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Objective@#To investigate the effect of Utrecht applicator on dosimetrics of targets and OARs in brachytherapy for advanced cervical cancer.@*Methods@#Data of patients with locally advanced cervical cancer who received brachytherapy with Utrecht Source Applicator from 2017 to 2018 in the Department of Radiotherapy, Cangzhou Hospital of Integrated Traditional Chinese and Western Medicine, Hebei province, were collected. The original plan was intracavitary /interstitial brachytherapy (IC/IS-BT). With the original contour and prescription dose unchanged, the implantation was removed and new intracavitary brachytherapy (IC) plan was designed. The dosimetric parameters of IC/IS plan and IC plan were compared and analyzed, and the effect of IS implantation on dose was evaluated.@*Results@#The D90 of HR-CTV was (88.68±1.84) Gy in IC/IS group and (85.54±0.54) Gy in IC group, with significant difference(t=6.200, P<0.05). In addition, conformity index of the IC/IS plan was significantly higher than that of the IC plan (IC/IS: 0.58±0.08, IC: 0.43±0.05; t=1.010, P<0.05). In terms of OAR, there was no significant difference in dosage between the two groups (P>0.05).@*Conclusions@#For the brachytherapy of locally advanced cervical cancer, the use of Utrecht Source Applicator can satisfy the prescription dose coverage. Adding IS insertion needle can improve the optimization space of the plan. Without exceeding the dose limit of OAR, the radiation dose to HR-CTV can be significantly increased, and the uniformity of dose distribution can be improved as well.
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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.