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."

Comments

A step forwards

[Anonymous Coward]

Personally I would have hoped they would already have a technology in place to stop lasers destroying vital parts of your body while in surgery.

How often does this happen?

[Gothmolly]

I mean, I know several people who've gotten LASIK surgery on their eyes, and its been around for years, yet I've never heard of a laser 'breaking' and damaging anything. Is this a solution looking for a problem?
I think self-monitoring fiber optics would be GREAT in the datacom industry... in the medical field its surely a 'nice to have'.

Re:How often does this happen?

[Hlewagastir]

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.

Re:How often does this happen?

[Anonymous Coward]

LASIK surgery is not without risk. But this technology is for example for removing clots around the heart (angioplasty), currently this is done using quite ordinary optic fibers if they go the laser route. (The most common methode is still a little balloon with a stent) This technology could improve the reliability a bit (but I never heard of anything going wrong, so....). Anyway, even with a breaking optical cable and shooting someone in the wrong place is less damaging then having to cut up someones sternum to do bypass surgery.

Re:How often does this happen?

[DrYak]

(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...)

Incident Rate?

[JoeShmoe950]

With the current "unsmart" lasers, what is the rate of misses right now? have there been any dangerous or even fatal laser misses, and how much safety will this new method actually bring about?

Wow

[gcnaddict]

"can harm you if they escape from their enclosures ... if a fiber wall is about to break"

That possible? Gee, thanks for making me not want to have LASIK done on my eyes >_ Seriously, I hope this technology comes out of testing and into RWU (Real world use) very soon. If this kind of news leaks out, public paranoia will be all the rage :P

More information

[whitehatlurker]

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.

Safety critical == timing, timing, timing

[Anonymous Coward]

On a medical robotics project a long while back for remote keyhole surgery we used ADA, partly for it's abiliy to mesh
with a formal spec and have the program 'proven'. No matter how you cut it (splash) the thing that bothered us most was that even when detecting a critical error there is always a timing factor, a certain number of cycles that would inevitably lie between the error being thrown and the system shutting down to a safe state. ADA is a strongly typed and very error safe language, but it is sluggish. A lot of damage can be done in a short space of time. In the end the solution was to break the prog into essentially two threads, one monitoring the other at all times and never more than 20ms from a total power shutdown. In 20ms you can do real damage with a laser that you cannot do with a mechanical device. I think few people realise just how much thought goes into these systems, and I have great respect for the difficulty of this problem.

A little overstated...

[stoneymonster]

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.

Re:A little overstated...

[frankmu]

i've used the KTP laser for laparoscopic ablation of endometriosis. these come with a flexible fiber you thread through a laparoscopy port. i don't think its a big deal most of the time. everyone in the room has eye protection when this thing is on, and the machine is on standby mode most of the time. i use CO2 mostly now. i am still VERY careful, so i won't burn myself or others. the CO2 laser is coupled to rigid tubing, so breakage isn't a big problem.

Re:A little overstated...

[mpoulton]

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.

Most older general-purpose surgical lasers that I'm aware of use a naked fiber, and I do believe it is a disaster waiting to happen. I don't know about the new lasers coming on the market today, but I have worked with 80's and 90's vintage lasers still in service and they have no protection. For example, the Laserscope 800 is a 20W green (523nm) or 90W IR (1064nm) Q-switched CW YAG laser for general surgery. Its disposable delivery fiber is a 300 micron step-index core with no protection other than the bonded plastic jacket with a diameter of about 1mm. Cheap telecom fiber is better protected than this! The same system is used on the Trimedyne 1000 and the Lasersonics, both of which are 100 watt YAG lasers. I intentionally broke a fiber on my Trimedyne at full power, and was amazed by how dangerous it can be. The fiber can easily be kinked or broken by accident, which instantly results in a white-hot meltdown and separation at the point of damage. The broken end of the fiber then springs back and vaporizes or ignites whatever it flops against, potentially including nearby personnel. It also randomly radiates incomprehensible amounts of extremely dangerous invisible light in God knows what direction, likely frying the retinas of anyone foolish enough not to have excellent leak-proof goggles on. Considering how much they charge for these disposable delivery fibers, one would think some form of metal armor could be included to reduce the chance of damage.

Re:A little overstated...

[norton_I]

I wouldn't mention this except that you shine 90W lasers into people, but a laser is either CW or Q-switched (though many can operate in both modes). Q-switching is a way of making a laser emit short pulses, (typically a few nanoseconds with peak power in the 10 kW region and up) the opposite of continuous wave. According to Laserscope's website, the 800 series are CW lasers, which can be switched for exposure times down to .1 seconds -- not the same as Q-switching.

Re:A little overstated...

[mpoulton]

I wouldn't mention this except that you shine 90W lasers into people, but a laser is either CW or Q-switched (though many can operate in both modes). Q-switching is a way of making a laser emit short pulses, (typically a few nanoseconds with peak power in the 10 kW region and up) the opposite of continuous wave. According to Laserscope's website, the 800 series are CW lasers, which can be switched for exposure times down to .1 seconds -- not the same as Q-switching.

QCW (quasi-continuous wave) would be a more correct term for the Laserscope. Indeed, in the scientific world, that what we would call it. However, in the medical laser industry, QCW isn't in the lexicon. I suppose it would confuse the doctors to have to learn more about how their lasers work. Instead, it is understood that a CW laser is one in which the active medium is continuously pumped, with or without a free-running Q-switch. This is how thew Laserscope works -- it is, in fact, Q-switched. The arc lamp in a laserscope runs as long as the unit is armed. The Q-switch does, too. At all times, the laser is producing a continuous train of very short pulses at about 20kHz. The exposure control is done with a mechanical shutter in the beam path which dumps the beam when it's not needed. The term CW is applied to lasers of this type to distinguish them from "pulsed" lasers in which the pump source is a flashlamp, even though both produce pulsed beams. For medical purposes, a Q-switched CW laser acts like a continuous beam, whereas a flashlamp pumped laser behaves completely differently. As you point out, in a plain semantic sense any laser with a Q-switch cannot truly be "continuous wave" -- but people call them that anyways instead of saying "continuously pumped". Even the manufacturers do this, as evidenced by Laserscope's website.

public health saves lives

[frankmu]

just a side comment. we should remember that PUBLIC HEALTH has saved more lives than surgeries and medicines. Vaccinations, smoking cessation, access to clean water, things like that. fiberoptics for communications will save more lives than laser surgery. as a physician, i have to remind my self that alot of what i do is just icing on the cake.