Surface as a motion surrogate for gated re-scanned pencil beam proton therapy

Zhang, Ye; Huth, I.; Wegner, M.; Weber, Damien Charles; Lomax, Anthony

doi:10.1088/1361-6560/aa66c5

Cited by 12 publications

(10 citation statements)

References 27 publications

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“…These effects should be taken into consideration during the determination and evaluation of the gating window. 36 As previously mentioned in Section 4.4.4, PCR could also efficiently mitigate interplay effects in the residual motion. 88 , 94 , 95 …”

Section: Review Of Current Motion Assessment and Motion‐management Te...mentioning

confidence: 91%

“…With motion hysteresis and irregularities, the residual motion within the gating window can be slightly larger than the intended window size. These effects should be taken into consideration during the determination and evaluation of the gating window 36 . As previously mentioned in Section 4.4.4, PCR could also efficiently mitigate interplay effects in the residual motion 88,94,95 …”

Section: Review Of Current Motion Assessment and Motion‐management Te...mentioning

confidence: 99%

“…35 4DD and D4DD could be calculated using selected phases; examples include phase-based gated treatment using a predefined gating window. 36,37 In such cases, the phases used for dose calculation should be clearly defined.…”

Section: Nomenclature and Definitionsmentioning

confidence: 99%

“…Optical surface imaging or tracking, which has been steadily gaining traction in the conventional X‐ray realm, is also being implemented in particle therapy. 36 When combined with X‐ray imaging, optical surface imaging can help to provide a complete picture for initial patient setup and intrafraction monitoring. It has also been used to monitor intrafractional patient motion, including BHs and respiratory gating, for photon and particle therapy.…”

Section: Review Of Current Motion Assessment and Motion‐management Te...mentioning

confidence: 99%

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AAPM Task Group Report 290: Respiratory motion management for particle therapy

Dong

Bert

et al. 2022

Medical Physics

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Dose uncertainty induced by respiratory motion remains a major concern for treating thoracic and abdominal lesions using particle beams. This Task Group report reviews the impact of tumor motion and dosimetric considerations in particle radiotherapy, current motion‐management techniques, and limitations for different particle‐beam delivery modes (i.e., passive scattering, uniform scanning, and pencil‐beam scanning). Furthermore, the report provides guidance and risk analysis for quality assurance of the motion‐management procedures to ensure consistency and accuracy, and discusses future development and emerging motion‐management strategies. This report supplements previously published AAPM report TG76, and considers aspects of motion management that are crucial to the accurate and safe delivery of particle‐beam therapy. To that end, this report produces general recommendations for commissioning and facility‐specific dosimetric characterization, motion assessment, treatment planning, active and passive motion‐management techniques, image guidance and related decision‐making, monitoring throughout therapy, and recommendations for vendors. Key among these recommendations are that: (1) facilities should perform thorough planning studies (using retrospective data) and develop standard operating procedures that address all aspects of therapy for any treatment site involving respiratory motion; (2) a risk‐based methodology should be adopted for quality management and ongoing process improvement.

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Section: Review Of Current Motion Assessment and Motion‐management Te...mentioning

confidence: 91%

Section: Review Of Current Motion Assessment and Motion‐management Te...mentioning

confidence: 99%

Section: Nomenclature and Definitionsmentioning

confidence: 99%

Section: Review Of Current Motion Assessment and Motion‐management Te...mentioning

confidence: 99%

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AAPM Task Group Report 290: Respiratory motion management for particle therapy

Dong

Bert

et al. 2022

Medical Physics

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“…Briefly put, instead of warping and accumulating the dose distribution on each image phase, our approach deforms the calculational dose grid as a function of time, the vectors for this deformation being extracted from 4D imaging such as 4DCT or 4DMRI (Boye et al). This approach allows to model motion effects at much higher temporal resolutions than the conventional approach, and many studies on the effects of motion and the effectiveness of motion mitigation strategies have been conducted using this 4D dose calculation (Bernatowicz et al (2013), Bernatowicz et al (2016), Knopf et al (2011), Knopf et al (2013), Dueck et al (2016), Gorgisyan et al (2017), Zhang et al (2012), Zhang et al (2013), Zhang et al (2014), Zhang et al (2015), Zhang et al (2016), Zhang et al (2017)). As such, and as is the case for all other components of a treatment planning system, such a 4DDC needs to be commissioned and verified, particularly its ability to model the complex effects of the temporal interplays between the delivery dynamics of PBS proton therapy and motion of the patient.…”

Section: Introductionmentioning

confidence: 99%

Experimental validation of a deforming grid 4D dose calculation for PBS proton therapy

et al. 2018

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The aim of this study was to verify the temporal accuracy of the estimated dose distribution by a 4D dose calculation (4DDC) in comparison to measurements. A single-field plan (0.6 Gy), optimised for a liver patient case (CTV volume: 403cc), was delivered to a homogeneous PMMA phantom and measured by a high resolution scintillating-CCD system at two water equivalent depths. Various motion scenarios (no motion and motions with amplitude of 10 mm and two periods: 3.7 s and 4.4 s) were simulated using a 4D Quasar phantom and logged by an optical tracking system in real-time. Three motion mitigation approaches (single delivery, 6[Formula: see text] layered and volumetric rescanning) were applied, resulting in 10 individual measurements. 4D dose distributions were retrospectively calculated in water by taking into account the delivery log files (retrospective) containing information on the actually delivered spot positions, fluences, and time stamps. Moreover, in order to evaluate the sensitivity of the 4DDC inputs, the corresponding prospective 4DDCs were performed as a comparison, using the estimated time stamps of the spot delivery and repeated periodical motion patterns. 2D gamma analyses and dose-difference-histograms were used to quantify the agreement between measurements and calculations for all pixels with [Formula: see text]5% of the maximum calculated dose. The results show that a mean gamma score of 99.2% with standard deviation 1.0% can be achieved for 3%/3 mm criteria and all scenarios can reach a score of more than 95%. The average area with more than 5% dose difference was 6.2%. Deviations due to input uncertainties were obvious for single scan deliveries but could be smeared out once rescanning was applied. Thus, the deforming grid 4DDC has been demonstrated to be able to predict the complex patterns of 4D dose distributions for PBS proton therapy with high dosimetric and geometric accuracy, and it can be used as a valid clinical tool for 4D treatment planning, motion mitigation selection, and eventually 4D optimisation applications if the correct temporal information is available.

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A simple method to measure the gating latencies in photon and proton based radiotherapy using a scintillating crystal

et al. 2023

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Background: In respiratory gated radiotherapy, low latency between target motion into and out of the gating window and actual beam-on and beamoff is crucial for the treatment accuracy. However, there is presently a lack of guidelines and accurate methods for gating latency measurements. Purpose: To develop a simple and reliable method for gating latency measurements that work across different radiotherapy platforms. Methods: Gating latencies were measured at a Varian ProBeam (protons, RPM gating system) and TrueBeam (photons, TrueBeam gating system) accelerator. A motion-stage performed 1 cm vertical sinusoidal motion of a marker block that was optically tracked by the gating system. An amplitude gating window was set to cover the posterior half of the motion (0-0.5 cm). Gated beams were delivered to a 5 mm cubic scintillating ZnSe:O crystal that emitted visible light when irradiated, thereby directly showing when the beam was on. During gated beam delivery, a video camera acquired images at 120 Hz of the moving marker block and light-emitting crystal. After treatment, the block position and crystal light intensity were determined in all video frames. Two methods were used to determine the gate-on (τ on ) and gate-off (τ off ) latencies. By method 1, the video was synchronized with gating log files by temporal alignment of the same block motion recorded in both the video and the log files. τ on was defined as the time from the block entered the gating window (from gating log files) to the actual beam-on as detected by the crystal light. Similarly, τ off was the time from the block exited the gating window to beam-off. By method 2, τ on and τ off were found from the videos alone using motion of different sine periods (1-10 s). In each video, a sinusoidal fit of the block motion provided the times T min of the lowest block position. The mid-time, T mid-light , of each beam-on period was determined as the time halfway between crystal light signal start and end. It can be shown that the directly measurable quantity T mid-light − T min = (τ off +τ on )/2, which provided the sum (τ off +τ on ) of the two latencies. It can also be shown that the beam-on (i.e., crystal light) duration ΔT light increases linearly with the sine period and depends on τ off − τ on : ΔT light = constant•period+(τ off − τ on ). Hence, a linear fit of ΔT light as a function of the period provided the difference of the two latencies. From the sum (τ off +τ on ) and difference (τ off − τ on ), the individual latencies were determined. Results: Method 1 resulted in mean (±SD) latencies of τ on = 255 ± 33 ms, τ off = 82 ± 15 ms for the ProBeam and τ on = 84 ± 13 ms,τ off = 44 ± 11 ms for the This is an open access article under the terms of the Creative Commons Attribution-NonCommercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.

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Surface as a motion surrogate for gated re-scanned pencil beam proton therapy

Cited by 12 publications

References 27 publications

AAPM Task Group Report 290: Respiratory motion management for particle therapy

AAPM Task Group Report 290: Respiratory motion management for particle therapy

Experimental validation of a deforming grid 4D dose calculation for PBS proton therapy

A simple method to measure the gating latencies in photon and proton based radiotherapy using a scintillating crystal

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