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"Donut's shape" radiosurgical treatment planning for large cystic metastatic brain tumors
M Hayashi1, M Chernov, N Tamura
1Department of Neurosurgery, Neurological Institute, Tokyo Women's Medical University, Tokyo, Japan. GKRmoto@aol.com
Background:
Radiosurgical management of large cystic metastatic brain tumors represents a significant challenge. Nevertheless, modified dose planning has shown beneficial results in such cases.
Method And Results:
"Donut's shape" radiosurgical treatment planning is based on the chain-like application of multiple, small-sized isocenters for selective coverage of the contrast-enhancing tumor capsule and minimal irradiation of the central cystic area. Such an approach was used for the management of large cystic intracranial metastases, which were not accompanied by a significant mass effect and did not require immediate volume reduction. Treatment was done using Leksell Gamma Knife model C with automatic positioning system. The majority of treated lesions showed significant shrinkage after radiosurgery and no major complications were met.
Conclusion:
Large cystic metastatic brain tumors may be successfully treated with gamma knife radiosurgery alone using the proposed "donut's shape" dose planning with coverage of the contrast-enhancing tumor capsule by multiple small-sized isocenters.
