Clinical utility of 4D FDG-PET/CT scans in radiation treatment planning

Michalis Aristophanous*, Ross I. Berbeco, Joseph H. Killoran, Jeffrey T. Yap, David J. Sher, Aaron M. Allen, Elysia Larson, Aileen B. Chen

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Purpose: The potential role of four-dimensional (4D) positron emission tomography (PET)/computed tomography (CT) in radiation treatment planning, relative to standard three-dimensional (3D) PET/CT, was examined. Methods and Materials: Ten patients with non-small-cell lung cancer had sequential 3D and 4D [ 18F]fluorodeoxyglucose PET/CT scans in the treatment position prior to radiation therapy. The gross tumor volume and involved lymph nodes were contoured on the PET scan by use of three different techniques: manual contouring by an experienced radiation oncologist using a predetermined protocol; a technique with a constant threshold of standardized uptake value (SUV) greater than 2.5; and an automatic segmentation technique. For each technique, the tumor volume was defined on the 3D scan (VOL3D) and on the 4D scan (VOL4D) by combining the volume defined on each of the five breathing phases individually. The range of tumor motion and the location of each lesion were also recorded, and their influence on the differences observed between VOL3D and VOL4D was investigated. Results: We identified and analyzed 22 distinct lesions, including 9 primary tumors and 13 mediastinal lymph nodes. Mean VOL4D was larger than mean VOL3D with all three techniques, and the difference was statistically significant (p < 0.01). The range of tumor motion and the location of the tumor affected the magnitude of the difference. For one case, all three tumor definition techniques identified volume of moderate uptake of approximately 1 mL in the hilar region on the 4D scan (SUV maximum, 3.3) but not on the 3D scan (SUV maximum, 2.3). Conclusions: In comparison to 3D PET, 4D PET may better define the full physiologic extent of moving tumors and improve radiation treatment planning for lung tumors. In addition, reduction of blurring from free-breathing images may reveal additional information regarding regional disease.

Original languageEnglish
Pages (from-to)e99-e105
JournalInternational Journal of Radiation Oncology Biology Physics
Volume82
Issue number1
DOIs
StatePublished - 1 Jan 2012
Externally publishedYes

Keywords

  • 4D PET/CT
  • Biological target volume
  • Lung cancer
  • Treatment planning

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