TY - JOUR
T1 - Dose-Volume Effects in Rat Thoracolumbar Spinal Cord
T2 - The Effects of Nonuniform Dose Distribution
AU - Philippens, Mariëlle E.P.
AU - Pop, Lucas A.M.
AU - Visser, Andries G.
AU - van der Kogel, Albert J.
N1 - Funding Information:
Supported by a grant from the Dutch Cancer Society (KUN-99-2080).
PY - 2007/9/1
Y1 - 2007/9/1
N2 - 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 192Ir γ-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%) 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 D24 (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 [ED50] = 32.3) and lateral WM (ED50 = 33.7 Gy) compared with the dorsal (ED50 = 25.9 Gy) and ventral nerve roots (ED50 = 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.
AB - 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 192Ir γ-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%) 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 D24 (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 [ED50] = 32.3) and lateral WM (ED50 = 33.7 Gy) compared with the dorsal (ED50 = 25.9 Gy) and ventral nerve roots (ED50 = 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.
KW - Dose-volume effects
KW - Nonuniform dose distribution
KW - Normal tissue complication probability
KW - Spinal cord
KW - White matter necrosis
UR - http://www.scopus.com/inward/record.url?scp=34547850172&partnerID=8YFLogxK
U2 - 10.1016/j.ijrobp.2007.05.027
DO - 10.1016/j.ijrobp.2007.05.027
M3 - Article
C2 - 17707274
AN - SCOPUS:34547850172
SN - 0360-3016
VL - 69
SP - 204
EP - 213
JO - International Journal of Radiation Oncology Biology Physics
JF - International Journal of Radiation Oncology Biology Physics
IS - 1
ER -