To Study The Feasibility Of Dose Escalation Guided By 1¹⁸F-FDG PET/CT For High Metabolic Region In Radiotherapy Of Locally Advanced NSCLC

BackgroundRadiotherapy is one of the main treatments for NSCLC patients.Local failure is the main reason for treatment failure in NSCLC patients.The study found that the failure of local control is highly correlated with the high metabolic area of ¹⁸F-FDG PET/CT before radiotherapy.A dose escalated of 50%SUV_max target area for pre-radiotherapy may improve local control of the patient with NSCLC.ObjectiveTo investigate the feasibility and dose distribution of standardized uptake value?SUV?gradient-guided locally advanced non-small cell lung cancer?NSCLC?-targeting dose escalation based on ¹⁸F-fludeoxyglucose?FDG?positron emission tomography/computed tomography?PET/CT?.MethodsPretreatment 18F-FDG PET/CT images of 50 patients with locally advanced NSCLC were retrospectively analyzed.Gross tumor volume?GTV?was delineated on PET/CT.The tumor metabolic sub-volume was segmented at 50%and 75%of the maximum SUV(SUV_max).The region<50%SUV_max was defined as GTV1;50-75%SUV_max was GTV2;and>75%SUV_max was GTV3.The planning target volumes1-3?PTV1-3?were obtained on GTV1-3:plan1 was designed for PTV with a prescription dose of 60 Gy;plan2 was designed by removing the upper dose limit of plan1;plan3 was designed for PTV1,PTV2 and PTV3with prescription doses of 60-66 Gy,66-72 Gy and?72 Gy,respectively;plan4 was designed for PTV1,PTV2 and PTV3 with prescription doses of?60 Gy,?66 Gy and?72 Gy,respectively.Dosimetric parameters were compared.Results1.The D2 and mean dose(D_mean)of PTV were significantly escalated in plan3 compared to plan1 and plan2.The D2 could be escalated to 78.5 Gy by 20%.The D_mean could be escalated to 70.5 Gy by 8.9%.The D2 and D_mean of each sub-volume in plan3 showed a gradual escalation trend with an increase in SUV,and the D2 and D_mean reached a maximum in PTV3.2.The difference in homogeneity index?HI?was statistically significant?p<0.05?.The HI significantly decreased,with a reduction of 16.7%in plan3 compared to that in plan1 and plan2.3.There was no statistically significant difference in the radiation dose of the lung,heart,and spinal cord among three treatment plans?p>0.05?.Although,Plan 4 can also increase the target dose,it has the potential to increase the risk of organ radiation.ConclusionsDose escalation based on the metabolic active sub-volume was feasible;it could be achieved in a sub-volume with high metabolic activity without increasing the organs at risk?OARs?radiation dose,which could potentially improve local disease control.