The radiation response of the cervical spinal cord of the pig: Effects of changing the irradiated volume

• Published in: International journal of radiation oncology, biology, physics Vol. 31; no. 1; pp. 51 - 55
• Main Authors: van den Aardweg, Gerard J.M.J., Hopewell, John W., Whitehouse, Elizabeth M.
• Format: Journal Article
• Language: English
• Published: New York, NY Elsevier Inc 1995; Elsevier
• Subjects: Animals; Applied radiobiology (equipment, dosimetry...); Biological and medical sciences; Biological effects of radiation; CNS; Dose-Response Relationship, Radiation; Female; Fundamental and applied biological sciences. Psychology; Gamma Rays; Neck; NTCP; Paralysis - etiology; Radiation Injuries, Experimental - pathology; Spinal cord; Spinal Cord - radiation effects; Swine; Time Factors; Tissues, organs and organisms biophysics; CNS; Spinal cord; NTCP; Performance evaluation; Correlation; In vitro; Premises; Cervical spinal cord; Pig; In vivo; Vertebrata; Gamma irradiation; Mammalia; Volume; Animal; Complication; Parameter; Artiodactyla; Irradiation field; Ungulata
• ISSN: 0360-3016; 1879-355X
• DOI: 10.1016/0360-3016(94)E0306-5

Purpose : An investigation of the field size effect for the cervical spinal cord of the pig after single doses of γ-rays. In this study, clinically relevant volumes of the spinal cord were irradiated. Methods and Materials : 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 60Co γ-source, at a dose rate 0.21-0.30 Gy/min. The incidence of radiation-induced paralysis was used as the endpoint. The data were analyzed using analysis and a normal tissue complication probability (NTCP-model. Results : 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 association with a 50% incidence of paralysis (ED 50) irrespective of the method of analysis. The ED 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 for paralysis was 7.5–16.5 weeks with no significant differences between dose and field size. Conclusion : No significant field size-related differences in response were detectable in the cervical spinal cord of mature pig after single irradiations, specifically at a clinically relevant level of effect (< ED 10).