Finite Element Analysis Of Cervical Vertebra Based On Protection Of Spinal Cord Radiotherapy And Clinical Trial

Spinal cord,noted as the life center of human,bears harsh restriction on limitation of radiation dose.Since the move frequency of cervical vertebra is extremely high and the anatomy is complicated,the protection of cervical spinal cord on radiotherapy seems difficult.The present method of localization couldn't completely stabilize cervical vertebra to avoid any deviation of angles and position during the whole radiotherapy procedure.This thesis established the finite element model of cervical vertebra and raised solutions on fixing position of spinal cord and correcting radiation dose.Because both the anatomic structure and forces of cervical vertebra are complicated,this thesis proposed the method of finite element modeling using clinical patients' CT images in order to study the impact imposed by the position change of cervical vertebra on localization of radiotherapy: All the images were collected from real clinical patients experiencing radiotherapy to ensure the effectiveness of modeling.The images extraction,mechanical properties importation,force analysis and et al are based on mimics,Hypermesh and Optistruct softwares.The results showed that force from one single side would cause movement of every vertebra towards different directions and leading to different displacements.Based on the results of the finite elements analysis,to increase the accuracy of localization,this thesis proposed using individualized three-dimensional conformal body phantom as the localization pattern,which significantly raised the repeatability of localization for cervicalvertebra comparing with standardized head pillow after clinical contrast experiments.However,for completely stabilization,some gaps still existed,which made errors when transforming localization accuracy to dose accuracy.In order to elevate the precision of radiotherapy,this thesis adopted deformation registration complying with three-dimensional conformal body phantom to produce registration images.This method was proved to be better on decreasing the dosage error after comparing dosage with similarity coefficient.