Document Detail


Dose-volume effects in rat thoracolumbar spinal cord: the effects of nonuniform dose distribution.
MedLine Citation:
PMID:  17707274     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
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 (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(%)) 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(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(50)] = 32.3) and lateral WM (ED(50) = 33.7 Gy) compared with the dorsal (ED(50) = 25.9 Gy) and ventral nerve roots (ED(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.
Authors:
Mariëlle E P Philippens; Lucas A M Pop; Andries G Visser; Albert J van der Kogel
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  International journal of radiation oncology, biology, physics     Volume:  69     ISSN:  0360-3016     ISO Abbreviation:  Int. J. Radiat. Oncol. Biol. Phys.     Publication Date:  2007 Sep 
Date Detail:
Created Date:  2007-08-20     Completed Date:  2007-10-15     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  7603616     Medline TA:  Int J Radiat Oncol Biol Phys     Country:  United States    
Other Details:
Languages:  eng     Pagination:  204-13     Citation Subset:  IM    
Affiliation:
Department of Radiation Oncology, Radboud University Nijmegen Medical Center, Nijmegen, The Netherlands. m.philippens@rther.umcn.nl
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MeSH Terms
Descriptor/Qualifier:
Animals
Dose-Response Relationship, Radiation
Iridium Radioisotopes
Lumbar Vertebrae
Male
Muscle Strength / radiation effects*
Paralysis / etiology
Paresis / etiology
Radiation Injuries, Experimental / pathology
Radiation Tolerance*
Rats
Rats, Wistar
Reflex / radiation effects*
Spinal Cord / pathology,  physiopathology,  radiation effects*
Thoracic Vertebrae
Chemical
Reg. No./Substance:
0/Iridium Radioisotopes

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