1. In an assembly for televised radioscopy which comprises a source of X-rays (101) means for generating a visual signal corresponding to the contour of image of the body organ in motion being examined (102, 103, 104) and a monitor provided with a screen (105), said visual signal being provided to said screen for reproducing the image of said body organ and a detecting device for the displacements of said body organ; the improvement which comprises a detecting device (106) which has an input (106a) to which said visual signal (A) is supplied, at least one output (106c) which is intended to be connected to the input of said monitor 105, a first processing electronic transducer device (108,109,125,126,127,128,130), capable of generating and overlapping a registering signal i which is overlapped with said visual signal (A), said registering signal i being capable of causing at least one tracing PR on the televised picture Q of the monitor 105, said tracing corresponding to at least one point of said contour of the image of the body organ in motion, said tracing PR having a luminosity different from the luminosity of the surrounding portion; a second processing electronic device comprising detecting means (110, 111, 114, 131, 134, 135, 136) capable of supplying at the output an electric signal indicative of the amount of the horizontal displacement of said tracing PR starting from a reference point T which is fixed with respect to the televised picture Q of the monitor 105 during the movement of the image of the same body organ; registering means (107) connected to the output of the detecting means (110, 111, 114, 131, 134, 135, 136) and capable of supplying a representation of the displacement of said point of the contour of the body organ being examined.