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- Title
4-Dimensional computed tomography-based ventilation and compliance images for quantification of radiation-induced changes in pulmonary function.
- Authors
Brown, Stephen; Chetty, Indrin J; Sharifi, Hoda; McDonald, Gary C; Zhong, Hualiang
- Abstract
<bold>Introduction: </bold>4-Dimensional computed tomography (4DCT)-based ventilation imaging is a promising technique for evaluating pulmonary function, but lung elasticity and mechanics are usually not part of the ventilation image analysis. In this study we demonstrate a 4DCT-based imaging technique that can be used to calculate regional lung compliance changes after radiotherapy (RT).<bold>Methods: </bold>Six lung cancer patients were included in this study. Four of the patients had 4DCT images acquired pre-RT, 3 and 9 months post-RT. Ventilation and compliance were calculated from the deformable image registration (DIR) of 4DCTs, performed from the end-inhale to the end-exhale breathing phase. Regional compliance was defined as the ratio of volumetric variation and associated stress in each voxel, representing lung elasticity and computed using a FEM-based framework. Ventilation, compliance and CT density were calculated for all pre-RT and post-RT 4DCTs and evaluation metrics were computed.<bold>Results: </bold>Average CT density changes were 13.6 ± 11.4HU after 3 months and 26.9 ± 15.8HU after 9 months. Ventilation was reduced at 3 months, but improved at 9 months in regions with dose ≥ 35 Gy, encompassing about 10% of the lung volume; compliance was reduced at both time-points. Radiation dose ≥ 35 Gy caused major change in lung density and ventilation, which was higher than that previously reported in the literature (i.e. 24 Gy).<bold>Conclusion: </bold>Lung tissue response is diverse with respect to CT density, ventilation and compliance. Combination of ventilation and compliance with CT density could be beneficial for understanding radiation-induced lung damage and consequently could help develop improved treatment protocols for lung cancer patients.
- Subjects
LUNG diseases; RADIATION-induced abnormalities; RADIOTHERAPY complications; COMPUTED tomography; DIAGNOSTIC imaging
- Publication
Journal of Medical Imaging & Radiation Oncology, 2019, Vol 63, Issue 3, p370
- ISSN
1754-9477
- Publication type
journal article
- DOI
10.1111/1754-9485.12881