Treatment planning for parotid sparing in the patient requiring bilateral neck irradiation

The use of three dimensional (3-D) planning techniques for treatment of head and neck cancers has primarily been used in cases which require only unilateral neck irradiation. However, tumors that require bilateral neck irradiation are commonly managed with parallel opposed treatment portals. A common morbidity associated with this standard form of treatment is xerostomia. In an effort to reduce the incidence of this debilitating side effect, a protocol has been developed which attempts to balance effective tumor control with preservation of salivary flow. Key to this protocol is the use of 3-D treatment planning. The close proximity of the targeted tissues to critical structures and the related dose requirements and/or restrictions of these tissues often require the treatment planner to utilize "non-standard" approaches to achieve the unique dose distributions necessary to meet protocol eligibility. This may include treatment planning options such as non-coplanar, non-axial beams; and modulation of beam intensity.