Room: Room 209
Purpose: This study reports the world-first clinical use of Venezia advanced gynecological applicator in HDR intracavitary and Syed brachytherapy for locally advanced cervical cancer treatment.
Methods: We have been clinically using the Venezia HDR applicator since July 2017. From November 2017 to February 2018, eleven patients with cervical cancer were treated using the advanced features/accessories of the Venezia applicator (Elekta, Stockholm), including two lunar ovoid tubes, one intrauterine tube, two vaginal caps, one perineal template, and needles with guiding tubes. Two of those patients (stage IIIB and IVA) were treated as a combined technique of interstitial Syed (6 and 11 needles) and Ring & Tandem (R&T-Syed). Both patients received 45Gy whole pelvis EBRT before brachytherapy. Afterwards, one patient received R&T-Syed with 28Gy in 4 fractions and the other patient received 26.4Gy in 4 fractions. GTV, IR-CTV and HR-CTV were contoured by physicians based on multi-parametric MRI. The first fraction treatment was then planned in Oncentra TPS (version-4.5.2) based on CT scans. Dose from R&T-Syed and EBRT were normalized to 2Gy-equivalent (EQD2). The full parameter addition based worksheet from American Brachytherapy Society was used for dosimetric evaluation of the EBRT and brachytherapy dose composite. Before treatment, the pre-treatment CT was registered to the initial planning CT to verify the applicator location and anatomical consistency.
Results: HR-CTV D90 for two cases were 88.0 GyÎ±/Î²=10 and 88.8 GyÎ±/Î²=10, respectively, while one case had GTV D90 of 117 GyÎ±/Î²=10. Bladder D2cc were 77.8 GyÎ±/Î²=3 and 77.3 GyÎ±/Î²=3; Rectum D2cc were 65.2 GyÎ±/Î²=3 and 65.6 GyÎ±/Î²=3; Sigmoid D2cc were 66.5 GyÎ±/Î²=3 and 64.7 GyÎ±/Î²=3.
Conclusion: The Venezia is capable of treating targets that cannot be covered by traditional applicators. In addition, the Venezia applicator can cover gross tumor with higher dose (150% of the prescription dose) while maintaining low dose to the critical structures.