Design, implementation, and assessment of an independent second-check system for proton and carbon-ion pencil-beam scanning: delivery-aware Monte Carlo and microdosimetric RBE-weighted dose
- 1Department of Radiation Oncology, Mayo Clinic Florida
Abstract
Background: Independent second checks for proton and carbon-ion pencil-beam scanning should assess the planned physical dose, the expected delivery sequence, and the model-dependent relative biological effectiveness (RBE)-weighted dose.
Objective: The aim of this study was to design, implement, and assess a traceable second-check system that combines delivery-aware Monte Carlo transport with microdosimetric RBE calculation for both particle species.
Methods: The system receives Digital Imaging and Communications in Medicine (DICOM) planning data, converts the discrete spot sequence into a predicted delivery sequence for dose-driven continuous scanning (DDCS), generates weighted particle histories, and performs independent TOPAS/Geant4 transport. It scores physical dose, dose-averaged linear energy transfer (LETd), and voxel-level microdosimetric quantities. For both beam types, the scored lineal-energy distribution is represented using abridged microdosimetry distribution methodology (AMDM) and processed with the Mayo Clinic Florida microdosimetric kinetic model (MCF MKM). The proton branch additionally produces a fixed-RBE-weighted dose using RBE = 1.1. No fixed-RBE model is used for carbon ions. Proton assessment included component tests, single-energy source, transport, and scoring checks at 70.0, 170.2, and 229.1 MeV, patient-level evaluations using de-identified plans, and operational timing. Carbon-ion assessment used a pre-existing Monte Carlo dataset to evaluate component-level handling and visualization of AMDM descriptors, the MCF MKM RBE factor, and RBE-weighted dose.
Results: The integrated workflow completed plan receiving, delivery-sequence generation, particle transport, physical and biological dose calculation, comparison, and report generation. The proton case for which detailed quantitative end-to-end results were reported was classified as REVIEW REQUIRED because not all dosimetric comparison criteria were met. A pre-existing carbon-ion dataset was used to verify the component-level handling and separate presentation of physical dose, AMDM descriptors, RBE factor, and RBE-weighted dose. Predicted DDCS timing and the stationary-versus-moving irradiation components were not benchmarked against machine logs or measurements.
Conclusion: A common delivery-aware platform was implemented to support independent physical dose and microdosimetric RBE-weighted dose assessment for proton and carbon-ion treatments while retaining beam-specific dose conventions and biological model information. Further local commissioning and multicase validation are required before clinical use.
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BibTeX
@article{tan2026design,
title = {{Design, implementation, and assessment of an independent second-check system for proton and carbon-ion pencil-beam scanning: delivery-aware Monte Carlo and microdosimetric RBE-weighted dose}},
author = {Jun Tan and Keith Furutani and Alessio Parisi and Shannon Hartzell and Chris Beltran},
journal = {Frontiers in Oncology},
year = {2026},
month = oct,
doi = {10.3389/fonc.2026.1949825},
url = {https://www.frontiersin.org/articles/10.3389/fonc.2026.1949825/full},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Design, implementation, and assessment of an independent second-check system for proton and carbon-ion pencil-beam scanning: delivery-aware Monte Carlo and microdosimetric RBE-weighted dose
AU - Jun Tan
AU - Keith Furutani
AU - Alessio Parisi
AU - Shannon Hartzell
AU - Chris Beltran
PY - 2026
DA - 2026/10/20
JO - Frontiers in Oncology
DO - 10.3389/fonc.2026.1949825
UR - https://www.frontiersin.org/articles/10.3389/fonc.2026.1949825/full
AB - Background: Independent second checks for proton and carbon-ion pencil-beam scanning should assess the planned physical dose, the expected delivery sequence, and the model-dependent relative biological effectiveness (RBE)-weighted dose. Objective: The aim of this study was to design, implement, and assess a traceable second-check system that combines delivery-aware Monte Carlo transport with microdosimetric RBE calculation for both particle species. Methods: The system receives Digital Imaging and Communications in Medicine (DICOM) planning data, converts the discrete spot sequence into a predicted delivery sequence for dose-driven continuous scanning (DDCS), generates weighted particle histories, and performs independent TOPAS/Geant4 transport. It scores physical dose, dose-averaged linear energy transfer (LETd), and voxel-level microdosimetric quantities. For both beam types, the scored lineal-energy distribution is represented using abridged microdosimetry distribution methodology (AMDM) and processed with the Mayo Clinic Florida microdosimetric kinetic model (MCF MKM). The proton branch additionally produces a fixed-RBE-weighted dose using RBE = 1.1. No fixed-RBE model is used for carbon ions. Proton assessment included component tests, single-energy source, transport, and scoring checks at 70.0, 170.2, and 229.1 MeV, patient-level evaluations using de-identified plans, and operational timing. Carbon-ion assessment used a pre-existing Monte Carlo dataset to evaluate component-level handling and visualization of AMDM descriptors, the MCF MKM RBE factor, and RBE-weighted dose. Results: The integrated workflow completed plan receiving, delivery-sequence generation, particle transport, physical and biological dose calculation, comparison, and report generation. The proton case for which detailed quantitative end-to-end results were reported was classified as REVIEW REQUIRED because not all dosimetric comparison criteria were met. A pre-existing carbon-ion dataset was used to verify the component-level handling and separate presentation of physical dose, AMDM descriptors, RBE factor, and RBE-weighted dose. Predicted DDCS timing and the stationary-versus-moving irradiation components were not benchmarked against machine logs or measurements. Conclusion: A common delivery-aware platform was implemented to support independent physical dose and microdosimetric RBE-weighted dose assessment for proton and carbon-ion treatments while retaining beam-specific dose conventions and biological model information. Further local commissioning and multicase validation are required before clinical use.
SN - 2234-943X
ER -