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- Title
Interfractional Variations of Tumor Centroid Position and Tumor Regression during Stereotactic Body Radiotherapy for Lung Tumor.
- Authors
Yanan Sun; Yufei Lu; Siguo Cheng; Wei Guo; Ke Ye; Huiyun Zhao; Xiaoli Zheng; Dingjie Li; Shujuan Wang; Chengliang Yang; Hong Ge
- Abstract
Purpose. To determine interfractional changes of lung tumor centroid position and tumor regression during stereotactic body radiation therapy (SBRT). Methods and Materials. 34 patients were treated by SBRT in 4-5 fractions to a median dose of 50Gy. The CT scans acquired for verification were registered with simulation CT scans. The gross target volume (GTV) was contoured on all verification CT scans and compared to the initial GTV in treatment plan system. Results. The mean (±standard deviation, SD) three-dimension vector shift was 5.2 ± 3.1 mm. The mean (±SD) interfractional variations of tumor centroid position were -0.7 ± 4.5mm in anterior-posterior (AP) direction, 0.2 ± 3.1mm in superior-inferior (SI) direction, and 0.4 ± 2.4mm in right-left (RL) direction. Large interfractional variations (⩾5 mm) were observed in 5 fractions (3.3%) in RL direction, 16 fractions (10.5%) in SI direction, and 36 fractions (23.5%) in AP direction. Tumor volume did not decrease significantly during lung SBRT. Conclusions. Small but insignificant tumor volume regression was observed during lung SBRT. While the mean interfractional variations of tumor centroid position were minimal in three directions, variations more than 5mm account for approximately a third of all, indicating additional margin for PTV, especially in AP direction.
- Publication
BioMed Research International, 2014, Vol 2014, p1
- ISSN
2314-6133
- Publication type
Article
- DOI
10.1155/2014/372738