The first clinical implementation of electromagnetic transponder‐guided MLC tracking

Keall, Paul J.; Colvill, Emma; O’Brien, Ricky; Ng, Jin Aun; Poulsen, Per Rugaard; Eade, Thomas; Kneebone, Andrew; Booth, Jeremy

doi:10.1118/1.4862509

Cited by 140 publications

(153 citation statements)

References 24 publications

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“…Current clinical implementations of tracking in photon radiotherapy [Kilby et al, 2010, Keall et al, 2014 can not be directly used in particle therapy, since they only provide the position of single internal points. Fassi et al [Fassi et al, 2015] were able to account for inter-and intra-fractional variability of patient's anatomical configuration with a designated modeling technique [Fassi et al, 2014].…”

Section: Treating Non-small Cell Lung Cancer With Particle Therapymentioning

confidence: 99%

In silico comparison of photons versus carbon ions in single fraction therapy of lung cancer

et al. 2016

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Stereotactic body image guided radiation therapy (SBRT) shows excellent results for the local control of early stage lung cancer. However, not all patients are eligible for SBRT, and advanced stage treatment is less successful and often associated with severe side effects. Scanned carbon ion therapy (PT) can deliver more conformal dose likely benefiting these patient groups.Therefore an in silico trial was conducted on early and advanced stage patients to identify potential advantages of PT. The patients were treated with SBRT at Champalimaud Center for the Unknown, Lisbon (Portugal). PT plans were simulated on 4DCTs, and rescanning was investigated for motion mitigation in 4D-dose calculations. A dedicated strategy for 4D intensity modulated particle therapy (IMPT) was developed and applied for advanced stage patients with multiple lesions. For clinically valid and reliable results the deformable image registrationnecessary for 4D-dose calculation -a quality assurance tool was developed and applied in the study.The results showed that target coverage was comparable in SBRT and PT, while PT delivered significantly lower doses to most critical structures, especially the heart, lungs, and esophagus.A highly complex case of advanced stage lung cancer could be treated in a single fraction of 24 Gy with PT, while SBRT could not deliver the full ablative dose treatment due to an excessive heart dose. The mean heart dose was reduced from 10 Gy to 0.8 Gy with PT for this specific patient.

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Section: Treating Non-small Cell Lung Cancer With Particle Therapymentioning

confidence: 99%

In silico comparison of photons versus carbon ions in single fraction therapy of lung cancer

et al. 2016

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“…Alternatively to these specialized treatment systems, tracking can also be integrated at conventional linear accelerators, which are widely used in clinics. This can be accomplished by either adapting the multi-leaf collimator, which is shaping the treatment field, to the changing target position (MLC tracking) [9,10,11], or by counter-steering the target motion with the treatment couch (couch tracking) [12,13]. Tracking allows for a reduction of the treatment volume with continuous irradiation.…”

Section: Introductionmentioning

confidence: 99%

Respiratory motion-management in stereotactic body radiation therapy for lung cancer – A dosimetric comparison in an anthropomorphic lung phantom (LuCa)

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Perrin

Peroni

et al. 2016

Radiotherapy and Oncology

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BACKGROUND AND PURPOSE The objective of this study was to compare the latest respiratory motion-management strategies, namely the internal-target-volume (ITV) concept, the midventilation (MidV) principle, respiratory gating and dynamic couch tracking. MATERIALS AND METH-ODS An anthropomorphic, deformable and dynamic lung phantom was used for the dosimetric validation of these techniques. Stereotactic treatments were adapted to match the techniques and five distinct respiration patterns, and delivered to the phantom while radiographic film measurements were taken inside the tumor. To report on tumor coverage, these dose distributions were used to calculate mean doses (Dmean), changes in homogeneity indices (ΔH2-98), gamma agreement, and areas covered by the planned minimum dose (A>Dmin). RESULTS All techniques achieved good tumor coverage (A>Dmin>99.0%) and minor changes in Dmean (±3.2%). Gating and tracking strategies showed superior results in gamma agreement and ΔH2-98 compared to ITV and MidV concepts, which seem to be more influenced by the interplay and the gradient effect. For lung, heart and spinal cord, significant dose differences between the four techniques were found (p<0.05), with lowest doses for gating and tracking strategies. CONCLUSION Active motion-management techniques, such as gating or tracking, showed superior tumor dose coverage and better organ dose sparing than the passive techniques based on tumor margins. This article has been accepted for publication and undergone full peer review but has not been through the copyediting, typesetting, pagination and proofreading process, which may lead to differences between this version and the Version of Record. Please cite this article as doi: 10.1016/j.radonc.2016.10.011 This article is protected by copyright. All rights reserved. AbstractBackground and Purpose: The objective of this study was to compare the latest respiratory motion-management strategies, namely the internal-target-volume (ITV) concept, the mid-ventilation (MidV) principle, respiratory gating and dynamic couch tracking. Materials and Methods: An anthropomorphic, deformable and dynamic lung phantom was used for the dosimetric validation of these techniques. Stereotactic treatments were adapted to match the techniques and five distinct respiration patterns, and delivered to the phantom while radiographic film measurements were taken inside the tumor. To report on tumor coverage, these dose distributions were used to calculate mean doses (Dmean), changes in homogeneity indices (ΔH 2-98 ), gamma agreement, and areas covered by the planned minimum dose (A >Dmin ).Results: All techniques achieved good tumor coverage (A >Dmin >99.0%) and minor changes in D mean (±3.2%). Gating and tracking strategies showed superior results in gamma agreement and ΔH 2-98 compared to ITV and MidV concepts, which seem to be more influenced by the interplay and the gradient effect. For lung, heart and spinal cord, significant dose differences between the four techniques were found (p<0.05), with l...

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“…6,18,19 The dynamic multileaf collimator (DMLC) tumor-tracking method using the Calypso system (Calypso Medical, Seattle, WA, USA), another direct tracking method, is now clinically available. 9 With either approach, the lookahead time for the future target position depends on system latency, and the frequency of prediction depends on the sampling interval of respiratory motion. 20 With direct tracking methods, baseline respiratory drift can be compensated for by reference to an adjacent position.…”

Section: Discussionmentioning

confidence: 99%

“…[5][6][7][8][9] Two basic approaches have been taken: direct and indirect tracking methods. 5 Direct tracking methods detect the target motion, whereas indirect tracking methods assess surrogate quantities and predict target motion based on surrogate motion.…”

Section: Discussionmentioning

confidence: 99%

“…1,2 Recent interest has focused on the dynamic tumor-tracking technique, which can dynamically reposition the radiation field in line with the position of the moving target. [5][6][7][8][9] One advantage of dynamic tumor-tracking is minimization of internal uncertainties without burdening patient respiration or prolonging treatment time. 7,10 The Vero4DRT (Mitsubishi Heavy Industries, Ltd., Hiroshima, Japan; and Brainlab, Feldkirchen, Germany) has two special features allowing dynamic tumor-tracking with realtime monitoring.…”

Section: Introductionmentioning

confidence: 99%

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Impact of sampling interval in training data acquisition on intrafractional predictive accuracy of indirect dynamic tumor‐tracking radiotherapy

et al. 2017

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Purpose: To explore the effect of sampling interval of training data acquisition on the intrafractional prediction error of surrogate signal-based dynamic tumor-tracking using a gimbal-mounted linac. Materials and methods: Twenty pairs of respiratory motions were acquired from 20 patients (ten lung, five liver, and five pancreatic cancer patients) who underwent dynamic tumor-tracking with the Vero4DRT. First, respiratory motions were acquired as training data for an initial construction of the prediction model before the irradiation. Next, additional respiratory motions were acquired for an update of the prediction model due to the change of the respiratory pattern during the irradiation. The time elapsed prior to the second acquisition of the respiratory motion was 12.6 AE 3.1 min. A four-axis moving phantom reproduced patients' three dimensional (3D) target motions and one dimensional surrogate motions. To predict the future internal target motion from the external surrogate motion, prediction models were constructed by minimizing residual prediction errors for training data acquired at 80 and 320 ms sampling intervals for 20 s, and at 500, 1,000, and 2,000 ms sampling intervals for 60 s using orthogonal kV x-ray imaging systems. The accuracies of prediction models trained with various sampling intervals were estimated based on training data with each sampling interval during the training process. The intrafractional prediction errors for various prediction models were then calculated on intrafractional monitoring images taken for 30 s at the constant sampling interval of a 500 ms fairly to evaluate the prediction accuracy for the same motion pattern. In addition, the first respiratory motion was used for the training and the second respiratory motion was used for the evaluation of the intrafractional prediction errors for the changed respiratory motion to evaluate the robustness of the prediction models. Results: The training error of the prediction model was 1.7 AE 0.7 mm in 3D for all sampling intervals. The intrafractional prediction error for the same motion pattern was 1.9 AE 0.7 mm in 3D for an 80 ms sampling interval, which increased larger than 1 mm in 10.0% of prediction models trained at a 2,000 ms sampling interval with a significant difference (P < 0.01) and up to 2.5% for the other sampling intervals without a significant difference (P > 0.05). The intrafractional prediction error for the changed respiratory motion pattern increased to 5.1 AE 2.4 mm in 3D for an 80 ms sampling interval; however, there was not a significant difference in the robustness of the prediction model between the 80 ms sampling interval and other sampling intervals (P > 0.05). Conclusions: Although the training error of the prediction model was consistent for the all sampling intervals, the prediction model using the larger sampling interval of the 2,000 ms increased the intrafractional prediction error for the same motion pattern. The realistic accuracy of the prediction model was difficult to estimate using the larger sa...

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The first clinical implementation of electromagnetic transponder‐guided MLC tracking

Abstract: The real-time beam-target correction method, electromagnetic transponder-guided MLC tracking, has been translated to the clinic. This achievement represents a milestone in improving geometric and dosimetric accuracy, and by inference treatment outcomes, in cancer radiotherapy.

Cited by 140 publications

References 24 publications

In silico comparison of photons versus carbon ions in single fraction therapy of lung cancer

In silico comparison of photons versus carbon ions in single fraction therapy of lung cancer

Respiratory motion-management in stereotactic body radiation therapy for lung cancer – A dosimetric comparison in an anthropomorphic lung phantom (LuCa)

Impact of sampling interval in training data acquisition on intrafractional predictive accuracy of indirect dynamic tumor‐tracking radiotherapy

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