John Lyman

Optimization of a treatment plan for radiation therapy will produce a plan with the highest probability for tumor control without exceeding an acceptable complication rate. To achieve this goal it is necessary to have a means to estimate probabilities of local control and normal tissue complication. In general, good treatment plans deliver a high uniform dose to the target volume and lower doses to the surrounding normal tissues. The tolerance dose values available for various normal tissues are usually assumed to apply to partial or full volumes of the tissue which have been uniformly irradiated. These values are the best guidelines for estimating complication probabilities in tissues that receive a uniform dose to a fraction of the tissue and no dose to the remainder. Dose-volume histograms are one means of evaluating the uniformity of the irradiation on the tissues. Frequently the normal tissues are not uniformly irradiated as is demonstrated by dose-volume histograms for different treatment plans. A recursive algorithm which uses these tolerance dose data has been written and can be applied to arbitrary dose-volume histograms to estimate the complication probability.

John T. Lyman, Complication Probability as Assessed from Dose-Volume Histograms, Radiation Research Supplement, Vol. 8, Heavy Charged Particles in Research and Medicine. Proceedings of a Symposium Held at the Lawrence Berkeley Laboratory, University of California, Berkeley, California, May 1-3, 1985 (Nov., 1985), pp. S13-S19

The present paper represents the first clinical report of the use of stereotactically-directed narrow beams of helium ions from the 184-inch Synchrocyclotron at the Lawrence Berkeley Laboratory for the radiosurgical treatment of life-threatening vascular disorders of the brain, including inoperable or inaccessible deep arteriovenous malformations (AVMs) and carotid artery-cavernous sinus fistulas ( CCFs ). We describe the methods developed for stereotactic neuroradiological imaging and stereotactic helium-ion Bragg peak radiosurgery in the evaluation and treatment of the first 55 patients with deep AVMs in a clinical research protocol. We discuss the diagnosis and epidemiological characteristics of the diseases, the neurosurgical and radiosurgical methods of treatment available and the initial experience of stereotactic helium-ion Bragg peak radiosurgery , including stereotactic neuroradiological evaluation, treatment planning, heavy-ion beams, patient treatment protocol, early clinical results, patient evaluation and follow-up studies planned, and conclusions thus far obtained.