Fatal Dose – Radiation Deaths linked to AECL Computer Errors (1994)

&gt;&gt;As a result of the Therac-25 accidents, the FDA now requires documentation on software for new medical and other products: a paper trail, in other words, that can be examined by an independent body and retraced for flaws.&lt;&lt;<p>Anyone have any idea if this can be looked at by the end user? I&#x27;m not a radiation technologist of the flavour mentioned in the article, I&#x27;m on the diagnostic side. I use an MR scanner with numerous software bugs that I have reported but which remain. Similarly, the scanner can be made to display data which it says it is going to use in the next scan, but which it isn&#x27;t. I suspected a bug and found the way to reproduce it. My last email listed 24 similar bugs (I&#x27;ve found more since) but other than a &quot;thanks, we will forward this on&quot; there has been no reply or comment. It is hard to imagine when this could be a safety issue, but it is a waste of valuable time, it is a waste of money and it&#x27;s frustrating when I have gone to the trouble of working out the exact way of creating the issues. If anyone is interested, the interface is so god awful that instead of having an on off button or switch interface, the scanner gets the user to type 1 or 0 for on and off into a text field. Some fields take other values like 1, 2 and 3. Some take decimal values like 0 to 1 in 0.1 increments. There is no pattern to what the user is expected to type. Yuck. This data is not properly sanitized either, and you can make the scanner say its &quot;doing&quot; something it&#x27;s not. Type in 1.999, and error message appears, the field corrects to 2.0 but the scanner does the thing that a setting of 1 would produce. These sorts of bugs occur all over the place.<p>Edit: The &quot;thanks&quot; email is the most positive I&#x27;ve ever got, my previous reports were me with statements like &quot;we have some very experienced users who haven&#x27;t had this issue&quot; when there were clear safety problems with earlier scanner implementations (The scanner was producing axial slices at a location different to where I asked for them to be, on a spine patient due in theatre - good luck operating on the correct vertebral level). Its FDA approved and its on the latest software release. I have undergone manufacturer training and have had additional training half a dozen times at my request and at the manufacturers request after my bug reports were met with &quot;you&#x27;re doing it wrong&quot;. I&#x27;m not, the software is buggy and I have some excellent and amazing screen shots and camera phone video of the bugs in action.

The Therac-25 case study is a tragic one, but fortunately it is not forgotten.<p>I work on medical devices (and have worked on radiotherapy devices previously) and the standards for quality systems and regulatory hurdles (which I occasionally see bemoaned here on HN) are there with good reason. In fact, Therac-25 is often cited when training new hires on quality (as required with any ISO-13485 compliant QMS).

One of the more infamous classes in Computer Science at Cal Poly SLO is &quot;Professional Responsibilities&quot;, is taught by Dr. Clark Turner. The class delves into Therac-25, and similar cases that have happened since. I found the class really interesting because it does make you question and think about the ethics of what you are building and what others have built.<p>Knowing about, and thinking about, the ACM Code of Ethics, Stuxnet, Therac-25, the Windows Security Patch Policy, and other problems our programming culture have come across is important. Realizing that the code we write can affect people in both positive and negative ways on a long and short term scale is something that can change both your product and how you build a product.

There was an article that appeared in the NY <i>Times,</i> a few years ago, that discusses the malfunctions of radiology equipment. There was one story, in particular, that stood out for me. It describes a, reportedly not unusual, malfunction&#x2F;crash of a linear accelerator used for Intensity Modulated Radiation Therapy (IMRT):<p>&quot;An error message asked [the medical physicist operating the device] if she wanted to save her changes before the program aborted. She answered yes.&quot;<p>How many programmers read that and cringe? I know I did. My guess is that the operating system being used for the device is some standard OS (Windows CE, maybe?) that is being repurposed to run the application and provide the GUI for the device. It&#x27;s not that this is necessarily bad, but I would think the most important thing to do would be to strip the OS (or UI) of the various &quot;user conveniences&quot; that in a life or death situation could have all kinds of unintended consequences.<p>If a person is coding or doing graphic design -- or typing up cooking recipes -- and a crash happens, it&#x27;s a good thing to have the opportunity to save your work. If 1 teaspoon of butter gets changed to 1 tablespoon because of some kind of data corruption, big deal. So your cookies come out terrible!<p>It&#x27;s quite a different matter if the application is coordinating 120 moving parts to direct a radiation beam onto a human body.<p>The article is here:<p><a href="http://www.nytimes.com/2010/01/24/health/24radiation.html?pagewanted=all&amp;_r=0" rel="nofollow">http:&#x2F;&#x2F;www.nytimes.com&#x2F;2010&#x2F;01&#x2F;24&#x2F;health&#x2F;24radiation.html?pa...</a>

Thanks, I hadn&#x27;t read this before.<p>For those that haven&#x27;t read it, here&#x27;s Levesons article on the Therac-25: <a href="http://sunnyday.mit.edu/papers/therac.pdf" rel="nofollow">http:&#x2F;&#x2F;sunnyday.mit.edu&#x2F;papers&#x2F;therac.pdf</a>

Related reading: <a href="http://www.amazon.ca/Set-Phasers-Stun-Design-Technology/dp/0963617885" rel="nofollow">http:&#x2F;&#x2F;www.amazon.ca&#x2F;Set-Phasers-Stun-Design-Technology&#x2F;dp&#x2F;0...</a>

At the time of Therac-25, FDA was only budgeted to investigate 6 percent of device applications.<p>Currently, the same mistakes made in the eighties with Therac-25 are being made in many radiation therapy devices. The two NY Times articles (Pulitzer Prize winning) in 2010 and 2011 describe some of the newer cases.<p>What&#x27;s shocking to me is that the incidents are always reported in isolation. People become briefly outraged, then the furor dies down until the next death.<p>Many of the comments in this thread suggest that people can&#x27;t or won&#x27;t face the fact that this is a current, ongoing problem of great complexity.<p>A couple of comments mentioned the coverage of Therac-25 in schools. Very little of what is taught in schools makes it into the programming of radiation therapy devices. History has shown that schooling is not a sufficient solution.<p>Other comments claim (erroneously) that the FDA is attending to the problem. The FDA has been carefully defanged by the medical device lobby. The FDA has gotten smarter, but has nowhere near the funding to keep pace with its charge and never will.<p>I wish I could say that I see some hope but I don&#x27;t see it.

&quot;A professor in computer engineering at the University of Toronto told me that, as a matter of course, his undergraduate students are warned about the risks of incrementing numbers in a computer program.&quot;<p>As someone with a computer science degree who was warned of such risks and studied the Therac-25 in my classes, this sentence made me realize how far we have to go as professionals. Something seemingly so simple as incrementing a number, one of the most common things done in a program, can cause serious problems (of course we have more help with this now than in the mid 80&#x27;s). Other people must read things like that and cement any distrust they have in computers and computer programmers. And they&#x27;re probably right to.

<i>The Therac-25&#x27;s software program, relatively crude by today&#x27;s standards, probably contained 101000 lines of code. At one error for every 500 lines, that works out to the possibility of twenty errors.</i><p>I&#x27;d say 200, not twenty.

I had a professor read this case study in a lecture.<p>It amazes me that merely one programmer was trusted with building the software for a radiation beam canon.

101000 lines, 500 lines per error gives about 200 errors, not 20

We covered this in my CS courses as well. I feel bad if anyone comes out of a CS program and isn&#x27;t exposed to the Therac-25 incident even if superficially.