Name
Shunyu Yan
Major
Molecular Bioscience / Biophysics
Class
2023
About
Shunyu Yan comes from Chongqing. She has been fascinated by Medical Physics since sophomore year, which drove her to conduct radiotherapy-related SW.
Shunyu Yan comes from Chongqing. She has been fascinated by Medical Physics since sophomore year, which drove her to conduct radiotherapy-related SW.
This research aims to investigate the effect of CBCT on positioning uncertainty and analyze the dose variation associated with it. Four cancer types were examined: brain, head & neck, breast, and esophagus. Positioning uncertainty analysis based on couch correction data indicates that breast and esophagus cancer have relatively lower positioning accuracy compared with brain and head & neck cancer. Respiratory effect and patients’ shape change are two essential factors contributing to positioning uncertainty. Besides, higher uncertainty is observed in the longitudinal direction, which is possibly due to the involuntary neck movement of patients during treatment. The dose distribution difference due to setup error is calculated by rigid image registration with the Varian Eclipse system. The actual dose distribution without image guidance rarely meets the requirement of V100 (≥95%) and D95 (≥100%). This indicates that the treatment of cancer patients without IGRT is not recommended. The benefit of IGRT with CBCT to patient localization accuracy decreases the risk of receiving unintended doses. This project helps to investigate the importance of IGRT with CBCT before treatment and quantify its role in radiotherapy. Future research may focus on exploring the correlation between setup error and dose distribution and clinical outcomes.
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