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Smart Optical Fibers Could Save Lives
Roland Piquepaille writes "Lasers are now commonly used for surgery. With them, you can recover a better sense of vision. Or a tumor inside your body can be eliminated. But these laser light beams, which are currently enclosed inside optical fibers, can harm you if they escape from their enclosures. But now, according to Technology Review, MIT researchers have designed smart optical fibers which can monitor their status while the laser is doing its magic inside you and shut it down if a fiber wall is about to break. So far, the technology is only working in labs, but it could be used for medical applications in a few years."
More information appears in a PDF linked off of Fink's bio page. Apparently they use tin in the coating as the conductor. When that melts, the circuit breaks.
.. paranoid crackpot leftover from the days of Amiga.
I work in the medical laser industry (as a software engineer, but I use the actual the devices all the time, and understand our hardware). We use a fiber laser. If the fiber were to break, the device would simply stop working.. because the fiber is clad in a metal armored jacket! I'm certain most delivery devices are similar. Part of the reason for this is you must maintain a minimum bend radius on the fiber, or it is very easy to exceed the total internal reflection constraints on it. The second thing is, our lasers have back reflection fault indicators, which also can go off if anything optically bad happens down the line. Anyone who knows of a medical device that has naked fiber being used to treat can feel free to correct me, but that sounds like a disaster waiting to happen for more reasons than the article states.
AFAIK lasik doesn't make use of fiber optics, the application for this, as I understand it is the use of fiber optics to guide high intensity laser beams internally to attack tumors directly without the need for highly invasive, potentially dangerous surgeries. The problem with using fiber optics in the past, and the reason why this has not been done, is that fiber optic cables can fail, and "leak" the energy from the laser beam into other nearby organs, potentially causing grave damage. This development allows one to detect when a fiber optic cable is about to fail, and shut down the system before severe damage is done, allowing doctors to make use of a technology which was not previously available to them due to concerns about safety.
I've done some research into complications of LASIK surgery as my father has had it done and I'm interested in getting it done myself. From what I can tell, problems are farily rare and are almost always correctable. When my father had his surgery done, there was a problem with his left eye. Since, he has been back twice and they paid for both surgeries. He now has perfect eyesight in both eyes. Don't get me wrong, safer is always better. But in all the searching I've found, all of the problems were due to a mistake on the surgeon, not faulty equipment. This is a very informative site I've found. http://www.allaboutvision.com/visionsurgery/lasik_ complication_1.htm
Someone save me from this sanity.
I work with 20 Watt NIR laser, and I've burned myself with it. When you hold your finger in the beam accidentally, it hurts, and you move your finger.
.this is not a sig
The thing here is that it is a collimated beam. The kind that doesn't really lose its power density over distance. So I can be burned many meters away. This light must be coupled into a fiber with a high numerical aperture lens - and by the same token the light must be collimated when leaving the fiber.
Straight out the end of a broken or cut fiber, the light is highly divergent. It would take less than a meter for the 20 W beam to become eye safe (but maybe not eye smart). The only way for a bare fiber to hurt anything is if it brushes right against it, and even then it's a pretty small wound compared to the size of any organ.
I'm interested to see their justification for all of this.
-m
http://www.rp-photonics.com/fiber_fuse.html
Basically light is absorbed at a point of damage in the fiber, creating a tiny plasma ball that burns backwards towards the source and destroys the fiber, preventing further output. The size of the plasma ball is very small (on the order of the size of the fiber core).
Maybe you just stuff some graphite between the bare fiber and the jacket. Then when the fiber core breaks it superheats a tiny bit of the graphite and begins the fiber fuse process - preventing further transmission of laser light.
And then maybe I just gave away a $1M invention.
-m
(FYI : I may be a doctor, but surgery isn't my speciality. I have only basic knowledge in that field)
LASIK is an external intervention. The laser source is delivering the energy almost directly.
The smart fibers aren't useful for surface operation, but for endocopies.
Endoscopie are internal surgery, but instead of cuting the patient open, you try to be the least invasive you can, and you only insert thin instruments throught small holes (either natural holes, or small incisions).
Optical fibers are usually employed to transmit images of the inside of a patient.
- But, in some type of endoscope, optical fibers can also be used to transmit laser pulse from an external source into the patient, and use the laser to "burn" targets, like tumors.
(I've never used or actually seen such endoscope. Only heard about them).
Here's where the smart fibers come into play
Altough, I've never heard about of such an operation going wrong.
Normally the system should be able to shut down in case of trouble, but them time it takes between the breaking of an optical fiber, and the time everything shuts down, some laser *may* have time to leak at the breaking site and harm the patient.
the point of such smart fiber is to detect faulty fiber *before* the actual break. ("This fiber is going to break soon, you should change the endoscope tip now !")
(Note: I don't know if the same fiber are used for everything (alternating in time) or if different fibers are used to transport visible-domain wavelenghts (lights / picture) and surgical laser)
There are also "laser-less" endoscopes.
- Other endoscope tubes may have an additionnal large channel used with some kind of miniature ultralong flexible tweezer to make biopsies (I've seen it in action). They're useful to access/investigate tumors "deep in the patient" like lung tumors (bonches are accessible entering from mouth), stomach ulcers (same path), or large-gut polyps (guess it, not the same entrance).
They're good, but they're large and the size of the target is limited because of the small size of the "tweezer-like" appendage (works best for biopsies)
- For surgical intervention in natural body cavities (like abdomen or knee joints) accessible from the skin surface, you use "image-only" optical fiber (the kind you also see in spy-movies where the spy use optical fibers to look through a ventilation or a keyhole), and pass long and thin instruments through 2 other small cuts on the surface.
(I've seen and assisted an operation on a women's ovaries. I've also seen such operation that were robot-assisted).
- And there's also a very trivial variant : a simple thin straight 2-3 mm large optical fiber to inspect the nasal cavities through the nostrils. Used by your regular doctor to inspect inside your nose. (I've used it. Great view on the mucosa, on the connection with the ears, on the "bumps" where the sinuses connects, etc...)
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