Patent GB-1216753-A (GB)
Title: Method of recording and reproducing picture information obtained by ultrasonic-pulse-echo sectional view examinations and apparatus for carrying the method into effect
IPC: G01N29/06
Filed: 1968-01-11
Abstract: 1,216,753. Ultrasonic inspection devices; local viewing. AKADEMIET FOR DE TEKNISKE VIDENSKABER SVEJSECENTRALEN. 11 Jan., 1968 [13 Jan., 1967], No. 1751/68. Headings H4D and H4F. A record of a complete cross-section of a body being scanned by an ultrasonic probe is built up as the scanning proceeds by applying echo signals to a video recorder whereby several superimposed, synchronized recordings are made on a carrier of magnetizable material. In the preferred embodiment, probe 1 (Fig. 2) transmits 1250 pulses/sec. and is scanned in turn in ten planes I, II, III, &c. to provide ten complete cross-sectional views of body 15. The deflection of oscilloscope 6 (Fig. 5) is linked by unit 7 to the probe movement and the oscilloscope is intensity-modulated by the echo signals to give a display of the cross-sections. The displayed cross-section is scanned by video camera 8 (at 25 frames/sec, with 500 lines per frame) under the control of synch. pulses on a control track of a magnetic drum, disc or tape loop in video recorder 10. The after-glow period of oscilloscope 6 is selected such that each image point persists long enough for it to be picked up by camera 8, but not long enough for residual images of previous frame periods to be picked up. The camera video signals are recorded in parallel diagonal tracks on the recording medium, the track length corresponding to a complete crosssection (frame), and individual points in the track corresponding to respective points in the cross-section. To permit analysis of echo signal amplitudes the echo signals are passed to ten gated amplitude discriminators 47a-47j (Fig. 5) (having consecutive, different discrimination levels a-j and gated in turn by frame synch. signals fed from recorder 10 over a ten-counter 42) whereby the discriminator outputs are sampled in turn in different frame periods and applied to -oscilloscope 6. Logic circuitry, including a hundred-counter 37 supplied with frame synch. pulses, so synchronizes the camera scanning and video recording that echo signals with the different amplitudes a-j are recorded in separate tracks; thus all echo signals of amplitude a and relating to cross-section I are recorded in a track (Ia) (Fig. 4), those of amplitude b for cross-section I are recorded in track (Ib) and so on, giving a hundred tracks in all for the ten cross-sections. For analysis the recorded tracks are played back to a television monitor 14 via ten intensity control circuits 49a-49j which are gated in synchronism with the gating of discriminators 47a-47j so that the display intensity is appropriate for the amplitude level associated with the particular track being displayed. The monitor 14 may be arranged to display the cross-sections simultaneously in staggered formation (e.g. along the diagonal of its screen) to give a three-dimensional effect, the display intensities of the crosssections being graded. A second monitor, 50, may be used to display echo signals of a selected amplitude range.