Thickening is the process that leads to band-like opacities as an X-ray finding. Here are a few examples:

Radiographic Findings in Chest Disease | Fundamentals of ... - Inkling
https://www.inkling.com/read/...brant.../radiographic-findin...‎
... thickening of this compartment produces parallel linear opacities radiating from the ... Thickening of the peripheral interstitium of the lung produces linear opacities that ....

Bronchiolitis obliterans organizing pneumonia: Pathogenesis ...
www.ncbi.nlm.nih.gov/pmc/articles/PMC2700454/‎
... linear and band-like opacities, subpleural opacities that can have disposition parallel or ...

Fleischner Society: Glossary of Terms for Thoracic Imaging - Inkling
https://www.inkling.com/read/imaging.../fleischner-society-g...‎
Free interactive eBook preview | Basic HRCT Patterns of Lung Disease |
... A parenchymal band is a linear opacity, usually 1–3 mm thick and up to 5 cm long that ...