Standard compensators for ENT therapy fields.
Radiotherapy of the ENT region is frequently applied through two parallel-opposed, lateral fields covering a volume from the maxillary sinus to the base of the neck, with the isocentre close to the angle of the mandible. The large variation in separation throughout this volume, in both the transverse and the coronal planes, leads to field inhomogeneities which are often resolved by the use of custom designed, two-dimensional compensators. This paper presents an alternative method of compensation using a set of one-dimensional, standard compensators applied in the coronal plane which, in conjunction with a wedge in the transverse plane, yields a uniform distribution throughout the treatment volume for the majority of patient configurations. The advantages of this technique are the immediate availability of a computerised treatment plan incorporating the compensator, an increase in the dose homogeneity obtainable over that without compensation and the elimination of any delay which may be incurred by the design and fabrication of custom made compensators.
Clark
B G
BG
McGill University, Department of Radiation Oncology, Montreal General Hospital, Quebec, Canada.
Evans
M D
MD
D006258:Head and Neck Neoplasms / Q000532:radiotherapy*; D006801:Humans; D011867:Radioisotope Teletherapy / Q000379:methods*; D011879:Radiotherapy Dosage; D013679:Technology, Radiologic / Q000295:instrumentation*