Tomosynthesis and coded aperture imaging: new approaches to three-dimensional imaging in diagnostic radiography
- 14 January 1977
- journal article
- research article
- Published by The Royal Society in Proceedings of the Royal Society of London. B. Biological Sciences
- Vol. 195 (1119) , 299-306
- https://doi.org/10.1098/rspb.1977.0010
Abstract
Imaging with X-radiation is one of the most important diagnostic methods in medicine. The present use of shadow projection results in the information on depth in three-dimensional objects being lost. Structures in different depth are superimposed generating a confusing image which is difficult to interpret. These problems are partly solved by the well-known method of tomography. It, however, generates only one layer, whose location in depth cannot exactly be settled beforehand, and is rather time and radiation dose-consuming. These problems are overcome by tomosynthesis which utilizes a conventional tomographic equipment to record a set of radiographs each taken from a different position of the X-ray source. Arbitrary layers of the X-ray object can then be synthesized under visual control by reconstructing the projection geometry with holographic or electronic methods. Since about 3 s are required to record the individual radiographs, this method is still restricted to slowly moving parts of the human body. The recording time can be reduced to a few milliseconds by coded aperture imaging. It employs a small number of simultaneously operated, point-like X-ray sources to record a correspondingly coded X-ray image of the patient. Images of layers in deliberately chosen depth can then be generated by post-processing. The paper will describe the theory and various optic and electronic systems for implementing the algorithms involved. Experimental results will be demonstrated.Keywords
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