Encrypted login | home

Program Information

Consistency of Treatment Volume Vs. Bladder and Rectum Anatomical Variations with Fractionated High-Dose Rate GYN Brachytherapy Using Multi Lumen Cylinders

M Shojaei

M Shojaei*, N Dumitru , S Pella , T Leventouri , Florida Atlantic University, Boca Raton, Florida


SU-I-GPD-J-104 (Sunday, July 30, 2017) 3:00 PM - 6:00 PM Room: Exhibit Hall

Purpose: This study will evaluate the consistency of the treated volume and the critical organs anatomical variation over the entire multi fractionated treatment. These variations can induce dose variation to the organs at risk which summarized over the entire treatment may manifest regions with high exposure. This study will look into the consistency of the High Dose Rate brachytherapy in GYN treatments using the MLC to provide a correct total maximum dose delivered to the PTV and the critical organs.

Methods: A retrospective analysis of 125 treatment plans of 30 cervical cancer patients that were generated in the treatment planning system Oncentra, and imported in Eclipse for registration and performing plan sum. A study was conducted to find the variations in the treated volume and the critical organs over the treated fractions. Landmarks and manual registration were done for each patient for all the fractions delivered to fulfill the prescription. Furthermore, the applicator’s average shift range in regard to the organs at risk was studied. Cumulative dose volume histograms were generated for all the organs such that the total delivered dose to the planning target volume and the critical organs can be evaluated.

Results: An isodose chart was generated and traced over the entire treatment and in the plan summation, with the 100%, 85%, 75% isodose lines. Maxima and minima of the PTV were analyzed in regards to the displacement of the cylinder and the position variation of the critical organs. Dose variations to the critical organs were observed.

Conclusion: Based on this study, significant variations were found between each fraction for bladder and rectum in a few of the patients. Deformable registration and adaptive planning are recommended for each additional fraction following the initial. Immobilization devices need improvement as well to prevent any displacement during transportation and treatment delivery.

Contact Email: