For this assignment, I want you to explore the issue of developing correct software. You will do that by writing a short research paper on the Therac-25 medical accelerator failure. 

Before we get to that, make sure that you read and fully understand the Northeastern Academic Integrity policy, which you
can find at http://www.northeastern.edu/osccr/academichonesty.html.

Throughout your careers you will be required to read, analyze, and present information and it absolutely crucial that you learn how to do this correctly, convincingly, and with the highest standards and integrity.

Therac-25 medical accelerator. "A radiation therapy device malfunctions and delivers lethal radiation doses at several medical facilities. Based upon a previous design, the Therac-25 was an "improved" therapy system that could deliver two different kinds of radiation: either a low-power electron beam (beta particles) or X-rays. The Therac-25's X-rays were generated by smashing high-power electrons into a metal target positioned between the electron gun and the patient. A second "improvement" was the replacement of the older Therac-20's electromechanical safety interlocks with software control, a decision made because software was perceived to be more reliable.
What engineers didn't know was that both the 20 and the 25 were built upon an operating system that had been kludged together by a programmer with no formal training. Because of a subtle bug called a, race condition,  a quick-fingered typist could accidentally configure the Therac-25 so the electron beam would fire in high-power mode but with the metal X-ray target out of position. At least five patients die; others are seriously injured. "

“An Investigation of the Therac-25 Accidents.”
Leveson, N.G.;   Turner, C.S.;

Published July 1993 Volume 26 Issue 7 IEEE Computer

"Between June 1985 and January 1987, six known accidents involved massive overdoses by the Therac-25 -with resultant deaths and serious injuries. "

The Therac-25 accidents are the most serious computer-related accidents to date (at least nonmilitary and admit- ted) and have even drawn the attention of the popular press.

Also read the following reports about the incident:
http://courses.cs.vt.edu/cs3604/lib/Therac_25/Therac_1.html

Later effort has been put to formally verify 
Formal Specification in medical field
Radiation Therapy Machine
http://www.radonc.washington.edu/physics/cnts/
Formal Safety Analysis
http://www.radonc.washington.edu/physics/cnts/iccr.html
Formal specification
http://www.radonc.washington.edu/prostaff/jon/z/machine.html

For your report, I want you to address the following questions.

1. What did you find out? Summarize in your own words. From what
sources? What is the evidence?

2. Present as strong an argument as you can that this was a
software error.

3. Present as strong an argument as you can that this was not a
software error, but an error in how the Therac-25 was used.

4. Which argument do you believe the most, 2 or 3?

5. What did you discover that was interesting or surprising to
you? Why?

6. What lessons did you learn? What conclusions did you draw?
Explain and justify.

The length of the paper should be 2-3 pages of 10-12 point
font, single spaced.  You must work on this with a partner. Read
the submission instructions for the class carefully. Only submit
one solution, and clearly identify who worked on the homework
assignment.