This work reports on the first seven patients treated with gating and baseline drift correction high-field MR-Linac system. Dosimetric analysis showed that active motion management system improved congruence to planned dose, efficiently mitigating detrimental effects of intrafraction in upper abdomen.

Novel motion-compensated treatment techniques on the MR-linac can address adverse intra-fraction motion effects. These involve beam gating or adaptations of plan based real-time magnetic resonance imaging (MRI) performed during treatment. For quality assurance (QA) these workflows, a multi-purpose platform is desirable. This should accommodate various phantoms, enabling multiple QA workflows. study aims to evaluate new IBA QUASAR Motion MR Platform for use in 1.5 T MR-linac. The was assessed...

Image-guided cardiac radioablation on a magnetic resonance-guided linear accelerator (MR-linac) is emerging as non-invasive treatment alternative for patients with arrhythmia. Precise target identification required such treatments. However, owing to concerns the use of gadolinium-based contrast agents during high-energy radiation, non-contrast alternatives must be considered. Native T1 mapping promising technique delineate myocardial scar which can serve surrogate target. Further, likely...

Objective.Stereotactic arrhythmia radioablation (STAR) is a novel, non-invasive treatment for refractory ventricular tachycardia (VT). The VT isthmus subject to both respiratory and cardiac motion. Rapid motion presents unique challenge. In this study, we provide first experimental evidence real-time cardiorespiratory motion-mitigated MRI-guided STAR on the 1.5 T Unity MR-linac (Elekta AB, Stockholm, Sweden) aimed at simultaneously compensating motions.Approach.A radiotherapy workflow was...

Background and purposeVMAT is not currently available on MR-linacs but could maximize plan conformality. To mitigate respiration without compromising delivery efficiency, MRI-guided MLC tumour tracking was recently developed for the 1.5 T Unity MR-linac (Elekta AB, Stockholm, Sweden) in combination with IMRT. Here, we provide a first experimental demonstration of VMAT + several lung SBRT indications.Materials methodsWe created central patient phantom plans (8×7.5 Gy, 2 arcs) peripheral (3×18...

Abstract Background Cardiac radioablation is a noninvasive stereotactic body radiation therapy (SBRT) technique to treat patients with refractory ventricular tachycardia (VT) by delivering single high‐dose fraction the VT isthmus. Cardiorespiratory motion induces position uncertainties resulting in decreased dose conformality. Electocardiograms (ECG) are typically used during cardiac MRI (CMR) acquire images predefined phase, thus mitigating image acquisition. Purpose We demonstrate...

Recently, multileaf collimator (MLC)-tracking has been technically and clinically demonstrated showing promising improvements of radiotherapy mobile sites. Furthermore, magnetic resonance imaging (MRI)-guided treatments have shown to provide superior targetting performance due on-line soft-tissue imaging. Hitherto, the combination MLC-tracking MRI not investigated using released hardware. In this note we aim describe technical feasibilty such a on operating MRI-linac.

Abstract Objective. Adaptive radiotherapy techniques available on the MR-linac, such as daily plan adaptation, gating, and dynamic tracking, require versatile dosimetric detectors to validate end-to-end workflows. Plastic scintillator (PSDs) offer great potential with features including: water equivalency, MRI-compatibility, time-resolved dose measurements. Here, we characterize performance of HYPERSCINT RP-200 PSD (MedScint, Quebec, CA) in a 1.5 T demonstrate its suitability for dosimetry,...

Hybrid MR-linac systems can use fast dynamic MR sequences for tumor tracking and adapt the radiation treatment in real-time. For this imaging latency must be as short possible. This work describes how different acquisition parameters influence latency. First, was measured Cartesian readouts with phase encode orderings linear, reverse-linear, high-low. Second, radial linear golden angle profile orderings. To reduce latency, a spatio-temporal (k-t) filter that suppresses k-space center of...

Purpose The treatment margins for lung stereotactic body radiotherapy (SBRT) are often large to cover the tumor excursions resulting from respiration, such that underdosage of can be avoided. Magnetic resonance imaging (MRI)‐guided multi‐leaf collimator (MLC) tracking potentially reduce influence respiration allow smaller margins. However, is accompanied by system latency may induce residual errors. Alternatively, a simpler mid‐position delivery combined with trailing used. Trailing reduces...

Intensity-modulated radiotherapy (IMRT) in combination with magnetic resonance imaging (MRI)-guided gated delivery represents the latest development treatment of abdominothoracic tumours on MR-linac. In contrast, volumetric-modulated arc therapy (VMAT) is typically used conventional linacs due to its superior efficiency and speed. Non-inferior VMAT plans were created a research planning system for eight lung cancer patients previously treated an delivered moving dosimeter using respiratory...

Dedicated motion compensated Magnetic Resonance Imaging (MRI) for radiotherapy treatment planning promises to mitigate effects on imaging. We demonstrate a novel insert an MRI safe phantom, which enables quality assurance of these image strategies. The capability analyse apparent slice thickness, positional accuracy and blur is demonstrated scenarios with without motion. A respiratory-compensated scan 4 mm trigger-window 16 peak-to-peak (p2p) showed +5.0% deviation from the nominal 2...

Respiratory motion management is important in abdominothoracic radiotherapy. Fast imaging of the tumor can facilitate multileaf collimator (MLC) tracking that allows for smaller treatment margins, while repeatedly full field-of-view necessary 4D dose accumulation. This study introduces a hybrid 2D/4D-MRI methodology be used simultaneous MLC and accumulation on 1.5 T Unity MR-linac (Elekta AB, Stockholm, Sweden).We developed uses multislice (SMS) accelerated MRI sequence, which acquires two...

The MR-Linac system offers a platform to adapt and monitor radiotherapy of tumors affected by continuous motion in real-time. However, real-time MRI technology is restricted 2D imaging, which limits performance. MR Signature Matching (MRSIGMA) recently developed 3D technique with the as target. MRSIGMA was tested only non-real-time scenario. This work develops implementation on Elekta Unity 1.5T MR-Linac, including raw data transmission an external computer, deep learning 4D reconstruction...

MR-guided thermal therapies, such as high-intensity focused ultrasound (MRgHIFU) and laser-induced therapy (MRgLITT) are increasingly being applied in oncology neurology. MRI is used for guidance since it can measure temperature noninvasively based on the proton resonance frequency shift (PRFS). For using PRFS thermometry, high temporal resolution large spatial coverage desirable. We propose to use parallel imaging technique simultaneous multislice (SMS) combination with controlled aliasing...

4D-MRI is becoming increasingly important for daily guidance of thoracic and abdominal radiotherapy. This study exploits the simultaneous multi-slice (SMS) technique to accelerate acquisition a balanced turbo field echo (bTFE) spin (TSE) coronal sequence performed on 1.5 T MRI scanners. SMS single-shot bTFE TSE sequences were developed acquire stack 52 2D images over 30 dynamics. Simultaneously excited slices separated by half view. Slices intersecting with liver-lung interface used as...

The heart is important in radiotherapy either as target or organ at risk. Quantitative T1 and T2 cardiac magnetic resonance imaging (qMRI) may aid definition for radioablation, biomarker cardiotoxicity assessment. Hybrid MR-linac devices could facilitate daily qMRI of the radiotherapy. aim this work was therefore to enable cardiac-synchronized mapping on a 1.5 T test reproducibility these sequences phantoms vivo between diagnostic MRI scanner.Cardiac-synchronized performed using wireless...

Abstract Purpose Develop a true real‐time implementation of MR signature matching (MRSIGMA) for free‐breathing 3D MRI with sub‐200 ms latency on the Elekta Unity 1.5T MR‐Linac. Methods MRSIGMA was implemented an external computer network connection to Stack‐of‐stars partial k z sampling used accelerate data acquisition and ReconSocket employed simultaneous transmission. Movienet computed 4D motion dictionary correlation analysis matching. A programmable phantom utilized evaluate respect...

Hybrid MR-linac systems enable intrafraction motion monitoring during radiation therapy. Since time-resolved 3D MRI is still challenging, various models have been developed that rely on 2D imaging. Continuous validation of these important for accurate dose accumulation mapping. In this study we used simultaneous multislice (SMS) imaging to improve the PCA-based modeling method previously (Stemkens et al 2016 Phys. Med. Biol. 61 5335-55). From additional simultaneously acquired slices,...

With the recent advent of hybrid MRI-guided radiotherapy systems, continuous intra-fraction MR imaging for motion monitoring has become feasible. The ability to perform real-time custom image reconstructions is however often lacking. In this work we present a low-latency streaming solution, ReconSocket, which provides stream k-space data from magnetic resonance (MRI) reconstruction servers.

Objective: To develop and evaluate a combined motion-assisted/gated MRHIFU heating strategy designed to accelerate the treatment procedure by reducing required number of sonications ablate target volume in pancreas.Methods: A planning method for using 4D-MRI motion characterization is introduced. Six healthy volunteers underwent on 3.0-T clinical scanner. Using displacement patterns, simulations were performed all three sonication approaches: gated, motion-assisted/gated, static. The needed...

Respiratory-correlated 4D-MRI may provide motion characteristics for radiotherapy but is susceptible to irregular breathing. This study investigated the effectiveness of visual biofeedback (VBF) guidance breathing regularization during acquisitions on an MR-linac.A simultaneous multislice-accelerated sequence was interleaved with a one-dimensional respiratory navigator (1D-RNAV) in 10 healthy volunteers 1.5T Unity MR-linac (Elekta AB, Stockholm, Sweden). Volunteer-specific amplitudes and...

Abstract Background Several (online) adaptive radiotherapy procedures are available to maximize healthy tissue sparing in the presence of inter/intrafractional motion during stereotactic body (SBRT) on an MR‐linac. The increased treatment complexity and motion‐delivery interplay these treatments require MR‐compatible phantoms with time‐resolved dosimeters validate end‐to‐end workflows. This is not possible currently phantoms. Purpose Here, we demonstrate a new commercial hybrid...