The determination of anatomical cross-sections using a radiotherapy simulator.

A system for obtaining anatomical cross-sections for treatment planning using a radiotherapy simulator is described. A fluorescent screen is viewed by a low light level Isocon television camera and the video signal is digitized and stored. Many projections of the phantom are obtained by rotating the simulator gantry. A convolution algorithm has been used to reconstruct chest sections in which skin and lung outlines are visible. The technique could also be used to make corrections to radiotherapy dose distributions where irradiation of lung tissue is involved.