Towards Personalized Imaging in Image-guided Radiotherapy

Recently, with the advent of linear accelerators equipped with on-board x-ray images and advanced imaging technologies, image-guided radiotherapy (IGRT) has gained worldwide momentum in the radio therapeutic management of cancers in terms of volumetric information-based accurate tumor localization, real-time patient setup and margin reduction [1,2]. The involved technologies include digital radiography, computed tomography (CT), cone beam CT (CBCT), magnetic resonance imaging (MRI), positron emission tomography (PET), and megavoltage electronic portal imaging device (EPID) etc. [1] Figure 1 illustrates the three modalities that have been most widely used in IGRT, where CT is primarily used for treatment planning dose calculation while kVCBCT and EPID are mainly for tumor localization and patient setup. By focusing highly conformal tumoricidal doses to the cancerous tissues, higher tumor control with reduced normal tissue complication is expected.