Abstract:

Objective To investigate the effect of changes in volume and position of the bladder and rectum on target volume in patients with advanced cervical cancer using intensity- modulated radiotherapy. Methods A total of 16 cases of intensity- modulated radiotherapy in patients with cervical cancer were analyzed，and CBCT imaging was performed at radiotherapy doses of 9 Gy/5f，18 Gy/10f，27 Gy/15f，36 Gy/20f and 48.6 Gy/27f. CBCT images were integrated with the original CT image，and the target volume and organs at risk （OARs） were outlined. Dose volume histograms （DVH） were used to analyze changes in volume，volume change rate and DICE similarity of rectum，bladder and other organs. Results Mean volume of bladder was 88.48-195.49 cm³；rectum，40.41-42.93 cm³；sigmoid，792.85-907.86 cm³；and intestine，38.49-49.05 cm³. Bladder volume varied significantly from 0f to 27 f （P<0.05），but the other organs did not differ significantly in volume change rate（delta V%，P>0.05） and in DICE similarity （DSC，P>0.05）. Bladder volume rate and rectal volume showed a significant negative correlation with the DSC of the gross target volume （GTV- T） and the corpus （CTV- T） （P<0.05）. Conclusions Volume and location of the bladder，rectum and other organs changed substantially during intensity- modulated radiation therapy of cervical cancer. Volume change rate of bladder and rectum negatively correlated with the DSC of GTV-T and CTV-T.