Objective: Investigate the temporal effects of focused ultrasound (FUS)-induced blood–brain barrier (BBB) opening in post-radiotherapy mouse brains. Methods and materials: C57B6 mice without tumors were used to simulate the scenario after gross total resection (GTR) of brain tumor. Radiation dose of 6 Gy x 5 was delivered to one-hemisphere of the mouse brain. FUS-induced BBB-opening was delivered to the irradiated and non-irradiated brain and was confirmed with MRI. Dynamic MRI was performed to evaluate blood vessel permeability. Two time points were selected: acute (2 days after radiation) and chronic (31 days after radiation). Results: BBB opening was achieved after FUS in the irradiated field as compared to the contralateral non-irradiated brain without any decrease in permeability. In the acute group, a trend for higher gadolinium concentration was observed in radiated field. Conclusion: Localized BBB-opening can be successfully achieved without loss of efficacy by FUS as early as 2 days after radiotherapy. Advances in knowledge: Adjuvant radiation after GTR is commonly used for brain tumors. Focused ultrasound facilitated BBB-opening can be achieved without loss of efficacy in the post-irradiated brain as early as 2 days after radiation therapy. This allows for further studies on early application of FUS-mediated BBB-opening.

Anal cancer is a rare malignancy with rising incidence. Definitive treatment with radiation and concurrent chemotherapy represent the standard of care for patients with non-metastatic disease. Advances in radiation delivery through the use of intensity-modulated radiotherapy have significantly reduced the toxic effects of treatment. Adaptive radiotherapy (ART) has emerged as a strategy to further enhance treatment precision and individualize therapy in response to patient-specific changes during the course of chemoradiotherapy. The rationale for ART in anal cancer stems from the recognition that significant anatomic and tumor changes can occur throughout the 5–6-week treatment course, including tumor shrinkage, weight loss, and variable rectal/bladder filling. This review discusses the role of ART in contemporary anal cancer management. We overview the principles of ART, delineate the technical workflows (including both computed tomography (CT) and MR-guided approaches), and examine how adaptive techniques are applied in treatment planning and delivery. We also review the clinical evidence to date, including dosimetric studies and emerging clinical trial data on ART in anal cancer, particularly its impact on outcomes and toxicity.