FEATURE MEDICAL
Body image
Keely Portway looks at some of the miniature imaging technology used in endoscopes
E
ndoscopy allows the examination and treatment of internal organs with minimal incision or invasion to the patient. In its simplest form,
an endoscope features a tiny camera and light source on the end of a long tube. The technology actually goes back centuries, with the first such invention often attributed to German physicist Philip Bozzini and his Lichtleiter device, or light conductor, which was first demonstrated in 1806 using a candle and concave mirrors to view and illuminate the inside of the body. Then, in 1853, French surgeon Antonin Desormeaux coined the term ‘endoscope’, demonstrating an instrument that improved on Bozzini’s model by using a gasogene mixture to generate more transparent light than regular candlelight. Medical technology has increased in sophistication over the years; now there are capsule endoscopes, such as CapsoVision’s CapsoCam Plus device, that a patient swallows to get images of their insides.
The CapsoCam Plus endoscope contains four cameras to give 360° panoramic lateral imaging of the small bowel.
Small is beautiful Size is a critical factor in developments in endoscopy, for obvious reasons, and so innovations in imaging technology are crucial to this market. Toshiba Imaging is one supplier of endoscope cameras; its 1.6mm diameter camera system includes an ultra-small CMOS sensor with 400 x 400-pixel resolution, 120-degree field of view lens, and an integrated LED. Meanwhile, OmniVision Technologies recently released its OH01A HD image sensor designed for endoscopes and catheters. It has a stacked-die architecture to keep it small, offering 1,280 x 800 resolution at 60 frames per second in a 2.5 x 1.5mm package. Shrinking the sensor, optics and lighting into a very small package creates its own set of challenges, as researchers at Johns Hopkins University discovered last year. The team developed two endoscopic
probes, one of which shrank the capabilities of a benchtop two-photon microscope into a device around 2mm in diameter. The second device is an optical coherence tomography (OCT) probe 500µm in diameter.
The instruments are able to image fine tissue structures and cell activity in small organs in sheep, rats and mice. If clinical
trials prove successful in supporting the instruments’ value in humans, it is hoped that this technology could ultimately help to reduce the need for invasive biopsies. Dr Xingde Li, professor of biomedical engineering at the University’s School of Medicine, commented: ‘These tools are able to look into organs, such as the bile duct, pancreas and lungs, giving us a faster and safer way to diagnose a variety of diseases.’
Two-photon imaging Two-photon microscopy uses cells’ native ability to glow without the use of injected dyes to gather information. The advantage is that the chemicals traditionally used to label biopsy samples in a lab could be harmful if used directly inside the human body. ‘We couldn’t simply shrink a microscope
that has dozens of distinct bulky parts,’ explained Li, ‘so we started a new design from scratch.’ A short-pulsed laser was used to create bursts of photons and transmit them down a specially designed, flexible fibre optic cable connected to the probe. They then travelled through a miniature lens, which also functions to refocus the light emitted by the cells and send it back to detectors through the same cable.
The CapsoCam Plus capsule endoscope has four cameras to give 360° panoramic lateral imaging 22 Electro Optics October 2019
The team designed the probe to capture 3D images by incorporating a very small scanner. The lens was carefully fashioned to focus the long-wavelength light emitted from the laser, while also collecting the short-wavelength fluorescence light emitted from the cells; the fibre optic cord, too, was
@electrooptics |
www.electrooptics.com
CapsoVision
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40
