Room: AAPM ePoster Library
Purpose: The motion of the liver and pancreas as a result of respiration is a challenge during stereotactic body radiation therapy (SBRT) treatment. Due to the relatively high doses and low number of fractions involved in SBRT treatment plans for liver and pancreatic cancers, accounting for target motion in radiation treatment planning is very essential. Therefore, the goal of this study is to analyze and quantify the motions of both the liver and pancreas to help develop a motion predictive algorithm for SBRT
Methods: We used a data set of 10 liver cancer patients and 10 pancreatic cancer patients who were treated via image-guided radiation therapy (IGRT) using the ViewRay™ MRI-Guided Real-Time On-Table Adaptive Radiotherapy (ROAR) at Barnes-Jewish Hospital. Two-dimensional MR images of the liver and pancreas projected onto the sagittal plane were taken across the span of each treatment fraction. The data was extracted and analyzed using MATLAB 2019b.
Results: Trends between all patients were found to be similar with most tumors having the tendency to move along the caudal-anterior direction. The average tumor shifts were 4.05 ± 1.54 mm and 2.66 ± 1.81 mm for all the liver patients and the pancreatic patients respectively. In addition, it was observed that intra-fractional variation in trend and magnitude of motion was minimal among patients.
Conclusion: Tumor shift variation among patients was found to differ significantly, but the observed intra-fractional variation for individual patients suggest that prediction of the motion should be possible.