The Study Of Spinal Cord Biosafety Of Image Guided Radiation Therapy Of Spine In Beagle

Objective:Section One: Establishment the model of the image guided radiation therapy ofspinal in beagle, by comparing the the biological safety effect in spinal cord of differentprograms spine image guided radiation therapy in beagle, inorder to screen the highesttotal irradiation doses.Section Two: Based on the orthogonal design principle, throughthe MRI, electromyography detecting radiotherapy after spinal cord injury, this paperdiscusses the spine IGRT plan: different levels of radiation dose, radiation field,segmentation dose rate, radiation angle to the influence degree of the spinal cord injury,in order to optimize the combination the biological safety of spinal cord best radiationscheme. Section Three: Based on the orthogonal design principle, through the HEstaining and transmission electron microscope, TUNEL (terminal deoxynucleotidyltransferase mediated dUTP nick and labeling) method, immunohistochemistry methodsand RT-PCR method were used after spinal cord injury, this paper discusses the spineIGRT plan: different levels of radiation dose, radiation field, segmentation dose rate,radiation angle to the influence degree of the spinal cord injury, in order to optimize thecombination the biological safety of spinal cord best radiation scheme.Methods:Section One: Select purebred beagles and six were randomly divided: Six beagleswere irradiated by eight different models of IGRT, and the total irradiation doses were50Gy60Gy70Gy80Gy90Gy and100Gy. Mimic a beagle clinical model of tumor inthe seventh and twelveth thoracic vertebrae. The samples of spinal cord and vertebralbody bone tissue were taken out from the same locum of the seventh and twelveththoracic vertebrae on third month after radiation. The samples of the vertebral body bone tissue were observed by the hematoxylin and eosin stain and the electron microscop. Thesamples of the spinal cord were observed by the hematoxylin and eosin stain and theelectron microscopee, to observe the change of the spinal nerve cells, spinal vascularendothelial cell ultrastructure. Terminal deoxynucleotidyl transferase mediated dUTPnick and labeling (TUNEL) technique was used to examine the apoptotic cells in thespinal nerve cells. Section Two: Spine IGRT plan includes: radiation dose (16Gy,20Gy),radiation field (5,7,9wilds), segmentation dose rate (4Gy/min,6Gy/min), radiationangle (equal angle, unequal angle), using L12(3×23) orthogonal test table to the abovefactors on distribution, a total of12beagles needed. Repeat the experiment two times, atotal of36beagles needed. Choose36male adult beagles, random number table methodrandom, in5weeks on the each beagles chest7～12vertebral bodies for IGRT.Conventional MRI and diffusion-weighted imaging (DWI) were carried out every2weeks before radiotherapy and after began to radiotherapy. Cortical somatosensoryevoked potential (CSEP) and motorevoked potentialminimum-error-probability (MEP)were carried out before radiotherapy and radiotherapy after12hours,1day,1week,2weeks respectively.Section Three: Spine IGRT plan includes: radiation dose (16Gy,20Gy), radiation field (5,7,9wilds), segmentation dose rate (4Gy/min,6Gy/min),radiation angle (equal angle, unequal angle), using L12(3×23) orthogonal test table to theabove factors on distribution, a total of12beagles needed. Repeat the experiment twotimes, a total of36beagles needed. Choose36male adult beagles, random number tablemethod random, in5weeks on the each beagles chest7～12vertebral bodies for IGRT.The samples of spinal cord were taken out on the3th month after radiation. The sampleswere observed by the hematoxylin and eosin stain and the electron microscope. Terminaldeoxyn-ucleotidyl transferase mediated dUTP nick and labeling (TUNEL) technique wasused to examine the apoptotic cells in the spinal cord. The expression of Caspase-3andCaspase-3mRNA were evaluated in spine by immunohistochemistry and RT-PCR.Results:Section One:①This research application method can simulate the spine clinicalimage-guided radiation therapy, the dog experiment smoothly, and good effect.②Theresults of the the hematoxylin and eosin stain and the electron microscope, and theexpression of Caspase-3and Caspase-3mRNA evaluated in spine byimmunohistochemistry and RT-PCRprompted that: if the total radiation dose was80Gy,then achieved osteonecrosis pathological standard, vertebral body bone regeneration were no longer. The total radiation dose if more than80Gy, the spinal cord biological safetycouldnot be guaranteed. Section Two:①DWI, CSEP and MEP can sensitively detectspinal cord injury after spine IGRT.②DWI, CSEP and MEP suggested: when radiationdose was16Gy, segmentation dose rate was4Gy/min, radiation field was9wilds andradiation angle was equal angle, the biological safety of the spinal cord was thebest.Section Three:①The results of the the hematoxylin and eosin stain and the electronmicroscope, the terminal deoxynucleotidyl transferase mediated dUTP nick and labeling(TUNEL) technique, and the expression of Caspase-3and Caspase-3mRNA evaluated inspine by immunohistochemistry and RT-PCR prompted that: when radiation dose was16Gy, segmentation dose rate was4Gy/min, radiation field was9wilds and radiationangle was equal angle, the biological safety of the spinal cord was the best.Conclusions:Section One:①Research provides a beagle accurate spine image-guided radiationtherapy model establishment method.②Through the screening beagle spine IGRTradiotherapy planning, to ensure the safety of the spinal cord in biological premise, the80Gy is the biggest total dose radiation therapy. Section Two:①DWI, CSEP and MEPcan sensitively detect spinal cord injury after spine IGRT. DWI, CSEP and MEP could bedetected in the spine IGRT periodically to prevent the occurrence of radioactive spinalcord damage occurs.②The better spine IGRT program is radiation dose of16Gy,segmentation dose rate of4Gy/min, radiation field of9wilds and radiation angle of equalangle.Section Three:①HE staining and transmission electron microscope, TUNELresults, immune histochemical method and RT-PCR method to detect Caspase3proteinand mRNA expression results and DWI, is the result of MEP and CSEP can match.②The better spine IGRT program is radiation dose of16Gy, segmentation dose rate of4Gy/min, radiation field of9wilds and radiation angle of equal angle.