Development of a hybrid magnetic resonance/computed tomography-compatible phantom for magnetic resonance guided radiotherapy

Kim, Min‐Joo; Lee, Seu-Ran; Song, Kwang Hyun; Baek, Hyeon‐Man; Choe, Bo-Young; Suh, Tae Suk

doi:10.1093/jrr/rrz094

Cited by 3 publications

(1 citation statement)

References 39 publications

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“…Various studies addressed the requirements of contrast materials that can be used in MRI as well as in RT. These studies characterized potential phantom materials for their applicability in MRgXT end-to-end tests by determining their CT value and visibility in different MRI sequences (Steinmann et al 2018), characterized different materials quantitatively in CT and MRI to simulate anthropomorphic image contrast in the pelvic region (Niebuhr et al 2016) or in the general soft tissue range (Kim et al 2020). Furthermore, anthropomorphic MRI phantom materials with individually adjustable T 1 and T 2 relaxation times at a magnetic field of 1.5 T are available using nickel-or gadolinium diethylenetriaminepentaacetic acid (Ni-, GD-DTPA) (Tofts et al 1993).…”

Section: Introductionmentioning

confidence: 99%

Development of phantom materials with independently adjustable CT- and MR-contrast at 0.35, 1.5 and 3 T

Elter

Hellwich²,

Dorsch³

et al. 2021

Phys. Med. Biol.

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Quality assurance in magnetic resonance (MR)-guided radiotherapy lacks anthropomorphic phantoms that represent tissue-equivalent imaging contrast in both computed tomography (CT) and MR imaging. In this study, we developed phantom materials with individually adjustable CT value as well as T 1 - and T 2 -relaxation times in MR imaging at three different magnetic field strengths. Additionally, their experimental stopping power ratio (SPR) for carbon ions was compared with predictions based on single- and dual-energy CT. Ni-DTPA doped agarose gels were used for individual adjustment of T 1 and T 2 at 0.35 , 1.5 and 3.0 T. The CT value was varied by adding potassium chloride (KCl). By multiple linear regression, equations for the determination of agarose, Ni-DTPA and KCl concentrations for given T 1 , T 2 and CT values were derived and employed to produce nine specific soft tissue samples. Experimental T 1 , T 2 and CT values of these soft tissue samples were compared with predictions and additionally, carbon ion SPR obtained by range measurements were compared with predictions based on single- and dual-energy CT. The measured CT value, T 1 and T 2 of the produced soft tissue samples agreed very well with predictions based on the derived equations with mean deviations of less than 3.5 % . While single-energy CT overestimates the measured SPR of the soft tissue samples, the dual-energy CT-based predictions showed a mean SPR deviation of only 0.2 ± 0.3 % . To conclude, anthropomorphic phantom materials with independently adjustable CT values as well as T 1 and T 2 relaxation times at three different magnetic field strengths were developed. The derived equations describe the material specific relaxation times and the CT value in dependence on agarose, Ni-DTPA and KCl concentrations as well as the chemical composition of the materials based on given T 1 , T 2 and CT value. Dual-energy CT allows accurate prediction of the carbon ion range in these materials.

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