Abstract：Objective To compare the volume, conformity index (CI), and degree of inclusion (DI) between internal gross tumor volumes (IGTVs) delineated based on ten phases of four-dimensional computed tomography (4DCT) and nine positron emission tomography (PET)-CT standardized uptake value (SUV) thresholds. Methods Fifteen patients with thoracic esophageal cancer sequentially underwent 3DCT, 4DCT, and FDG PET-CT of the thorax simulation. IGTVs were delineated on ten phases of 4DCT images and then combined to obtain IGTV10. IGTVPET2.0, IGTVPET2.5, IGTVPET3.0, IGTVPET3.5, IGTVPET20%, IGTVPET25%, IGTVPET30%, IGTVPET35%, and IGTVPET40% were delineated on PET images based on different SUV thresholds (≥2.0, 2.5, 3.0, and 3.5) and percentages of SUVmax(≥20%, 25%, 30%, 35%, and 40%). The volume, CI, and DI were compared between IGTVs by paired t test. The correlations of centroid distance with CI and DI were determined by Pearson correlation analysis. Results The volumes of IGTVPET2.5 and IGTVPET20% were similar to that of IGTV10, with volume ratios of 0.92(P=0.985) and 1.08(P=0.886), respectively. The CIs of IGTVPET2.0 vs IGTV10, IGTVPET2.5 vs IGTV10, and IGTVPET20% vs IGTV10 were similar (0.53, 0.52, and 0.53;P=0.432, 1.00, and 0.414), but they were significantly higher than the CIs of other IGTVPET vs IGTV10(0.33—0.50, P=0.000—0.047). No significant differences existed between the DIs of IGTV10 in IGTVPET2.5(0.67) and IGTV10 in IGTVPET20%(0.70)(P=0.542) and between the DIs of IGTVPET2.5 in IGTV10(0.74) and IGTVPET20% in IGTV10(0.72)(P=0.539). Conclusions IGTVPET2.5 and IGTVPET20% have similar volumes and good spatial matching compared with IGTV10.
. Comparison between IGTVs based on ten phases of 4DCT and nine PET-CT SUV thresholds in primary thoracic esophageal cancer[J]. Chinese Journal of Radiation Oncology, 2014, 23(3): 226-229.
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