Abstract

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Title:: Bedplate correction in intensity-modulated radiotherapy plan: a dosimetric analysis

Author(s):: ZHOU Jun; HUANG Sheng; LIU Chongwu; Department of Oncology, Sichuan Provincial Corps Hospital CAPF, Leshan 614000, China

Keywords:: ; Keywords: intensity-modulated radiotherapy; accelerator bedplate; bedplate correction; dosimetry

Abstract:: Abstract: Objective To analyze the dosimetric effects of the correlation of accelerator bedplate and positioning bedplate in intensity-modulated radiotherapy (IMRT) plan. Methods Fourteen patients with esophageal cancer receiving chest positioning of carbon board and 14 postoperative patients with cervical cancer receiving abdominal positioning of organic board were selected. IMRT plans were designed with corrected bedplate or uncorrected bedplate. A total of 4 groups of plan data were obtained. Then IMRT plans were imported into the verification phantom for plan verification. Five dose verification reference points were selected at the isocenter layer, and the absorbed dose at reference points were measured with ionization chamber dosimeter. The statistical analysis was performed on the measured 10 groups of data. Results The average attenuation of bedplate was 3.4%-6.6%. The dose error of bedplate before and after correction was 3.0%-4.5% in patients with esophageal cancer, with an average of 3.8%, P=0.000; while the dose error of bedplate before and after correction was 3.5%-4.6% in postoperative patients with cervical cancer, with an average of 4.1%, P=0.000. Conclusion In the process of IMRT planning, if the back beam or back-flank beam passes through the bedplate, the dose attenuation of the bedplate should be considered and the dose correction must be performed on accelerator bedplate and positioning bedplate.