DEPTH-DOSE TABLES FOR 6 MV X RAYS FOR USE WITH A CONSTANT SOURCE-LESION DISTANCE.

IN view of the desirable depth dose characteristics of high-energy radiations for treating deep-seated tumors, many supervoltage radiation therapy machines of different designs, constructions, and energies have appeared in the market. One of the most recent additions is the Varian Associates 6 Mev linear electron accelerator for x-ray and electron therapy. This accelerator is designed with a can-tilevered treatment couch so that rotational-, multiple-, or single-port treatments can be administered without moving the patient. Of course, in such a system the source-skin distance will change with changes in the direction of the beam. To our knowledge, constant SLD dose tables for 6 Mv x rays are not available. In fact, relatively little depth-dose information has been published, and this has been for only one source-skin distance. We have prepared a set of tables2 of central axis depth doses for use with 6 Mv x rays at a constant source-lesion distance of 100 cm. Published data for 4 and 8 Mv x rays were use...