Abstract: In conjunction with a linear accelerator or a cobalt-60 teletherapy machine disposed in a room having a head mounted for rotation about a horizontal epicenter axis, and wherein the head is adapted to direct a high energy beam at right angles to and intersecting said axis at an isocenter, there is provided right-angularly related opposed pairs of lasers whose beams are focused upon said isocenter. This is to assure that when an isolated area of a patient's body to be treated is located at said isocenter, with the laser beams impinging upon said isolated area, that the high energy beams will at all times pass into said isolated area, as the radiation head is rotated up to 360 degrees about said epicenter axis. The present laser alignment fixture includes a support base adjustably mounted upon a universally adjustable patient platform. A turntable on said support base has a telescope mount with top, bottom and side walls and a longitudinal bore.

Abstract: A condition responsive circuit for generating an output signal upon the opening of a switch. An FET draws nominal current when the switch is closed. When the switch is opened the FET conducts to generate an output. The output may include an audio alarm, an oscillator and a transmitter to generate an alarm at a distant location, or a visual indicator.