Research For The Veractity Of Functional Imaging Using Volume Intergral Model On Cone-Beam CT

Cancer(tumour)is one of the major diseases which threaten human life and health.Radiation therapy(radiotherapy)destructs cellular structure with ray beams,which is the primary means of cancer therapy.The image-guided radiotherapy(IGRT)improves the accuracy of radiotherapy.Compared with anatomic imaging,functional imaging has better performance in tumor detection.Cone-beam computed tomography(CBCT)is one of equipments for IGRT.CBCT has better image result and less radiation dose than traditional CT equipments.Because of the slow scanning speed,CBCT has not been able to perform functional imaging.However,based on the regularity of density change of tissue,functional imaging simulation can be completed by CBCT perfusion model.It realizes the integration of anatomic and functional imaging.In the research of CBCT functional imaging,the description of projection process will affect the functional imaging results.Therefore,it is very important to study the CBCT projection model.This thesis has completed the following work:1.This thesis has established volume integral model based on CBCT scanning features.Since the scanning situation of center plane of CBCT is the same as fan-beam CT's,this thesis used the tomographic image from fan-beam CT as the scanned object of the research on CBCT functional imaging simulation.Then this thesis obtained simulated projection data by using volume integral model.In order to reduce the cost of time in volume integral model,this thesis used GPU to calculate the projection data of different position of detector detects under the same rotation angle,which improved the operation speed of volume integral model.2.This thesis has used the voxel time density model to get the time density curve(TDC)of the voxel from volume integral model and original image and analyzed the fitting degree of the curves by correlation coefficient.The result showed that the average correlation coefficient between volume integral model and original image is 83.99%.3.This thesis has used the hemodynamic model to solve the perfusion results.Comparing the similarity of the simulated perfusion results obtained from volume integral model with other projection models in different area of tissue and combining with cost of time,the veractity of using volume integral model to implement CBCT functional imaging was verified.