Treatment of Central Nervous System Tumors on Combination MR-Linear Accelerators: Review of Current Practice and Future Directions

Bryant, John Michael; Doniparthi, Ajay; Weygand, Joseph; Cruz-Chamorro, Ruben; Oraiqat, Ibrahim M.; Andreozzi, Jacqueline; Graham, Jasmine; Redler, Gage; Latifi, Kujtim; Feygelman, Vladimir; Rosenberg, Stephen A.; Yu, Hsiang-Hsuan Michael; Oliver, Daniel E.

doi:10.3390/cancers15215200

Cited by 2 publications

(1 citation statement)

References 121 publications

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“…While MR-linacs are predominantly employed for irradiating mobile tumors in the abdominal, thoraic, or pelvic region [ 3 , 4 ], the high soft tissue contrast of MRI and the potential for online treatment plan adaptation also allows intracranial treatments with increased precision. Intracranial treatments at MR-linacs can be performed with smaller target volumes and reduced neurotoxicity compared to treatments at conventional linacs [ 2 , 5 – 7 ]. Another key feature of MR-linacs, not yet fully exploited in clinical practice, is the technical feasibility of functional MRI.…”

Section: Introductionmentioning

confidence: 99%

Repeatability quantification of brain diffusion-weighted imaging for future clinical implementation at a low-field MR-linac

Rabe,

Dietrich,

Forbrig

et al. 2024

Radiat Oncol

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Background Longitudinal assessments of apparent diffusion coefficients (ADCs) derived from diffusion-weighted imaging (DWI) during intracranial radiotherapy at magnetic resonance imaging-guided linear accelerators (MR-linacs) could enable early response assessment by tracking tumor diffusivity changes. However, DWI pulse sequences are currently unavailable in clinical practice at low-field MR-linacs. Quantifying the in vivo repeatability of ADC measurements is a crucial step towards clinical implementation of DWI sequences but has not yet been reported on for low-field MR-linacs. This study assessed ADC measurement repeatability in a phantom and in vivo at a 0.35 T MR-linac. Methods Eleven volunteers and a diffusion phantom were imaged on a 0.35 T MR-linac. Two echo-planar imaging DWI sequence variants, emphasizing high spatial resolution (“highRes”) and signal-to-noise ratio (“highSNR”), were investigated. A test–retest study with an intermediate outside-scanner-break was performed to assess repeatability in the phantom and volunteers’ brains. Mean ADCs within phantom vials, cerebrospinal fluid (CSF), and four brain tissue regions were compared to literature values. Absolute relative differences of mean ADCs in pre- and post-break scans were calculated for the diffusion phantom, and repeatability coefficients (RC) and relative RC (relRC) with 95% confidence intervals were determined for each region-of-interest (ROI) in volunteers. Results Both DWI sequence variants demonstrated high repeatability, with absolute relative deviations below 1% for water, dimethyl sulfoxide, and polyethylene glycol in the diffusion phantom. RelRCs were 7% [5%, 12%] (CSF; highRes), 12% [9%, 22%] (CSF; highSNR), 9% [8%, 12%] (brain tissue ROIs; highRes), and 6% [5%, 7%] (brain tissue ROIs; highSNR), respectively. ADCs measured with the highSNR variant were consistent with literature values for volunteers, while smaller mean values were measured for the diffusion phantom. Conversely, the highRes variant underestimated ADCs compared to literature values, indicating systematic deviations. Conclusions High repeatability of ADC measurements in a diffusion phantom and volunteers’ brains were measured at a low-field MR-linac. The highSNR variant outperformed the highRes variant in accuracy and repeatability, at the expense of an approximately doubled voxel volume. The observed high in vivo repeatability confirms the potential utility of DWI at low-field MR-linacs for early treatment response assessment.

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Section: Introductionmentioning

confidence: 99%

Repeatability quantification of brain diffusion-weighted imaging for future clinical implementation at a low-field MR-linac

Rabe,

Dietrich,

Forbrig

et al. 2024

Radiat Oncol

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Controversies in neuro-oncology: Focal proton versus photon radiation therapy for adult brain tumors

Eekers,

Zegers,

Ahmed

et al. 2024

Neuro-Oncology Practice

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Radiation therapy (RT) plays a fundamental role in the treatment of malignant and benign brain tumors. Current state of the art photon- and proton-based RT combines more conformal dose distribution of target volumes and accurate dose delivery while limiting the adverse radiation effects. Several studies have demonstrated that proton therapy (PT) provides reduced dose to healthy brain parenchyma compared with photon-based (xRT) radiation techniques. However, whether dosimetric advantages translate into superior clinical outcomes for different adult brain tumors remains an open question. This review aims at critically reviewing the recent studies on PT in adult patients with brain tumors, including glioma, meningiomas and chordomas, to explore its potential benefits compared with xRT.

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Treatment of Central Nervous System Tumors on Combination MR-Linear Accelerators: Review of Current Practice and Future Directions

Cited by 2 publications

References 121 publications

Repeatability quantification of brain diffusion-weighted imaging for future clinical implementation at a low-field MR-linac

Repeatability quantification of brain diffusion-weighted imaging for future clinical implementation at a low-field MR-linac

Controversies in neuro-oncology: Focal proton versus photon radiation therapy for adult brain tumors

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