Simulator mounted Moiré topography camera for constructing compensating filters

A technique has been developed and implemented by which individualized Ellis compensating filters can be rapidly and accurately produced from Moiré topographic photographs. A novel Moiré camera has been designed such that it has been possible to mount it on a radiotherapy simulator. The camera does not interfere with normal use of the simulator but can be deployed as needed. Depth of missing tissue contours are produced by the camera over the treatment field, accurately registered to the patient's simulated treatment position. An optical enlargement technique is used to transfer the depth of missing tissue contours in the photograph to a lead sheet compensating filter.