Ultrathermics Ultrasound Hyperthermia System
Ultrathermics was (past tense) a startup company I worked at several years ago. I joined them as the manager of the mechanical engineering group, my first job as a manager. I was only the tenth employee hired by them.
They had a very interesting product they were developing - an ultrasound hyperthermia system for treating psoriasis. Similar to ultrasound imaging systems that can let doctors see your body internals, the UT100 used lower frequency (about 1 megahertz) ultrasound at very high levels to produce heat. Due to the lower frequency used, the ultrasound was absorbed in the first few millimeters of the skin, producing heat. Where an imaging ultrasound machine would generate about 200 milliwatts of acoustic energy at around 3 megahertz, the UT100 generated about 75 watts (not milliwatts) of acoustic energy at about 1 megahertz.
The system was used to produce heating to about 110 degrees F of the skin to combat psoriasis, a fairly common skin disease. This "hyperthermia" treatment seemed to interfere with the diseased skin cells that caused the psoriasis and really did help relieve the symptoms. Other methods of psoriasis treatment included smearing coal tar (uck!) on the skin. The hyperthermia treatment was much more pleasant, cleaner and more effective.
This is a photo of one of the first production UT100 machines we built. At the end of the long arm is the 6" diameter ultrasound transducer that pumped the ultrasound energy into the patient's skin. The yellowish bag hanging from it is a water filled flexible membrane that allowed water to circulate between the transducer and the skin. This was important for two reasons. First, ultrasound does not go through air, so the membrane allows a good acoustic "coupling" between the flat, rigid transducer and the patient. Second, without some form of heat removal, the high powered ultrasound would seriously burn the patients skin. The UT100 system had a very sophisticated temperature control system to maintain the water temperature at the skin within +/- .1 degree C.
Inside the UT100 was a large "fluid" subsystem that had a couple of fluid pumps, a giant heat exchanger and two water heater elements. All of these combined to allow a great deal of precision control over the flow and temperature of the water.
This is a diagram of the fluid system in the UT100. I was one of the architects of the system and was responsible for the detail mechanical design of the fluid system. It was a closed system that provided an external reservoir so that some water could be let in or let out to expand or contract the flexible transducer membrane.
The most difficult part of the whole system was what we affectionately called the "bubble hotel" (bubbles check in but they never check out....). This was a modified centrifugal fluid pump in the system that worked to not only "degas" the water to remove dissolved air, but also capture any free air bubbles in the water. This was important since bubbles that stuck to the flexible membrane at the transducer acted like acoustic lenses and created pinpoint hotspots on the patients skin. They could also cause the transducer to overheat and fail if they stuck to the face of the transducer too. As the trapped bubbles collected in the "bubble hotel", a float switch was eventually activated that turned on a "bubble " pump to extract the collected bubbles. All totaled, there were three pumps in this system - the main water circulation pump, the "bubble hotel" pump and the "bubble extraction" pump.
This drawings shows how
the main reservoir I designed was setup. It had lots of plumbing
and some limit "float" switches to keep from sucking in
air when the reservoir ran low. It also had an overflow reservoir
to catch the "burp" if the operator deflated the
membrane by a large amount.
In the end, Ultrathermics failed. It was bought by a competitor company in Utah and driven into the ground. Towards the end, they tried to adapt the UT100 to be used for treating cancer tumors with hyperthermia in conjunction with chemotherapy, but it did not prove economically viable.
Last updated: November 09, 1996