Radiation Treatment Planning Using Positron Emission and Computed Tomography for Lung and Pharyngeal Cancers: A Multiple-Threshold Method for [{sup 18}F]Fluoro-2-Deoxyglucose Activity

Journal Article · Tue Jun 01 00:00:00 EDT 2010 · International Journal of Radiation Oncology, Biology and Physics

DOI:https://doi.org/10.1016/j.ijrobp.2009.05.025· OSTI ID:21372279

Okubo, Mitsuru ^[1]; Nishimura, Yasumasa ^[1]; Nakamatsu, Kiyoshi ^[1]; Okumura, Masahiko R.T. ^[2]; Shibata, Toru; Kanamori, Shuichi ^[1]; Hanaoka, Kouhei R.T. ^[2]; Hosono, Makoto ^[3]

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1. Department of Radiation Oncology, Kinki University School of Medicine, 377-2 Ohno-Higashi, Osaka-Sayama, Osaka 589-8511 (Japan)
2. Department of Central Radiological Service, Kinki University School of Medicine, 377-2 Ohno-Higashi, Osaka-Sayama, Osaka 589-8511 (Japan)
3. Department of PET, Kinki University School of Medicine, 377-2 Ohno-Higashi, Osaka-Sayama, Osaka 589-8511 (Japan)

Purpose: Clinical applicability of a multiple-threshold method for [{sup 18}F]fluoro-2-deoxyglucose (FDG) activity in radiation treatment planning was evaluated. Methods and Materials: A total of 32 patients who underwent positron emission and computed tomography (PET/CT) simulation were included; 18 patients had lung cancer, and 14 patients had pharyngeal cancer. For tumors of <=2 cm, 2 to 5 cm, and >5 cm, thresholds were defined as 2.5 standardized uptake value (SUV), 35%, and 20% of the maximum FDG activity, respectively. The cervical and mediastinal lymph nodes with the shortest axial diameter of >=10 mm were considered to be metastatic on CT (LNCT). The retropharyngeal lymph nodes with the shortest axial diameter of >=5 mm on CT and MRI were also defined as metastatic. Lymph nodes showing maximum FDG activity greater than the adopted thresholds for radiation therapy planning were designated LNPET-RTP, and lymph nodes with a maximum FDG activity of >=2.5 SUV were regarded as malignant and were designated LNPET-2.5 SUV. Results: The sizes of gross tumor volumes on PET (GTVPET) with the adopted thresholds in the axial plane were visually well fitted to those of GTV on CT (GTVCT). However, the volumes of GTVPET were larger than those of GTVCT, with significant differences (p < 0.0001) for lung cancer, due to respiratory motion. For lung cancer, the numbers of LNCT, LNPET-RTP, and LNPET-2.5 SUV were 29, 28, and 34, respectively. For pharyngeal cancer, the numbers of LNCT, LNPET-RTP, and LNPET-2.5 SUV were 14, 9, and 15, respectively. Conclusions: Our multiple thresholds were applicable for delineating the primary target on PET/CT simulation. However, these thresholds were inaccurate for depicting malignant lymph nodes.

• OSTI ID: 21372279
• Journal Information: International Journal of Radiation Oncology, Biology and Physics, Vol. 77, Issue 2; Other Information: DOI: 10.1016/j.ijrobp.2009.05.025; PII: S0360-3016(09)00770-6; Copyright (c) 2010 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; ISSN 0360-3016
• Country of Publication: United States
• Language: English

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