Let me see your liver …Wednesday, July 4th, 2012 by Roberto Saracco
May be you heard this phrase by your doctor but of course you understood it was just a way of saying: “let me check your liver” followed by some abdomen manipulation by the doctor’s hands.
Actually, in a few years the phrase will really mean that the doctor wants “to see” your liver (or lungs, bladder, whatever…) with her eyes!
This will be possible because of an ingenious invention by CalTech researchers.
They have found a way to make light interact with ultrasound waves. This phenomena has been known for quite some time but thanks to the application of computers and software the researchers have been able to trace the interactions and then to reconstruct what goes on under the skin when a laser beam is aimed at you.
As you can see in the schematics here once light (the greenish arrow on the left) hits the skin it scatters, its photons basically go everywhere and this is why you won’t be able to see anything.
If you apply a ultrasound beam focussed in a certain point (which is what happen when you do a ultrasound scanning (and you see the result on a monitor in black and white…) photons will interact with the sound waves and this will lead to a (measurable) shift in their frequency (the interaction results in an energy transfer from the sound wave to the photon and hence its change in frequency). This is shown in the schematics by the green segments. This change can be detected and makes it possible to reconstruct backwards the path of the photons given the image of the point where the interaction has occurred. By changing the focus point of the ultrasound beam one can scan the tissue.
From the doctor point of view it will feel like really seeing your liver on his computer screen!
So far the experiment has been able to look at 2.5 mm under the skin but researchers are convinced they can go as deep as 10″, and that would basically give a doctor the capability to look at every part inside your body.
And this is just half the story. Being able to see helps the diagnoses but it can also help curing. By increasing the intensity of the laser beam and focussing it the doctor can “cut” under the skin, without cutting the skin! Additionally, it will make possible to fight some cancers by just illuminating it (this is something that is already been done for skin cancers where the patient is given a drug that fixes itself n cancer cells and that once activate by a beam of light kills the cell. Using ultrasound light focussing it will be possible to illuminate cells inside the body.
Just imagine what this may mean in the future: a doctor may be able to see “inside” his patient from a remote location, provided the patient is given a “reading/scanning” device that he can move on his body while the doctors from her studio focus the ultrasound beam to see what she wants to see. This may require quite a bit of bandwidth (not for the focussing command but to get the images back with no delay so that she can regulate the focussing beam as needed) but having lot of bandwidth is not going to be a problem, isn’t it?