Ultrasonic apparatus for thermotherapy with variable frequency for suppressing cavitation

摘要

An ultrasonic diagnosis apparatus for raising tissue temperature for hypothermic treatments, including an ultrasonic source for generating an ultrasonic treatment wave and a driving means for driving the ultrasonic source such that a frequency of the ultrasonic treatment wave generated by the ultrasonic source changes with time. The frequency of the ultrasonic treatment wave is changed along the time axis. By this change in frequency, some bubbles formed by cavitation as a result of the ultrasonic treatment wave are divided, and some bubbles are collapsed and therefore eliminated. Side effect cavitation and spread of a thermal degeneration area is suppressed, and thermal degeneration can be accurately induced in a desired area, thereby realizing a reliable, safe ultrasonic thermotherapy. Since cavitation is positively suppressed, the total treatment period can be shortened because cavitation would otherwise interfere with and slow down the thermal degeneration process. Therefore, treatment throughput can be improved as compared with a case in which cavitation is left to naturally break and disappear.