USE OF MULTIPLANAR REFORMATTED RADIOGRAPHIC AND DIGITALLY RECONSTRUCTED RADIOGRAPHIC IMAGES FOR PLANNING CONFORMAL RADIATION-THERAPY

A three-dimensional treatment planning system capable of gantry, colli mator, and table rotations is required for a noncoplanar conformal the rapy, Unfortunately, such a system is not widely available, A method i n which multiplanar reformatted radiographic (MPR) and digitally recon structed radiographic (DRR) images are used is presented for conformal treatment of brain tumors. A head phantom containing a target volume was scanned on a computed tomographic (CT) simulator, The coronal MPR images were digitized on a treatment plan ning system to create a conf ormal block of the planned treatment field, The DRR images were genera ted on the CT simulator with the setup parameters calculated from the treatment planning system, A second set of conformal blocks was genera ted based on DRR images of the fields, The accuracy of the MPR- and DR R-generated blocks was verified on the vertex field, The differences b etween the actual planning target volume and the field edges of the MP R and DRR blocks were within +/-4 mm and +/-2 mm, respectively, The au thors conclude that the MPR and DRR images could be successfully used to generate conformal blocks and for treatment planning of noncoplanar beams in radiation therapy.