ULTRASMALL-ANGLE ROENTGEN TOMOGRAPHY

FIELD: computer tomography. SUBSTANCE: computer tomography is based on obtaining image by means of dispersed small-angle radiation. To enhance measurement sensitivity, dispersion recording is performed within ultrasmall angles from 0 to 1 deg with respect to incident beam direction. Fan beams of low divergence formed by collimator are directed to object. Special spatial filter positioned behind object is used for separation of radiation dispersed to ultrasmall angles. Spatial filter is essentially structure similar to collimator. In this structure collimator sections transparent to radiation are overlapped by nontransparent sections of filter. In this case, radiation does not pass to spatially-sensitive detector positioned behind filter if object is not available. When object is placed between collimator and spatial filter detector records dispersion directed to ultrasmall angles of radiation. To record radiation passed through object in direction of primary beam, detector elements are installed in non-transparent sections of filter. In addition to tomogram in dispersed radiation, this makes it possible to obtain tomographic picture for absorbed radiation. In other variant of device, filter sections overlapping transparent sections of collimator, partially absorb radiation passed through object along direction of incident beams and reduce it to level of dispersed radiation intensity. One of the device circuits allows determination of object dispersion function within limits of primary beam. Tomographic picture of object is restored on basis of dispersion data obtained for different angles of approach of object relative to "source - collimator - detector" system. EFFECT: enhanced accuracy of measurements. 8 cl, 9 dwg