Researchers at the Massachusetts Institute of Technology have developed a biomedical imaging system that has the potential to replace a $100,000 piece of lab equipment with components that cost just hundreds of dollars.
The system uses a technique called fluorescence lifetime imaging, which has applications in DNA sequencing and cancer diagnosis, among other things, meaning the work could have implications for both biological research and clinical practice.
In traditional fluorescence lifetime imaging, the imaging system emits a burst of light, much of which is absorbed by the sample, and then measures how long it takes for returning light particles, or photons, to strike an array of detectors.
To make the measurement as precise as possible, the light bursts are extremely short. The fluorescence lifetimes pertinent to biomedical imaging are in the nanosecond range. This means traditional fluorescence lifetime imaging uses light bursts that last just picoseconds, or thousandths of nanoseconds.
Off-the-shelf depth sensors like the Kinect, however, use light bursts that last tens of nanoseconds, which is sufficient for the purpose of gauging objects' depth by measuring the time it takes light to reflect off of them and return to the sensor.
However, the report noted that based on current results, it would appear to be too coarse-grained for fluorescence lifetime imaging.
The theme of MIT's work is to take the electronic and optical precision of a big, expensive microscope and replace it with sophistication in mathematical modeling.
The MIT researchers reported the new work in the Nov. 20 issue of the journal Optica. Ayush Bhandari, a graduate student at the MIT Media Lab and one of the system's developers, is the first author on the paper, and is joined by associate professor of media arts and sciences Ramesh Raskar and Christopher Barsi, a former research scientist in Raskar's group who now teaches physics at the Commonwealth School in Boston.
The depth sensors that the researchers used in their experiments—the Kinect and others—had arrays of roughly 20,000 light detectors each, and the most accurate results came when the detector was 2.5 meters away from the biological sample.
The report notes that setup doesn't afford the image resolution that existing fluorescence lifetime imaging microscopes do.
However, while denser arrays of detectors and optics that better control the emission and gathering of light would inflate the cost of the researchers' system beyond the $100 that a Microsoft Kinect costs, it still shouldn't be nearly as expensive as current fluorescence lifetime imaging systems.