Image-Guided Thoracic Surgery using a Mobile C-Arm for CBCT: Image Quality, Dose, and First Experience in Imaging the Fully Deflated Lung

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1 Image-Guided Thoracic Surgery using a Mobile C-Arm for CBCT: Image Quality, Dose, and First Experience in Imaging the Fully Deflated Lung S Schafer, 1 A Uneri, 1 DJ Mirota, 1 S Nithiananthan, 1 JW Stayman, 1 W Zbijewski, 1 G Kleinszig, 2 C Schmidgunst, 2 M Sussman, 1 and JH Siewerdsen 1 1. The Johns Hopkins University 2. Siemens Healthcare AG Johns Hopkins University Schools of Medicine and Engineering Video-Assisted Thoracoscopic Surgery Early-stage lung cancer detection Low-dose CT screening Sub-palpable nodule (< 10 mm) Thoracoscopic Surgery Minimally invasive technique using intercostal ports Comparable to open thoracic surgery with the benefits of minimal invasive surgery Nodule Identification Preoperative marking (e.g. Hookwire) High error rate (15%) Design of an intraoperative C-Arm centered guidance system Mayo Clinic 1

2 C-Arm Centered Guidance System Mobile C-Arm for CBCT Flat-Panel Detector Motorized Orbit Geometric Calibration High-Speed 3D reconstruction Isotropic Voxel Size: 0.3 mm Dedicated Guidance System Fusion of data sets Tool tracking Video augmentation Thoracoscope 30 Scope Dedicated calibration Image Quality - CNR phantom - Fresh torso cadaver - Porcine specimens (inflated and deflated lung) Radiation Dose - QRM thorax phantom - Minimum-dose protocols - Fusion of CT/CBCT - Tracked thoracoscope - Video overlay of CBCT and planning data Experimentation 2

3 Imaging the Deflated Lung Imaging Task: soft-tissue nodules in the deflated lung -Porcine model, freshly diseased, ventilated -Deflation of the lung after breach of pleura Inflated Deflated Phantom Study CNR and Dose -10% air retention in lung ~ HU contrast -Target: CNR ~1 1.5 mm 0.9 mm 0.3 mm Slice Thickness (mm) Radiation Dose (mgy) 3

4 Animal Model Nodule Study Porcine Model: Inflated Lung 3 mm Nodule 6 mm Nodule Radiation Dose (mgy) Animal Model Nodule Study Porcine Model: Inflated and Deflated Lung 7.22mGy / 1.63 msv Slice Thickness (mm) Slice Thickness (mm) Inflated Collapsed Inflated Collapsed 4

5 Animal Model Nodule Study Porcine Model: Inflated Lung MIP Rendering Calibration -Extrinsic, intrinsic parameters -Radial, decentering, thin prism -Checkerboard pattern -Overlay accuracy Video stream CT rendering Preclinical Testing -Plastinated Lung -Anthropomorphic Phantom -Cadaver Specimen -Simulated nodule -Anatomical Structure -Targeting 5

6 Non-Calibrated Calibrated ε 4 ε 3 ε 1 ε 2 ε= 9.71 mm ε= 2.35 mm 6

7 Thoracoscope Navigation - Tracked Camera - Virtual Structures - Tool Indicator - Target Delineation Slice Navigation - Tracked Pointer -Planned Structures - Target Delineation -CT enhanced Conclusion Radiation Dose Nodules visible in inflated and deflated lung Scan dose allows repeat intraoperative scanning Thoracoscopic Video Overlay Target overlay useful for wedge resection Critical structure overlay useful for segmentectomies and lobectomies Surgical Experimentation Data sources integrated: intraoperative CBCT, preoperative data (CT, planning), video stream Future Work Registration methods from inflated to collapsed Deformation estimation from video stream 7

8 Conclusion Surgical Experimentation Data sources integrated: intraoperative CBCT, preoperative data (CT, planning), video stream Phantom and cadaver studies in vivo studies (future work) Workflow simplification Future Work - Improved registration methods from inflated to collapsed - Deformation estimation from video stream - Motion-compensation reconstruction (motion artifacts from contralateral lung) - Further dose reduction possible with advanced reconstruction methods Acknowledgments The I-STAR Laboratory Imaging for Surgery, Therapy, and Radiology Hopkins Collaborators School of Medicine: M. Sussman, D. Reh, G. Gallia, M. Mahesh J. Khanna, J. Carrino, S. Mears, A. Machado School of Engineering: R. Taylor, G. Hager, J. Prince, J. Lee. Funding Support National Institutes of Health Siemens Healthcare (XP, Erlangen) 8