Cone-Beam Computed Tomography (CBCT) cannot directly scan to access Time-Density Curve (TDC) in the functional imaging. In order to solve the problem, a mathematical model of CBCT imaging was proposed to get the perfusion parameters. First, the area integral model of the simulated projection data was established, the CBCT projection data was simulated by using the New Zealand white rabbits Dynamic Contrast Enhanced CT (DCE-CT) image. The function model was established by using the projection data and the model parameters were solved by using optimization numerical technique. The approximate TDC of each voxel was obtained, the correctness of function model was verified by comparing the approximate TDC and the actually measured TDC. The perfusion parameters were solved by using the deconvolution model and the optimization parameters. The similarity of the simulation TDC solved by area integral model and actual TDC reached 82.91%. The simulation TDC could be used to calculate the perfusion parameters and get pseudo color image. CBCT projection data and function model can be used to get approximate TDC of voxel and tissue perfusion parameters, and achieve the purpose of CBCT functional imaging.

In order to realize function imaging guided radiotherapy combined with image-guided radiotherapy and function imaging, this paper studied the possibility of Computed Tomography (CT) perfusion imaging using cone-beam CT on image-guided radiotherapy. To solve the problem that Cone-Beam Computed Tomography (CBCT) cannot obtain precise Time-Density Curve (TDC) because of low speed imaging, this paper proposed a method of modeling a mathematically model based on projection data. At first, the CBCT projection data was simulated with computer simulation technology. Then the density values of voxel were mathematical modeled. Finally, concrete parameters were calculated using computer programming and computer optimal solution technology. The experiment proves that the TDC received from the proposed model and the Dynamic Contrast Enhanced CT (DCE-CT) have high similarity. Hence, it can be proved that realizing CBCT in image-guided radiotherapy perfusion imaging by the proposed model was feasible.