Abstract book - ESTRO meets Asia

S100 ESTRO meets Asia 2018

PO-243 Dosimetric plan evaluation of HDR tandem and ovoid brachytherapy in locally advanced cervical cancer A. Waheed 1 1 Aga Khan University Hospital, Radiation Oncology, Karachi, Pakistan Purpose or Objective The intracavitary vaginal brachytherapy is an integral part in the treatment of locally advanced cervical cancer. High Dose Rate (HDR) brachytherapy allows shorter treatment times, better tumor control and eliminates radiation exposure hazards. Several studies have validated the use of HDR brachytherapy by using 2-Dimensional (2D) treatment planning. The purpose of this study is to evaluate 2D HDR Brachytherapy planning of our patients in terms of dose distribution in order to accurately determine bladder and rectal doses Material and Methods The study involved a cohort of 20 patients of locally advanced cervical cancer (IIB – IVB) treated with definitive chemoradiation therapy. All patients were given External Beam Radiation (EBRT) with concurrent chemotherapy before Brachytherapy. Mean age was 52 years, out of 20 patients 9 were given 5040 cGy / 28 fractions and 11 were given 4500 cGy / 25 fractions of EBRT. Tandem and ovoid brachytherapy was delivered at a dose of 8 Gy / fraction for 3 fractions. Twelve patients were given cisplatin alone while 08 were given cisplatin and gemcitabine. The Brachytherapy therapy planning was done on Manchester system and dose limits were determined by American Brachytherapy society guidelines. The plans were optimized to take into consideration the mean dose to the bladder, rectum and point A. Results The mean rectal, bladder and point A doses were 408cGy, 468.7cGy and 747cGy respectively. Two patients were identified in which mean rectal and bladder doses were greater than 75% & 80% of the total prescribed dose This study demonstrated that although the optimal doses were delivered using 2D HDR brachytherapy planning in majority of patients, but the factors like variability in applicator insertions and packing resulted in increased dose to OARS in few patients. PO-244 Assessment of applicator stability in two packing techniques of HDR brachytherapy of cervical cancer R. Dhanapalan 1 , N. Patil 1 , S. Kandasamy 1 , J. Pandjatcharam 1 1 Jipmer, Department of Radiotherapy, Puducherry, India Purpose or Objective In HDR intracavitary brachytherapy of cervical cancer, optimal vaginal packing with gauze helps to reduce radiation doses to the rectum and bladder. Balloon packing has been evaluated in a few trials. In this study, we aim to assess the stability of the applicator by comparing the rectal and bladder doses between pre and post-treatment CT plans in both packing techniques. Material and Methods 27 patients and 54 data sets from the clinical trial registered with CTRI number CTRI/2018/04/013460 were included in the analysis. Each patient underwent both packing techniques. Combined packing includes foleys catheter balloon threaded onto tandem and inflated with 30ml along with gauze packing. CT based treatment plans with 8.5Gy prescribed to Point A were generated. Patients were treated and post-treatment CT scans were taken before the removal of the applicator. Post-treatment CT plans were generated with the same dwell points and dwell times as pre-treatment CT plans. Comparison of rectal and bladder doses between pre and post-treatment respectively Conclusion

CT plans was done using paired samples t-test for each packing technique. Mean time interval between CT simulation and treatment and also the time between treatment and post-treatment CT scans were calculated. Results Mean time interval between CT simulation and treatment is 91 minutes and the time interval between treatment

and post-treatment CT scan is 26 minutes. Dosimetric values are tabulated in table 1

Conclusion Stability of the applicator assessed by comparing rectal and bladder doses between pre and post-treatment CT plans was not statistically significant in both vaginal gauze and combined packing technique. PO-245 Patterns of loco-regional recurrence after definitive chemo-radiotherapy for cervical cancer G. Babu 1 , S. Mathews 1 , P.G. Jayaprakash 2 , P. George 3 , A. Kumar 1 , J. Joseph 1 , F. James 1 1 Regional Cancer Centre, Department of Radiation Oncology, Thiruvanathapuram, India 2 Regional Cancer Centre-Retired, Department of Radiation Oncology, Thiruvanathapuram, India 3 Regional Cancer Centre, Department of Epidemiology and Statistics, Thiruvanathapuram, India Purpose or Objective The addition of concurrent chemotherapy to radiotherapy and the incorporation of three-dimensional (3D) imaging into brachytherapy have resulted in improved loco- regional control and cure rates in the last two decades. While concurrent chemotherapy was readily incorporated into practice, the uptake of technological advancements