The effect of fractionated doses of radiation on mouse spinal cord

Journal Article · Mon Sep 20 04:00:00 EDT 1993 · International Journal of Radiation Oncology, Biology and Physics; (United States)

DOI:https://doi.org/10.1016/0360-3016(93)90242-N· OSTI ID:6568866

Lo, Y C ^[1]; Taylor, J M.G.; McBridge, W H; Withers, H R ^[2]

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1. Univ. of California, Los Angeles, CA (United States) Memorial Sloan-Kettering Cancer Center, New York, NY (United States)
2. Univ. of California, Los Angeles, CA (United States)

The purpose was to determine: (a) the dose-response relationship and latent time to paralysis following fractionated doses of radiation in mice, (b) the values of parameters for isoeffect curves, and (c) whether these parameters depend on the size of dose per fraction and the severity of injury. The spinal cords (T[sub 9]-L[sub 5]) of 608 C[sub 3]Hf/Sed/Kam mice were irradiated with fractionated doses of x-radiation. Three levels of neurological damage were used to grade the spinal cord response. Animals which did not develop paralysis were observed for at least 18 months after irradiation. The fractionated schedules consisted of either 2, 3, 4, 6, 10, or 20 fractions in addition to single doses. For the fractionated regimes the daily fraction size ranged from 2 Gy to 24 Gy, and for single doses the range was 12 Gy to 52 Gy. Both the latent time to paralysis and the incidence of paralysis were considered as endpoints. For analysis of the sparing associated with fractionation, the dose points were divided into two groups: a [open quotes]low damage[close quotes] group consisting of doses of near or less than the ED[sub 50] at 450 days and a [open quotes]high damage[close quotes] group consisting of doses much larger than the ED[sub 50] at 450 days in which there was 100% incidence of paralysis. The latent time depended on the radiation dose; for each fixed fraction number the latent period became progressively shorter with higher total doses. Differences in histology in fractionation sensitivity are observed between the two groups. The low damage data in each fractionation treatment are the important data in the analysis of long-term incidence of paralysis. On the other hand, the high damage data were emphasized for the analysis of latency. Three statistical methods (mixture model, Cox model, and Fe-plot) were used to fit the linear-quadratic dose response model and the [open quotes]Nominal Standard Dose[close quotes] (NSD) model. 29 refs., 4 figs., 5 tabs.

• OSTI ID: 6568866
• Journal Information: International Journal of Radiation Oncology, Biology and Physics; (United States), Journal Name: International Journal of Radiation Oncology, Biology and Physics; (United States) Vol. 27:2; ISSN 0360-3016; ISSN IOBPD3
• Country of Publication: United States
• Language: English

Related Subjects

560152* -- Radiation Effects on Animals-- Animals
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
ANIMALS
BIOLOGICAL EFFECTS
BIOLOGICAL RADIATION EFFECTS
CENTRAL NERVOUS SYSTEM
DOSE-RESPONSE RELATIONSHIPS
DOSIMETRY
FRACTIONATED IRRADIATION
IRRADIATION
MAMMALS
MICE
NERVOUS SYSTEM
RADIATION EFFECTS
RODENTS
SPINAL CORD
TIME DELAY
VERTEBRATES