Toward the development of intrafraction tumor deformation tracking using a dynamic multi-leaf collimator

Ge, Yuanyuan; O’Brien, Ricky; Shieh, Chun‐Chien; Booth, Jeremy; Keall, Paul J.

doi:10.1118/1.4873682

Cited by 59 publications

(49 citation statements)

References 51 publications

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“…This limitation is mirrored in the dose reconstruction process (12) and will likely be mitigated in the future with further development of the MLC tracking technology to account for rotation and deformation (19,20). This increase in information obtained during treatment would also help to inform dose reconstruction for better estimates of delivered treated doses.…”

Section: Discussionmentioning

confidence: 99%

Multileaf Collimator Tracking Improves Dose Delivery for Prostate Cancer Radiation Therapy: Results of the First Clinical Trial

Colvill

Booth

O’Brien

et al. 2015

International Journal of Radiation Oncology*Biology*Physics

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Funding: This study was supported by Varian Medical Systems through partial trial funding and an equipment loan.Conflict of interest: P.J.K. is one of the inventors on an issued patent and a submitted patent application on multileaf collimator tracking. Acknowledgments:The authors thank Esben Worm and Prabhjot Juneja for their valuable help with dose reconstruction development, and Julie Baz for improving the clarity and readability of the manuscript. SummaryMultileaf collimator tracking has been implemented for the first time in a prospective prostate cancer clinical trial. Dose reconstruction was performed for 475 treatment fractions for 15 patients. Comparison of patients' original planned dose with the calculated treated dose with and without MLC tracking demonstrates that implementation of MLC tracking results in a higher agreement between delivered and planned doses. The implications are potentially improved patient outcomes and more reliable radiobiological parameter determination. AbstractPurpose: To test the hypothesis that multileaf collimator (MLC) tracking improves the consistency between the planned and delivered dose compared with the dose without MLC tracking, in the setting of a prostate cancer volumetric modulated arc therapy trial. Methods and Materials:Multileaf collimator tracking was implemented for 15 patients in a prostate cancer radiation therapy trial; in total, 513 treatment fractions were delivered. During each treatment fraction, the prostate trajectory and treatment MLC positions were collected. These data were used as input for dose reconstruction (multiple isocenter shift method) to calculate the treated dose (with MLC tracking) and the dose that would have been delivered had MLC tracking not been applied (without MLC tracking). The percentage difference from planned for target and normal tissue dose-volume points were calculated. The hypothesis was tested for each dose-volume value via analysis of variance using the F test. Results:Of the 513 fractions delivered, 475 (93%) were suitable for analysis. The mean difference and standard deviation between the planned and treated MLC tracking doses and the planned and without-MLC tracking doses for all 475 fractions were, respectively, PTV D99% -0.8% ± 1.1% versus -2.1% ± 2.7%; CTV D99% -0.6% ± 0.8% versus -0.6% ± 1.1%; rectum V65% 1.6% ± 7.9% versus -1.2% ± 18%; and bladder V65% 0.5% ± 4.4% versus -0.0% ± 9.2% (P<.001 for all dose-volume results). Conclusion:This study shows that MLC tracking improves the consistency between the planned and delivered doses compared with the modeled doses without MLC tracking. The implications of this finding are potentially improved patient outcomes, as well as more reliable dose-volume data for radiobiological parameter determination.

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Section: Discussionmentioning

confidence: 99%

Multileaf Collimator Tracking Improves Dose Delivery for Prostate Cancer Radiation Therapy: Results of the First Clinical Trial

Colvill

Booth

O’Brien

et al. 2015

International Journal of Radiation Oncology*Biology*Physics

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“…MLC tracking technology has been clinically implemented for translational target tracking 35 and demonstrated to account for tumor rotation 36 and deformation 37 in phantom cases.…”

Section: Discussionmentioning

confidence: 99%

Functional imaging equivalence and proof of concept for image-guided adaptive radiotherapy with fixed gantry and rotating couch

Feain

Shieh

White

et al. 2016

Advances in Radiation Oncology

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PurposeThe purpose of this article is to present the first imaging experiments to demonstrate the functional equivalence between a conventional rotational gantry and a fixed-beam imaging geometry, and the feasibility of an iterative image-reconstruction technique under gravitational deformation.Methods and materialsExperiments were performed using an Elekta Axesse with Agility MLC and XVI, a custom-built rotating phantom stage, a Catphan QA phantom, and a porcine heart. For the imaging equivalence, a conventional cone beam computed tomography (CBCT) of the Catphan was acquired, as well as a set of 660 x-ray projections with a static gantry and rotating Catphan. Both datasets were reconstructed with the Feldkamp-Davis-Kress (FDK) algorithm, and the resultant volumetric images were compared using standard metrics. For imaging under gravitational deformation, a conventional CBCT of the Catphan and a set of 660 x-ray projections with a static gantry and rotating Catphan were also acquired with a porcine heart. The conventional CBCT was reconstructed using FDK. The projections that were acquired with the heart rotating were sorted into angular bins and reconstructed with prior image constrained compressed sensing using a deformation-blurred FDK prior. Deformation was quantified with B-spline transformation-based deformable image registration.ResultsFor imaging equivalence, the difference between the two Catphan images was consistent with Poisson noise. For imaging under gravitational deformation, the conventional CBCT porcine heart image (ground truth at 0 degrees) matched the static gantry, rotating heart reconstruction with a mean magnitude of <3 mm and maximum magnitude of <5 mm of the deformation vector field. The mean deformation of the rotating heart was 3.0 to 8.9 mm, up to 16.1 mm maximum deformation. Deformation was mainly observed in the direction of gravity.ConclusionsWe have demonstrated imaging equivalence in cone beam CT reconstructions between rigid phantom images acquired with a conventional rotating gantry and with a fixed-gantry and rotating phantom. We have presented a method for image reconstruction under a fixed-beam imaging geometry using a deformable phantom.

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“…However, it suffers from prolonged treatment time due to repeated verifications before each beam delivery and can only treat small tumor volumes. Tracking with gantry‐mounted linear accelerators has been limited to research using phantoms . In most of these studies, system latency due to image acquisition, image saving and reading, tumor detection and aperture adjustment has been identified as one of the challenges for real‐time adaptive treatment .…”

Section: Introductionmentioning

confidence: 99%

Feasibility of predicting tumor motion using online data acquired during treatment and a generalized neural network optimized with offline patient tumor trajectories

et al. 2018

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Toward the development of intrafraction tumor deformation tracking using a dynamic multi-leaf collimator

Cited by 59 publications

References 51 publications

Multileaf Collimator Tracking Improves Dose Delivery for Prostate Cancer Radiation Therapy: Results of the First Clinical Trial

Multileaf Collimator Tracking Improves Dose Delivery for Prostate Cancer Radiation Therapy: Results of the First Clinical Trial

Functional imaging equivalence and proof of concept for image-guided adaptive radiotherapy with fixed gantry and rotating couch

Feasibility of predicting tumor motion using online data acquired during treatment and a generalized neural network optimized with offline patient tumor trajectories

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