18F-FDG PET Definition of Gross Tumor Volume for Radiotherapy of Non–Small Cell Lung Cancer: Is a Single Standardized Uptake Value Threshold Approach Appropriate?

Article Figures & Data

Download figure
Open in new tab
Download powerpoint
FIGURE 1.
(A) CT_GTV vs. PET_GTV-CT_GTV at threshold of 20%. (B) CT_GTV vs. optimal threshold with best-fit logarithmic regression curve.
Download figure
Open in new tab
Download powerpoint
FIGURE 2.
Fused PET and CT coronal images of patient with stage I NSCLC. CT image of tumor (white) can be seen within larger PET image of tumor. Contours represent gross tumor volume (inner contour), clinical target volume (middle contour), and planning target volume (outer contour).

TABLE 1

Comparison of PET_GTV and CT_GTV

↵* GTV determined by PET with 40% SUV_max threshold.
↵† Optimal threshold is percentage threshold that yields 1:1 volumetric match between PET- and CT-delineated tumors.

TABLE 2

Methods of Tumor Delineation by PET and CT in Several Studies

Study	Method of tumor delineation by PET and CT
Erdi et al. (10)	40% threshold
Kiffer et al. (11)	Visual interpretation
Mah et al. (13)	50% threshold
Vanuytsel et al. (14)	Identification only
Nestle et al. (15)	50% threshold
Bradley et al. (9)	40% threshold
Deniaud-Alexandre et al. (19)	50% threshold
Giraud et al. (17)	40% threshold
Brianzoni et al. (21)	40% threshold
Ashamalla et al. (20)	Visual interpretation