A system for producing and recording images of inhomogeneities in otherwise homogeneous objects having a plane or locally substantially plane surface, by ultrasonic examination according to the pulse-echo method, wherein
- at least one ultrasonic probe can be moved over the surface of the object in steps of predetermined lengths along a rectilinear scanning path containing the projection on the surface of the central axis of the sound beam,
- position signal producing means produces digital signals containing information on the position on said surface of the successive points of incidence of the sound beam,
- ultrasonic equipment makes said probe emit, on completion of each step of movement, at least one short pulse of ultrasonic energy into the object, and produces, on receipt of an echo pulse, digital signals containing information on the amplitude of said echo pulse, and on the length of the sound path from said point of incidence to the reflecting point causing the echo pulse,
- digital computing means, including a first electronic matrix memory for data produced by the examination, said first matrix memory having storage addresses arranged in lines and columns associated with a similar, corresponding network of lines and columns of rectangular coordinates in the sectional plane through the object defined by the scanning path of the ultrasonic probe and the central axis of the sound beam, stores at each storage address data representing said echo amplitudes, and adds, on receipt of a new data item, said new data item to the sum of data items previously stored at said storage address,
- first control means stores in said first matrix memory, upon receipt of said position signals and said echo pulse signals, data representing said echo amplitudes at all storage addresses located on a circle, having as its center the storage address associated with said point of incidence, and having as its radius the distance in said first matrix memory corresponding to said length of the sound path through the object,
- a video screen terminal controls the scanning movement of said ultrasonic probe, controls the functioning of said ultrasonic equipment, said digital computing means, and said first control means, and displays sectional images derived from data stored in said first matrix memory,
- recording means produces permanent, electronically readable records of data stored in said first matrix memory, and of sectional images displayed on said screen terminal,
- printing means produces permanent prints of images displayed on said screen terminal,
- said ultrasonic probe can be moved over the surface of the object along a number of successive, parallel rectilinear scanning paths at predetermined intervals,
- said digital computing means further includes a second electronic matrix memory for data produced by the examination, said second matrix memory having storage addresses arranged in lines and columns associated with a similar, corresponding network of lines and columns of rectangular coordinates in a projection plane parallel to the surface of the object, where each storage address stores sums of data items representing said echo amplitudes, characterized in that:
- said digital computing means further includes second control means which, on completion of each movement of said ultrasonic probe along the length of a scanning path, reads from the storage addresses arranged in each column of said first matrix memory the highest sum of data items stored in said column, stores said highest sums of data items at the corresponding storage addresses in said second matrix memory in the column associated with the line of intersection between said sectional plane and said projection plane, and resets all storage addresses in said first matrix memory at zero value;
- said video screen terminal further controls the functioning of said second control means, and displays projection images derived from data stored in said second matrix memory;
- and
- said recording means further produces permanent electronically readable records of data stored in said second matrix memory.