Defining How Photons Touch Flesh
SAN FRANCISCO, Jan. 29, 2010 – The discussion started out strangely, then gathered steam. Steven Jacques, SPIE Fellow and professor of biomedical optics at Oregon Health & Science University in Portland waited quietly at the front of the conference room as it slowly filled. But he wasn’t there to present another paper or even to deliver a plenary talk.
As the filling of the space slowed to a trickle, Jacques related that the program – a roundtable discussion of biophotonics standards – would be handicapped by the absence of two of the scheduled participants. Because of a nettling confusion with SPIE over scheduling, Jacques’ colleagues, Gary Tierney and Brian Wilson, were unable to attend. Nonetheless, Jacques told the audience of about 80 people, the show would go on.
Steven Jacques of Oregon Heath & Science University valiantly tries to describe both speckle imaging and tissue spectroscopy within 10 minutes during the Hot Topics session at BiOS. Photo by Lynn Savage.
Biophotonic technologies, according to Jacques, are lacking core standards that have propelled other areas of industry. Lasers, for example, have firmly set standards of output, beam quality, and other attributes, but aim a laser beam at a tissue sample and all bets are off. Various light wavelengths have different results when aimed at the same sample, and different types of tissue – brain slices, epidermal layers and kidney tumors, to name just a few – react differently to the same wavelength.
According to Jacques, patient safety and efficacious treatments aren’t the only reasons to have set standards in place regarding the interaction of light and living matter. Fiber optic-based medical devices cannot be compared accurately, for example, unless there is a standard against which their contact efficiencies can be measured. The size of polystyrene balls and their tendency to agglomerate also are bereft of published standards.
“All the little details are important,” Jacques said. And none have been addressed by standards. “Everyone is acting on their own; we need a unified system,” he added. Jacques also warned that doctors don’t trust any new device or technique that doesn’t offer the solid, traceable background that standards supply.
As the audience began to chime in with their thoughts, it became very apparent how seriously some of the major organizations consider the current lack of standards.
Robert Nordstrom of the National Institutes of Health in Rockville, Md., noted that, despite the maturity of the technology, PET/CT still struggles with standardization. He pointed to bio-imaging phantoms as an important piece of the puzzle. Phantoms are synthetic models that mimic the light absorption and reflectance of various tissues. Without solid standards, the ability of phantoms to provide accurate results is doubtful.
David Allen of the National Institute of Standards and Technology in Gaithersburg, Md., added that the NIST has recently begun examining the bio-imaging field, and is also interested in the phantoms problem.
Audience members representing the Optical Society of America and the UK government brought up the issue of how standards should be published as they are developed. Joseph Izatt, professor of biomedical engineering at Duke University, and editor of the forthcoming Biomedical Optics Express from the OSA, said that the new publication would certainly be interested in publishing papers that support standards. He also stated that the journal will offer open data access.
Throughout the meeting – and well into the remainder of Photonics West – there was a feeling of defined purpose dedicated to taking the first steps toward defining the ways that light affects biological tissue.
Jacques said that he looked forward to furthering the discussion at next year’s conference, hopefully with all of his colleagues there.
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