@article{25679d89ac124cb3a5b7b6b30f069d54,
title = "Residual radiation damage in murine lung assessed by pneumonitis",
abstract = "The amount of radiation damage remaining in mouse lung has been assessed by retreatment from 1 to 6 months after a range of first doses. Pneumonitis at 196 days after retreatment was used as the endpoint. Lungs were first irradiated with a range of single doses (6-10 Gy). Ten Gy was the highest dose that, on its own, produced no changes in breathing rate or deaths due to pneumonitis. One to 6 months later lungs were retreated with a full range of single doses. Isoeffect doses were calculated for lethality for all retreatment times after each priming dose. The amount of residual damage remaining in the lung has been calculated as both a proportion of first doses and as the effect equivalent of remembered dose. Following a 10 Gy first dose, there was evidence of remembered irradiation injury at all retreatment intervals. After a 6 Gy priming dose, the lungs could be retreated to tolerance. The amount of residual damage was proportional to the size of first dose and was highest at 1 month (27% after 6 Gy and 70% after 10 Gy) and lowest after 3 months (0% after 6 Gy and 46% after 10 Gy). This partial recovery of lung function between 1 and 3 months was followed by an increase in amount of damage {"}remembered{"}; that is, a reduction in the retreatment dose that could be delivered. The proportion of residual damage after 10 Gy was never less than 25%. The data suggest an early target cell depletion and regeneration in the lung (within 3 months), the extent of which is dependent on the size of initial injury.",
keywords = "Lung, Pneumonitis, Radiation, Residual damage, Retreatment",
author = "Terry, {N. H.A.} and Tucker, {S. L.} and Travis, {E. L.}",
note = "Funding Information: The data have been analyzed in terms of the extra dose manuscript. Histological data was supported in part by the NCI Cancer Center Support Grant CA-16672--Centralized Histopathology Laboratory. Animals used in this study were maintained in facilities approved by the American Association for Accreditation of Laboratory Animal Care and in accordance with current United States Department of Agriculture and Department of Health and Human Services, National Institutes of Health regulations and standards. Accepted for publication 2 December 1987. Funding Information: In clinical practice it is sometimes necessary to treat a recurrent tumor in a site previously irradiated with a full course of radiotherapy. Surprisingly, little data, either clinical or experimental, are available concerning the radiation response of previously treated tissues. The few experimental data that do exist are predominantly for acutely responding normal tissues, primarily skin, in which it has been shown that, for acute skin reactions, a maximum of 10% of the first dose is remembered as long as 8 months after irradiation. 1'2'5'16-18 These data are in good agreement with the few clinical studies which suggest that the tolerance of retreated normal tissues is remarkably similar to that of naive normal tissues, but only for acute responses. 1L ~5 * Dept. of Experimental Radiotherapy. t Dept. of Biomathematics. Supported by the National Institutes of Health, National Cancer Institute grant CA-38106. Reprint requests to: Dr. N.H.A. Terry. Acknowledgments--The authors are grateful to Mr. M.W. AI-dana for his technical assistance, Mr. T.L. Watkins and his staff, who took great care in the production and maintenance of the animals, and Deborah Thomas Elum for the preparation of the Few clinical data and little experimental data are available on the response of previously irradiated late responding normal tissues. One such tissue that has been studied in some detail is spinal cord 10'12'13'14'25 in which 30-50% of the original dose remained. However, these experimental studies only extend for retreatment up to 2 months after the first dose. No data are available at longer retreatment intervals when, because of the slowly proliferating nature of the target cells in such tissues, more residual damage might be expressed.",
year = "1988",
month = may,
doi = "10.1016/0360-3016(88)90015-6",
language = "English (US)",
volume = "14",
pages = "929--938",
journal = "International journal of radiation oncology, biology, physics",
issn = "0360-3016",
publisher = "Elsevier Inc.",
number = "5",
}