Charles C. Rogers

CT-assisted assessment of bladder and rectum dose in gynecological implants

Eight patients who received gynecological implants with Fletcher-Suit type applicators were involved in this study. An orthogonal pair of films and computed tomographic scans were obtained for each patient. In the CT study, judicious use of contrast materials and selective window and level settings permitted clear delineation of the bladder and the rectum boundaries relative to the implanted applicators. In comparison to reference organ doses derived from the orthogonal film pair method, the maximum organ doses estimated from the CT-assisted evaluation were considerably higher, by approximately twofold on the average. The differences between the values estimated from the two methods vary from patient to patient, being highly dependent on the individual anatomy and the geometry of the implanted sources. These preliminary results point to the inaccuracy of the conventional method of estimating organ doses. CT-assisted evaluation may be necessary to accurately calculate organ doses in gynecological applications.

Coronary arteriosclerosis and arterosclerosis in fast neutron or photon irradiated dogs

Abstract Thirty-nine adult male beagles received either fast neutron or photon irradiation to the right thorax to obtain values for the relative biological effectiveness (RBE) of fast neutrons as assessed by quantitative parameters of lung function. Fast neutrons (15 MeV avg.) were delivered in 4 fx/wk for six weeks to total doses of 1000, 15010, 2250 or 3375 rad while the photon irradiated dogs received total doses of 3000, 4500 or 6750 rad in the same fractionation schedule. The right atrium and coronary groove of the heart were included in the irradiated field. Cholesterol levels (and triglyceride levels when obtainable) were measured prior to irradiation and every three months until death. Arteries were graded (0, negative to 5, severe) for endothelial proliferation, disruption and duplication of the elastic lamina, perivascular fibrosis and the presence of foamy macrophages. All dogs that survived 75 days post-irradiation developed arterial changes; two neutron irradiated dogs showed severe atherosclerotic plaque formation. Data suggest an RBE between 4 and 5.

Clinical observations of early and late normal tissue injury and tumor control in patients receiving fast neutron irradiation

Abstract The clinical experience of the first 211 patients treated at MANTA from October 1973 to May 1978 is described. Acute cutaneous, mucosal, gastrointestinal reactions and late effects including myelitis, damage to brain, bowel, soft tissue and mandibular necrosis are described. A review of tumor response data is also submitted.

Clinical observations of early and late normal tissue injury in patients receiving fast neutron irradiation

This communication describes early and late normal tissue effects in 177 patients treated totally or in part by 15 MeV neutrons from the Naval Research Laboratory Cyclotron in Washington, D.C. between October 1973 and December 1976. Late normal tissue reactions were found to be greater than would be expected from careful observation of the early clinical responses to neutron treatment. Neutron prescriptions must be written based on the late effect tolerance level experience which is being accumulated at several neutron therapy facilities.

Pathologic Findings in Canine Brain Irradiated with Fractionated Fast Neutrons or Photons

Thirty-seven adult male purebred beagles received total doses of 1333, 2000, 3000, or 4500 rad of fast neutrons (15 MeV av) in 4 fractions/week for 7 weeks to the entire brain. Nineteen dogs received 4000, 6000, or 9000 rad of photons (/sup 60/Co) in an identical fractionation pattern. Dogs receiving 4500, 3000, and 2000 rad of neutrons and 9000 rad of photons developed neurologic signs and died or were euthanatized when moribund followed irradiation. Cerebrospinal fluid contained excess protein and erythrocytes during and sometimes before the generally brief course. The onset of neurologic symptoms was usually followed by a moribund state in less than 48 h. The relative biological effectiveness (RBE) as measured by onset of neurologic symptoms and mortality was greater than 4.5. Gross changes included hemorrhage, edema, and malacia primarily in the white matter, especially the corona radiata, cerebellar white matter, corpus callosum, and corpus fornicis. One beagle developed a brain tumor and died 1207 days following 1333-rad neutron irradiation.

Effects of fractionated doses of fast neutrons and photons on the normal canine lung: relative biological effectiveness values obtained by radionuclide studies.

Abstract Thirty nine adult male beagles received either fast neutron or photon irradiation to the right thorax. There were 2 unirradiated control dogs. Twenty four dogs received fast neutrons with a mean energy of 15 MeV to total doses of 1000, 1500, 2250 or 3375 rad delivered in 4 fx/wk for 6 weeks. Fifteen dogs received total doses of 3000, 4500 or 6750 rad of photons ( 60 Co) in the same fractionation pattern. Radionuclide evaluations of pulmonary function were performed pre-irradiation and every three months post-irradiation for 1 year. These included: (1) radioaerosol deposition of an insoluble radiocolloid, 99m Tc-phytate; (2) 133 Xe ventilation studies; and (3) 99m Tc-macroaggregated albumin perfusion images. Values for the relative biological effectiveness (RBE) of fast neutrons in producing changes in these parameters have been obtained by plotting the changes from pre-irradiation values in the right lung as a function of the total dose. RBE values for the relative deposition of aerosol and the relative distribution of volume and perfusion have been obtained at 3, 6, 9 and 12 months post-irradiation. The relative biological effectiveness (RBE) for neutron damage to normal lung tissue was always greater than 4 in the clinical dose range of 4000–6000 rad of photons.

RTOG phase I study on fast neutron teletherapy for squamous cell carcinoma of the esophagus

Abstract From August, 1977, through January, 1981, the Radiation Therapy Oncology Group sponsored a Phase I study (RTOG 77-09) on the use of fast neutrons for treating inoperable squamous cell carcinomas of the esophagus. A total of 39 evaluable patients were treated with curative intent using either fast neutrons alone or in combination with low LET irradiation as part of a mixed beam fractionation scheme. Actuarial survival curves are presented for both the “neutrons alone” and the “mixed beam” treatment groups. There was no significant survival difference between these groups of patients. The projected survival at two years is less than 10%, which is comparable with megavoltage photon results for an unselected series of patients. The size of the primary lesion and the initial Karnofsky performance status were found to be the most important prognostic indications for prolonged survival. Sixteen of 39 patients were felt to have achieved local clearance of their tumor at some time during their follow-up with the median time until a local recurrence being 17 months. Treatment related complications and patterns of metastatic spread are discussed. In general, it appeared that the response of large tumors to neutron irradiation resulted in necrosis and fistula formation. In many cases this was accompanied by persistent/ recurrent tumor within the high dose radiation volume.

Fast neutron irradiation for locally advanced pancreatic cancer

Abstract Nineteen patients with locally advanced pancreatic cancer and one patient with islet cell cancer were treated with 1700–1750 neutron rad alone or in combination with 5-flourouracil to exploit the theoretic advantages of higher linear energy of transfer, and lower oxygen enhancement ration of neutrons. Only 5 of 14 (36%) obtained partial tumor regression. The median survival for all patients with pancreatic cacer was 6 months, which is less than that reported with 5-flouracil and conventional photon irradiation. Gastrointestinal toxicity was considerable; hemprrhagic gastritis in five patients, colitis in two and esophagitis in one. One patient developed radiation myelitis. We therefore, caution any enthusiasm for this modality of therapy until clear evidence of a therapeutic advantage over photon therapy is controlled clinical trials.

Treatment experience: Locally advanced sarcomas with 15 MeV fast neutrons

Experience with ten evaluable osseous sarcomas and ten evaluable advanced soft tissue sarcomas treated with neutrons of a mean neutron energy of 15 MeV are described. Neutron irradiation with or without conventional megavoltage radiotherapy is an effective modality in the treatment of these patients. No correlation between response rate and grade or whether fast neutrons alone or combined with megavoltage radiotherapy was noted. Those patients receiving a neutron dose of 2195 neutron plus gamma rads or greater all had a complete response.

Pathologic effects of fractionated fast neutrons or photons on the pancreas, pylorus and duodenum of dogs

Thirty-nine adult male Beagles received either fast neutron or photon irradiation to the right thorax to determine the relative biological effectiveness (RBE) of fast neutrons on normal pulmonary tissue. The right anterior abdomen was included in the field of radiation. Twenty-four dogs (six/group) received fast neutrons with an average energy of 15 MeV to total doses of 1000, 1500, 2250 or 3375 rad in four fractions per week for six weeks. Fifteen dogs received 3000, 4500 or 6750 rad of photons (five/group) in an identical fractionation pattern. All neutron irradiated dogs receiving 3375 and 2250 rad and one receiving 1500 rad developed clinical signs of pancreatic, hepatic and gastrointestinal disturbances. The liver enzymes of these dogs became elevated and they died or were euthanatized in extremis 47-367 days after irradiation. Only one 6750 rad photon dog developed similar signs and died 708 days post-irradiation. Five neutron and 10 photon exposed dogs died of other causes. Neutron-induced lesions in the stomach and duodenum included hemorrhages, erosions, ulcerations and fibrosis. Ulcers perforated the GI tract of five dogs. Pancreatic lesions included degranulation and necrosis of acinar cells, fibrosis ans atrophy. Islet cells were not obviously damaged. All lesions were associated with degenerative and occlusive vascular changes. The RBE of fast neutrons, assessed by clinical signs, gross and microscopic pathology, is approximately 3-4.5 for pancreas and about 4.5 for pylorus and duodenum.