PUSHPA NAGA CH
TATA MEMORIAL HOSPITAL
SENIOR RESEARCH FELLOW

Umesh Mahantshetty
Professor
Tata Memorial Hospital

Yogesh Ghadi
Medical Physicist
Tata Memorial Hospital

Dheera Aravindakshan
Medical Physicist
Tata Memorial Hospital

Lavanya Gurram
Assistant Professor
Tata Memorial Hospital

Jamema Swamidas
Medical Physicist
Tata Memorial Hospital

Supriya Chopra
Associate professor
Tata Memorial Hospital

Background and Purpose: A newly designed, add on cap template which fits to the commercially available Vienna ring applicator allows for additional oblique needles in the lateral parametrium (1). Here we report a dosimetric comparison of the advanced Vienna Brachytherapy (BT) application utilizing the oblique needles (Vienna-II) as compared to Vienna Application without utilizing the oblique needles (Vienna-I).

Methods: A total of 30 cervical cancer patients treated with Vienna-II advanced BT Application between Jan 2011 and Dec 2016 were analyzed. All patients were delivered with 45-50 Gy of EBRT followed by 2 BT applications to a dose of 21-28 Gy in 3-4 fractions prescribed to High Risk CTV (HR-CTV). The EBRT and BT doses were normalized to EQD2 and compiled. Three dimensional treatment planning based on MRI (n=27)/CT (n=3) imaging was done. The planning principles included standard loading pattern for the intracavitary applicator with stepwise dwell weight adaptation and needle loading optimization (maximum 20% of intracavitary contribution) to achieve an optimal target coverage and organ at risk (OAR) sparing. Optimized plans of Vienna-I application loading only parallel needles were generated retrospectively at a reasonably similar OAR doses to achieve optimum target doses. The resultant DVH parameters of target coverage and OAR’s were compared to the treated Vienna-II plan.

Results: The mean (±SD) HRCTV volume was 63 ± 20 cm3. The mean (±SD) needles loaded in Vienna-I and Vienna-II plan were 5 (±1) and 8 (±2), respectively. The total oblique needles used were 3 (±2), while the mean depth of needle insertion was 4.5 (±0.2) cm. Significant differences for Vienna-II as compared to Vienna-I plans were derived for dose application to the target volume; HR-CTV, D98 was 75±7 Gy Vs. 65±6 Gy (p=<0.001) and D90 was 85±9 Gy Vs. 74±9 Gy (p=<0.001). On the contrary, mean ± SD 2cm3 doses to OAR’s were similar for bladder: 89±11 Gy Vs. 84±12 Gy (p=<0.001), rectum: 71±7 Gy Vs. 69±7 Gy (p=<0.001) and sigmoid: 70±10 Gy Vs. 68±10 Gy (p=<0.001). An absolute dosimetric gain of 11 Gy to target volume was achieved with comparable doses to OAR.

Conclusions: The Vienna-II BT application using additional oblique needles allows for better target doses with optimal sparing of OAR’s in cervical tumors with persistent lateral parametrial disease at the time of BT.

References

1. Berger D, Pötter R, Dimopoulos JC, et al. New Vienna applicator design for distal parametrial disease in cervical cancer. Brachytherapy. 2010 Apr 1;9:S51-2.


← Back to all abstracts