Fast Digital Tomosynthesis for LIVE Radiation Therapy GTC 2015 – San Jose, CA, USA Alexandros-Stavros Iliopoulos 1 Nikos Pitsianis 2 , 1 Xiaobai Sun 1 Fang-Fang Yin 3 Lei Ren 3 1 Department of Computer Science, Duke University 2 Department of Electrical and Computer Engineering, Aristotle University of Thessaloniki 3 Department of Radiation Oncology, Duke University School of Medicine March 19, 2015
Outline 1 Introduction: IGRT & LIVE 2 Cone-beam operators 3 Experiments 4 Discussion 5 Acknowledgements Iliopoulos, Pitsianis, Sun, Yin, Ren Fast Digital Tomosynthesis for LIVE Radiation Therapy GTC15 March 19, 2015 1 / 29
Outline 1 Introduction: IGRT & LIVE 2 Cone-beam operators 3 Experiments 4 Discussion 5 Acknowledgements Iliopoulos, Pitsianis, Sun, Yin, Ren Fast Digital Tomosynthesis for LIVE Radiation Therapy GTC15 March 19, 2015 2 / 29
Image-guided radiation therapy (IGRT) ❼ Highly focused radiation delivery ❼ Volumetric imaging information – Can eliminate early-stage cancer – Pre-treatment planning (above) – Accurate targeting is critical ⋆ On-board target verification during treatment – Post-evaluation Iliopoulos, Pitsianis, Sun, Yin, Ren Fast Digital Tomosynthesis for LIVE Radiation Therapy GTC15 March 19, 2015 3 / 29
Image-guided radiation therapy: challenges ❼ Dynamic deformation: 1 – Intrafraction (respiration, etc) – Tumor displacement, growth/shrinkage – Deviates from planning data – Hampers targeting precision – Complicates projection registration ❼ Clinical considerations for on-board imaging: 2,3 digital XCAT phantom 4D-CT – Low dose – Rapid acquisition (plus tissue deformation for real body) ⋆ High-fidelity, fast digital processing 1 Redmond et al . IJROBP (75), 2009 2 Maurer et al . Medical Physics (37), 2010 3 Ren et al . Medical Physics (41), 2014 Iliopoulos, Pitsianis, Sun, Yin, Ren Fast Digital Tomosynthesis for LIVE Radiation Therapy GTC15 March 19, 2015 4 / 29
Digital Tomosynthesis (DTS) with LIVE DTS (limited-angle scan) CBCT (full scan) patient patient acquisition scan angle: 20 ∘ ∼ 60 ∘ scan angle: 360 ∘ / ∼ 200 ∘ scan time: ∼ 1 min scan time: < 10 sec scan dose: ≤ 1 cGy scan dose: 1 ∼ 8 cGy reconstruction slice Iliopoulos, Pitsianis, Sun, Yin, Ren Fast Digital Tomosynthesis for LIVE Radiation Therapy GTC15 March 19, 2015 5 / 29
Digital Tomosynthesis (DTS) with LIVE DTS (limited-angle scan) CBCT (full scan) patient patient acquisition l a o scan angle: 20 ∘ ∼ 60 ∘ scan angle: 360 ∘ / ∼ 200 ∘ g E scan time: ∼ 1 min scan time: < 10 sec V I L scan dose: ≤ 1 cGy scan dose: 1 ∼ 8 cGy reconstruction slice Iliopoulos, Pitsianis, Sun, Yin, Ren Fast Digital Tomosynthesis for LIVE Radiation Therapy GTC15 March 19, 2015 5 / 29
LIVE overview ❼ Purpose: High-fidelity reconstruction of dynamic volume from limited-angle on-board projections – LIVE is the first prototype of its kind ❼ Key idea: – Use 4D planning CT as prior data – Model on-board volume as deformation of prior CT ❼ Methods: – Prior respiratory motion model + free-form (voxel-wise) deformation field – Complementary kV-MV projections ⋆ Iterative deformable registration (computation-intensive) Ren et al . IJROBP (82), 2012 Zhang et al . Medical Physics (40), 2013 Ren et al . Medical Physics (41), 2014 Iliopoulos, Pitsianis, Sun, Yin, Ren Fast Digital Tomosynthesis for LIVE Radiation Therapy GTC15 March 19, 2015 6 / 29
LIVE imaging/therapy system One of the radiosurgery systems at Duke (Novalis Tx) 1 1 Chang et al . JACMP (33), 2012 Iliopoulos, Pitsianis, Sun, Yin, Ren Fast Digital Tomosynthesis for LIVE Radiation Therapy GTC15 March 19, 2015 7 / 29
LIVE imaging/therapy system radiotherapy/MV kV source source kV detector MV detector One of the radiosurgery systems at Duke (Novalis Tx) 1 1 Chang et al . JACMP (33), 2012 Iliopoulos, Pitsianis, Sun, Yin, Ren Fast Digital Tomosynthesis for LIVE Radiation Therapy GTC15 March 19, 2015 7 / 29
LIVE DTS algorithm 1 3D volume + phase respiratory phases selection reference on-board volume prior 4D-CT volume rendering V ( φ ) V ( φ r ) phase estimation respiratory DFE refinement & initial DFE motion field DRR-OBI DRR-OBI ∂ ∂φ [ ∇ xyz V ( φ )] registration registration principal motion components on-board proj. images P ( θ ) image stack 1 Zhang et al . Med Phys (40), 2013 Iliopoulos, Pitsianis, Sun, Yin, Ren Fast Digital Tomosynthesis for LIVE Radiation Therapy GTC15 March 19, 2015 8 / 29
LIVE DTS algorithm 1 output input pre-processing model-based free-form deformation field deformation field 3D volume + phase estimation estimation respiratory phases selection reference on-board volume prior 4D-CT volume rendering V ( φ ) V ( φ r ) phase estimation respiratory DFE refinement & initial DFE motion field DRR-OBI DRR-OBI ∂ ∂φ [ ∇ xyz V ( φ )] registration registration principal motion components on-board proj. images P ( θ ) image stack 1 Zhang et al . Med Phys (40), 2013 Iliopoulos, Pitsianis, Sun, Yin, Ren Fast Digital Tomosynthesis for LIVE Radiation Therapy GTC15 March 19, 2015 8 / 29
LIVE DTS algorithm 1 3D volume + phase respiratory phases selection volume reference on-board volume prior 4D-CT volume rendering V ( φ ) V ( φ r ) field estimate deformation phase estimation (DFE) respiratory DFE refinement & initial DFE motion field DRR-OBI DRR-OBI ∂ ∂φ [ ∇ xyz V ( φ )] registration registration principal motion components projections on-board proj. images P ( θ ) image stack 1 Zhang et al . Med Phys (40), 2013 Iliopoulos, Pitsianis, Sun, Yin, Ren Fast Digital Tomosynthesis for LIVE Radiation Therapy GTC15 March 19, 2015 8 / 29
LIVE DTS algorithm 1 3D volume + phase respiratory phases selection reference on-board volume prior 4D-CT volume rendering V ( φ ) V ( φ r ) phase estimation respiratory DFE refinement & initial DFE motion field DRR-OBI DRR-OBI ∂ ∂φ [ ∇ xyz V ( φ )] registration registration principal motion (iterative) components computational bottleneck on-board proj. images P ( θ ) image stack 1 Zhang et al . Med Phys (40), 2013 Iliopoulos, Pitsianis, Sun, Yin, Ren Fast Digital Tomosynthesis for LIVE Radiation Therapy GTC15 March 19, 2015 8 / 29
Iterative DRR-OBI registration 1. Digitally reconstructed Planning CT DRR ( θ = 1 ◦ ) forward radiographs (DRRs) for projections volume-image registration DRR [ k ] V [ k ] θ (︄ Planning CT DRR ( θ = 1 ◦ ) OBI ( θ = 1 ◦ ) )︄ ∑︂ f [ k ] 2. Registration fidelity f = , θ θ DRR [ k ] OBI [ k ] θ θ 3. Deformation field estimate ∇ p f ( θ ) backward (DFE) update along pixel projections and voxel gradients ∇ DRR f [ k ] ∇ V f [ k ] V [ k +1] θ Iliopoulos, Pitsianis, Sun, Yin, Ren Fast Digital Tomosynthesis for LIVE Radiation Therapy GTC15 March 19, 2015 9 / 29
A glance at output and timing Planning CT DRR OBI DTS DRR 1m25s vs. 1h30m 1,2 6m22s 5m23s 1 Yan et al . Medical Physics (34), 2007 2 Zhang et al . Medical Physics (40), 2013 Iliopoulos, Pitsianis, Sun, Yin, Ren Fast Digital Tomosynthesis for LIVE Radiation Therapy GTC15 March 19, 2015 10 / 29
Outline 1 Introduction: IGRT & LIVE 2 Cone-beam operators 3 Experiments 4 Discussion 5 Acknowledgements Iliopoulos, Pitsianis, Sun, Yin, Ren Fast Digital Tomosynthesis for LIVE Radiation Therapy GTC15 March 19, 2015 11 / 29
❼ ❼ ❼ Forward & backward cone-beam projections + θ − θ detector object y x z − θ + θ source Staub & Murphy. Medical Physics (40), 2013 Feldkamp et al . JOSAA (1), 1984 Katsevich. IJMMS (21), 2003 Iliopoulos, Pitsianis, Sun, Yin, Ren Fast Digital Tomosynthesis for LIVE Radiation Therapy GTC15 March 19, 2015 12 / 29
❼ ❼ Forward & backward cone-beam projections ❼ Forward projections: DRR generation + θ − θ detector – Volumetric ray-casting operator (primary effects) – Secondary effects (scatter, etc) beyond this talk FWD object y x z − θ + θ source Staub & Murphy. Medical Physics (40), 2013 Feldkamp et al . JOSAA (1), 1984 Katsevich. IJMMS (21), 2003 Iliopoulos, Pitsianis, Sun, Yin, Ren Fast Digital Tomosynthesis for LIVE Radiation Therapy GTC15 March 19, 2015 12 / 29
❼ Forward & backward cone-beam projections ❼ Forward projections: DRR generation + θ − θ detector – Volumetric ray-casting operator (primary effects) – Secondary effects (scatter, etc) beyond this talk BWD object ❼ Backward projections: DFE update – Filtered back-projection operator y x z − θ + θ source Staub & Murphy. Medical Physics (40), 2013 Feldkamp et al . JOSAA (1), 1984 Katsevich. IJMMS (21), 2003 Iliopoulos, Pitsianis, Sun, Yin, Ren Fast Digital Tomosynthesis for LIVE Radiation Therapy GTC15 March 19, 2015 12 / 29
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