The success of radiotherapy treatment relies in accurately localizing the target region
close to tumor as well as avoiding damage to the nearby healthy organ. In order to control the tumor
growth and minimize side effects to the patient, it is crucial to make some substantial modifications
on the patient’s anatomy due to the reduction of the patient’s weight; shrinkage of the tumor; and
the edema of the tissue before the treatment. For surgery consideration, an efficient registration
method to delineate the clinically critical objects in computed tomography images obtained from
the radiation treatment process is needed. Over the last decades, the Deformable Image Registration
Model has undergone intensive investigation from researchers in the fields of computer vision, remote
sensing, and etc. Despite the significant progress that has been made, deformable registration
remains a challenging problem in the field of radiotherapy. In this paper, we discuss several Cancer
Growth Models, as well as the Deformable Image Registration techniques used in Radiotherapy
treatment and finally, the model of Quenching-induced deactivation of photosensitizer to improve
phototherapy of cancer will be introduced.