Upright radiation therapy systems: Requirements, performance and benefits

Upright radiotherapy treatment, though historically explored, is re-emerging as a viable approach for delivering stereotactic radiosurgery (SRS) and stereotactic body radiation therapy (SBRT). While most radiotherapy is administered with patients in a supine or prone position, treating patients in an upright position may offer significant advantages. This includes improved patient comfort, reduced lung motion, and increased accessibility for non-ambulatory or pain-limited patients that would be changed with current supine treatments. Technological advancements in patient simulation, immobilization, and image guidance now allow for safe and effective upright treatment delivery. A major limitation in adopting upright radiotherapy has been the lack of commercially available upright imaging systems needed throughout the radiotherapy process. Recent developments, including the adaptation of existing linear accelerators for upright imaging and the introduction of specialized upright CT and patient positioning systems, have worked to address this challenge. Additionally, innovative solutions for treatment planning, including synthetic imaging techniques and deformable image registration, are enhancing the feasibility of upright treatment workflows. Patient setup and motion management are critical in SRS/SBRT, where precision is paramount. Recent studies have demonstrated sub-millimeter accuracy in upright treatment positioning, comparable to conventional supine techniques. Moreover, upright radiotherapy presents economic benefits by reducing infrastructure costs and enabling more compact treatment centers. This paper explores the technological advancements supporting upright SRS/SBRT, its clinical implications, and the necessary steps for widespread adoption. With ongoing vendor collaborations and further research, upright radiotherapy has the potential to become a standard approach, expanding treatment accessibility while maintaining high precision and efficacy.