Therac 25

Butler, Instructor Imagine that your doctor has recently informed you that you have cancer, most probably terminal, and your only hope for a cure involves radiation therapy. How much are you going to question the radiation process and equipment?

Therac 25

How a series of simple computer errors sabotaged a state-of-the-art medical wonder. The sixty-one-year-old manicurist who worked at a local hair salon had had a lump successfully removed from her left breast a few months earlier.

She needed a dose of radiation treatment in the adjacent lymph nodes to make sure there would be no recurrence.

The machine being used to treat Yarborough was a recent acquisition at Kennestone: Yarborough took off her top and her bra and settled in the treatment room for an electron treatment beamed high on the left side of her Therac 25.

The usual treatment delivered a dose of around rads: It would last only a few seconds, during which Yarborough would feel nothing.

But this day, when the Therac 25 activated the machine, Yarborough said she immediately felt this red-hot sensation. But he did his duty, and telephoned AECL up in Ottawa to ask whether a Therac could ever project the electron beam without spreading it properly as the machine was supposed to do.

Not possible, he was told three days later. Yarborough returned in two weeks. She said she felt tingling inside her body and growing pain.

Therac 25 by Adam Pettle

There was a red mark the size of a dime on her chest. There was also a larger pink circle of skin high on the left side of her back. The damage done by radiation depends upon its strength, what proportion of the body is exposed, and whether it strikes any vital organs. One thousand rads can be fatal if it is spread over the entire body.

Physicist Still later estimated that Yarborough probably received between 15, and 20, rads on that dime-sized space. He shot beams into water and into the air of the treatment room.

The Accidents

The machine worked fine. But Still, a forty-year-old Georgian with a broad southern drawl, describes himself as "a troublemaker. I make a lot of noise. There were, Still says, unpleasant results. The site where the beam had entered was now a hole.

Over the next few months surgeons twice tried to graft healthy skin over the wound but each time the grafted skin rotted and died. Her left arm became paralyzed except when it spasmed. At that point they settled.

Case Materials

She died in when her car was hit by a truck on the highway near Marietta. Katie Yarborough was the first of the Therac accidents. The Therac looked like a giant version of one of those kitchen electric mixers, with a treatment table slid underneath in the bowl position.Therac Machado.

Hughes Aircraft. Ethics in Computing Links. Contact Us. A History of the Introduction and Shut Down of Therac Therac was released on the market in In , all treatment with the eleven machines in operation was suspended. The Therac's software was developed from the Therac's software, which was developed from the Therac-6's software.

One programmer, over several years, revised the Therac-6 software into the Therac software (AECL has not released any information about the programmer or his credentials). The Therac was a radiation therapy machine produced by Atomic Energy of Canada Limited (AECL) in after the Therac-6 and Therac units (the earlier units had been produced in partnership with CGR of France)..

It was involved in at least six accidents between and , in which patients were given massive overdoses of radiation.: Because of concurrent programming errors, it. Ask Hackaday: Managing Inspiration.

For most of us, hacking is a hobby, something to pass a few idle hours and satisfy our need to create. Precious few of us get to live the dream of being paid to.

Therac 25

Therac was a medical linear accelerator, a device used to treat cancer. What made Therac unique at the time of its use was the software. Not only did the software ease the laborious set-up process, but it also monitored the safety of the machine. The Therac had two main types of operation: a low energy mode and a high energy mode.

The first mode consisted of an electron beam of rads that was aimed at the patient directly.

Killed by a Machine: The Therac | Hackaday