Review and recommendations on deformable image registration uncertainties for radiotherapy applications

Abstract

Deformable image registration (DIR) is a versatile tool used in many applications in radiotherapy (RT). DIR algorithms have been implemented in many commercial treatment planning systems providing accessible and easy-to-use solutions. However, the geometric uncertainty of DIR can be large and difficult to quantify, resulting in barriers to clinical practice. Currently, there is no agreement in the RT community on how to quantify these uncertainties and determine thresholds that distinguish a good DIR result from a poor one. This review summarises the current literature on sources of DIR uncertainties and their impact on RT applications. Recommendations are provided on how to handle these uncertainties for patient-specific use, commissioning, and research. Recommendations are also provided for developers and vendors to help users to understand DIR uncertainties and make the application of DIR in RT safer and more reliable.

Improving hybrid image and structure-based deformable image registration for large internal deformations

“…Our aim is to explore this option further, for instance, if applying ANACONDA+ in an adaptive cervical cancer treatment planning setting. Within that work, it would also be of interest to do a thorough validation study, both including other metrics, inspired by Brock et al (2017), Nenoff et al (2023), as well as a more diverse patient set to show under which circumstances ANACONDA+ is robust and accurate for dose accumulation. The recent review article by Murr et al (2023) points out the importance of such studies.…”

“…Despite the widespread usage of DIR, deformation algorithms encounter challenges when dealing with complex deformations that involve significant anatomical changes and organ displacements, leading to DIR uncertainties (Nenoff et al 2023). Such scenarios commonly arise in reRT cases, where a considerable time gap may exist between image acquisitions (Nix et al 2022, Vásquez Osorio et al 2023; also in pelvic cases, characterized by difficulties in achieving consistent bladder and rectum filling (Thörnqvist et al 2010) and internal risk organ movements (Ghose et al 2015); and, finally, in brachytherapy procedures, where an applicator is present in only one of the images (Vásquez Osorio et al 2015).…”