Characterization of the onboard imaging unit for the first clinical magnetic resonance image guided radiation therapy system

Hu, Yanle; Rankine, L; Green, Olga L.; Kashani, Rojano; Li, H. Harold; Li, Hua; Nana, Roger; Rodriguez, Vivian; Santanam, Lakshmi; Shvàrtsman, Sh. M.; Victoria, J.R.; Wooten, H; Dempsey, James F.; Mutic, Sasa

doi:10.1118/1.4930249

Cited by 52 publications

(59 citation statements)

References 8 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…However, in order to obtain sufficient SNR, the density of 19 F needs to be increased on the molecular basis which is accomplished through perfluorination in which all 1 H atoms in a hydrocarbon chain are replaced with 19 F atoms. 64,69 These perfluorocarbons (PFCs) are similar to common organic compounds in their molecular structure except that they are very electronegative.…”

Section: Biomarkers and Mrimentioning

confidence: 99%

“…Since then other sites have followed suit with clinically treating with their VRS such as the University of California, Los Angeles (Los Angeles, CA). 22 Hu et al 19 evaluated the VRS' image quality as compared with the American College of Radiology's guidelines for the Washington University VRS and found that the system met all American College of Radiology and vendor specifications. Hu et al 19 measured slice position error to be ,1 mm, slice thickness error was ,0.5 mm and the resolved high-contrast spatial resolution was 0.9 mm.…”

mentioning

confidence: 99%

“…22 Hu et al 19 evaluated the VRS' image quality as compared with the American College of Radiology's guidelines for the Washington University VRS and found that the system met all American College of Radiology and vendor specifications. Hu et al 19 measured slice position error to be ,1 mm, slice thickness error was ,0.5 mm and the resolved high-contrast spatial resolution was 0.9 mm. Geometric distortions for the 20-and 35-cm-diameter spherical volumes were 0.1 and 0.18 cm, respectively, for high spatial resolution three-dimensional images and 0.08 and 0.2 cm for two-dimensional (2D) high temporal cine images.…”

mentioning

confidence: 99%

“…Geometric distortions for the 20-and 35-cm-diameter spherical volumes were 0.1 and 0.18 cm, respectively, for high spatial resolution three-dimensional images and 0.08 and 0.2 cm for two-dimensional (2D) high temporal cine images. 19 The VRS is not the only MR-gRT option. Several other options exist and will soon be operating clinically.…”

mentioning

confidence: 99%

“…The unit is called the "MRIdian®" or "ViewRay system" (VRS). 19,20 The system has three doubly focused multileaf collimated 60 Co sources mounted on a ring, straddled by a 0.35-T MRI. 20 Both the therapy and the imaging system share the same isocentre, which allows for simultaneous imaging and treatment.…”

mentioning

confidence: 99%

See 4 more Smart Citations

The future of image-guided radiotherapy will be MR guided

Pollard

Wen

Sadagopan

et al. 2017

BJR

168

133

View full text Add to dashboard Cite

Advances in image-guided radiotherapy (RT) have allowed for dose escalation and more precise radiation treatment delivery. Each decade brings new imaging technologies to help improve RT patient setup. Currently, the most frequently used method of three-dimensional pre-treatment image verification is performed with cone beam CT. However, more recent developments have provided RT with the ability to have on-board MRI coupled to the teleradiotherapy unit. This latest tool for treating cancer is known as MR-guided RT. Several varieties of these units have been designed and installed in centres across the globe. Their prevalence, history, advantages and disadvantages are discussed in this review article. In preparation for the next generation of image-guided RT, this review also covers where MR-guided RT might be heading in the near future.

show abstract

Section: Biomarkers and Mrimentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

See 3 more Smart Citations

The future of image-guided radiotherapy will be MR guided

Pollard

Wen

Sadagopan

et al. 2017

BJR

168

133

View full text Add to dashboard Cite

show abstract

MRI quality control for low‐field MR‐IGRT systems: Lessons learned

Gach

Curcuru

Wittland

et al. 2019

J Applied Clin Med Phys

Self Cite

View full text Add to dashboard Cite

Purpose: To present lessons learned from magnetic resonance imaging (MRI) quality control (QC) tests for low-field MRI-guided radiation therapy (MR-IGRT) systems.Methods: MRI QC programs were established for low-field MRI-60 Co and MRI-Linac systems. A retrospective analysis of MRI subsystem performance covered system commissioning, operations, maintenance, and quality control. Performance issues were classified into three groups: (a) Image noise and artifact; (b) Magnetic field homogeneity and linearity; and (c) System reliability and stability.Results: Image noise and artifacts were attributed to room noise sources, unsatisfactory system cabling, and broken RF receiver coils. Gantry angle-dependent magnetic field inhomogeneities were more prominent on the MRI-Linac due to the high volume of steel shielding in the gantry. B 0 inhomogeneities measured in a 24-cm spherical phantom were <5 ppm for both MR-IGRT systems after using MRI gradient offset (MRI-GO) compensation on the MRI-Linac. However, significant signal dephasing occurred on the MRI-Linac while the gantry was rotating. Spatial integrity measurements were sensitive to gradient calibration and vulnerable to shimming.The most common causes of MR-IGRT system interruptions were software disconnects between the MRI and radiation therapy delivery subsystems caused by patient table, gantry, and multi-leaf collimator (MLC) faults. The standard deviation (SD) of the receiver coil signal-to-noise ratio was 1.83 for the MRI-60 Co and 1.53 for the MRI-Linac. The SD of the deviation from the mean for the Larmor frequency was 1.41 ppm for the MRI-60 Co and 1.54 ppm for the MRI-Linac. The SD of the deviation from the mean for the transmitter reference amplitude was 0.90% for the MRI-60 Co and 1.68% for the MRI-Linac. High SDs in image stability data corresponded to reports of spike noise.Conclusions: There are significant technological challenges associated with implementing and maintaining MR-IGRT systems. Most of the performance issues were identified and resolved during commissioning.

show abstract

Evaluation of cine imaging during multileaf collimator and gantry motion for real‐time magnetic resonance guided radiation therapy

Kielbasa

Meeks

Kelly

et al. 2020

J Applied Clin Med Phys

View full text Add to dashboard Cite

Real-time magnetic resonance guided radiation therapy (MRgRT) uses 2D cine imaging for target tracking. This work evaluates the percent image uniformity (PIU) and spatial integrity of cine images in the presence of multileaf collimator (MLC) and gantry motion in order to simulate sliding window and volumetric modulated arc therapy (VMAT) conditions. Methods: Percent image uniformity and spatial integrity of cine images were measured (1) during MLC motion, (2) as a function of static gantry position, and (3) during gantry rotation. PIU was calculated according to the ACR MRI Quality Control Manual. Spatial integrity was evaluated by measuring the geometric distortion of 16 measured marker positions (10 cm or 15.225 cm from isocenter). Results: The PIU of cine images did not vary by more than 1% from static linac conditions during MLC motion and did not vary by more than 3% during gantry rotation. Banding artifacts were present during gantry rotation. The geometric distortion in the cine images was less than 0.88 mm for all points measured throughout MLC motion. For all static gantry positions, the geometric distortion was less than 0.88 mm at 10 cm from isocenter and less than 1.4 mm at 15.225 cm from isocenter. During gantry rotation, the geometric distortion remained less than 0.92 mm at 10 cm from isocenter and less than 1.60 mm at 15.225 cm from isocenter. Conclusion: During MLC motion, cine images maintained adequate PIU, and the geometric distortion of points within 15.225 cm from isocenter was less than the 1 mm threshold necessary for real-time target tracking and gating. During gantry rotation, PIU was negatively affected by banding artifacts, and spatial integrity was only maintained within 10 cm from isocenter. Future work should investigate the effects imaging artifacts have on real-time target tracking during MRgRT.

show abstract

Characterization of the onboard imaging unit for the first clinical magnetic resonance image guided radiation therapy system

Abstract: The onboard imaging unit of the first commercial MR-IGRT system meets ACR, NEMA, and vendor specifications.

Cited by 52 publications

References 8 publications

The future of image-guided radiotherapy will be MR guided

The future of image-guided radiotherapy will be MR guided

MRI quality control for low‐field MR‐IGRT systems: Lessons learned

Evaluation of cine imaging during multileaf collimator and gantry motion for real‐time magnetic resonance guided radiation therapy

Contact Info

Product

Resources

About