The Ethos system (version 2.0, Varian Medical Systems, Palo Alto, CA) is an online adaptive radiotherapy (ART) platform that can automatically replan based on the daily anatomical structure and achieve precise dose delivery. However, the highly automated online ART workflow may sometimes lead to excessive dose accumulation within the target in adaptive plan. This article reports a cervical cancer case in which hot spots appeared in the adaptive plan during adaptive treatment session. In these adaptive plans with hot spots, the edge of target was close to the multi-leaf collimator (MLC) boundary, resulting in limited leaf movement and reduced modulation flexibility. Therefore, we propose an improved online ART workflow to correct the deviation of the target, which effectively reduced the risk of hot spots in adaptive plan. This article discusses the problem occurrence, clinical response strategies and improved ART workflow, aiming to provide reference for improving the quality of adaptive plan and safety and stability of ART.
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Jiang et al. (2026) studied this question.
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