ABSTRACT
Objective To study the correlation between dose-volummetrics and changes of pulmona- ry function tests(PFTs), and to study the ability of standard dose-volummetrics to predict these changes after radiotherapy. Methods Pulmonary function was measured in 39 patients with inoperable lung cancer one week before and 2-4 months after radiotherapy. The pulmonary function parameters were the forced vital ca- pacity(FVC), forced expiratory volume in ls (FEV 1.0) and diffusion capacity of carbon monoxide(DL- CO). Dose-volumrnetrics were V_(10), V_(15), V_(20), V_(25), V_(30), V_(35), V_(40), CTV_(100), CTV_(95), CTV_(90), CTV_(80), lung D_(mean), V_(eff) and NTCP. Pearson and line regression analysis was performed to determine whether the correlation exis- ted between the metrics and the changes of PFTs. Results No correlation was found between the dose- volummetrics and the changes in PFTs. Excluding patients(n=15) with pretreatment atelectasis, signifi- cant correlation was found between the dose-volummetrics (V_(20), V_(25), V_(30), V_(35), V_(40), GTV, V_(eff) and D_(mean)) and the PFTs changes(r=0.469-0.695, P≤0.05). Therefore, the re-expansion may have jesperdized the proper data to the present record. Multivariate analysis showed that V_(30) was the risk factor to affect the chan- ges of FEV 1.0 and DLCO(P=0.046、0.041). The pulmonary function of patients with V_(30)≥18% was worse than patients with V_(30)