Investigating the use of virtual 4DCT from 4DMRI in gated carbon ion radiation therapy of abdominal tumors

Meschini, Giorgia; Vai, Alessandro; Paganelli, Chiara; Molinelli, S.; Maestri, Davide; Fontana, Giulia; Pella, Andrea; Vitolo, Viviana; Valvo, Francesca; Ciocca, Mario; Baroni, Guido

doi:10.1016/j.zemedi.2020.08.005

Cited by 8 publications

(17 citation statements)

References 50 publications

(76 reference statements)

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“…One limitation of the study consists in the restricted field of view of the 4DMRI (12.5 cm in the right-left direction), which was due to imaging constraints and the trade-off between temporal and spatial resolution. 9,29 The availability of 4DMRI data with extended field of view 7,30 would lead to better DIR performance and improved motion model estimations over the entire irradiated patient anatomy. Another limitation is the small number of patient data sets acquired for our analysis.…”

Section: Discussionmentioning

confidence: 99%

An MRI framework for respiratory motion modelling validation

et al. 2021

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Introduction: Respiratory motion models establish a correspondence between respiratory-correlated (RC) 4-dimensional (4D) imaging and respiratory surrogates, to estimate time-resolved (TR) 3D breathing motion. To evaluate the performance of motion models on real patient data, a validation framework based on magnetic resonance imaging (MRI) is proposed, entailing the use of RC 4DMRI to build the model, and on both (i) TR 2D cine-MRI and (ii) additional 4DMRI data for testing intra-/inter-fraction breathing motion variability. Methods: Repeated MRI data were acquired in 7 patients with abdominal lesions. The considered model relied on deformable image registration (DIR) for building the model and compensating for inter-fraction baseline variations. Both 2D and 3D validation were performed, by comparing model estimations with the ground truth 2D cine-MRI and 4DMRI respiratory phases, respectively. Results: The median DIR error was comparable to the voxel size (1.33 9 1.33 9 5 mm 3 ), with higher values in the presence of large inter-fraction motion (median value: 2.97 mm). In the 2D validation, the median estimation error on anatomical landmarks' position resulted below 4 mm in every scenario, whereas in the 3D validation it was 1.33 mm and 4.21 mm when testing intra-and inter-fraction motion, respectively. The range of motion described in the cine-MRI was comparable to the motion of the building 4DMRI, being always above the estimation error. Overall, the model performance was dependent on DIR error, presenting reduced accuracy when interfraction baseline variations occurred. Conclusions: Results suggest the potential of the proposed framework in evaluating global motion models for organ motion management in MRI-guided radiotherapy.

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Section: Discussionmentioning

confidence: 99%

An MRI framework for respiratory motion modelling validation

et al. 2021

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“…The end‐exhale CT from the pCT and end‐exhale MR were deformably registered with Bspline DIR (plastimatch.org), thus obtaining a 3D DVF limited to the MR FOV. The DVF was then extended to the FOV of the entire patient anatomy by replicating the motion components at the boundary of the FOV (i.e., in correspondence to the two extreme sagittal slices) to the surrounding voxels 16 . The pCT was therefore deformed according to the resulting DVF to match the abdominal anatomy of the end‐exhale MR, yielding the reference vCT (Figure 1a).…”

Section: Methodsmentioning

confidence: 99%

“…The 3D DVF corresponding to each pair was estimated by propagating to all adjacent planes the right–left and superior–inferior motion components from the coronal DVF, and the antero‐posterior information from the sagittal DVF 26 . Due to the abdominal compression applied at CNAO, we assumed negligible motion of the spinal cord and ribs, thus considering the estimated motion only within the lower‐thorax and abdomen 13–16 . The reference vCT was finally deformed according to the resulting 3D DVF, thus reconstructing a virtual 3D CT corresponding to each pair of 2D cine‐MRI frames (Figure 1c).…”

Section: Methodsmentioning

confidence: 99%

“…21,27 In this study, we aim at exploiting MRI-guidance for CIRT of pancreas cancer patients, by investigating an approach for the clinical evaluation of gating treatment robustness. Specifically, we integrated the technique of the virtual CT (vCT) from MRI 15,16 with the 3D reconstruction from 2D cine-MRI 26 in order to produce TR vCTs for off -line dose recalculations. We validated the adopted method for the abdominal district on a digital phantom, 28,29 and we performed geometrical and dosimetric quantifications of the impact of breathing motion variability on patients' data for gated CIRT of pancreas cancer.…”

Section: Introductionmentioning

confidence: 99%

“…To overcome these limitations, magnetic resonance imaging (MRI) can be considered, as it offers radiation‐free acquisitions, improved soft‐tissue contrast, and both RC 4D and time‐resolved (TR) fast sequences 8,9 . RC 4DMRI can be used to investigate intra‐ and inter‐fraction motion variability, 10–12 by generating virtual 4DCT from repeated 4DMRI for treatment planning and verification 13–16 . TR 3D images still present insufficient spatiotemporal resolution 9 ; however, TR 2D cine‐MRI can be acquired to describe cycle‐to‐cycle breathing variations 17 …”

Section: Introductionmentioning

confidence: 99%

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Time‐resolved MRI for off‐line treatment robustness evaluation in carbon‐ion radiotherapy of pancreatic cancer

et al. 2022

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In this study, we investigate the use of magnetic resonance imaging (MRI) for the clinical evaluation of gating treatment robustness in carbonion radiotherapy (CIRT) of pancreatic cancer. Indeed, MRI allows radiation-free repeated scans and fast dynamic sequences for time-resolved (TR) imaging (cine-MRI), providing information on inter-and intra-fraction cycle-to-cycle variations of respiratory motion. MRI can therefore support treatment planning and verification, overcoming the limitations of the current clinical standard, that is, four-dimensional computed tomography (4DCT), which describes an "average" breathing cycle neglecting breathing motion variability. Methods: We integrated a technique to generate a virtual CT (vCT) from 3D MRI with a method for 3D reconstruction from 2D cine-MRI, to produce TR vCTs for dose recalculations. For eight patients, the method allowed evaluating inter-fraction variations at end-exhale and intra-fraction cycle-to-cycle variability within the gating window in terms of tumor displacement and dose to the target and organs at risk. Results:The median inter-fraction tumor motion was in the range 3.33-12.16 mm, but the target coverage was robust (-0.4% median D 95% variation). Concerning cycle-to-cycle variations, the gating technique was effective in limiting tumor displacement (1.35 mm median gating motion) and corresponding dose variations (-3.9% median D 95% variation). The larger exposure of organs at risk (duodenum and stomach) was caused by inter-fraction motion, whereas intra-fraction cycle-to-cycle dose variations were limited. Conclusions: This study proposed a method for the generation of TR vCTs from MRI, which enabled an off -line evaluation of gating treatment robustness and suggested its feasibility to support treatment planning of pancreatic tumors in CIRT.

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Impact of different respiratory gating methods on target delineation and a radiotherapy plan for solitary pulmonary tumors

Shang,

Duan,

Yin

et al. 2024

Cancer Medicine

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Background and PurposeRespiratory movement has an important impact on the radiotherapy for lung tumor. Respiratory gating technology is helpful to improve the accuracy of target delineation. This study investigated the value of prospective and retrospective respiratory gating simulations in target delineation and radiotherapy plan design for solitary pulmonary tumors (SPTs) in radiotherapy.MethodsThe enrolled patients underwent CT simulation with three‐dimensional (3D) CT non gating, prospective respiratory gating, and retrospective respiratory gating simulation. The target volumes were delineated on three sets of CT images, and radiotherapy plans were prepared accordingly. Tumor displacements and movement information obtained using the two respiratory gating approaches, as well as the target volumes and dosimetry parameters in the radiotherapy plan were compared.ResultsNo significant difference was observed in tumor displacement measured using the two gating methods (p > 0.05). However, the internal gross tumor volumes (IGTVs), internal target volumes (ITVs), and planning target volumes (PTVs) based on the retrospective respiratory gating simulation were larger than those obtained using prospective gating (group A: pIGTV = 0.041, pITV = 0.003, pPTV = 0.008; group B: pIGTV = 0.025, pITV = 0.039, pPTV = 0.004). The two‐gating PTVs were both smaller than those delineated on 3D non gating images (p < 0.001). V5Gy, V10Gy, V20Gy, V30Gy, and mean lung dose in the two gated radiotherapy plans were lower than those in the 3D non gating plan (p < 0.001); however, no significant difference was observed between the two gating plans (p > 0.05).ConclusionsThe application of respiratory gating could reduce the target volume and the radiation dose that the normal lung tissue received. Compared to prospective respiratory gating, the retrospective gating provides more information about tumor movement in PTV.

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Investigating the use of virtual 4DCT from 4DMRI in gated carbon ion radiation therapy of abdominal tumors

Cited by 8 publications

References 50 publications

An MRI framework for respiratory motion modelling validation

An MRI framework for respiratory motion modelling validation

Time‐resolved MRI for off‐line treatment robustness evaluation in carbon‐ion radiotherapy of pancreatic cancer

Impact of different respiratory gating methods on target delineation and a radiotherapy plan for solitary pulmonary tumors

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