FUNCTIONAL IMAGING IN TREATMENT PLANNING OF BRAIN-LESIONS

Purpose: Explore the use of functional imaging data in radiation treat ment planning of brain lesions. Methods and Materials: Compare the tre atment-planning process with and without the use of functional brain i maging for clinical cases where functional studies using either single photon emission computed tomography or magnetic resonance imaging are available. Results: A method to register functional image data with p lanning image studies is needed for functional treatment planning, Fun ctional volumes are not simply connected regions, One activation study may produce many isolated functional areas, After finding the functio nal volumes and registering the functional information with the planni ng imaging data, the tools used for conventional three-dimensional tre atment planning are sufficient for functional treatment planning, Howe ver, the planning system must provide dose-volume histograms for volum es of interest that consist of isolated pieces. Treatment plans that s pare functional brain while providing identical target coverage can be constructed for lesions situated near the functional volume, However, the dose to other areas of the brain may be increased. Conclusions: F unctional imaging will make determination of dose response of eloquent areas of the brain possible when combined with volumetric dose inform ation and neuropsychological evaluation prior to and after radiation t herapy, Realizing the full potential of functional imaging studies wil l require improved delineation of activated volumes and determination of the uncertainties in functional volume delineation. Optimization of treatment plans by minimizing dose to volumes activated during functi onal imaging studies should be used cautiously, because the dose to '' silent,'' but possibly eloquent, brain may be increased. Copyright (C) 1997 Elsevier Science Inc.