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Feasibility and constraints of Bragg peak FLASH proton therapy treatment planning

Lövgren, Nathalie ; Fagerström Kristensen, Ingrid LU and Petersson, Kristoffer LU (2024) In Frontiers in Oncology 14.
Abstract

Introduction: FLASH proton therapy (FLASH-PT) requires ultra-high dose rate (≥ 40 Gy/s) protons to be delivered in a short timescale whilst conforming to a patient-specific target. This study investigates the feasibility and constraints of Bragg peak FLASH-PT treatment planning, and compares the in silico results produced to plans for intensity modulated proton therapy (IMPT). Materials and method: Bragg peak FLASH-PT and IMPT treatment plans were generated for bone (n=3), brain (n=3), and lung (n=4) targets using the MIROpt research treatment planning system and the Conformal FLASH library developed by Applications SA from the open-source version of UCLouvain. FLASH-PT beams were simulated using monoenergetic spot-scanned protons... (More)

Introduction: FLASH proton therapy (FLASH-PT) requires ultra-high dose rate (≥ 40 Gy/s) protons to be delivered in a short timescale whilst conforming to a patient-specific target. This study investigates the feasibility and constraints of Bragg peak FLASH-PT treatment planning, and compares the in silico results produced to plans for intensity modulated proton therapy (IMPT). Materials and method: Bragg peak FLASH-PT and IMPT treatment plans were generated for bone (n=3), brain (n=3), and lung (n=4) targets using the MIROpt research treatment planning system and the Conformal FLASH library developed by Applications SA from the open-source version of UCLouvain. FLASH-PT beams were simulated using monoenergetic spot-scanned protons traversing through a conformal energy modulator, a range shifter, and an aperture. A dose rate constraint of ≥ 40 Gy/s was included in each FLASH-PT plan optimisation. Results: Space limitations in the FLASH-PT adapted beam nozzle imposed a maximum target width constraint, excluding 4 cases from the study. FLASH-PT plans did not satisfy the imposed target dose constraints (D95% ≥ 95% and D2%≤ 105%) but achieved clinically acceptable doses to organs at risk (OARs). IMPT plans adhered to all target and OAR dose constraints. FLASH-PT plans showed a reduction in both target homogeneity (p < 0.001) and dose conformity (non-significant) compared to IMPT. Conclusion: Without accounting for a sparing effect, IMPT plans were superior in target coverage, dose conformity, target homogeneity, and OAR sparing compared to FLASH-PT. Further research is warranted in treatment planning optimisation and beam delivery for clinical implementation of Bragg peak FLASH-PT.

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author
; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Bragg peak, feasibility studies, FLASH radiotherapy, intensity-modulated proton therapy, proton therapy
in
Frontiers in Oncology
volume
14
article number
1369065
publisher
Frontiers Media S. A.
external identifiers
  • scopus:85192520694
  • pmid:38737902
ISSN
2234-943X
DOI
10.3389/fonc.2024.1369065
language
English
LU publication?
yes
id
06961816-e2ad-432a-98fa-3cdec09d364e
date added to LUP
2024-06-10 12:50:01
date last changed
2025-10-29 11:35:36
@article{06961816-e2ad-432a-98fa-3cdec09d364e,
  abstract     = {{<p>Introduction: FLASH proton therapy (FLASH-PT) requires ultra-high dose rate (≥ 40 Gy/s) protons to be delivered in a short timescale whilst conforming to a patient-specific target. This study investigates the feasibility and constraints of Bragg peak FLASH-PT treatment planning, and compares the in silico results produced to plans for intensity modulated proton therapy (IMPT). Materials and method: Bragg peak FLASH-PT and IMPT treatment plans were generated for bone (n=3), brain (n=3), and lung (n=4) targets using the MIROpt research treatment planning system and the Conformal FLASH library developed by Applications SA from the open-source version of UCLouvain. FLASH-PT beams were simulated using monoenergetic spot-scanned protons traversing through a conformal energy modulator, a range shifter, and an aperture. A dose rate constraint of ≥ 40 Gy/s was included in each FLASH-PT plan optimisation. Results: Space limitations in the FLASH-PT adapted beam nozzle imposed a maximum target width constraint, excluding 4 cases from the study. FLASH-PT plans did not satisfy the imposed target dose constraints (D<sub>95%</sub> ≥ 95% and D<sub>2%</sub>≤ 105%) but achieved clinically acceptable doses to organs at risk (OARs). IMPT plans adhered to all target and OAR dose constraints. FLASH-PT plans showed a reduction in both target homogeneity (p &lt; 0.001) and dose conformity (non-significant) compared to IMPT. Conclusion: Without accounting for a sparing effect, IMPT plans were superior in target coverage, dose conformity, target homogeneity, and OAR sparing compared to FLASH-PT. Further research is warranted in treatment planning optimisation and beam delivery for clinical implementation of Bragg peak FLASH-PT.</p>}},
  author       = {{Lövgren, Nathalie and Fagerström Kristensen, Ingrid and Petersson, Kristoffer}},
  issn         = {{2234-943X}},
  keywords     = {{Bragg peak; feasibility studies; FLASH radiotherapy; intensity-modulated proton therapy; proton therapy}},
  language     = {{eng}},
  publisher    = {{Frontiers Media S. A.}},
  series       = {{Frontiers in Oncology}},
  title        = {{Feasibility and constraints of Bragg peak FLASH proton therapy treatment planning}},
  url          = {{http://dx.doi.org/10.3389/fonc.2024.1369065}},
  doi          = {{10.3389/fonc.2024.1369065}},
  volume       = {{14}},
  year         = {{2024}},
}