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Integrated MRI-guided proton therapy planning: Accounting for the full MRI field in a perpendicular system

Journal Article


Abstract


  • Purpose: To present a first study on the treatment planning feasibility in perpendicular field MRI-integrated proton therapy that considers the full transport of protons from the pencil beam scanning (PBS) assembly to the patient inside the MRI��scanner. Methods: A generic proton PBS gantry was modeled as being integrated with a realistic split-bore MRI system in the perpendicular orientation. MRI field strengths were modeled as 0.5, 1, and 1.5��T. The PBS beam delivery and dose calculation was modeled using the TOPAS Monte Carlo toolkit coupled with matRad as the optimizer engine. A water phantom, liver, and prostate plans were evaluated and optimized in the presence of the full MRI field distribution. A simple combination of gantry angle offset and small PBS nozzle skew was used to direct the proton beams along a path that closely follows the reference planning scenario, that is, without magnetic��field. Results: All planning metrics could be successfully achieved with the inclusion of gantry angle offsets in the range of 8 (Formula presented.) ���29 (Formula presented.) when coupled with a PBS nozzle skew of 1.6 (Formula presented.) ���4.4 (Formula presented.). These two hardware-based corrections were selected to minimize the average Euclidean distance (AED) in the beam path enabling the proton beams to travel inside the patient in a path that is close to the original path (AED smaller than 3��mm at 1.5��T). Final dose optimization, performed through further changes in the PBS delivery, was then shown to be feasible for our selection of plans studied yielding comparable plan quality metrics to reference��conditions. Conclusions: For the first time, we have shown a robust method to account for the full proton beam deflection in a perpendicular orientation MRI-integrated proton therapy. These results support the ongoing development of the current prototype��systems.

Publication Date


  • 2022

Citation


  • Burigo, L. N., & Oborn, B. M. (2022). Integrated MRI-guided proton therapy planning: Accounting for the full MRI field in a perpendicular system. Medical Physics, 49(3), 1853-1873. doi:10.1002/mp.15398

Scopus Eid


  • 2-s2.0-85123259224

Web Of Science Accession Number


Start Page


  • 1853

End Page


  • 1873

Volume


  • 49

Issue


  • 3

Place Of Publication


Abstract


  • Purpose: To present a first study on the treatment planning feasibility in perpendicular field MRI-integrated proton therapy that considers the full transport of protons from the pencil beam scanning (PBS) assembly to the patient inside the MRI��scanner. Methods: A generic proton PBS gantry was modeled as being integrated with a realistic split-bore MRI system in the perpendicular orientation. MRI field strengths were modeled as 0.5, 1, and 1.5��T. The PBS beam delivery and dose calculation was modeled using the TOPAS Monte Carlo toolkit coupled with matRad as the optimizer engine. A water phantom, liver, and prostate plans were evaluated and optimized in the presence of the full MRI field distribution. A simple combination of gantry angle offset and small PBS nozzle skew was used to direct the proton beams along a path that closely follows the reference planning scenario, that is, without magnetic��field. Results: All planning metrics could be successfully achieved with the inclusion of gantry angle offsets in the range of 8 (Formula presented.) ���29 (Formula presented.) when coupled with a PBS nozzle skew of 1.6 (Formula presented.) ���4.4 (Formula presented.). These two hardware-based corrections were selected to minimize the average Euclidean distance (AED) in the beam path enabling the proton beams to travel inside the patient in a path that is close to the original path (AED smaller than 3��mm at 1.5��T). Final dose optimization, performed through further changes in the PBS delivery, was then shown to be feasible for our selection of plans studied yielding comparable plan quality metrics to reference��conditions. Conclusions: For the first time, we have shown a robust method to account for the full proton beam deflection in a perpendicular orientation MRI-integrated proton therapy. These results support the ongoing development of the current prototype��systems.

Publication Date


  • 2022

Citation


  • Burigo, L. N., & Oborn, B. M. (2022). Integrated MRI-guided proton therapy planning: Accounting for the full MRI field in a perpendicular system. Medical Physics, 49(3), 1853-1873. doi:10.1002/mp.15398

Scopus Eid


  • 2-s2.0-85123259224

Web Of Science Accession Number


Start Page


  • 1853

End Page


  • 1873

Volume


  • 49

Issue


  • 3

Place Of Publication