Re-Irradiation: Current Status, Challenges and Opportunities
Description
Re-irradiation is increasingly used for patients with local recurrence or new tumors adjacent to a previously irradiated site. However, high-level evidence on re-irradiation is scarce, particularly the safety and toxicity from cumulative dose. Moreover, there is substantial heterogeneity across institutions in the methods to evaluate cumulative dose. A major obstacle is the lack of widely available functionalities and tools for reliable image registration and for assessment of 3D cumulative dose in equivalent dose in 2-Gy fractions (EQD2) with organ-specific a/b and recovery factors. Image registration in re-irradiation can be challenging especially if there are substantial anatomical changes induced by previous irradiation such as fibrosis. Deformable image registration may allow for a more accurate and consistent assessment of cumulative dose compared to rigid registration. Normal tissue imaging biomarkers could potentially be used to assess organ-specific recovery from previous irradiation, thereby may allow individualized assessment of safety of re-irradiation. This symposium seeks to bring together experts to discuss the current status of re-irradiation and imaging-related challenges and opportunities for advancing re-irradiation. The first speaker, Dr. Mayo will describe the current status of imaging, planning and evaluation of re-irradiation. The second speaker, Dr. Osorio will describe the potential for deformable image registration to improve accuracy and consistency in quantifying cumulative dose and discuss challenges. Finally, Dr. Yamamoto will review normal tissue imaging biomarkers for assessment of radiotherapy-induced injury and discuss their potential uses in the setting of re-irradiation.