The radiation response of the cervical spinal cord of the pig: Effects of changing the irradiated volume
- Dr. Daniel den Hoed Cancer Centre, Rotterdam (Netherlands)
- Univ. of Oxford, Headington (United Kingdom)
An investigation of the field size effect for the cervical spinal cord of the pig after single doses of {gamma}-rays. In this study, clinically relevant volumes of the spinal cord were irradiated. The effects of the local irradiation of different lengths of the spinal cord (2.5 cm, 5.0 cm, and 10.0 cm) have been evaluated in mature pigs (37-43 weeks). Single doses of 25-31 Gy were given using a {sup 60}Co {gamma}-source, at a dose rate of 0.21-0.30 Gy/min. The incidence of radiation-induced paralysis was used as the endpoint. The data were analyzed using probit analysis and a normal tissue complication probability (NTCP)-model. Twenty-five animals out of a total of 53 developed paralysis, with histological evidence of parenchymal and vascular changes in their white matter. The slope of the dose-response curves decreased with the decrease in field size; however, there was no significant difference at the radiation dose associated with a 50% incidence of paralysis (ED{sub 50}) irrespective of the method of analysis. The ED{sub 50} values {+-} standard errors ({+-} SE) were 27.02 {+-} 0.36 Gy, 27.68 {+-} 0.57 Gy, and 28.28 {+-} 0.78 Gy for field lengths of 10, 5, and 2.5 cm, respectively. Analysis of the data with a normal tissue complication probability (NCTP) model gave similar results. The latent period of paralysis was 7.5-16.5 weeks with no significant differences between dose and field size. No significant field size-related differences in response were detectable in the cervical spinal cord of mature pigs after single dose irradiations, specifically at a clinically relevant level of effect (< ED{sub 10}). 21 refs., 1 fig., 1 tab.
- OSTI ID:
- 86312
- Journal Information:
- International Journal of Radiation Oncology, Biology and Physics, Vol. 31, Issue 1; Other Information: PBD: 1 Jan 1995
- Country of Publication:
- United States
- Language:
- English
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