The Application Of Image Guided Intensity Modulated Hypofraction Radiotherapy In Locally Advanced Non-small Cell Lung Cancer

Objective:To compare the differences in set-up errors between grey-scale,bone and manual matching models with CT-on-rail while applying image guided intensity modulated hypofractionated radiotherapy(IGIMHR)to locally advanced non-small cell lung cancer(LA-NSCLC),and to analyze the short-term efficacy and incidence of acute side effects,in order to provide reference for the selection of approriate image registration modes and radiotherapy in clinical treatment of LA-NSCLC.Methods:Simulated position,CT scan and target volume delineation based on enhanced CT or PET/CT were performed on 24 randomly selected patients diagnosed with LA-NSCLC with application of IGIMHR,and the finale field setup were formulated by physical and clinical therapists.From the beginning,each patient received CT-on-rail scan per week.The obtained images undergone online registrations with CT images for radiotherapy planning in 3 different aspects,including grey-scale,bone and manual models.To compare their differences in set-up errors,the translation deviations in X-axis,Y-axis and Z-axis were collected and analyzed statistically.Meanwhile,20 patients diagnosed with LA-NSCLC with application of intensity-modulated radiation therapy were randomly selected.The short-time efficacy and acute side effect incidence of the two groups were recorded to evaluate its feasibility,effectiveness and safety.Results:1.Among 84 CT-on-rail scan results from 24 patients,Y-axis presented the largest translation deviations,followed by X-axis,and then Z-axis.The differences between above three groups were statistically significant(P<0.05).Compared with bone model,the translation errors of grey-scale model on X,Y,Z axes were significantly reduced(P<0.05).Meanwhile,grey-scale model presented lower translation deviations on X and Z axes than manual model,which was statistically significant(P<0.05).However,grey-scale and manual modes showed no difference on Y-axis(P>0.05).2.The two groups were evaluated for short-term efficacy 1 month after treatment,with complete remission(CR)rates of 20.83% and 5.00%,partial remission(PR)rates of 66.67% and 55.00%,and effective rates of 87.50% and60.00%.Acute toxic side effects mainly manifested as acute myelosuppression and grade 1,2 radiation pneumonitis,radiation esophagitis and radiation skin damage,the incidence rates were 75.00% and 70.00%,41.67% and 40.00%,54.17% and50.00%,respectively.54.17% and 45.00%.Conclusions:1.CT-on-rail could reduce set-up errors in LA-NSCLC patients treated with IGIMHR.The grey-scale model would be the top priority,while the combination of manual fine-tuning might be adopted in practice to achieve the best accuracy.2.Since IGIMHR exhibited definite efficacy but no significant increase in acute toxicity,we deemed it feasible and secure.