The Therac-25 Software DisasterThe Therac-25 is a computerized medical radiotherapy machine for cancer patients. In the period from June 1985 to January 1987, it was the cause of six fatal or near-fatal overdoses. These incidents are the result of a combination of factors that can be seen as unethical actions carried out across the ranks of the hierarchy, from manufacturers to the FDA. The Therac-25 is a dual-mode medical linear accelerator that is used to target patients' less sensitive tumor cells. The Therac-25 was not the first generation of this product. The previous versions, Therac-6 and Therac-20, were very similar, however the Therac-25 used more advanced technology. Compared to the Therac-20, the Therac-25 is more compact, versatile and easier to use. All these additional features are consequences of its reliance on software, rather than hardware. In this article I will evaluate the problematic actions that lead to poor product design (“Death and Denial”). The main factor contributing to poor design can be found in software programming. The first mistake made was that a single programmer was responsible for the software in all three different versions of the Therac. Because the individual programmer was negligent of their responsibilities, many problems arose within the software. Examples of the programmer's unethical behavior include his failure to inform his supervisor of possible dangers resulting from the absence of safety features outside of the software. The programmer also used unprotected memory, incorrect initialization, and did not properly test the software. Because a single programmer designed all three generations of the product, new iterations reused the same software. ("System security... half of the document... entrusted to one individual; however, the actions of all involved failed to adequately address the correct issues. References Leveson, Nancy G., Turner Clark S." An Investigation of the Therac-25 Accidents.” Online Ethics Center for Engineering and Science, February 16, 2006. April 15, 2014. http://www.onlineethics.org/Resources/Cases/therac25.aspxLeveson, Nancy G "Medical Devices: Therac-25." Massachusetts Institute of Technology, April 19, 2014. http://sunnyday.mit.edu/papers/therac.pdfPorrello, Anne Marie "Death and Denial: The Failure of THERAC-25, A Medical Linear Accelerator.” April 22, 2014. California Polytechnic State University http://users.csc.calpoly.edu/~jdalbey/SWE/Papers/THERAC25.html“System Computing Cases.org”. computingcases.org/case_materials/therac/analysis/Safety.html