Four-dimensional computed tomography ventilation imaging-guided radiotherapy planning in different techniques for...

This simulation study aims to integrate four-dimensional computed tomography (4DCT) ventilation imaging into functional planning using different radiotherapy (RT) techniques and compare the dosimetric differences across these techniques.

4DCT ventilation images from eighteen lung cancer patients were created using Jacobian values obtained via deformable image registration and a ventilation imaging algorithm. For each patient, we designed both anatomical and functional plans using intensity-modulated radiotherapy (IMRT), hybrid IMRT (static plus IMRT beams treated concurrently), and volumetric modulated arc therapy (VMAT). Dosimetric parameters were systematically compared, with particular attention to the functional lung (FL) radiation dose.

The results showed that regardless of the RT technique (IMRT, hybrid IMRT, or VMAT), functional planning reduced fV₅ (fVx: percentage of functional lung volume receiving ≥ x Gy), fV₁₀, fV₂₀, fV₃₀, and functional mean lung dose (fMLD), while maintaining planning target volume (PTV) dosimetric coverage. Although functional planning increased the radiation dose to most organs at risk (OARs), these increases were not statistically significant. Among the different RT techniques, compared with f-hybrid IMRT, both f-IMRT and f-VMAT reduced radiation dose to the FL and OARs, while achieving superior PTV conformity. Further comparison between f-IMRT and f-VMAT showed that f-VMAT resulted in a lower mean dose (D_mean) to the esophagus.

Compared with anatomical planning, functional planning reduces the radiation dose to the FL while preserving target dose coverage and meeting dose constraints for OARs. Among the RT techniques for functional planning, f-VMAT may serve as the preferred technique.