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Article Dans Une Revue Medical Physics Année : 2023

Scatter correction of 4D cone beam computed tomography to detect dosimetric effects due to anatomical changes in proton therapy for lung cancer

Henning Schmitz
  • Fonction : Auteur
Moritz Rabe
  • Fonction : Auteur
Guillaume Janssens
  • Fonction : Auteur
Simon Rit
Katia Parodi
  • Fonction : Auteur
Claus Belka
  • Fonction : Auteur
Florian Kamp
  • Fonction : Auteur
Guillaume Landry
  • Fonction : Auteur
  • PersonId : 1235160
Christopher Kurz
  • Fonction : Auteur

Résumé

Background: The treatment of moving tumor entities is expected to have superior clinical outcomes, using image-guided adaptive intensity-modulated proton therapy (IMPT). Purpose: For 21 lung cancer patients, IMPT dose calculations were performed on scatter-corrected 4D cone beam CTs (4DCBCT cor) to evaluate their potential for triggering treatment adaptation. Additional dose calculations were performed on corresponding planning 4DCTs and day-of-treatment 4D virtual CTs (4DvCTs). Methods: A 4DCBCT correction workflow, previously validated on a phantom, generates 4DvCT (CT-to-CBCT deformable registration) and 4DCBCT cor images (projection-based correction using 4DvCT as a prior) with 10 phase bins, using day-of-treatment free-breathing CBCT projections and planning 4DCT images as input. Using a research planning system, robust IMPT plans administering eight fractions of 7.5 Gy were created on a free-breathing planning CT (pCT) contoured by a physician. The internal target volume (ITV) was overridden with muscle tissue. Robustness settings for range and setup uncertainties were 3% and 6 mm, and a Monte Carlo dose engine was used. On every phase of planning 4DCT, day-of-treatment 4DvCT, and 4DCBCT cor , the dose was recalculated. For evaluation, image analysis as well as dose analysis were performed using mean error (ME) and mean absolute error (MAE) analysis, dose-volume histogram (DVH) parameters, and 2%/2-mm gamma pass rate analysis. Action levels (1.6% ITV D98 and 90% gamma pass rate) based on our previous phantom validation study were set to determine which patients had a loss of dosimetric coverage. Results: Quality enhancements of 4DvCT and 4DCBCT cor over 4DCBCT were observed. ITV D 98% and bronchi D 2% had its largest agreement for 4DCBCT cor-4DvCT, and the largest gamma pass rates (>94%, median 98%) were found for 4DCBCT cor-4DvCT. Deviations were larger and gamma pass rates were smaller for 4DvCT-4DCT and 4DCBCT cor-4DCT. For five patients, deviations were larger than the action levels, suggesting substantial anatomical changes between pCT and CBCT projections acquisition. Conclusions: This retrospective study shows the feasibility of daily proton dose calculation on 4DCBCT cor for lung tumor patients. The applied method is of clinical interest as it generates up-to-date in-room images, accounting for This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
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Origine : Publication financée par une institution
Licence : CC BY - Paternité

Dates et versions

hal-04022308 , version 1 (09-03-2023)

Identifiants

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Henning Schmitz, Moritz Rabe, Guillaume Janssens, Simon Rit, Katia Parodi, et al.. Scatter correction of 4D cone beam computed tomography to detect dosimetric effects due to anatomical changes in proton therapy for lung cancer. Medical Physics, 2023, 50 (8), pp.4981-4992. ⟨10.1002/mp.16335⟩. ⟨hal-04022308⟩
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