Experimental Study Of Different Spinal IGRT Programs By Detection Of MRI In Radiated Spinal Cord Injury

Objective: Explore different spine image guided radiation therapy (IGRT) optimizedprograms through detecting the spinal cord injury by magnetic resonance imaging(MRI).Methods: Choose36male adult Beagles according to L12(3x23) orthogonal table IGRTin7~12thoracic vertebral.Conventional MRI and diffusion weighted imaging (DWI)were carried out every2weeks before radiotherapy and after began to radiotherapy; andin3months after radiotherapy of live animals were put to death to take the dog of thesame segment, the same location in (thoracic vertebral7~12) spinal cord.HE andTUNEL staining was used to observe the morphological changes in the spinal cord cellsunder light microscope. Results:①MRI: in conventional radiotherapy began4weeks ofvisible T1WI,T1WI、T2WI signals corresponding vertebrae were increased,6weeksbetween normal and abnormal vertebral " boundaries "; but the spinal T1WI, T2WIshowed no abnormality. By the DWI sequence can be seen, in beagle dogs afterradiotherapy, the spinal cord and peripheral muscle signal increased, the highest signal at6weeks. Diffusion coefficient values in DWI table (apparent diffusion coefficient, ADC)in each group were increased in different degrees after radiotherapy, and the ADC valueswere between groups. Conclusion: DWI is more sensitive than the conventional MRI onradiation injury of spinal cord detection, can be detected in the spinal IGRT regularly, inorder to prevent the occurrence of radiation injury of spinal cord. The better spinal IGRTprogram is the single dose of16Gy, dose rate for4Gy/min, field number as9wild and theequal angle.