A dosimetric analysis of combined intracavitary/interstitial brachytherapy for locally advanced cervical cancer / 中华放射医学与防护杂志

ABSTRACT

Objective To compare the dosimetric differences between intracavitary brachytherapy in combination with interstitial brachytherapy or not for locally advanced cervical cancer.Methods From May 2016 to March 2017,35 patients with locally advanced cervical cancer treated with combined external beams and intracavitary/interstitial brachytherapy were selected in this study.The prescription of intensity-modulated radiation therapy was46.8-50.4 Gy/26-28 fractions,1.8 Gy/fraction.The prescription for combined intracavitary/interstitial brachytherapy was 7 Gy/fraction × 4,once per week.Each patient was first implanted with a three tube applicator for brachytherapy,and the CT images were acquired for treatment planning.The three tube applicator was removed before a uterine tube and needles were implanted,thereafter planning images were acquired again.Dose to the targets and organs at risk were evaluated respectively for the two groups.Results A total of 212 brachytherapy plans were developed,including 106 intracavitary and 106 endoluminal combined interstitial plans.The target dose in endoluminal combined interstitial brachytherapy was significantly higher than that of intracavitary treatment alone,where D90 of the high-risk clinical target volume (CTV) and moderate CTV were both significantly increased (t =-6.01,-2.73,P ＜ 0.05).The D2 cm3 of the bladder,rectum and sigmoid colon were significantly reduced (t=3.07,4.52,2.91,P＜0.05).Conclusions The application of the endoluminal combined interstitial brachytherapy for locally advanced cervical cancer can significantly increase the target dose,and reduce the dose to organs at risk such as the bladder,rectum and sigmoid colon.