Non-Intrusive 3D View of Subcutaneous Tumors

Chris writes: "A holographic imaging system gives the first visual "fly-through" of living tumors just under the skin. David Nolte and colleagues from Purdue University, US, have developed an optical imaging system that allows clinicians to "fly-through" near-surface tumors in real time. In the scheme, a laser fires 100 fs probe pulses into the skin. The pulses weakly reflect from varying depths below the surface and are compared to a coherent reference pulse which, thanks to a time-of-flight measurement, originates from a known depth. A hologram then rejects unwanted, incoherent light leaving only the useful, image-bearing signal. Only a fraction of a nanowatt of optical power is required to write the hologram. A joystick controlling the depth of the reference pulse allows the clinician to explore the tumor. For example, to probe deeper into the tumor, the clinician simply pushes the joystick forward. The reflected pulses are then compared to this new reference and new depth information is written onto the hologram."

According to my notes: very short range

[Yarn]

This optical coherence method (OCT) has been used to examine retinal defects for about 5 years now.

In the eye it has the benefit of a nearly clear path to the tissue being analysed. 100micron resolution is commonly acheived.

On the skin the depth that can be analysed is less than a millimeter, so this is really only of use for skin cancers.

There are far more exciting systems in development, which allow deeper investigation (at the cost of resolution alas) and can also determine tissue type by florescence spectra.

Compare that with this method...

[morcheeba]

U of Texas [utexas.edu] has done this chemically using glycerol to dry out tissues. Most impressive are the pictures [utexas.edu]. The story is a bit dated, but at the time, they had only done this with hamsters. previous slashdot story [slashdot.org]