Background: CT based 3 dimensional imaged based brachytherapy allows volumetric optimization with 3 D planning leading to better tumor coverage and critical organ sparing as compared to 2 D radiography based brachytherapy.
Material and Methods: Between Nov 2017 and Nov 2018, sixteen patientsdiagnosed cases of carcinoma cervix received EBRT 46Gy over 23 fractions or 50 Gy over 25 fractions with concurrent Inj Cisplatin 40 mg per metre square weekly. These patients were treated with 31 sessions of CT based Intracaviatary brachytherapy. After intracavitary application non-contrast CT simulation was performed. HRCTV, Bladder, Rectum and Sigmoid were contoured on Oncentra. Dose to point A, ICRU Bladder and Rectal points were recorded. DVH parameters HRCTV(D90, D100), Volumetric doses 1cc and 2 cc for bladder, rectum and sigmoid were recorded. The mean ICRU points were compared with mean 1cc, 2cc doses. Point A doses were also compared with HRCTV.
Results: The mean Point A dose delivered was 100.3% of prescribed dose as compared to mean D90 =76.6% and D100= 55.23% respectively. This study showed that mean HRCTV doses were lower than Point A doses. Organ at Risk OAR analysis showed that bladder received 88.7% of prescribed dose at ICRU bladder point. While Volumetric 1cc and 2cc mean doses were 113.4% and 102.4% of prescribed dose respectively. Dose delivered at rectal ICRU point was 81.7% as compared to 1cc and 2cc which were 69.4% and 62.03% of prescribed dose respectively. DVH analysis showed that Sigmoid received mean 1cc and 2cc dose 40.62 % and 34.39% of prescribed dose respectively.
Conclusion: Our study suggests that HRCTV doses are lower than point A doses while DVH parameters do not correlate with ICRU points. Volumetric 2cc and 1cc bladder doses are higher than ICRU bladder dose while 2cc and 1cc rectal doses are lower than ICRU rectal point dose.
