• tookitogo (github)

    The "field light" mode is not a laser. It's like an overhead or slide projector, projecting an area of light, the whole point being to let the operator position the metal baffles to block off areas that are not supposed to be irradiated. The light is a stand-in for the radiation.

  • NotAThingThatHappens (unregistered)

    Random link not working as intended, I suspect. Unless the point was to waste time and provoke these kinds of comments.

  • (nodebb)

    As someone who recently completed a round of radiation treatments (and remembers well the incident back in the 1980's) this was quite familiar. In my case, the focal point was only 1mm from my Aorta. But the Dr. was encouraging...if there was a misalignment or other issue, I would b dead before I even realized any pain.

  • Prime Mover (unregistered) in reply to NotAThingThatHappens

    Works perfectly well. You're probably typing too fast.

  • Barf4Eva (unregistered)

    wow... what an article. Thank you for this!

  • (nodebb)

    Why would they remove the hardware safety features? What people do to save a buck.

  • /df (unregistered)

    In the UK, the Post Office ("Britain's Most Trusted Brand" TM) took a very similar attitude regarding the accuracy of its Horizon branch accounting software, causing several hundred innocent staff to be prosecuted (the Post Office could do that itself for historical reasons). The difference from AECL was that the PO staff actually knew that the software couldn't count for a toffee and concealed its quality issues from the victims.


  • Worf (unregistered) in reply to Donald Herman

    I believe the hardware safety features weren't removed, they just weren't designed in. Therac-6 and Therac-20 had them built in, while Therac-25 was a brand new design offering the ability to have higher doses. The big problem was that with all the weight in the radiation head and such required, it was not possible to include hardware interlocks, thus relying on software to do the right thing and have internal interlocks in that.

    Back when Therac-25 was designed, software was pretty simple and could be understood by one person looking over it. You also typically wrote the code for the hardware, since an "operating system" was a rather fanciful concept still.

    You still see this today - many times older computers may have to be booted off of floppy disks to run systems. Because when the system was designed, hard drives were rare and expensive and many other things. The modern thing of using modern storage in ancient computers is quite new. Heck, many aircraft still had a floppy drive so you could update the internal navigational database. Some airlines retrofitted them to support more modern equipment (basically replacing the drive unit with a new box that took a USB stick - basically the drive unit was replaced with a new one containing a Gotek floppy emulator).

  • NotAThingThatHappens (unregistered) in reply to Prime Mover

    I wouldn't know. Browser has been working fine for years, I refuse to test any further.

  • Deep (unregistered)
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  • Deep (unregistered)
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  • MaryD (unregistered)
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  • ABDUL RAHEEM (unregistered) in reply to NotAThingThatHappens
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  • vanbcguy (unregistered) in reply to Donald Herman

    Hardware safety devices fail - they imply mechanical movement, which means environmental factors become a concern. A microswitch that detects a detent in the turntable is just as likely to stick open as closed given the right circumstances. This was probably less about cutting out parts and more about improving reliability in the field, despite it having the exact opposite effect.

  • redshirt (unregistered)

    TRWTF is... well obviously nothing can trump the Therac-25 incident.

    But the new TRWTF is that, after NotAThingThatHappens's last comment (538787), there are five probably perfectly valid comments "held for moderation" , yet a blatant spammer right after them somehow managed to not be caught in moderation.

  • EnormousTurd (unregistered)
    Comment held for moderation.
  • NLCB Play Whe Result (unregistered)
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