February 12, 2015
Looking for skin cancer is hard work. The best way to find it is by carefully looking at someone’s skin for lesions and other signs of cancer. Since standing in a doctor’s office while he or she scrutinizes your skin one inch at a time is as impractical as it is awkward, doctors often rely on photos when searching for melanoma.
But we have a lot of skin, so doctors often have to settle for a low-resolution image of a wide area or a high-resolution image of a very small area. Limited range and resolution can limit doctors’ ability to find cancer markers, and doing both types of scans can be time-consuming and expensive.
Now, Duke University electrical engineers Daniel Marks and David Brady think they have the solution, the gigapixel camera, which they say can photograph the whole body with enough resolution for a doctor to see miniscule features on the skin.
You’ve heard of megapixels – probably in smartphone commercials battling over which phone sports the best camera – well a gigapixel is 1000 megapixels. To put that in perspective, the latest iPhone’s camera has eight megapixels, an IMAX movie camera has about 70, and the very best professional digital cameras can scrape together about 200.
Brady developed the original gigapixel camera in 2012, and at the time, it was the highest resolution camera in the world – it has since been eclipsed by the ARGUS-IS, a 1.8 gigapixel camera used in drone surveillance.
While Brady’s camera no longer boasts the highest resolution, Brady and Marks were able to adapt it for a unique application: the clinic. The two engineers tweaked the design to produce the Whole Body Dermascope (WBD), which can provide an image of the whole body with high enough resolution for doctors to see what they need to see.
For example, the WBD can take a single picture of someone two-meters-tall and a doctor would be able to see any detail larger than three ten-thousandths of an inch — about a tenth the thickness of a sheet of paper.
This would allow a doctor to examine a patient’s skin from wide-out to see signs of any problems and then zoom in to check out anything he or she thinks could be a sign of trouble, all from two pictures (front and back). The extremely high resolution could also allow doctors to track the size of lesions or moles over time to determine whether and how quickly they are growing. Brady and Marks presented this concept at The Optical Society’s annual meeting October 19-23, 2014.
The gigapixel camera is actually a bit of a misnomer. It should be gigapixel cameras as Brady’s imager is actually a collection of dozens of individual cameras arranged in a box. The box looks more or less like a camera: solid but for an aperture on one side to let in light. Inside the box the individual cameras are arranged in a dome shape around a spherical lens.
The lens redirects light from many directions out to the whole dome of cameras. Then a computer compiles the images from all of the individual cameras to make one coherent image. If that wasn’t complex enough, each camera can be individually adjusted to brighten, darken and sharpen the image.
The original design was built for a shot of something far away, so when Brady and Marks adapted the design for a close-up in the clinic, they moved the individual cameras further from the center of the “dome” to focus on a person close-up.
The next step for the WBD is a clinical trial, where Marks will debut a 63-camera version of the gigapixel camera, complete with its own lighting. The gigapixel device still does not match the best small-area scanners in terms of how far doctors can zoom in, but the engineers hope that the ability to image the whole body in one shot will make up for the thousandths of a millimeter difference.
Marks and Brady also say the WBD could be useful in telemedicine — that is having an off-site doctor search the images for cancer. The introduction of more WBDs could allow patients far from large hospitals to receive a diagnosis from doctors whom they would not normally be able to see.
— Daniel Lane
Daniel Lane covers science, engineering, medicine and the environment in North Carolina.