Is a Deep Learning Based Segmentation Model Trained on planning CTs Transferable for Segmentation of Organs at Risk in Replanning CTs?

There is a significant difference in the segmentation of OARs in planning and replanning radiotherapy CT images, and the deep learning segmentation model constructed based on planning radiotherapy CTs is not suitable for the segmentation of OARs in replanning radiotherapy CT images. This highlights the need for re-modeling based on replanning CTs and also inspires us to incorporate the prior information contained in planning CTs and their labels into the OARs contouring of corresponding replanning radiotherapy CTs. These will, to some extent, provide insights into potential avenues for enhancing the future segmentation efficacy of adaptive radiotherapy.