ABSTRACT
Objective To investigate the clinical application of Utrecht applicator in three-dimensional image-guided brachytherapy (3D-IGBT) for locally advanced cervical cancer,as well as its application discipline in intracavitary/interstitial (IC/IS) therapy.Methods A retrospective analysis was performed for the clinical data of 45 patients with locally advanced cervical cancer who received radical radiotherapy,and the patients received external beam radiotherapy followed by 3D-IGBT.A total of 130 times (n =45) of IC/IS therapy were performed,and the patients who received such therapy were all enrolled.The patients who met the target dose fractionation defined in the plan were enrolled as group A (n=37,86 times),and the other patients were enrolled as group B (n=22,44 times).Two groups difference was analyzed with Group t-test.Results The frequencies of use of 15-,20-,and 25-mm ovoids by the applicator were 50.0％,20.0％,and 30.0％,respectively,and the 30-mm ovoid was not used.A total of 499 needles were used,and the frequencies of use of 6,7,10,and 11 insertion holes were 23.1％,21.2％,21.2％,and 24.1 ％,respectively.Group A had a significantly lower mean number of the needles than group B (3.7 vs.4.2,P=0.008).Compared with group B,group A had a significantly lower mean high-risk clinical target volume (CTV)(40.71±18.43 cm3 vs.51.81±14.74 cm3,P=0.001),as well significantly lower width and height of high-risk CTV (P=0.011 and 0.006),but the thickness of high-risk CTV was similar between the two groups (P=0.595).The difference between height and insertion depth (DH) was similar between the two groups (P=0.366).Group A had a smaller difference between width and pinhole distance Dw than group B (P=0.007).Conclusions When IC/IS therapy is performed for locally advanced cervical cancer,the 15-,20-,and 25-mm ovoids of Utrecht applicator and 6,7,10,and 11 insertion holes are frequently used.When the number of needles is no less than 4 and the depth is no less than 3 cm,width is the major factor which affects the planned dose.