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J T Lyman

Publications and source records attributed to J T Lyman.

At least 37 records · Page 2Linked to original sources
PubMed1987

Optimization of radiation therapy, III: A method of assessing complication probabilities from dose-volume histograms.

To predict the likelihood of success of a therapeutic strategy, one must be able to assess the effects of the treatment upon both diseased and healthy tissues. This paper proposes a method for determining the probability that a healthy organ that receives a non-uniform distribution of X-irradiation, heat, chemotherapy, or other agent will escape complications. Starting with any given dose distribution, a dose-cumulative-volume histogram for the organ is generated. This is then reduced by an interpolation scheme (involving the volume-weighting of complication probabilities) to a slightly different histogram that corresponds to the same overall likelihood of complications, but which contains one less step. The procedure is repeated, one step at a time, until there remains a final, single-step histogram, for which the complication probability can be determined. The formalism makes use of a complication response function C(D, V) which, for the given treatment schedule, represents the probability of complications arising when the fraction V of the organ receives dose D and the rest of the organ gets none. Although the data required to generate this function are sparse at present, it should be possible to obtain the necessary information from in vivo and clinical studies. Volume effects are taken explicitly into account in two ways: the precise shape of the patient's histogram is employed in the calculation, and the complication response function is a function of the volume.

Humans↗
PubMed1985

Precision, high dose radiotherapy: helium ion treatment of uveal melanoma.

We report on 75 patients with uveal melanoma who were treated by placing the Bragg peak of a helium ion beam over the tumor volume. The technique localizes the high dose region very tightly around the tumor volume. This allows critical structures, such as the optic disc and the macula, to be excluded from the high dose region as long as they are 3 to 4 mm away from the edge of the tumor. Careful attention to tumor localization, treatment planning, patient immobilization and treatment verification is required. With a mean follow-up of 22 months (3 to 60 months) we have had only five patients with a local recurrence, all of whom were salvaged with another treatment. Pretreatment visual acuity has generally been preserved as long as the tumor edge is at least 4 mm away from the macula and optic disc. The only serious complication to date has been an 18% incidence of neovascular glaucoma in the patients treated at our highest dose level. Clinical results and details of the technique are presented to illustrate potential clinical precision in administering high dose radiotherapy with charged particles such as helium ions or protons.

Adult↗
PubMed1985

Complication probability as assessed from dose-volume histograms.

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.

Dose-Response Relationship, Radiation↗
PubMed1985

Heavy charged-particle Bragg peak radiosurgery for intracranial vascular disorders.

The program at Donner Pavilion has applied nuclear medicine research to the diagnosis and radiosurgical treatment of life-threatening intracranial vascular disorders that affect approximately one million Americans. Stereotactic heavy-ion Bragg peak radiosurgery, using narrow beams of heavy ions (helium), demonstrates superior biological and physical characteristics in brain over X and gamma rays and protons, viz., improved dose distribution in the Bragg peak, sharp lateral and distal borders, and less multiple scattering and range straggling for the same residual range in CNS tissue. Examination of CNS tissue response and alteration of cerebral blood-flow dynamics related to heavy-ion Bragg peak radiosurgery is being undertaken using three-dimensional treatment planning and quantitative imaging utilizing cerebral angiography, computerized tomography (CT), magnetic resonance imaging (MRI), cine-CT, xenon X-ray CT, and positron emission tomography (PET). Also under examination are the physical properties of narrow heavy-ion beams for improving methods of dose delivery and dose distribution and for establishing clinical RBE/LET and dose-response relationships for human CNS tissues. Based on the evaluation and treatment with stereotactically directed narrow beams of heavy ions of over 130 patients, with cerebral angiography and CT scanning, and with MRI and radioisotope scanning of selected patients, plus extensive clinical and neuroradiological follow-up, it appears that heavy-ion radiosurgery obliterates intracranial arteriovenous malformations or protects against rebleeding with reduced morbidity and mortality.

Adult↗
PubMed1984

Postmortem examination of 22 pancreatic carcinoma patients treated with helium ion irradiation.

Postmortem findings are available in this report in 22 patients with pancreatic carcinoma treated with helium ions at Lawrence Berkeley Laboratory; California. This represents the largest group evaluated histologically in the literature and is the first report evaluating effects of particle radiation in pancreatic tissue. Patient survival after therapy averaged 9 months. Most died of infection and/or pulmonary emboli. Local control was achieved in 27%. The pancreatic tumors had histologically more severe radiation changes than nontumor bearing pancreas. Irradiated bone marrow was severely hypocellular, and irradiated skin was atrophic. Five patients had radiation injury in the gastrointestinal tract. The spinal cord, liver, and kidneys showed no damage. This study demonstrates the safety of helium particle irradiation with present therapeutic planning. Injury to tumor was seen without excessive damage to adjacent tissues.

Adult↗
PubMed1984

Delayed sequelae of pituitary irradiation.

Since 1958, 781 patients at Lawrence Berkeley Laboratory have received helium-particle stereotactic radiosurgery to the adenohypophysis. Autopsy findings in 15 of these patients are reported. Ten patients received pituitary radiation (average dose, 116 Gy in six fractions) for progressive neovascularization retinopathy due to diabetes mellitus. Evidence of a time-dependent course of progressive fibrosis in their pituitary glands was found. Five patients were treated for eosinophilic adenomas. Although they had lower average doses of radiation (56 Gy in six fractions), their pituitary glands showed cystic cavitation of the adenomas. The adenomas thus appeared more radiosensitive than the normal pars anterior, which, in turn, was more radiosensitive than the adjacent neurohypophysis. No significant radiation changes were found in the surrounding brain or cranial nerves. The endocrine organs under pituitary control showed varying degrees of atrophy, and clinical tests revealed progressive hypofunction. It was concluded that charged-particle therapy produced a sharply delineated focal radiation lesion confined to the pituitary gland but did not cause injury to the critical structures of the surrounding central nervous system.

Acromegaly↗
PubMed1984

Stereotactic heavy-ion Bragg peak radiosurgery for intra-cranial vascular disorders: method for treatment of deep arteriovenous malformations.

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.

Adult↗
PubMed1983

Biological response across a ridge filter carbon ion Bragg peak.

The dose distribution of carbon ion beams was modified to cover 14 cm peak width using a ridge filter suitable for clinical application. The results of cell survival as a function of depth of penetration of carbon ions and the mouse skin (foot) response at the proximal-, mid-, and distal-peak positions using four daily fractions are reported. The objective of these studies is to verify whether the dose distribution in the peak region is properly compensated to produce uniform biological effect. The implications of the shape of the dose distribution in the peak region to radiotherapy application are discussed.

Animals↗
PubMed1982

Treatment of cancer with heavy charged particles.

A clinical radiotherapeutic trial using heavy charged particles in the treatment of human cancers has accrued over 400 patients since 1975, 378 of whom were treated with particles and 28 with low LET photons as control patients. Heavy charged particle radiotherapy offers the potential advantages of improved dose localization and/or enhanced biologic effect, depending on particle selected for treatment. Target sites have included selected head and neck tumors, ocular melanomata, malignant gliomata of the brain, carcinoma of the esophagus, carcinoma of the stomach, carcinoma of the pancreas, selected juxtaspinal tumors and other locally advanced, unresectable tumors. A Phase III prospective clinical trial has been started in carcinoma of the pancreas using helium ions. Phase I-II studies are underway with heavier particles such as carbon, neon and argon ions in order to prepare for prospective Phase III trials. Silicon ions are also under consideration for clinical trial. These studies are supported by the United States Department of Energy and National Institutes of Health.

Adult↗
PubMed1982

Clinical problems in radiotherapy of carcinoma of the pancreas.

Since 1975, 94 patients with localized unresectable carcinoma of the pancreas have been irradiated using helium and heavier particles at the University of California Lawrence Berkeley Laboratory. Despite surgical exploration and an extensive diagnostic workup including radiological, nuclear medicine, and computer-assisted tomographic studies, many patients proved to have occult liver metastases manifested within 9 months post treatment. In addition, local and regional control of the primary neoplasm (approximately 20%) has been difficult to obtain even with doses of 6000 equivalent rad in 7 1/2 weeks. Gastric and biliary obstruction have required surgical bypass procedures since irradiation has not been successful in relieving obstructive symptoms. Evidence of gastrointestinal injury has been present in postradiation therapy in approximately 10% of patients, a figure which might be higher if more patients had a longer survival (average 10 months). Some patients require pancreatic enzyme supplementation because of pancreatic deficiency either secondary to tumor or treatment. Further improvement in local control and survival requires better diagnostic methods for evaluation of local and metastatic spread, improved therapy for local and regional disease, as well as therapy directed at occult liver metastases that are frequently present.

Adenocarcinoma↗
PubMed1981

Misonidazole enhancement of radiation-induced growth delay in rat rhabdomyosarcoma tumours exposed to accelerated carbon and neon ions.

The response of a rat rhabdomyosarcoma tumour was assessed by measurements of radiation-induced growth delay resulting from administration of the hypoxic cell sensitizer misonidazole in combination with single and fractionated doses of X-rays and charged-particle radiation. Enhancement ratios of 1.8--2.1 were obtained following single doses of misonidazole (500 mg/kg i.p.) and 225 kV X-rays. Single doses of misonidazole with either carbon-ion or neon-ion radiation in the 4 cm extended-peak ionization region led to enhancement ratios of 1.2--1.3. When combined misonidazole (300 mg/kg i.p.) and X-ray treatments were given in four daily fractions, the enhancement ratios decreased to 1.2--1.5. However, a four-fraction schedule using either carbon-ion or neon-ion radiation in combination with misonidazole gave enhancement ratios of 1.1--1.3, which are similar to the values obtained for single-dose schedules with the sensitizer and charged-particle radiation.

Animals↗
PubMed1980

Current status of clinical particle radiotherapy at Lawrence Berkeley Laboratory.

Clinical experience with charged particle irradiation of human cancers has been underway at the University of California Lawrence Berkeley Laboratory. Over 150 patients have been irradiated with heavy charged particle beams including helium, carbon, neon, and argon ions. Pilot studies have included such tumor sites as glioma of the brain, carcinoma of the esophagus, carcinoma of the pancreas, carcinoma of the stomach, ocular melanoma, and carcinoma of the uterine cervix. Prospective studies are planned to investigate the improved dose localization potential (helium) and the enhanced biologic and physical dose potential (carbon, neon) in a controlled trial against the best available megavoltage irradiation techniques.

Argon↗