GB530477A - Method of and apparatus for obtaining cross-sections of bodies by means of x-rays - Google Patents

Abstract

530,477. R÷ntgen-ray kinematograph, and optical projection apparatus. PHILIPS LAMPS, Ltd. June 24, 1939, No. 18484. Convention date, June 27, 1938. [Classes 97 (i) and 98 (i)] To produce an X-ray image of a section of a body, indicated by way of example as a cylinder 3 with a less permeable core 4, a beam of X-rays 10 passing transversely through the body is limited by a slotted diaphragm 5 to a narrow beam in the plane of the section, which forms a narrow strip-like image on a film 7. A number of such partial radiographs are taken from different directions, the X-ray source, screen, and film 7 being rotated round an axis passing through a fixed point in the section without changing the distances between them and the axis of rotation. Each strip-like radiograph is then enlarged laterally to give an image of the kind shown at 9, Fig. 2, and the enlarged images are superposed in the same angular relationship as that which existed between the directions from which they were taken. Fig. 2a shows the effect of combining two images taken from directions with an angle α between them, the result of combining a sufficient number of such images taken from directions extending over an angle of 180 degrees when a substantially parallel beam of rays is employed, or over 360 degrees when the beam is not parallel, being to form the desired image of the section. By continuous relative rotation of the object and the X-ray apparatus a band composed of coalescing strip images may be obtained, Fig. 7 showing an apparatus for this purpose, in which an X-ray tube 38 projects an image through a slot diaphragm 40 of a section of an object supported on a rotary platform 42, the image being received on a film mounted on a roller 41 which is rotated in synchronism with the platform 42. To obtain a picture of the cross-section, the developed film is placed on a cylinder 23, Fig. 6, of the same size as the cylinder 41 and is illuminated by a point source of light 25 within it. The beam passing a slit diaphragm 24 is enlarged in a transverse direction by cylindrical lenses 26, 27 and the image is received on a sensitive plate 9 which is rotated in synchronism with the cylinder 23. A composite image is thereby formed on the plate representing a synthesis of the images formed by the projection of every part of the film through the slit. The Specification as open to inspection under Sect. 91 also refers to a similar method for obtaining a visual image in which a mirror or lens system is employed after the cylindrical lens 27 to rotate the image at the same angular speed as that of the cylinder carrying the film. A modification of the apparatus shown in Fig. 7 is also referred to in which, for the purpose of obtaining images of successive sections, the platform 42 is uniformly raised or lowered as well as rotated, and a continuous band of film replaces the cylindrical film on the roller 41. This subject-matter does not appear in the Specification as accepted.