Effects of different bladder filling volumes on target area and organs at risk during three-dimensional brachytherapy of postoperative early cervical cancer / 中华放射医学与防护杂志

ABSTRACT

Objective:To investigate the optimal bladder filling volume in the 3D brachytherapy of postoperative cervical cancer.Methods:Totally 111 early cervical cancer patients with positive incisal margins or insufficient safety boundaries were included. The normal saline 50, 60, 70, 80, 90, and 100 ml were filled into their bladders, and accordingly six groups were determined, and 66, 69, 66, 69, 72, 56 person-times in each group, respectively. The CT-based simulation positioning was performed. According to the ICRU 89 report, high-risk clinical target volume and organs at risk such as bladder and rectum were delineated. The Oncentra planning system was used to prepare the treatment program. The high-risk clinical target volume (HR-CTV), D90, and the D2 cm 3 and D1 cm 3 of organs at risk under different volumes were recorded. Results:Compared to the 60 ml group, the volume and dosage of HR-CTV in the groups of 50, 70, 80, 90, and 100 ml had no significant difference ( P>0.05). The D2 cm 3 and D1 cm 3 of the bladder and rectum of patients in these groups significantly decreased, and the difference was statistically significant ( tbladder = 3.21, 5.83, 2.89, 12.95, 7.96, Pbladder = 0.031, 0.010, 0.041, 0.000, 0.001; trectum = 2.94, 4.66, 2.53, 5.89, 4.13, Prectum = 0.037, 0.024, 0.049, 0.005, 0.028). The pairwise comparison among these groups except for the 60 ml group showed that the volume and dosage of HR-CTV and the D2 cm 3 and D1 cm 3 of bladder and rectum had no significant difference ( P > 0.05). Moreover, the D2 cm 3 and D1 cm 3 of sigmoid colon and small intestine of these groups had no significant difference ( P > 0.05). Conclusions:In the 3D brachytherapy of postoperative early cervical cancer, a bladder filling volume of 60 ml can ensure the volume and dose of HR-CTV and can protect the bladder and rectum compared with other filling volumes.