, it may be necessary to use several throwaway catheters because one may not contain sufficient phase-change material. Calculations have shown the feasibility of this approach, provided that a phase-change material that has the desired characteristics can be found.Multiple Colon Antennas
Multiple colon catheter antennas can be phased and directed toward the prostate to provide localized temperature gradients in the regions of the prostate located near the colon. Cooling must be provided to protect the colon and the intervening tissue. Prostate cancer often begins in the prostate near the colon and should be treatable with this technique. Computer simulations show that by adjusting the locations of the microwave radiators and the phases of their microwave signals, the heating centers in the prostate can be adjusted to necrose critical regions only.Single Urethra Antenna and Two Colon Antennas
Combinations of urethra and colon microwave radiators can be used to provide treatment appropriate to specific problems. Generally, one microwave catheter in the urethra, when working together with one or more catheters in the colon, can provide localized heating to satisfy most requirements. By adjustment of frequency, phase, directionality, and duration of the microwave radiation, one can select from among a wide array of heating profiles in the prostate.Patents
This technology is being made available through JSC’s Technology Transfer and Commercialization Office, which seeks to transfer technology into and out of NASA to benefit the space program and U.S. industry. NASA invites companies to inquire about the licensing possibilities for the Microwave Treatment of Prostate Cancer and Hyperplasia (MSC-23049-1) for commercial applications.