Background and purpose: To investigate the incorporation of data from single-photon emission computed tomography (SPECT) or hyperpolarized helium-3 magnetic resonance imaging ((3)He-MRI) into intensity-modulated radiotherapy (IMRT) planning for non-small cell lung cancer (NSCLC).
Material and methods: Seven scenarios were simulated that represent cases of NSCLC with significant functional lung defects. Two independent IMRT plans were produced for each scenario; one to minimise total lung volume receiving >or=20Gy (V(20)), and the other to minimise only the functional lung volume receiving >or=20Gy (FV(20)). Dose-volume characteristics and a plan quality index related to planning target volume coverage by the 95% isodose (V(PTV95)/FV(20)) were compared between anatomical and functional plans using the Wilcoxon signed ranks test.
Results: Compared to anatomical IMRT plans, functional planning reduced FV(20) (median 2.7%, range 0.6-3.5%, p=0.02), and total lung V(20) (median 1.5%, 0.5-2.7%, p=0.02), with a small reduction in mean functional lung dose (median 0.4Gy, 0-0.7Gy, p=0.03). There were no significant differences in target volume coverage or organ-at-risk doses. Plan quality index was improved for functional plans (median increase 1.4, range 0-11.8, p=0.02).
Conclusions: Statistically significant reductions in FV(20), V(20) and mean functional lung dose are possible when IMRT planning is supplemented by functional information derived from SPECT or (3)He-MRI.