7 research outputs found
Dictionary learning-based reverberation removal enables depth-resolved photoacoustic microscopy of cortical microvasculature in the mouse brain
Evaluation of 2D and 3D ultrasound tracking algorithms and impact on ultrasoundâguided liver radiotherapy margins
Purpose: Compensation for respiratory motion is important during abdominal cancer treatments. In this work we report the results of the 2015 MICCAI Challenge on Liver Ultrasound Tracking and extend the 2D results to relate them to clinical relevance in form of reducing treatment margins and hence sparing healthy tissues, while maintaining full duty cycle.Methods: We describe methodologies for estimating and temporally predicting respiratory liver motion from continuous ultrasound imaging, used during ultrasoundâguided radiation therapy. Furthermore, we investigated the tradeâoff between tracking accuracy and runtime in combination with temporal prediction strategies and their impact on treatment margins.Results: Based on 2D ultrasound sequences from 39 volunteers, a mean tracking accuracy of 0.9 mm was achieved when combining the results from the 4 challenge submissions (1.2 to 3.3 mm). The two submissions for the 3D sequences from 14 volunteers provided mean accuracies of 1.7 and 1.8 mm. In combination with temporal prediction, using the faster (41 vs 228 ms) but less accurate (1.4 vs 0.9 mm) tracking method resulted in substantially reduced treatment margins (70% vs 39%) in contrast to midâventilation margins, as it avoided nonâlinear temporal prediction by keeping the treatment system latency low (150 vs 400 ms). Acceleration of the best tracking method would improve the margin reduction to 75%.Conclusions: Liver motion estimation and prediction during freeâbreathing from 2D ultrasound images can substantially reduce the inâplane motion uncertainty and hence treatment margins. Employing an accurate tracking method while avoiding nonâlinear temporal prediction would be favorable. This approach has the potential to shorten treatment time compared to breathâhold and gated approaches, and increase treatment efficiency and safety.</br