Method for determining the density of bodies by means of penetrating rays and apparatus for carrying out said method

摘要

In the illustrated embodiments radiant energy at a plurality of distinct energy levels (each above 150 keV) is directed along one or more primary beam paths, and a series of detectors are arranged to receive scatter radiation from the same or successive points irradiated by the primary beam energy, with the detectors either collecting scatter energy over identical solid angles and at identical mean scattering angles or having their respective outputs equalized to a common scattering sample for each respective scatter energy spectrum. By relatively shifting a group of detectors a linear or layer region can be scanned, and the respective outputs from each detector can be individually recorded for subsequent processing to eliminate the effects of multiple scattering and unequal mean scattering angles. With detectors stationary, a time series of respective output signals from each detector can be recorded to facilitate the study of local ventilation of defined zones in the lungs, for example. By suitable processing, the output signals can be converted to numerical density readings and/or an accurate graphical display of density variations in a region of medical interest.