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Article Dans Une Revue International Journal of Radiation Oncology, Biology, Physics Année : 2016

First clinical investigation of CBCT and deformable registration for adaptive proton therapy of lung cancer

Résumé

Purpose: An adaptive proton therapy workflow using cone-beam computed tomography (CBCT) is proposed. It consists of an online evaluation of a fast range-corrected dose distribution based on a virtual CT (vCT). This may be followed by more accurate offline dose recalculation on the vCT which may trigger a rescan CT (rCT) for replanning. Methods and Materials: The workflow was tested retrospectively on twenty consecutive lung cancer patients. A diffeomorphic Morphons algorithm was used to generate the lung vCT, by deforming the average planning CT (pCT) onto the CBCT. An additional correction step was applied to account for anatomical modifications that cannot be modeled by deformation alone. A set of clinical indicators for replanning were generated based on water equivalent thickness (WET) and dose statistics, and compared to those obtained on a rCT. The fast dose approximation consisted of warping the initial planned dose onto the vCT based on changes in WET. Potential under/over-ranges were assessed as variation in WET at the target’s distal surface. Results: The range-corrected dose from the vCT reproduced similar clinical indicators as the rCT. The workflow performed well under different clinical scenarios: atelectasis, lung reinflation and different types of tumor response. Between vCT and rCT, we found a difference in the measured 95% percentile of the over-ranges distribution of 3.4±2.7mm. The limitations of the technique consisted of inherent uncertainties of deformable registration and drawbacks of CBCT imaging. The correction step was adequate when gross errors occurred but could not recover subtle anatomical or density changes in tumors with complex topology. Conclusions: A proton therapy workflow based on CBCT provided similar clinical indicators as rCT on lung patients with considerable anatomical changes.
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Dates et versions

hal-03358704 , version 1 (29-09-2021)

Identifiants

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Catarina Veiga, Guillaume Janssens, Ching-Ling Teng, Thomas Baudier, Lucian Hotoiu, et al.. First clinical investigation of CBCT and deformable registration for adaptive proton therapy of lung cancer. International Journal of Radiation Oncology, Biology, Physics, 2016, 95 (1), pp.549-559. ⟨10.1016/j.ijrobp.2016.01.055⟩. ⟨hal-03358704⟩
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