TY - JOUR
T1 - PET CT Thresholds for Radiotherapy Target Definition in Non-Small-Cell Lung Cancer
T2 - How Close are we to the Pathologic Findings?
AU - Wu, Kailiang
AU - Ung, Yee C.
AU - Hornby, Jennifer
AU - Freeman, Marc
AU - Hwang, David
AU - Tsao, Ming S.
AU - Dahele, Max
AU - Darling, Gail
AU - Maziak, Donna E.
AU - Tirona, Romeo
AU - Mah, Kathy
AU - Wong, C. Shun
PY - 2010
Y1 - 2010
N2 - Purpose: Optimal target delineation threshold values for positron emission tomography (PET) and computed tomography (CT) radiotherapy planning is controversial. In this present study, different PET CT threshold values were used for target delineation and then compared pathologically. Methods and Materials: A total of 31 non-small-cell lung cancer patients underwent PET CT before surgery. The maximal diameter (MD) of the pathologic primary tumor was obtained. The CT-based gross tumor volumes (GTVCT) were delineated for CT window-level thresholds at 1,600 and -300 Hounsfield units (HU) (GTVCT1); 1,600 and -400 (GTVCT2); 1,600 and -450 HU (GTVCT3); 1,600 and -600 HU (GTVCT4); 1,200 and -700 HU (GTVCT5); 900 and -450 HU (GTVCT6); and 700 and -450 HU (GTVCT7). The PET-based GTVs (GTVPET) were autocontoured at 20% (GTV20), 30% (GTV30), 40% (GTV40), 45% (GTV45), 50% (GTV50), and 55% (GTV55) of the maximal intensity level. The MD of each image-based GTV in three-dimensional orientation was determined. The MD of the GTVPET and GTVCT were compared with the pathologically determined MD. Results: The median MD of the GTVCT changed from 2.89 (GTVCT2) to 4.46 (GTVCT7) as the CT thresholds were varied. The correlation coefficient of the GTVCT compared with the pathologically determined MD ranged from 0.76 to 0.87. The correlation coefficient of the GTVCT1 was the best (r = 0.87). The median MD of GTVPET changed from 5.72cm to 2.67cm as the PET thresholds increased. The correlation coefficient of the GTVPET compared with the pathologic finding ranged from 0.51 to 0.77. The correlation coefficient of GTV50 was the best (r = 0.77). Conclusion: Compared with the MD of GTVPET, the MD of GTVCT had better correlation with the pathologic MD. The GTVCT1 and GTV50 had the best correlation with the pathologic results.
AB - Purpose: Optimal target delineation threshold values for positron emission tomography (PET) and computed tomography (CT) radiotherapy planning is controversial. In this present study, different PET CT threshold values were used for target delineation and then compared pathologically. Methods and Materials: A total of 31 non-small-cell lung cancer patients underwent PET CT before surgery. The maximal diameter (MD) of the pathologic primary tumor was obtained. The CT-based gross tumor volumes (GTVCT) were delineated for CT window-level thresholds at 1,600 and -300 Hounsfield units (HU) (GTVCT1); 1,600 and -400 (GTVCT2); 1,600 and -450 HU (GTVCT3); 1,600 and -600 HU (GTVCT4); 1,200 and -700 HU (GTVCT5); 900 and -450 HU (GTVCT6); and 700 and -450 HU (GTVCT7). The PET-based GTVs (GTVPET) were autocontoured at 20% (GTV20), 30% (GTV30), 40% (GTV40), 45% (GTV45), 50% (GTV50), and 55% (GTV55) of the maximal intensity level. The MD of each image-based GTV in three-dimensional orientation was determined. The MD of the GTVPET and GTVCT were compared with the pathologically determined MD. Results: The median MD of the GTVCT changed from 2.89 (GTVCT2) to 4.46 (GTVCT7) as the CT thresholds were varied. The correlation coefficient of the GTVCT compared with the pathologically determined MD ranged from 0.76 to 0.87. The correlation coefficient of the GTVCT1 was the best (r = 0.87). The median MD of GTVPET changed from 5.72cm to 2.67cm as the PET thresholds increased. The correlation coefficient of the GTVPET compared with the pathologic finding ranged from 0.51 to 0.77. The correlation coefficient of GTV50 was the best (r = 0.77). Conclusion: Compared with the MD of GTVPET, the MD of GTVCT had better correlation with the pathologic MD. The GTVCT1 and GTV50 had the best correlation with the pathologic results.
KW - Non-small-cell lung cancer
KW - PET CT
KW - computed tomography
KW - gross tumor volume
KW - pathology
KW - positron emission tomography
KW - target definition
UR - http://www.scopus.com/inward/record.url?scp=77952564033&partnerID=8YFLogxK
U2 - https://doi.org/10.1016/j.ijrobp.2009.05.028
DO - https://doi.org/10.1016/j.ijrobp.2009.05.028
M3 - Article
C2 - 19836163
SN - 0360-3016
VL - 77
SP - 699
EP - 706
JO - International Journal of Radiation Oncology Biology Physics
JF - International Journal of Radiation Oncology Biology Physics
IS - 3
ER -