Abstract: Objective To detect hypoxia status of non-small cell lung cancer with serial ⁹⁹Tc^m -4，9-diaza-3，3，10，10-tetramethyldodecan-2,11-dione dioxime (HL91) SPECT images and predict the short-time curative effect about radiotherapy in lung cancer. Methods Thirty-one patients with non-small cell lung cancer underwent SPECT imaging at 4h and 24h after injecting ⁹⁹Tc^m-HL91,respectively.Regions of interest(R0Is)were drawn in the tumor(T)and contralateral position(N)and the radioactivity ratios of tumor to normal(T/N)were calculated semiquantitatively.Then patients treated by three-dimensional conformal radiotherapy(3D-CRT)underwent ⁹⁹Tc^m-HL91 hypoxia imaging two days before and after radiotherapy，respectively.Patients were divided into low intake group and high intake group according to the T/N value( 24h) before radiotherapy,the changes of T/N value after radiotherapy was analyzed on the transaxial view. Results The short-time effective power of radiotherapy patients in low intake group were higher than that in high intake group（P<0.05).There was a significantly statistical difference between these groups（P<0.05). Conclusion Technetium-99m-labeled HL91 hypoxia imaging of lung cancer can be used to predict its short-time curative effect after radiotherapy.