Abstract

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Title:: Measurement of changes in bladder volume and dosimetric variations in intensity-modulated radiotherapy for cervical cancer

Author(s):: MIN Mengzhen; QIU Minmin; ZHONG Jiajian; XIAO Zhenhua; DENG Yongjin; Department of Radiation Oncology, the First Affiliated Hospital, Sun Yat-sen University, Guangzhou 510080, China

Keywords:: ; cervical cancer; bladder volume; cone beam CT; dosimetric variation

Abstract:: Objective To measure and study the changes in bladder volume and dosimetric variations during intensity-modulated radiotherapy for cervical cancer. Methods The bladder was segmented based on cone beam (CBCT) image to obtain the shape of bladder that reflects the actual treatment condition. The segmented structure was transplanted into a planning CT image for comparison, and the dose was calculated to obtain the changes in bladder volume and dosimetric variations. Results The bladder volume in CBCT image was generally smaller than that in planning CT image, and the bladder volume showed a decreasing trend with the increase of the course of treatment. Because of the effects of volume changes, the bladder dose in CBCT image was generally higher than that in planning CT image. The intersection volume percentage of bladder structure and PTV2 was strongly correlated with Dmean and V50 (correlation coefficient=0.700, 0.785), with statistical significance (P=0.000), which indicated that there was an obvious linear relationship. Conclusion The measurement results of this study provides references for the limitation of bladder dose in radiotherapy plan for cervical cancer.