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To Study the Feasibility of Targeted Dose Escalation for High Metabolic Region in Radiotherapy of Locally Advanced NSCLS

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H Deng

H Deng1,2*, G Gong2 , Y Yin2 , (1) School of Medicine and Life Sciences, University of Jinan-Shandong Academy, Jinan, Shandong Province, (2) Shandong Cancer Hospital Affiliated to Shandong University, Jinan, Shandong Province


SU-I-GPD-T-385 (Sunday, July 30, 2017) 3:00 PM - 6:00 PM Room: Exhibit Hall

Purpose: To investigate dose escalation by metabolic sub-volume based on standard uptake values (SUV) gradient of pre-treatment 18F-FDG PET/CT for locally advanced Non-Small-Cell Lung Cancer(NSCLC) radiotherapy.

Methods: The pre-treatment 18F-FDG PET/CT images of 29 patients with locally advanced NSCLC were analyzed retrospectively. GTV was delineated on the PET/CT fusion images. Tumor metabolic sub-volume was segmented according to the threshold of 50% and 75% maximum standard uptake values (SUVmax). The region of under 50% SUVmax was defined as GTV1, from 50% to 75% SUVmax was defined as GTV2,over 75% SUVmax was defined as GTV3. PTV, PTV1, PTV2 and PTV3 were expend from GTV, GTV1, GTV2 and GTV3, and different plans were designed subsequently. Different plans were designed for PTVs, plan1 was designed for PTV with prescription dose 60Gy, and plan2 was designed for PTV1, PTV2 and PTV3 with prescription dose 60-66Gy, 66-72Gy and ≥72Gy, respectively. The dosimetric parameters of tumor target and organs at risk (OARs) were compared.

Results: The target dose and mean dose in Plan2 were significantly increased compared to those in Plan1. The maximum dose of target can reach to 80Gy, and the mean dose of PTV3 was increased by 19%(from 63.7Gy to 75.8Gy) (P<0.05), PTV2 was increased by 11%(from 63.5Gy to 70Gy) (P<0.05), and the dose increased of PTV1 was not significant (from 62.6Gy to 64.4Gy) (P>0.05). HI (Homogeneity indices) was decreased with the increase of maximum dose for Plan2. There was no statistically significant difference in radiation dose of OARs between two plans(P> 0.05).

Conclusion: Dose escalation based on metabolic sub-volume from 18F-FDG PET/CT was feasible, and radiation dose escalation of sub-volume with high metabolic activity can be achieved without increasing the OARs dose.

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