[en] (1) The procedure is for back projection in the form of a tomographic picture of a member, characterised in that the strip pictures are written onto the signal plate by a conversion pick-up unit; and that to the address inputs of the pick-up unit voltages are applied that represent a rotating coordinate system. (2) Procedure following claim 1 characterised by the fact that the voltages are respectively applied as sawtooth waveform horizontal and vertical television deflections. (3) Procedure following claims 1 and 2, characterised that in order to correct the television deflection voltages for the effect of a fan shaped radiation beam, first one and then the other of the amplitudes is modulated. (G.C.)