The Therac-25 machine accidents refer to a series of tragic incidents involving a medical radiation therapy machine called the Therac-25 in the 1980s and early 1990s. The Therac-25 was designed to deliver precise radiation doses to cancer patients to treat tumors. However, a combination of software and hardware flaws in the machine's design led to catastrophic consequences.

The accidents occurred due to a software-related issue known as a "race condition," where multiple software processes in the machine could overlap and cause dangerous overdoses of radiation to patients. This software flaw, combined with inadequate hardware safety interlocks, allowed lethal radiation doses to be administered to patients.

Several patients suffered severe injuries, including burns and radiation poisoning, as a result of these accidents. Some patients even lost their lives. Investigations into the Therac-25 accidents revealed the critical importance of thorough testing, software quality control, and proper safety mechanisms in medical equipment.

These incidents had a significant impact on the field of medical device regulation and the importance of safety in software development for medical applications. They serve as a cautionary tale about the potential dangers of inadequate design, testing, and quality control in critical healthcare technology.