A simplified alternative to orthogonal field overlap when irradiating a tracheostomy stoma or the hypopharynx

Abstract

Orthogonal field arrangements are usually employed to irradiate a tumor volume which includes a tracheostomy stoma or the hypopharynx. This approach may produce a significantly greater dose than intended to a small segment of the cervical spinal cord because of field overlap at depth from divergence of the beams. Various sophisticated approaches have been proposed to compensate for this overlap. All require marked precision in reproducing the fields on a daily basis. We propose a simplified approach of initially irradiating the entire treatment volume by saterior and posterior opposed fields. Opposed lateral fields that exclude the spinal cord would then provide local boost treatment. A case example and computer-generated isodose curves are presented.