Digital cameras are very useful for taking holiday snaps, but they are also useful tools for imaging inside and outside the body. For example, dentists use digital imaging to improve diagnosis and treatment. Cameras on the end of probes that can move around inside your mouth are linked to screens, so the dentist can see more clearly inside the mouth and show the patient exactly what is going on. Digital camera technology includes endoscopy, capsule endoscopy and digital image-based elasto-tomography (DIET).
With endoscopy (Greek for “look inside”), a very small camera on the end of a flexible tube is inserted into the body through an opening, and manoeuvred around. The camera transmits pictures and allows doctors to see what is happening inside. This method is commonly used to check out a patient’s large intestine, to look for problems like tumours or inflammation. It can also be used to view the oesophagus and upper gastrointestinal tract.
At the beginning of last century, doctors tried to use lighted telescopes to look inside the human body. Most of these systems had rigid tubes, but a system with a flexible tube was invented by Dr Rudolph Schindler in the 1930s. The results from these devices were often frustrating, prompting young doctor Basil Hirschowitz to experiment with the use of fibre optics in the early 1950s.
At first, there was too much light lost in the process, so Hirschowitz, along with physics Professor C.W. Peters and student Larry Curtiss, decided to refine the technology. They discovered that, if they coated the fibres in another glass, loss of light was completely eliminated because the coating created a condition of total internal reflection where the light being transmitted was bounced off the glass cladding. This also meant the signal would still be transmitted if the fibre was curved.
Hirschowitz and his co-workers created a working prototype in 1957 and he used it to view the inside of his own stomach. In 1960, his invention – now in commercial production – was used to examine the stomach of a patient. His fellow doctors were impressed by the clarity of the images and adopted the endoscope to view other parts of the human body such as the lungs, colon and abdomen.
Today, the technology can be used for more than just viewing the body – the end of the probe can include instruments, allowing doctors to treat the conditions that they find. Endoscopes can also be hooked up to video screens where medical staff can view a real time tour of your insides – a sort of medical YouTube.
With capsule endoscopy, a camera, a wireless radio transmitter, four LED lights and a battery are fitted into a pill-sized unit that is swallowed by the patient. The pill moves through the digestive tract naturally and is expelled at the end in the usual manner. Images are constantly transmitted to antenna pads on the body, then to a recording unit worn around the patient’s waist, and the pictures are downloaded to a computer and strung together into a movie.
Digital image-based elasto-tomography (DIET)
Digital image-based elasto-tomography (DIET) uses digital cameras to image motion on the outside of the body to work out what is going on in the tissue underneath. Dr Eli van Houten (University of Canterbury) uses this technique in his research into better breast cancer screening (detection).