ABSTRACT
In recent years, software and microprocessors have replaced many of the electromechanical components traditionally used in medical devices and control systems. Software has been substituted for the hard-wired relay logic and keyboards, and video displays have been substituted for switches and dials. Device manufacturers have the potential to improve their products without making changes to the hardware by simply distributing a new copy of the control software. But this advantage does not come without a price. Not only is the production of high-quality software very difficult and time consuming, it introduces the possibility for new kinds of hazards. For example, the linear accelerators that are used for cancer radiation therapy treatments pose risks to the patient and to the device user from electrical shock, radiation exposure, and mechanical collisions caused by runaway software.
