SCIENCE

Life in 3-D Motion

Recent months have brought an upsurge in interest in 3-D film and television. Progress is also being made in research into the use of 3-D images in the field of medical science. As a result of joint research by institutes such as the National Center for Child Health and Development and Aloka, Professor Takeyoshi Dohi of the University of Tokyo has developed the technology to film inside the human body with ultrasonic testing equipment and convert the data into a 3-D image in real time. Miho Kawasaki interviewed Professor Dohi.

When we think about 3-D images, we tend to assume that special eyeglasses are required to view them, such as was the case for the hit movie Avatar last year. However, eyeglasses are not required to view the 3-D images developed by Professor Dohi.

“3-D images requiring special eyeglasses simply use an optical illusion to show a flat object in three dimensions,” explains Professor Dohi. “This is not suited to surgery, which requires the actual condition to be accurately determined without stress. So I addressed the practical implementation of three-dimensional imaging technology that is visible to the naked eye.”


Professor Dohi has applied the principle of integral photography discovered by the Frenchman Gabriel Lippmann in 1908.

When a subject is captured on film by placing a multifaceted lens (comprising multiple convex lenses) in front of the camera film, multiple subject images are exposed on the film. When light is directed on that film from behind and reflects through the multifaceted lens a second time, the subject appears to float three-dimensionally in front of the observer’s eyes.

“Lippmann discovered this principle, based on photography, but it sank into obscurity without ever reaching fruition. It has finally borne fruit today, 100 years later, with the advances in computer programming technology.

“For our purposes, when the ultrasonic wave is transmitted from a close position, the individual ultrasonic waves interfere with each other, preventing accurate data from being obtained. Previously, therefore, four-directional reception was considered the limit. However, this time Aloka restricted the direction of transmission and reception of each ultrasonic wave, changing the frequency of four ultrasonic waves for each, thereby inhibiting the interference of the other ultrasonic waves and successfully producing eight-directional reception for the first time. With images that employ four-directional reception, the surgical forceps had appeared blurred and thick, but now the image is clear and we are able to ascertain the exact shape.”


Professor Dohi explains the background to the research.

“There is a disease called myelomeningocele. It is a congenital disease where the spinal cord protrudes from the spinal column, but treating it in the mother’s uterus would allow the baby to be born healthy. However, abdominal operations pose a high risk to the health of the mother and child. Endoscopic surgery entails looking at a flat image, which means that how deep to insert the instrument is largely dependent on the experience of the physician, and there are also parts of the image that are hidden in shadow. Using our 3-D image system, as well as minimizing the impact in the bodies of mother and unborn baby, we will also be able to accurately determine where to operate. Our 3-D image system will be effective for adult diseases too, such as brain tumors, where the lesion is located deep inside the body and for which it is normally difficult to see how far a surgical instrument reaches.”

Professor Dohi says of the future of his 3-D image system:

“I would like to see physicians using it for actual medical treatment. Within a few years it will find widespread practical application. In the field of therapeutic instruments, engineering knowledge has still not been used sufficiently in comparison with testing equipment. I believe that we have a role to play, to use our engineering knowledge and research to develop the range of tools necessary for new medical treatment to cure diseases that are difficult to treat.”

Miho Kawasaki is a freelance writer.

Concept of 3-D image stereoscopic display