The Clinical Use Of The Ring Applicator With IC/IS-IGBT In The Treatment Of Cervical Cancer

Objective:To analysis the clinical use of the Ring applicator combined intracavitary/interstitial with locally advanced cervical cancer,to find out the indications about this applicator.Methods:This study included 95 patients with locally advanced cervical cancer treated with radical radiotherapy from November 2014 to October 2016.There were 43 patients received external beam radiotherapy(45Gy/25f)followed by the combined intracavitary/interstitial brachytherapy with the Ring applicator.Among them,61 times(group IC/IS)were used in the combination of intracavitary/interstitial with the Ring applicator,then these treatments plan were be replanned in the intracavitary brachytherapy alone(group IC).Compared the dose results of the two groups with paired t tests.Explored the relationship between the HR-CTV D90 with the target volume.Four planes were selected in the vertical direction of the uterine cervix,above the surface of the Ring,at the distance of 1cm below ICRU-A,ICRU-A,at the distance of 1 cm above ICRU-A,and the four planes were divided into eight same sections which were marked from NO.1?8 at clockwise.The relationship of the HR-CTV and D90 were analyzed,and prescribed dose curve encompassed sections of HR-CTV were described.Results:The use rate of Ring applicator was 45.3%in china,and only D=26mm types were used.The HR-CTV D90 in group IC/IS were significantly higher than that of group IC alone(p=0.00/0.00).The D2cm3 value about Group IC/IS in bladder and rectum were significantly lower than those in group IC alone(p=0.00/0.01).There was no significant difference between the two groups of D2cm3 in sigmoid colon and small intestines(p=0.091/0.199).The prescribed dose coverage rate of group IC/IS was 93.2%,which was significantly higher than that of group IC alone in each direction.Prescribed dose coverage of target less than 60%were at 3(48.1%),4(44.4%),6(51.8%),7(44.4%)directions in the plane B,at 3(44.4%),4(48.1%),6(44.4%),7(51.8%)in the plane C,at the 6(44.4%),7(51.8%)directions in plane D.The distance from prescription dose curve to cervix-axis larger than 20mm at 3,4,6,7 directions on plane B,17.8mm at all directions on plane C,17mm at all directions on plane D.Conclusion:In china,the Ring applicator can be used in locally advanced cervical cancer with limited conditions,only about half of patients can be treated with the Ring applicator.The extension of tumor invasion more than 20mm?17.8mm?17mm,the intracavitary alone can not meet the clinical requirements.In such a case,patients should be treated with the combined interstitial/intracavitary brachytherapy.