Intensity modulated conformal therapy for intracranial lesions.

ABSTRACT

The Peacock planning and delivery system was used to create treatment plans and deliver these plans to patients. The system involves an arc therapy delivery of small (2 cm long) slices of radiation combined with indexing of the couch to achieve target coverage. Two clinical examples are shown to demonstrate the system's capability and evaluate the resources required to produce and deliver the plans. One plan is an optic sheath meningioma and the other is a craniopharyngioma that surrounded the optic chiasm. The optic sheath meningioma was treated to 50 Gy in 25 fractions. The treatment involved delivery of two arcs. The total time to set up the patient and deliver the treatment was less than 15 min. Planning and plan validation after computed tomography required approximately 3 days. The patient had 100% restoration of her field of vision and is stable 3 years post therapy. The second patient is a 9-year-old who had a craniopharyngioma which surrounded the optic chiasm. The tumor was treated to 50.4 Gy in 28 fractions and the dose to the optic chiasm was limited to 45 Gy. The treatment required three arcs and total treatment time was less than 20 min. The patient is stable 15 months post therapy. The system is able to create and deliver radiation patterns that are unique. These plans can be created and delivered in times that rival conventional forward planning conformal radiotherapy systems that cannot produce or conveniently deliver such plans.