Medical applications of holographic stereograms

Abstract

A method for displaying 3D images of medical objects by using holographic stereogram is described together with basic properties of reconstructed images of cylindrical holographic stereograms. INTRODUCTI ONA holographic stereogram (HS) is a synthesized hologram from an original film which consists of a series of ordinary photographs taken from different directions of an object, and is possible to apply to an object whose hologram is very difficult or impossible to take with conventional techniques [U. Such a feature of HS can be used for 3D display of medical images such as X-ray images, computer assisted tomogrphy (CT) images, nuclear magnetic reasonance images (MRI) or ultrasonic images of a patient. CYLINDRICAL HOLOGRAPHI C STEREOGRAMSThe original film of the medical HS is taken by rotating around the body axis of a patient a U-shaped arm equipment, one end of which has a pulse X-ray source and the other end a movie camera with an image intensifier [2]. Synthesis of HS is carried out by using a special optical system, the hologram is shaped into a cylinder, and is reconstructed by illuminating the hologram with a small white light source located on the axis of the cylinder. Such a HS is called multiplex hologram (MH), the most popular HS, and the reconstructed image can be observed in the cylinder. The formation of reconstructed image is made in unusual way, and fundamental properties of reconstructed images of MH are studied mainly for distortion and resolution, and optimum conditions for minimizing the distortion are made clear [3,4]. Computer processing in the original images to make distortion-free reconstructed images is also proposed [5]. Resolution of reconstructed images is mainly due to the size of the reconstructing source if the original image has enough resolution, and an optimum source size for reconstructing MH is suggested [6]. 398 / SPIE Vol. 1238 Three-Dimensional Holography: Science, Culture, Education (1989) Downloaded From: http://proceedings.spiedigitallibrary.org/ on 06/25/2016 Terms of Use: http://spiedigitallibrary.org/ss/TermsOfUse.aspx HOLOGRAM OF MEDICAL OBJECTSIn general, X-ray images in medical use are of low contrast, and high quality reconstructed images from these original images cannot be expected. Computer processing of original images is employed to improve the quality of images, and this system brings the possibility of expanding kinds of medical images to synthesize HS [7]. A set of CT images are used for synthesizing HS of bones. CT images give sectional images of a patient perpendicularly to the body axis. Computer processing is applied to extract bones from the tomograms, and to reconstruct surface reconstruction images of the bone by piling up these sectional images with the aid of interpolation technique. A series of projected images are calculated onto planes around the body axis, displayed frame by frame on a CRT screen, and recorded on a movie film for using as an original film for synthesizing HS. MH of skull of a living patient is successfully synthesized by usin...