Effects of megavoltage computed tomographic scan methodology on setup verification and adaptive dose calculation in helical TomoTherapy

作者：Jian Zhu, Tong Bai, Jiabing Gu, Ziwen Sun, Yumei Wei, Baosheng Li, Yong Yin · 发表于：Radiation Oncology · 年份：2018 · DOI：10.1186/s13014-018-0989-y · 被引用次数：15 · 研究领域：Advanced Radiotherapy Techniques、Effects of Radiation Exposure、Advances in Oncology and Radiotherapy

BACKGROUND: To evaluate the effect of pretreatment megavoltage computed tomographic (MVCT) scan methodology on setup verification and adaptive dose calculation in helical TomoTherapy. METHODS: Both anthropomorphic heterogeneous chest and pelvic phantoms were planned with virtual targets by TomoTherapy Physicist Station and were scanned with TomoTherapy megavoltage image-guided radiotherapy (IGRT) system consisted of six groups of options: three different acquisition pitches (APs) of 'fine', 'normal' and 'coarse' were implemented by multiplying 2 different corresponding reconstruction intervals (RIs). In order to mimic patient setup variations, each phantom was shifted 5 mm away manually in three orthogonal directions respectively. The effect of MVCT scan options was analyzed in image quality (CT number and noise), adaptive dose calculation deviations and positional correction variations. RESULTS: MVCT scanning time with pitch of 'fine' was approximately twice of 'normal' and 3 times more than 'coarse' setting, all which will not be affected by different RIs. MVCT with different APs delivered almost identical CT numbers and image noise inside 7 selected regions with various densities. DVH curves from adaptive dose calculation with serial MVCT images acquired by varied pitches overlapped together, where as there are no significant difference in all p values of intercept & slope of emulational spinal cord (p = 0.761 & 0.277), heart (p = 0.984 & 0.978), lungs (p = 0.992 & 0.980),...