Dose-Volume Effects in Rat Thoracolumbar Spinal Cord: The Effects of Nonuniform Dose Distribution
- Department of Radiation Oncology, Radboud University Nijmegen Medical Center, Nijmegen (Netherlands)
Purpose: To investigate dose-volume effects in rat spinal cord irradiated with nonuniform dose distributions and to assess regional differences in radiosensitivity. Methods and Materials: A total of 106 rats divided into three groups were irradiated with {sup 192}Ir {gamma}-rays at a high dose rate. The groups were irradiated with one, two, or six catheters distributed around the thoracolumbar spinal cord to create different dose distributions. After irradiation, the animals were tested for motor function for 9 months. The response was defined as motor dysfunction and WM or nerve root necrosis. Dose-response data were analyzed with a probit analysis as function of the dose level at a percentage of the volume (D{sub %}) and with different normal tissue complication probability models. Additionally, the histologic responses of the individual dose voxels were analyzed after registration with the histologic sections. Results: The probit analysis at D{sub 24} (24% of the volume) gave the best fit results. In addition, the Lyman Kutcher Burman model and the relative seriality model showed acceptable fits, with volume parameters of 0.17 and 0.53, respectively. The histology-based analysis revealed a lower radiosensitivity for the dorsal (50% isoeffective dose [ED{sub 50}] = 32.3) and lateral WM (ED{sub 50} = 33.7 Gy) compared with the dorsal (ED{sub 50} = 25.9 Gy) and ventral nerve roots (ED{sub 50} = 24.1 Gy). Conclusions: For this nonuniform irradiation, the spinal cord did not show typical serial behavior. No migration terms were needed for an acceptable fit of the dose-response curves. A higher radiosensitivity for the lumbar nerve roots than for the thoracic WM was found.
- OSTI ID:
- 21036217
- Journal Information:
- International Journal of Radiation Oncology, Biology and Physics, Vol. 69, Issue 1; Other Information: DOI: 10.1016/j.ijrobp.2007.05.027; PII: S0360-3016(07)00940-6; Copyright (c) 2007 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA); ISSN 0360-3016
- Country of Publication:
- United States
- Language:
- English
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