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WE‐E‐AUD A‐02: Real‐Time Motion‐Adapted‐Optimization (MAO) Guided TomoTherapy Delivery
Author(s) -
Lu W,
Chen M,
Chen Q,
Mauer C,
Ruchala K,
Lucas D,
Zhang J,
Olivera G
Publication year - 2008
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.2962769
Subject(s) - tomotherapy , computer science , projection (relational algebra) , imaging phantom , dosimetry , computer vision , artificial intelligence , real time computing , simulation , algorithm , nuclear medicine , medicine , radiation therapy
Purpose: IMRT delivery follows planned leaf sequences, which are optimized before treatment delivery. Real‐time variations, such as respirations, are hardly to be modeled in planning procedure. We developed a real‐time Motion‐Adapted‐Optimization (MAO)‐guided delivery technique in TomoTherapy SM treatments. This technique models the radiation delivery with the real‐time motion as a negative feedback system. It updates the motion‐encoded cumulative dose and optimizes the leaf sequence in real‐time, right before the delivery of each projection. Method and Materials: TomoTherapy SM treatment delivery consists of thousands of projections with projection time around 200–500 ms. The leaf latency plus transition of TomoTherapy® binary MLC takes less than 50 ms. Real‐time MAO is to optimize leaf sequence of the coming projection right before its execution. It consists of several real‐time procedures including “motion detection and prediction”, “motion‐encoded dose accumulation” and “leaf sequence optimization” for the coming projection. To update leaf sequence in real‐time, all above procedures must be executed within 150 ms. We developed ultra‐fast algorithms and codes to approach such critical goal. We implemented and tested this technique with the TomoTherapy® research system. The integrated system includes a real time camera system and a programmable motor‐driven phantom. We tested different TomoTherapy SM plans with various simulated and real respiration traces. We used film dosimetry to verify and validate the final results. Results: MAO‐guided delivery runs smoothly in the integrated TomoTherapy® system. The whole MAO procedure takes less 100 ms per projection. Both simulated motion and real respiration of ∼2cm amplitude, the real‐time MAO‐guided delivery doses matched with the planning dose within 3% and 3mm criteria, for a typical TomoTherapy SM treatment configuration. No hot and cold spots are noticeable. Conclusion: We present a novel technique for real‐time MAO‐guided delivery within current TomoTherapy® hardware. Simulations and experiments conceptually proved this technique. Further validation and clinical implementation are underway.