What was the most important difference between the Therac-20 and its successor the Therac-25?
The main difference between the Therac-20 and its successor the Therac-25, was in the operational methodology and the incorporation of a direct electron beam. The Therac-20 employed a dual-mode functionality, enabling it to function as both an electron beam therapy and a photon beam therapy apparatus. However, due to design flaws and coding errors in the software, it led to several accidents, overdoses, and patient injuries.
Conversely, the purpose of the Therac-25 was to rectify the problems of the Therac-20 and provide enhanced accuracy and regulation in radiation therapy. The Therac-25 exclusively employed electron beam therapy, hence losing the dual-mode functionality. The primary purpose of the electron beam was to administer precise and efficient treatment to superficial tumours.
Although the Therac-25 was designed with the aim of enhancing safety and precision, it gained notoriety due to a sequence of mishaps and excessive radiation exposure. These incidents were primarily caused by software glitches and deficiencies. The Therac-25 events sparked considerable apprehension regarding the safety of medical devices and underscored the significance of thorough testing and quality assurance throughout their development.