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Purpose: The spot position is an important beam parameter in the quality assurance of scanning proton therapy. In this study, we investigated dosimetric impact of systematic 15 spot position errors (SSPE) in spot scanning proton therapy using three types of optimization methods of head and neck tumor. Materials and Methods: The planning simulation was performed with ± 2 mm model SSPE in the X and Y directions. Treatment plans were created using intensity-modulated proton therapy (IMPT) and single-field uniform dose (SFUD). IMPT plans were created by two optimization methods: with worst-case optimization (WCO-IMPT) and without (IMPT). For clinical target volume (CTV), D95%, D50%, and D2cc were used for analysis. For organs at risk (OAR), Dmean was used to analyze the brain, cochlea, and parotid, and Dmax was used to analyze brainsetem, chiasm, optic nerve, and cord. Results: For CTV, the variation (1 standard deviation) of D95% was ± 0.88%, 0.97% and 0.97% to WCO-IMPT, IMPT, and SFUD plan. The variation of D50% and D2cc of CTV showed <0.5% variation in all plans. The dose variation due to SSPE was larger in OAR, and worst-case optimization reduced the dose variation, especially in Dmax. The analysis results showed that SSPE has little impact on SFUD. Conclusions: We clarified the impact of SSPE on dose distribution for three optimization methods. SFUD was shown to be a robust treatment plan for OARs, and the WCO can be used to increase robustness to SSPE in IMPT. [ABSTRACT FROM AUTHOR]

Abstract  An aneurysm of the middle-colic artery, associated with segmental arterial mediolysis (SAM), is a rare condition. This report describes a case of a middle-colic artery aneurysm that was associated with SAM. A 57-year-old man was admitted to our hospital because of severe abdominal pain. A rupture of a middle-colic artery aneurysm was diagnosed by computed tomography, and angiography showed that it may have been associated with SAM. The ruptured aneurysm was successfully treated with transcatheter arterial embolization. Transcatheter arterial embolization might be one of the best treatments for such a complicated aneurysm occurring in a visceral artery. [ABSTRACT FROM AUTHOR]