Abstract
Since the construction of the first commercial scanner for routine medical diagnosis implementing the principles of computerised tomography by Hounsfield in 1973 and its worldwide adoption, the use of various types of ionising and non-ionising radiations for tomographic imaging and other applications has been under continuous study. In this work a neutron beam has been used as the probe in order to obtain tomographic images, in transmission and emission modes, of the internal structure and elemental composition of test objects respectively. Various methods of neutron transmission tomography were studied and developed. A collimated He-3 proportional counter, a conventional combination of film/Gd-converter in a single cassette and a 35inm camera were employed as the detecting systems. A computerised video camera-based microdensitometer was used to digitise the radiographs obtained and a method to improve image noise was developed and tested. The technique of computerised tomography has also been applied to image elemental distributions, in the section of interest, employing delayed gamma-rays emitted by the object following neutron irradiation. The technique is not suitable in the case when very long-lived, very short-lived or stable isotopes are produced therefore a technique novel employing prompt gamma-rays emitted by the object during irradiation was developed and tested in this work. This technique has been termed Neutron Capture Prompt Gamma-ray Emission Tomography.