Effect of bladder volume change on normal tissue doses in 3D conformal brachytherapy for cervical cancer / 中华放射肿瘤学杂志

ABSTRACT

Objective To evaluate the effect of bladder volume change on the doses to normal tissues in cervical cancer patients undergoing external three-dimensional conformal radiotherapy (3DRT)plus 3D conformal brachytherapy (3DCBT).Methods The study included 56 patients with cervical cancer who were admitted to our hospital from 2012 to 2013 and received radical external 3DRT and 3DCBT.During 3DCBT,the doses to 0.1,1.0,and 2.0 cm3(D0.1 cm3,D1.0cm3,and D2.0cm3,respectively) for the rectum,small intestine,sigmoid colon,and bladder under different bladder filling status (empty,50,100,and 150 ml) were compared and analyzed by paired t-test.Results The rectum D0.1cm3 with bladder volumes of 50and 100 ml were significantly reduced compared with that with an empty bladder (P =0.000,0.000).The D0.1 cm3,D1.0cm3,and D2.0cm3 for the small intestine with bladder volumes of 50,100,and 150 ml were significantly reduced compared with those with an empty bladder (P =0.008,0.000,0.000 and 0.000,0.000,0.000 or 0.000,0.000,0.000).The D0.1 cm3,D1.0cm3,and D2.0cm3 for the bladder with bladder volumes of 100 and 150 ml were significantly increased compared with those with an empty bladder (P =0.000,0.000 and 0.000,0.000 or 0.000,0.000).Conclusions The doses to the bladder and small intestine are influenced by different bladder filling status,but the doses to the rectum and sigmoid colon show no significant variation.The increase in bladder volume is helpful in reducing the dose to the small intestine.Without any change in the bladder dose,the bladder volume of 50 ml is more beneficial to reduce the dose to the small intestine than those of 100 and 150 ml.