Quantitative analysis of image quality for acceptance and commissioning of an <scp>MRI</scp> simulator with a semiautomatic method

Chen, Xinyuan; Dai, Jianrong

doi:10.1002/acm2.12311

Cited by 3 publications

(2 citation statements)

References 26 publications

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“…The geometric accuracy assessment (called spatial integrity test in this report) should be performed at isocenter and two or more locations off-center in three planes. (Mah et al 2002, Jackson et al 2010, Chen and Dai, 2018, Tijssen et al 2019 In our evaluation, the spatial integrity errors were less than 0.5 mm in each direction for both MRgRT systems.…”

Section: Discussionmentioning

confidence: 62%

Characterizing MR Imaging isocenter variation in MRgRT

Kim

Maraghechi

et al. 2020

Biomed. Phys. Eng. Express

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We characterized MRI isocenter variation at various gantry positions in two 0.35 T MRgRT systems using two independent methods. First, image center-based quantification was employed on 3D volumetric and 2D cine images of a 24 cm diameter spherical phantom at various gantry positions in the MRI QA mode. The center of the phantom images was identified to quantify the variation of the imaging center at each gantry position. Second, image registration-based quantification was used in radiotherapy mode. 3D volumetric MRIs of a cylindrical phantom were acquired and corresponding image registration from MRI to planning CT was performed. The shifts of the couch were identified to quantify the variation of the imaging center. For verification of noticeable MRI isocenter variation, star-shot pattern measurements with five beams were delivered on the radio-chromic film inserted into the phantom after the couch was shifted. The center of the star-shot pattern was identified to quantify the variation of the imaging center. The proposed methods for measuring MRI isocenter variation were demonstrated with MR-LINAC and MR-60 Co systems. Both of the MRgRT systems had field inhomogeneities <5 ppm over a 24 cm diameter spherical volume (DSV) and spatial integrity distortion: <1 mm within 100 mm radius and <2 mm within 175 mm radius. The MRI isocenter of the MR-LINAC system showed noticeable 3D variation (max magnitude: 1.8 mm) compared to that of MR-60 Co system (max magnitude: 0.9 mm) relative to the reference gantry positions. In addition, 2D variations (max magnitude) of the MRI isocenter from sagittal cine images were 0.9 mm for the MR-LINAC system and 0.5 mm for the MR-60 Co system. Two proposed methods quantified the MRI isocenter variation for various gantry positions in two 0.35 T MRgRT systems. The results of significant isocenter variation in the MR-LINAC system requires further investigation to determine the cause.

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Section: Discussionmentioning

confidence: 62%

Characterizing MR Imaging isocenter variation in MRgRT

Kim

Maraghechi

et al. 2020

Biomed. Phys. Eng. Express

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“…Ginn et al used two commercially available phantoms to comprehensively assess the spatial distortion of a 0.35 T MRIguided radiotherapy system (21). The ACR phantom can measure the geometric distortion, gradient/radiofrequency (RF) subsystem, the percent image uniformity (PIU), and other ordinary MRI scanner imaging parameters (22). Self-designed geometric distortion phantoms have a considerable history.…”

Section: Discussionmentioning

confidence: 99%

A Comparison of the Distortion in the Same Field MRI and MR-Linac System With a 3D Printed Phantom

Liu

Rong

et al. 2021

Front. Oncol.

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PurposeA 3D printed geometric phantom was developed that can be scanned with computed tomography (CT) and magnetic resonance imaging (MRI) to measure the geometric distortion and determine the relevant dose changes.Materials and MethodsA self-designed 3D printed photosensitive resin phantom was used, which adopts grid-like structures and has 822 1 cm2 squares. The scanning plan was delivered by three MRI scanners: the Elekta Unity MR-Linac 1.5T, GE Signa HDe 1.5T, and GE Discovery-sim 750 3.0T. The geometric distortion comparison was concentrated on two 1.5T MRI systems, whereas the 3.0T MRI was used as a supplemental experiment. The most central transverse images in each dataset were selected to demonstrate the plane distortion. Some mark points were selected to analyze the distortion in the 3D direction based on the plane geometric distortion. A treatment plan was created with the off-line Monaco system.ResultsThe distortion increases gradually from the center to the outside. The distortion range is 0.79 ± 0.40 mm for the Unity, 1.31 ± 0.56 mm for the GE Signa HDe, and 2.82 ± 1.48 mm for the GE Discovery-sim 750. Additionally, the geometric distortion slightly affects the actual planning dose of the radiotherapy.ConclusionGeometric distortion increases gradually from the center to the outside. The distortion values of the Unity were smaller than those of the GE Signa HDe, and the Unity has the smallest geometric distortion. Finally, the Unity’s dose variation best matched with the standard treatment plan.

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