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New handheld device for deeper melanoma imaging

August 10, 2014



New handheld device for deeper melanoma imaging



A new handheld device that uses lasers and sound waves may change the way doctors treat and diagnose melanoma, according to a team of researchers from Washington University in St. Louis.

The instrument, described in a paper published in The Optical Society's (OSA) journal Optics Letters, is the first that can be used directly on a patient and accurately measure how deep a melanoma tumor extends into the skin, providing valuable information for treatment, diagnosis or prognosis, Medical Web Times reported.

Melanoma is the fifth most common cancer type in the United States, and incidence rates are rising faster than those of any other cancer. It's also the deadliest form of skin cancer, causing more than 75 percent of skin-cancer deaths.

The thicker the melanoma tumor, the more likely it will spread and the deadlier it becomes, says dermatologist Lynn Cornelius, one of the study's coauthors. Being able to measure the depth of the tumor in vivo enables doctors to determine prognoses more accurately, potentially at the time of initial evaluation, and plan treatments and surgeries accordingly.

The problem is that current methods can't directly measure a patient's tumor very well. Because skin scatters light, high-resolution optical techniques don't reach deep enough.

Recently, researchers, including Wang, have applied an approach called photoacoustic microscopy, which can accurately measure melanoma tumors directly on a patient's skin, thus allowing doctors to avoid uncertainty in some circumstances.

The technique relies on the photoacoustic effect, in which light is converted into vibrations. In the case of the new device, a laser beam shines into the skin at the site of a tumor.

Melanin, the skin pigment that's also in tumors, absorbs the light, whose energy is transferred into high-frequency acoustic waves. Unlike light, acoustic waves don't scatter as much when traveling through skin.

Tumor cells will produce more melanin than the surrounding healthy skin cells, and as a result, the acoustic waves can be used to map the entire tumor with high resolution.

The device has a detector that can then turn the acoustic signal into a three-dimensional image on a screen.





Learning from origami to design

new materials

A challenge increasingly important to physicists and materials scientists in recent years has been how to design controllable new materials that exhibit desired physical properties rather than relying on those properties to emerge naturally, says University of Massachusetts Amherst Physicist Christian Santangelo.

According to dailynewsen.com, Santangelo and physicist Arthur Evans and polymer scientist Ryan Hayward at UMass Amherst, with others at Cornell and Western New England University, are using origami-based folding methods for "tuning" the fundamental physical properties of any type of thin sheet.

This may eventually lead to development of molecular-scale machines that could snap into place and perform mechanical tasks.

At a physics meeting a couple of years ago, Santangelo mentioned the unusual properties of a special type of origami fold called Miura-ori to fellow physicist Jesse Silverberg of Cornell, a long-time origami enthusiast.

Miura-ori, named after the astrophysicist who invented the technique, is a series folded parallelograms that change the stiffness of a sheet of paper based only on the crease pattern.

Also known as tessellation, this special folding, which occurs naturally in some leaves and tissues, arranges a flat surface using a repeated pattern of alternating mountain-and-valley zigzag folds.

Objects folded this way contract when squeezed, a bit like an accordion, so they can be packed into a very small shape but unfolded with little effort from the corners.

This technique has been used in space to launch satellites with solar arrays that can be unfolded using only a few small motors at the edges.

Santangelo explains, "As you compress most materials along one axis, they expand in other directions. In other words, squeezing a hunk of material causes it to leak out the sides."

A rare class of materials, however, does the opposite. If you compress them along one direction, they collapse uniformly in all directions.

"Miura-ori shows us how to use this property to make new devices. Exotic materials can be formed from traditional materials simply by altering microscopic structure," Santangelo said.


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Source: Iran Daily


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