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QC laser microscope to slash cancer diagnosis time

12 Sep 2012

Daylight Solutions to develop commercial prototype of "game-changing" instrument that will yield results in minutes rather than days.

The US National Science Foundation (NSF) has awarded quantum cascade laser (QCL) pioneer Daylight Solutions just over $420,000 to help commercialize a new kind of microscope that promises to reduce cancer diagnosis times drastically.

The Phase II small business innovation research (SBIR) grant follows initial work under a $149,000 Phase I award last year to demonstrate that a broadly tunable infrared microscope based on QCL sources and microbolometer detectors was feasible.

Now the company will spend two years working to develop a commercial prototype and prepare for a production scale-up, with the NSF describing the technology as a “game-changer” for infrared microscopy in automated cancer screening.

Today, cancer screening is dominated by histology, in which thin slices of tissue from biopsies are analyzed by specialists. But the technique is time-consuming and flawed. Fourier Transform infrared (FTIR) spectrometers can be used instead, but the nature of the scanning optical system and its need for cooled mercury cadmium telluride (MCT) infrared detectors means that such tools are bulky, expensive and slow.

“Recent research demonstrates that infrared microscopy offers the resolution and tissue identification capabilities necessary for it to be used in automated algorithms for cancer screening,” notes the NSF’s abstract on the topic, but adds:

“In spite of this potential usefulness, infrared microscopy has been confined to select laboratories. This is in part due to existing FTIR technology that does not allow the reduction in size and cost, nor increase in acquisition speed and resolution, necessary to make infrared microscopy a common analytical technique.”

Cancer screening time “reduced to three minutes”
Systems featuring MCT detectors have an added disadvantage, in that the sensor technology is export-controlled by the US Department of State because it is widely used in military applications.

But with advances in QCL technology now supporting broadly tunable laser sources that operate across the mid-infrared region – the part of the spectrum that holds crucial “chemical fingerprint” data in the form of light absorption caused molecular by molecular vibrations – that looks set to change.

“The QCL microscope to be built in Phase II will revolutionize infrared microscopy instrumentation,” continues the NSF abstract. “Based on demonstrated performance of components in Phase I, it is estimated that the time to screen a tissue array for signs of cancer will be reduced from six days with a FTIR microscope to just three minutes with a QCL microscope.”

As well as using different light sources, the QCL microscope now under development also uses different detectors. Unlike MCT sensors, microbolometer focal plane arrays (FPAs) are not export-controlled. Until recently, however, they have not been suitable for an infrared microscope because of a relative lack of sensitivity in the mid-infrared.

But now the higher output powers possible thanks to advances in QCL laser technology and Daylight’s external-cavity designs means that microbolometers can be used. Earlier this year, the company released a new range of mode-hop-free lasers spanning the mid-infrared wavelength range between 4 µm and 10.5 µm.

Daylight says that the Phase I part of the NSF-backed microscope development yielded a benchtop instrument capable of generating a full infrared image at every pixel contained within an image.

In the tests conducted so far, the working prototype has been used mostly to image pharmaceutical and chemical samples, and the company told optics.org that it had now identified a number of researchers willing to provide biopsy-like samples during the next stage of development.

In a statement announcing the Phase II award, the company’s president and COO Paul Larson echoed the “game-changing” potential in chemical imaging, adding that aside from medical diagnostics, the technology also had potential commercial use in forensics and food safety applications.

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