Re: Selecting embedded Linux for a new medical device project (LONG)
- From: Janaka <janakas@xxxxxxxxxxxx>
- Date: Thu, 04 Oct 2007 17:02:53 -0700
On Oct 4, 12:12 pm, "DavidK" <PleaseRepl...@xxxxxxxxxxxxxx> wrote:
Hi,
I've just begun working on a new project for a medical device, and I'm in
the early stages of deciding which RTOS we'll use.
To summarize the device, it's a medical device that will have a graphical
user interface (and possibly a touchscreen), a control knob to set the power
level, a footswitch, an RF power generator, and an 'applicator' that's
connected to the system by a long cable.
The doctor will use the device by setting the desired power level using the
knob (the knob position is read by the software), and when the footswitch is
pressed, the device will deliver the appropriate level of RF energy to the
patient via an applicator. During the 'treatment', the device will display
the setpoint power level, the measured power level, the time in seconds
since the treatment was started, and the temperature of the patient's tissue
that's being 'treated'. The device will emit a beep tone every three
seconds during 'treatment' to indicate that RF energy is being applied.
When the doctor deems the 'treatment' is complete, he will release the
footswitch, and the RF power will be turned off. Data aquisition
(temperature and measured power level) will be performed every 10ms or so.
Of course the final device, including its software, will be run through
rigorous testing and clinical trials as required by the US FDA. But it
would be nice to select an operating system that has been used successfully
in safety-critical (such as medical) applications, so that I won't be the
first one going down that road with the OS we select.
At this stage, we have not decided which CPU will be used, but I suspect it
will be a single-board computer (such as a PC/104 form factor) with an Intel
x86 or compatible processor.
I am considering using embedded / RT Linux for this project, to help keep
costs down by avoiding operating system per-copy royalty charges. How
should I go about selecting a particular distro or Linux? I was reading
about uCLinux, but it doesn't seem to have been ported to Intel x86 CPUs
yet.
Any links or tips in selecting a particular version of Linux is appreciated!
David K
In my humble opinion; I would not use embedded Linux as the critical
operating system for a safety critical system. Following thread gives
some more info if you are interested on how some others will use Linux
in medical devices or how I would use it.
http://groups.google.com.au/group/comp.os.linux.embedded/browse_frm/thread/aa080701ded96de3/e33dfb197f4e8cbe?hl=en&lnk=st&q=&rnum=20#e33dfb197f4e8cbe
Don't get me wrong, I am a big advocate of open source and Linux.
However we are talking about the safety of someone here. Personally I
would make the safetly critical parts of any system as simple as
possible. Possibly using HW circuit, FPGA/PLD or bonafied (and safety
critical tested) RTOS to control it. And use Linux to provide all the
bells and whistles, like GUI/UI, network access, data streaming,
remote operation and data storage.
Reasons are that I think Embedded Linux is too generic and too
highlevel for a safety critical system. And if something goes wrong
it will be harder to track because of the complexity and also as you
increase the complexity, the points of failure becomes greater. And
you will most likely spend more money verifying and getting linux up
to a safety critical standard. On the other hand if you use a
certified safety critical RTOS (there are a few of them around ) you
will get a big initial licensing cost and a smaller product
certification and verification costs.
If you decide to go with Linux you will probably have to branch off
from the Linux main source and that means you take away one of the
advantages of using Linux.
Please let me know if any opposing arguments.
Cheers
J
P.S. Another bit of advice; I wouldn't go for a x86 architecture for
the CPU because they dont have long production lifespans. Which means
you'll have to replace the CPU every few years, and hence get each new
HW revision re-tested for medical use. Given that medical devices
takes few years to go through product to market, you might get stuck
with a never ending cycle.
.
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