© Zhang et al.; licensee BioMed Central. Background: To validate a gradient-based segmentation method for gross tumor volume(GTV) delineation on 8 F-fluorothymidine (FLT)positron emission tomography (PET)/ computer tomography (CT) in esophageal squamous cell cancer through pathologic specimen, in comparison with standardized uptake values (SUV) threshold-based methods and CT. The corresponding impact of this GTV delineation method on treatment planning was evaluated. Methods and materials: Ten patients with esophageal squamous cell cancer were enrolled. Before radical surgery, all patients underwent FLT-PET/CT. GTVs were delineated by using four methods. GTV GRAD , GTV 1.4 and GTV 30%max were segmented on FLT PET using a gradient-based method, a fixed threshold of 1.4 SUV and 30% of SUV max , respectively. GTV CT was based on CT data alone. The maximum longitudinal tumor length of each segmented GTV was compared with the measured tumor length of the pathologic gross tumor length (L Path ). GTV GRAD , GTV 1.4 and GTV 30%max were compared with GTV CT by overlap index. Two radiotherapy plannings (plan GRAD ) and (plan CT ) were designed for each patient based on GTV GRAD and GTV CT . The dose-volume parameters for target volume and normal tissues, CI and HI of plan GRAD and plan CT were compared. Results: The mean ± standard deviation of L Path was 6.47 ± 2.70 cm. The mean ± standard deviation of L GRAD ,L 1.4 , L 30%max and L CT were 6.22 ± 2.61, 6.23 ± 2.80, 5.95 ± 2.50,7.17 ± 2.28 cm, respectively. The Pearson correlation coefficients between L Path and each segmentation method were 0.989, 0.920, 0.920 and 0.862, respectively. The overlap indices of GTV GRAD , GTV 1.4 , GTV 30%max when compared with GTV CT were 0.75 ± 0.12, 0.71 ± 0.12, 0.57 ± 0.10, respectively. The V 5 , V 10 , V 20 , V 30 and mean dose of total-lung,V 30 and mean dose of heart of plan GRAD were significantly lower than plan CT . Conclusions: The gradient-based method provided the closest estimation of target length. The radiotherapy plannings based on the gradient-based segmentation method reduced the irradiated volume of lung, heart in comparison to CT.
Zhang, G., Han, D., Ma, C., Lu, J., Sun, T., Liu, T., … Yin, Y. (2015). Gradient-based delineation of the primary GTV on FLT PET in squamous cell cancer of the thoracic esophagus and impact on radiotherapy planning. Radiation Oncology, 10(1). https://doi.org/10.1186/s13014-014-0304-5