Monte Carlo assessment of beam deflection and depth dose equivalent variation of a carbon-ion beam in a perpendicular magnetic field

Akbari, Mahmoudreza; Karimian, Alireza

doi:10.1016/j.ejmp.2019.04.016

Cited by 7 publications

(4 citation statements)

References 22 publications

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“…The presence of a high-intensity perpendicular magnetic field affected on C-ion beam traversing in water can change the ion range (due to detur effect), and this issue can be found in our previous work [13], which has been demonstrated by applying the Monte Carlo simulation. The resulting of the retraction of the range is caused by the curvature of the track.…”

Section: Jinst 15 T05006mentioning

confidence: 85%

“…In the case of MRI-guided C-ion radiotherapy (MRgCT) scenario, as a therapeutic approach for future potential MR-guided particle therapy [13,14], it is well-known that charged particles will be affected by the Lorentz force and, therefore, the C-ion beam will be deflected in the presence of the magnetic field. The resulting change of the depth-dose curve with a retraction of the range is caused by the curvature of the track (detur effect) [14].…”

Section: Introductionmentioning

confidence: 99%

“…Monte Carlo simulations have recently been applied to the transport of C-ion beams in the presence of magnetic fields [13,14]. Moreover, the accuracy of the proton ions transport calculations compared to experimental data in the presence of a magnetic field has been proved so far.…”

Section: Introductionmentioning

confidence: 99%

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Impact of transverse magnetic fields on water equivalent ratios in carbon-ion radiotherapy

Akbari

Karimian

2020

J. Inst.

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The correct estimation of water equivalent ratio (WER) and the associated errors is highly important for the delivery of carbon-ion (C-ion) beams. In the case of MRI-guided C-ion radiotherapy (MRgCT) scenario, as a therapeutic approach for future potential MR-guided particle therapy, C-ion beam will be deflected in the presence of the magnetic field. The curvature of the track causes a retraction of the range. This range variation might be different in various materials, which leads to change the WER values. To evaluate the WER variations versus magnetic field strength, in this research work, WER of some materials, including bladder, brain, prostate, muscle, bone, polymethylmethacrylate (PMMA), polyoxymethylene (POM), polyethyleneterephthalate (PET), titanium (Ti), gold (Au), platinum (Pt); potentially encountered in C-ion radiotherapy dosimetry were assessed. A mono-energetic C-ion beam, incident on a volume containing materials as mentioned above, was simulated using the FLUKA Monte Carlo code. To validate the simulated C-ion beams, the ion ranges in the water at the calculated energies (100-400 MeV/n) were compared with experimental and analytical data reported in the literature. Moreover, the calculated WER results were compared with available experimental data in the absence of the magnetic field. The WER values were calculated for the materials mentioned above in the presence of 0.35, 1.5, and 3 T magnetic fields and compared to the case without a magnetic field. Good agreement with the experimental data regarding range prediction in water was achieved. No change in the WER value was observed at 100 MeV/n and 0.35 T for all the studied materials and energies. In the case of bladder, brain, and prostate, and muscle materials, no change in WER values was observed by changing the magnetic field strength up to 3 T at the range of the studied energies. The maximum change in WER values by applying the magnetic fields is relevant to the Ti material (−0.4%), which occurs at 400 MeV/n energy and 3 T magnetic field. Considering the potential encounter of the studied materials in 1Corresponding author.

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Section: Jinst 15 T05006mentioning

confidence: 85%

Section: Introductionmentioning

confidence: 99%

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Impact of transverse magnetic fields on water equivalent ratios in carbon-ion radiotherapy

Akbari

Karimian

2020

J. Inst.

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“…Over the last 10 years, there has been increasing interest in both academic and industry circles about the potential to integrate MRI scanners with other imaging or therapeutic systems. To date, two fully realized commercial MRI-Linac systems and two prototype systems exist (Fallone 2014, Keall et al 2014, Lagendijk et al 2014, Mutic and Dempsey 2014, whilst prototype systems have been investigated for MR-Angiography systems (Fahrig et al 2001), MR-proton systems (Schellhammer et al 2018, van der Kraaij et al 2020, and proposed for MR-carbon systems (Akbari and Karimian 2019). In each of these situations, the second modality would normally rotate around the patient to function; therefore, the integrated system design must somehow enable this relative rotation between device and patient.…”

Section: Introductionmentioning

confidence: 99%

Magnetic modeling of actively shielded rotating MRI magnets in the presence of environmental steel

Whelan¹,

Leghissa²,

Amrei³

et al. 2021

Phys. Med. Biol.

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Rotating MRI systems could enable novel integrated medical devices such as MRI-Linacs, MRI-xray-angiography systems, and MRI-proton therapy systems. This work aimed to investigate the feasibility of rotating actively shielded superconducting MRI magnets in the presence of environmental steel—in particular, construction steel in the floor of the installation site. Two magnets were investigated: a 1.0 T split bore magnet, and a 1.5 T closed bore magnet. Each magnet was scaled to emulate field strengths of 0.5, 1.0, and 1.5 T. Finite Element Modeling was used to simulate these magnets in the presence of a 3 × 4 m steel plate located 1250 mm or 1400 mm below the isocenter. There are two possible rotation directions: around the longitudinal (z) axis or around the transverse (x) axis. Each model was solved for rotation angles between 0 and 360° in 30° intervals around each of these axes. For each simulation, a 300 mm DSV was extracted and decomposed into spherical harmonics. For the closed-bore magnet, total induced perturbation for the zero degree rotation angle was 223, 432, and 562 μT peak-to-peak (pk–pk) for the 0.5, 1.0, and 1.5 T models respectively (steel at 1250 mm). For the split-bore magnet, the same numbers were 1477, 16747, and 1766 μT. The substantially higher perturbation for the split-bore magnet can be traced to its larger fringe field. For rotation around the z-axis, total perturbation does not change as a function of angle but is exchanged between different harmonics. For rotation around the x-axis, total perturbation is different at each rotation angle. For the closed bore magnet, maximum perturbations occurred for a 90° rotation around the transverse axis. For the split-bore magnet, the opposite was observed, with the same 90° rotation yielding total perturbation lower than the conventional position. In all cases, at least 95% of the total perturbation was composed of 1st and 2nd order harmonics. The presence of environmental steel poses a major challenge to the realization of an actively shielded rotating superconducting MRI system, requiring some novel form of shimming. Possible shimming strategies are discussed at length.

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Comparison of different deep learning architectures for synthetic CT generation from MR images

2021

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Monte Carlo assessment of beam deflection and depth dose equivalent variation of a carbon-ion beam in a perpendicular magnetic field

Cited by 7 publications

References 22 publications

Impact of transverse magnetic fields on water equivalent ratios in carbon-ion radiotherapy

Impact of transverse magnetic fields on water equivalent ratios in carbon-ion radiotherapy

Magnetic modeling of actively shielded rotating MRI magnets in the presence of environmental steel

Comparison of different deep learning architectures for synthetic CT generation from MR images

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