Stereotactic Arrhythmia Radioablation (STAR): Assessment of cardiac and respiratory heart motion in ventricular tachycardia patients - A STOPSTORM.eu consortium review

R, Stevens; Hazelaar, Colien; Fast, Martin F.; Mandija, Stefano; Grehn, Melanie; Cvek, Jakub; Knybel, Lukáš; Dvořák, Pavel; Pruvot, Étienne; Verhoeff, J.; Blanck, Oliver; Elmpt, Wouter van

doi:10.1016/j.radonc.2023.109844

Cited by 17 publications

(11 citation statements)

References 46 publications

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“…The motion is likely the highest in this segment but is not necessarily representative of the left ventricular motion in the other segments. The motion extents in the other segments of the heart might be higher or lower depending on the patient specific anatomy and condition 13 …”

Section: Discussionmentioning

confidence: 99%

“…The treatment target region in the myocardial wall is subject to cardiorespiratory motion that induces position uncertainties, which makes it challenging to achieve a conformal dose delivery 13 . In addition, adjacent organs at risk (OARs) and cardiac substructures are dose sensitive and the cardiorespiratory motion‐induced dosimetric uncertainties raise radiation‐induced toxicity concerns.…”

Section: Introductionmentioning

confidence: 99%

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Experimental demonstration of real‐time cardiac physiology‐based radiotherapy gating for improved cardiac radioablation on an MR‐linac

Akdag,

Borman,

Mandija

et al. 2024

Medical Physics

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BackgroundCardiac radioablation is a noninvasive stereotactic body radiation therapy (SBRT) technique to treat patients with refractory ventricular tachycardia (VT) by delivering a single high‐dose fraction to the VT isthmus. Cardiorespiratory motion induces position uncertainties resulting in decreased dose conformality. Electocardiograms (ECG) are typically used during cardiac MRI (CMR) to acquire images in a predefined cardiac phase, thus mitigating cardiac motion during image acquisition.PurposeWe demonstrate real‐time cardiac physiology‐based radiotherapy beam gating within a preset cardiac phase on an MR‐linac.MethodsMR images were acquired in healthy volunteers (n = 5, mean age = 29.6 years, mean heart‐rate (HR) = 56.2 bpm) on the 1.5 T Unity MR‐linac (Elekta AB, Stockholm, Sweden) after obtaining written informed consent. The images were acquired using a single‐slice balance steady‐state free precession (bSSFP) sequence in the coronal or sagittal plane (TR/TE = 3/1.48 ms, flip angle = 48, SENSE = 1.5, , voxel size = , partial Fourier factor = 0.65, frame rate = 13.3 Hz). In parallel, a 4‐lead ECG‐signal was acquired using MR‐compatible equipment. The feasibility of ECG‐based beam gating was demonstrated with a prototype gating workflow using a Quasar MRI4D motion phantom (IBA Quasar, London, ON, Canada), which was deployed in the bore of the MR‐linac. Two volunteer‐derived combined ECG‐motion traces (n = 2, mean age = 26 years, mean HR = 57.4 bpm, peak‐to‐peak amplitude = 14.7 mm) were programmed into the phantom to mimic dose delivery on a cardiac target in breath‐hold. Clinical ECG‐equipment was connected to the phantom for ECG‐voltage‐streaming in real‐time using research software. Treatment beam gating was performed in the quiescent phase (end‐diastole). System latencies were compensated by delay time correction. A previously developed MRI‐based gating workflow was used as a benchmark in this study. A 15‐beam intensity‐modulated radiotherapy (IMRT) plan ( Gy) was delivered for different motion scenarios onto radiochromic films. Next, cardiac motion was then estimated at the basal anterolateral myocardial wall via normalized cross‐correlation‐based template matching. The estimated motion signal was temporally aligned with the ECG‐signal, which were then used for position‐ and ECG‐based gating simulations in the cranial–caudal (CC), anterior–posterior (AP), and right–left (RL) directions. The effect of gating was investigated by analyzing the differences in residual motion at 30, 50, and 70% treatment beam duty cycles.ResultsECG‐based (MRI‐based) beam gating was performed with effective duty cycles of 60.5% (68.8%) and 47.7% (50.4%) with residual motion reductions of 62.5% (44.7%) and 43.9% (59.3%). Local gamma analyses (1%/1 mm) returned pass rates of 97.6% (94.1%) and 90.5% (98.3%) for gated scenarios, which exceed the pass rates of 70.3% and 82.0% for nongated scenarios, respectively. In average, the gating simulations returned maximum residual motion reductions of 88%, 74%, and 81% at 30%, 50%, and 70% duty cycles, respectively, in favor of MRI‐based gating.ConclusionsReal‐time ECG‐based beam gating is a feasible alternative to MRI‐based gating, resulting in improved dose delivery in terms of high rates, decreased dose deposition outside the PTV and residual motion reduction, while by‐passing cardiac MRI challenges.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Experimental demonstration of real‐time cardiac physiology‐based radiotherapy gating for improved cardiac radioablation on an MR‐linac

Akdag,

Borman,

Mandija

et al. 2024

Medical Physics

Self Cite

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“…While this ensures the target is treated, it leads to significant radiation to surrounding non-target tissues. It is also important to note that the ITV is most often generated from respiratory 4DCT [15,23], where the cardiac motion simply presents as a blurring in the respiratory-binned images. This is generally acceptable when cardiac-induced motion has minimal dosimetric impact due to the smaller amplitude compared to respiratory motion.…”

Section: Introductionmentioning

confidence: 99%

“…Stevens et al published a review of target motion in VT patients and found that detailed cardiorespiratory motion data for cardiac radioablation is still limited, despite growing numbers of patients being treated [23]. Cardiac-specific ITVs were only reported in one study by Bellec et al, where the increase in target volume due to cardiac contraction ranged from 39% to 75% in 4 patients [31].…”

Section: Introductionmentioning

confidence: 99%

Left ventricle segment-specific motion assessment for cardiac-gated radiosurgery

Poon,

Thompson,

Deyell

et al. 2024

Biomed. Phys. Eng. Express

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PurposeCardiac radiosurgery is a non-invasive treatment modality for ventricular tachycardia, where a linear accelerator is used to irradiate the arrhythmogenic region within the heart. In this work, cardiac magnetic resonance (CMR) cine images were used to quantify left ventricle (LV) segment-specific motion during the cardiac cycle and to assess potential advantages of cardiac-gated radiosurgery.MethodsCMR breath-hold cine images and LV contour points were analyzed for 50 controls and 50 heart failure patients with reduced ejection fraction (HFrEF, EF<40%). Contour points were divided into anatomic segments according to the 17-segment model, and each segment was treated as a hypothetical treatment target. The optimum treatment window (one fifth of the cardiac cycle) was determined where segment centroid motion was minimal, then the maximum centroid displacement and treatment area were determined for the full cardiac cycle and for the treatment window. Mean centroid displacement and treatment area reductions with cardiac gating were determined for each of the 17 segments.ResultsFull motion segment centroid displacements ranged between 6-14 mm (controls) and 4-11 mm (HFrEF). Full motion treatment areas ranged between 129-715 mm2 (controls) and 149-766 mm2 (HFrEF). With gating, centroid displacements were reduced to 1 mm (controls and HFrEF), while treatment areas were reduced to 62-349 mm2 (controls) and 83-393 mm2 (HFrEF). Relative treatment area reduction ranged between 38-53% (controls) and 26-48% (HFrEF).ConclusionThis data demonstrates that cardiac cycle motion is an important component of overall target motion and varies depending on the anatomic cardiac segment. Accounting for cardiac cycle motion, through cardiac gating, has the potential to significantly reduce treatment volumes for cardiac radiosurgery.

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“…The ITV is most often established using respiratory‐binned 4DCT to quantify the target motion. 15 , 16 The ITV is created from a composite of target volumes delineated on each respiratory phase of the 4DCT, or may be generated from a maximum or average intensity projection (maximum or average pixel densities for all phase images). An additional 2 to 5 mm is then added to create the planning target volume (PTV), which accounts for set‐up uncertainty and treatment delivery inaccuracies.…”

Section: Introductionmentioning

confidence: 99%

Analysis of left ventricle regional myocardial motion for cardiac radioablation

Poon,

Thompson,

Deyell

et al. 2024

J Applied Clin Med Phys

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PurposeLeft ventricle (LV) regional myocardial displacement due to cardiac motion was assessed using cardiovascular magnetic resonance (CMR) cine images to establish region‐specific margins for cardiac radioablation treatments.MethodsCMR breath‐hold cine images and LV myocardial tissue contour points were analyzed for 200 subjects, including controls (n = 50) and heart failure (HF) patients with preserved ejection fraction (HFpEF, n = 50), mid‐range ejection fraction (HFmrEF, n = 50), and reduced ejection fraction (HFrEF, n = 50). Contour points were divided into segments according to the 17‐segment model. For each patient, contour point displacements were determined for the long‐axis (all 17 segments) and short‐axis (segments 1–12) directions. Mean overall, tangential (longitudinal or circumferential), and normal (radial) displacements were calculated for the 17 segments and for each segment level.ResultsThe greatest overall motion was observed in the control group—long axis: 4.5 ± 1.2 mm (segment 13 [apical anterior] epicardium) to 13.8 ± 3.0 mm (segment 6 [basal anterolateral] endocardium), short axis: 4.3 ± 0.8 mm (segment 9 [mid inferoseptal] epicardium) to 11.5 ± 2.3 mm (segment 1 [basal anterior] endocardium). HF patients exhibited lesser motion, with the smallest overall displacements observed in the HFrEF group—long axis: 4.3 ± 1.7 mm (segment 13 [apical anterior] epicardium) to 10.6 ± 3.4 mm (segment 6 [basal anterolateral] endocardium), short axis: 3.9 ± 1.3 mm (segment 8 [mid anteroseptal] epicardium) to 7.4 ± 2.8 mm (segment 1 [basal anterior] endocardium).ConclusionsThis analysis provides an estimate of epicardial and endocardial displacement for the 17 segments of the LV for patients with normal and impaired LV function. This reference data can be used to establish treatment planning margin guidelines for cardiac radioablation. Smaller margins may be used for patients with higher degree of impaired heart function, depending on the LV segment.

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Stereotactic Arrhythmia Radioablation (STAR): Assessment of cardiac and respiratory heart motion in ventricular tachycardia patients - A STOPSTORM.eu consortium review

Cited by 17 publications

References 46 publications

Experimental demonstration of real‐time cardiac physiology‐based radiotherapy gating for improved cardiac radioablation on an MR‐linac

Experimental demonstration of real‐time cardiac physiology‐based radiotherapy gating for improved cardiac radioablation on an MR‐linac

Left ventricle segment-specific motion assessment for cardiac-gated radiosurgery

Analysis of left ventricle regional myocardial motion for cardiac radioablation

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