Image-Guided Radiotherapy Toward Mobile Tumor

Radiotherapy aims to deliver the prescribed radiation dose to the entire volume of moving tumor while avoiding high radiation to the adjacent healthy tissues. Due to the physiological factors, (e.g. respiratory and, to a lesser extent, cardiac motion) the tumor and its surrounding tissue inside the thorax or abdomen move dynamically. Thus the subsequent targeting uncertainty existing in intra-fractional tumor motion and deformation became the main obstacle of intensity- modulated radiation therapy (IMRT), which also gives large challenges to image-guided radiotherapy (IGRT). This article gave an overview of real-time image-guided technologies for radiotherapy, and consisted of four parts of contents, i.e. the article (1) expressly clarified the primary characteristics and the problems in dynamic radiotherapy; (2) introduced the current application level of radiotherapy on imaging, tumor detection, dealing with tumor motion and dynamic treatment; (3) compared solving methods in dealing with the intra-fractional tissue motion; (4) summarized the main aspects and the development direction of the dynamic radiotherapy.