The stereo-focused BSD2000 heat therapy machine, Sigma60 radiator, manufactured by BSD, USA. The heat therapy machine includes: (1) Quadrupole amplifier: The amplifier is a loop array that provides four independent phase-controlled channels, each with a maximum output power of 500 Watts, operating frequency of 60 to 120 MHz, and phase control range of 60 to 170 degrees. The weight, phase and frequency of each channel can be controlled. (2) Sigma60 radiator: It includes 8 groups of dipole antennas placed on a transparent plastic housing to form a circular array, each group of antennas consists of two single slit dipoles arranged in a long row. The treatment is performed by controlling the output power and phase of each quadrant so that the center of thermal field focus is located at the desired tumor site. (3) Coupling and skin cooling system: Deionized water is used to couple between the radiator and human skin, while the water in the water capsule is circulated for skin cooling and its water temperature is adjustable. (4) Computer control system: During the treatment process, all treatment parameters are controlled by computer. (5) Vital signs monitoring system.