Determination of internal target volume using selective phases of a 4-dimensional computed tomography scan.

Published

Journal Article

PURPOSE: Internal target volume (ITV) is frequently determined by contouring of gross tumor volumes (GTV) on 10 phases of a 4-dimensional computed tomography (4DCT) study set for lung cancer radiotherapy. This study aimed to investigate the possibility of generating ITV by using selective phases of a 4DCT scan. METHODS AND MATERIALS: The 4DCT scans of 20 patients with lung cancer were included in this study. GTVs were contoured on 10 phases in Focal4D (CMS, St Louis, MO). Different ITVs were derived by encompassing volumes of contours from selective phases. ITV10 was the combination of GTVs on all of the 10 phases and served as the gold standard volume. All of the other ITVs were smaller and within ITV10. The ratios of the volumes of these ITVs to ITV10 were calculated and used as a criterion to determine the similarity of different ITVs to ITV10. ITV2 represented the ITV derived by using end-inhalation and end-exhalation (0% + 50%). ITV3E was derived from contouring the 3 phases at end-inhalation, mid-exhalation, and end-exhalation (0% + 20% + 50%). ITV3I was derived from contouring the 3 phases at end-inhalation, mid-inhalation, and end-exhalation (0% + 70% + 50%). ITV4 was derived by contouring the 4 phases at end-inhalation, mid-inhalation, end-exhalation, and mid-exhalation (0% + 20% + 50% + 70%). ITV6E was derived from contouring the 6 consecutive phases during exhalation (0% + 10% + 20% + 30% + 40% + 50%). ITV6I was derived from contouring the 6 consecutive phases during inhalation (50% + 60% + 70% + 80% + 90% + 0%). The volumes of ITVs were calculated and compared. RESULTS: ITV6I showed excellent agreement with ITV10 (volume ratio ITV6I/ITV10 = 0.975). ITV4 and ITV6E showed good agreement with ITV10 (ITV6E/ITV10 = 0.939, ITV4/ITV10 = 0.944). The volume ratios ITV3I/ITV10 and ITV3E/ITV10 were 0.927 and 0.906, respectively. ITV2 did not agree well with ITV10 (ITV2/ITV10 = 0.888). CONCLUSIONS: Contouring all phases during inhalation provides a good estimate of the ITV. However, the ITV may be underestimated if only contouring on 2 extreme phases.

Full Text

Duke Authors

Cited Authors

  • Cao, J; Cui, Y; Champ, CE; Liu, H; Xiao, Y; Werner-Wasik, M; Yu, Y

Published Date

  • July 2012

Published In

Volume / Issue

  • 2 / 3

Start / End Page

  • 186 - 192

PubMed ID

  • 24674122

Pubmed Central ID

  • 24674122

Electronic International Standard Serial Number (EISSN)

  • 1879-8519

Digital Object Identifier (DOI)

  • 10.1016/j.prro.2011.09.004

Language

  • eng

Conference Location

  • United States