Transverse analogue tomography in radiotherapy

This paper describes the design and development of a single unit to combine the advantages of precision high-energy simulation and X-ray body scanning. Good detail transverse-axial-tomograms are produced on the basis of analogue technology where the X-ray density values of the slice of the object are produced in analogue instead of digital form. In broad terms, the development of this unit now for the first time enables the radiotherapist (after localising the tumour site by conventional diagnostic X-ray screening on the simulator) to proceed immediately (without moving the patient) to transverse-axial-tomography, slicing the target volume to give three dimensional evidence of the spread and position of the growth relative to adjacent normal structures. This information is fed into a computer-controlled treatment-planning system quickly to facilitate the preparation of precise treatment presciriptions. The running costs and the staff needed to operate and maintain this dual-function machine do not appear greater than the normally accepted requirements for a conventional radiotherapy simulator.