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Clinical Implementation and Evaluation of a Limited-Angle Intrafraction Verification (LIVE) System for Lung Radiotherapy

Y Zhang

Y Zhang1*, G Ding2 , X Liu3 , F Yin1 , L Ren1 , (1) Duke University Medical Center, Durham, NC, (2) Vanderbilt University , Nashville, TN, (3) Medical Physics Graduate Program, Duke University, Durham, NC


SU-H3-GePD-J(A)-4 (Sunday, July 30, 2017) 4:00 PM - 4:30 PM Room: Joint Imaging-Therapy ePoster Lounge - A

Purpose: LIVE has been previously developed for 4D intrafraction target verification during arc delivery or between 3D/IMRT beams [1,2]. Simulation and experimental studies using anthropomorphic phantoms demonstrated the accuracy of LIVE using limited-angle kV/MV projections. This study aims to develop a workflow for implementing the LIVE system for its clinical evaluation through lung cancer patient trials.

Methods: Patient planning 4D-CT and on-board 4D-CBCT scans were acquired. On-board 4D-CT image volume was generated phase by phase by deforming the prior CT volume based on the on-board kV projections acquired for each respiratory phase over the full scanning angle. This on-board 4D-CT was used as the ground-truth images for LIVE evaluation. Both limited angle on-board kV and MV projections were generated from on-board 4D-CT using Monte-Carlo simulation. Using the prior planning CT image and the limited angle kV and MV projections from the Monte-Carlo simulation, the on-board 4D-CBCT was reconstructed by LIVE and was compared to the ground-truth on-board 4D-CT to evaluate its accuracy. Note that the angles used in this study to simulate the kV and MV projections were from a clinical 4D-CBCT scan for a real patient.

Results: A feasible clinical workflow for evaluation of the LIVE system has been established. 4D images of one lung cancer patient has been used for proving the methodology of evaluation. Preliminary validation showed that LIVE can reconstruct lung tumor volume accurately using kV and portal MV projections acquired within orthorgonal-30° scanning angle. More patient studies are warranted to further evaluate LIVE for different treatment techniques and patient scenarios.

Conclusion: LIVE has a great potential for 4D intrafraction verification of lung cancer radiotherapy. The establishment of this clinical process allows us to comprehensively evaluate the system through a large cohort of patients to optimize and implement LIVE effectively in clinical practice.

Funding Support, Disclosures, and Conflict of Interest: This work was supported by NIH grant R01 CA-184173.

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