Imaging for pelvic radiotherapy

Three dimensional (3D) imaging is key to the successful planning and delivery of pelvic radiotherapy treatment and is integrated into every step of the radiotherapy treatment pathway. Diagnostic and therapeutic imaging technology has evolved in the last decade, increasing the complexity of imaging choices available for target localisation, and introducing soft tissue visualisation into the treatment room. These technologies are particularly relevant to pelvic targets where the ability to identify the soft tissue target in 3D and the surrounding organs at risk (OAR) with clarity have driven the development of advanced planning techniques and adaptive strategies, leading to reduced margins and clinical benefit of reduced toxicity and personalisation of radiotherapy delivery. This article will review the importance of imaging in pelvic radiotherapy at key points in the radiotherapy planning pathway namely target delineation, verification and adaptation.