[Medical radiography with fast neutrons (author's transl)].

For physical reasons, radiography by neutrons produces radiographs which are quite different from x-ray images. Biological objects can be transradiated only by fast neutrons. Selective simultaneous recording of neutron images is accomplished best by using cellulose nitrate (CN) foils, used with a track etching method in order to exclude thermal neutrons and gamma quanta. A neutron-radiography set-up in connection with a research reactor is described, as well as optimal conditions for developing the CN foils and the optical display of the resultant image. Image quality of the individual CN foil is characterised by minimal interior unsharpness (35 mu) and a small range of blackening when compared with radiographic film (about 1). Image contrast can be increased by the use of many foils. In addition, this results in a reduction of maximal radiation dose to below 10 rem. Study of isolated spines has shown that fat and necrotic tumours can be demonstrated by neutron radiography without being superimposed by calcium-containing bone, even if these changes cannot be seen on a x-ray radiograph because of the regular bone structure. It appears that neutron radiography can be superior to conventional radiography for the diagnosis of abnormalities with bones, or of areas surrounded by bone. The use of neutron radiography in patients can, at the moment, only be justified for individuals undergoing neutron therapy for the treatment of tumours.