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1. W. Li, T. G. Purdie, M. Taremi, S. Fung, A. Brade, B. C. Cho, A. Hope, A. Sun, D. A. Jaffray, A. Bezjak, and J. P. Bissonnette, “Effect of immobilization and performance status on intrafraction motion for stereotactic lung radiotherapy: analysis of 133 patients,” Int. J. Radiat. Oncol., Biol., Phys. 81, 15681575 (2011).
2. T. G. Purdie, J. P. Bissonnette, K. Franks, A. Bezjak, D. Payne, F. Sie, M. B. Sharpe, and D. A. Jaffray, “Cone-beam computed tomography for on-line image guidance of lung stereotactic radiotherapy: localization, verification, and intrafraction tumor position,” Int. J. Radiat. Oncol., Biol., Phys. 68, 243252 (2007).
3. B. Cho, P. R. Poulsen, A. Sawant, D. Ruan, and P. J. Keall, “Real-time target position estimation using stereoscopic kilovoltage/megavoltage imaging and external respiratory monitoring for dynamic multileaf collimator tracking,” Int. J. Radiat. Oncol., Biol., Phys. 79, 269278 (2011).
4. J. R. van Sornsen de Koste, M. Dahele, H. Mostafavi, S. Senan, L. van der Weide, B. J. Slotman, and W. F. Verbakel, “Digital tomosynthesis (DTS) for verification of target position in early stage lung cancer patients,” Med. Phys. 40, 091904 (11pp.) (2013).
5. D. A. Jaffray and J. H. Siewerdsen, “Cone-beam computed tomography with a flat-panel imager: initial performance characterization,” Med. Phys. 27, 13111323 (2000).
6. K. Choi, L. Xing, A. Koong, and R. Li, “First study of on-treatment volumetric imaging during respiratory gated VMAT,” Med. Phys. 40, 040701 (4pp.) (2013).
7. R. Li, J. H. Lewis, X. Jia, T. Zhao, W. Liu, S. Wuenschel, J. Lamb, D. Yang, D. A. Low, and S. B. Jiang, “On a PCA-based lung motion model,” Phys. Med. Biol. 56, 60096030 (2011).
8. R. Li, X. Jia, J. H. Lewis, X. Gu, M. Folkerts, C. Men, and S. B. Jiang, “Real-time volumetric image reconstruction and 3D tumor localization based on a single x-ray projection image for lung cancer radiotherapy,” Med. Phys. 37, 28222826 (2010).
9. L. Ren, J. Zhang, D. Thongphiew, D. J. Godfrey, Q. J. Wu, S. M. Zhou, and F. F. Yin, “A novel digital tomosynthesis (DTS) reconstruction method using a deformation field map,” Med. Phys. 35, 31103115 (2008).
10. L. Ren, I. J. Chetty, J. Zhang, J. Y. Jin, Q. J. Wu, H. Yan, D. M. Brizel, W. R. Lee, B. Movsas, and F. F. Yin, “Development and clinical evaluation of a three-dimensional cone-beam computed tomography estimation method using a deformation field map,” Int. J. Radiat. Oncol., Biol., Phys. 82, 15841593 (2012).
11. J. Wang and X. Gu, “High-quality four-dimensional cone-beam CT by deforming prior images,” Phys. Med. Biol. 58, 231246 (2013).
12. F. F. Yin, H. Guan, and W. Lu, “A technique for on-board CT reconstruction using both kilovoltage and megavoltage beam projections for 3D treatment verification,” Med. Phys. 32, 28192826 (2005).
13. J. Dang, L. Ouyang, X. Gu, and J. Wang, “Deformation vector fields (DVF)-driven image reconstruction for 4D-CBCT,” Med. Phys. 40, 457 (2013).
14. W. Lu, M. L. Chen, G. H. Olivera, K. J. Ruchala, and T. R. Mackie, “Fast free-form deformable registration via calculus of variations,” Phys. Med. Biol. 49, 30673087 (2004).
15. E. Y. Sidky and X. Pan, “Image reconstruction in circular cone-beam computed tomography by constrained, total-variation minimization,” Phys. Med. Biol. 53, 47774807 (2008).
16. W. P. Segars, M. Mahesh, T. J. Beck, E. C. Frey, and B. M. Tsui, “Realistic CT simulation using the 4D XCAT phantom,” Med. Phys. 35, 38003808 (2008).

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Currently, no 3D or 4D volumetric x-ray imaging techniques are available for intrafraction verification of target position during actual treatment delivery or in-between treatment beams, which is critical for stereotactic radiosurgery (SRS) and stereotactic body radiation therapy (SBRT) treatments. This study aims to develop a limited-angle intrafraction verification (LIVE) system to use prior information, deformation models, and limited angle kV-MV projections to verify target position intrafractionally.

The LIVE system acquires limited-angle kV projections simultaneously during arc treatment delivery or in-between static 3D/IMRT treatment beams as the gantry moves from one beam to the next. Orthogonal limited-angle MV projections are acquired from the beam's eye view (BEV) exit fluence of arc treatment beam or in-between static beams to provide additional anatomical information. MV projections are converted to kV projections using a linear conversion function. Patient prior planning CT at one phase is used as the prior information, and the on-board patient volume is considered as a deformation of the prior images. The deformation field is solved using the data fidelity constraint, a breathing motion model extracted from the planning 4D-CT based on principal component analysis (PCA) and a free-form deformation (FD) model. LIVE was evaluated using a 4D digital extended cardiac torso phantom (XCAT) and a CIRS 008A dynamic thoracic phantom. In the XCAT study, patient breathing pattern and tumor size changes were simulated from CT to treatment position. In the CIRS phantom study, the artificial target in the lung region experienced both size change and position shift from CT to treatment position. Varian Truebeam research mode was used to acquire kV and MV projections simultaneously during the delivery of a dynamic conformal arc plan. The reconstruction accuracy was evaluated by calculating the 3D volume percentage difference (VPD) and the center of mass (COM) difference of the tumor in the true on-board images and reconstructed images.

In both simulation and phantom studies, LIVE achieved substantially better reconstruction accuracy than reconstruction using PCA or FD deformation model alone. In the XCAT study, the average VPD and COM differences among different patient scenarios for LIVE system using orthogonal 30° scan angles were 4.3% and 0.3 mm when using kV+BEV MV. Reducing scan angle to 15° increased the average VPD and COM differences to 15.1% and 1.7 mm. In the CIRS phantom study, the VPD and COM differences for the LIVE system using orthogonal 30° scan angles were 6.4% and 1.4 mm. Reducing scan angle to 15° increased the VPD and COM differences to 51.9% and 3.8 mm.

The LIVE system has the potential to substantially improve intrafraction target localization accuracy by providing volumetric verification of tumor position simultaneously during arc treatment delivery or in-between static treatment beams. With this improvement, LIVE opens up a new avenue for margin reduction and dose escalation in both fractionated treatments and SRS and SBRT treatments.


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752b84549af89a08dbdd7fdb8b9568b5 journal.articlezxybnytfddd
Scitation: A limited-angle intrafraction verification (LIVE) system for radiation therapy