International journal of radiation oncology, biology, physics
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Int. J. Radiat. Oncol. Biol. Phys. · May 1993
Why shorter half-times of repair lead to greater damage in pulsed brachytherapy.
Pulsed Brachytherapy consists of replacing continuous irradiation at low dose-rate with a series of medium dose-rate fractions in the same overall time and to the same total dose. For example, pulses of 1 Gy given every 2 hr or 2 Gy given every 4 hr would deliver the same 70 Gy in 140 hr as continuous irradiation at 0.5 Gy/hr. If higher dose-rates are used, even with gaps between the pulses, the biological effects are always greater. Provided that dose rates in the pulse do not exceed 3 Gy/hr, and provided that pulses are given as often as every 2 hr, the inevitable increases of biological effect are no larger than a few percent (of biologically effective dose or extrapolated response dose). However, these increases are more likely to exceed 10% (and thus become clinically significant) if the half-time of repair of sublethal damage is short (less than 1 hr) rather than long. This somewhat unexpected finding is explained in detail here. ⋯ More biological damage will be done (compared with traditional low dose rate brachytherapy) in tissues with short T1/2 (0.1-1 hr) than in tissues with longer T1/2 values.
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Int. J. Radiat. Oncol. Biol. Phys. · May 1993
Comparative StudyMarrow toxicity of fractionated vs. single dose total body irradiation is identical in a canine model.
We explored in dogs the marrow toxicity of single dose total body irradiation delivered from two opposing 60Co sources at a rate of 10 cGy/min and compared results to those seen with total body irradiation administered in 100 cGy fractions with minimum interfraction intervals of 6 hr. Dogs were not given marrow transplants. ⋯ Within the limitations of the experimental design, we conclude that single-dose and fractionated total body irradiation have comparable marrow toxicity in dogs.
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Int. J. Radiat. Oncol. Biol. Phys. · May 1993
Randomized Controlled Trial Multicenter Study Clinical TrialInfluence of location and extent of surgical resection on survival of patients with glioblastoma multiforme: results of three consecutive Radiation Therapy Oncology Group (RTOG) clinical trials.
The influence of tumor site, size, and extent of surgery on the survival of patients with glioblastoma multiforme treated on three consecutive prospectively randomized Radiation Therapy Oncology Group trials employing surgery and irradiation plus or minus chemotherapy was studied. ⋯ We conclude that biopsy only yields inferior survival to more extensive surgery for patients with glioblastoma multiforme treated with surgery and radiation therapy.