Differences in the definition of internal target volumes using slow CT alone or in combination with thin-slice CT under breath-holding conditions during the planning of stereotactic radiotherapy for lung cancer

Satoshi Seki, Etsuo Kunieda, Atsuya Takeda, Tomoaki Nagaoka, Hossain M. Deloar, Takatsugu Kawase, Junichi Fukada, Osamu Kawaguchi, Minoru Uematsu, Atsushi Kubo

Research output: Contribution to journalArticle

11 Citations (Scopus)


Purpose: To investigate how the delineations of the internal target volume (ITV) made from 'slow' CT alter with reference to 'thin-slice' CT. Materials and methods: Thin-slice CT images taken under breath-holding conditions and slow CT images taken under shallow-breathing conditions (8 s/image) of 11 lung cancers were used for this study. Five radiation oncologists delineated ITV of the 11 lesions using slow CT images (ITV1), and then redefined them with reference to thin-slice CT images (ITV2). SD-images (standard deviation image) were created for all patients from ITV images in order to visualize the regional variation of the ITVs. Results: The mean value of ITV2 was smaller than that initially defined by ITV1. There was no significant change in ITV1 and ITV2 between operators with regard to standard deviation in volume. There was a significant difference in the distribution of the ratio of ITV1 to ITV2 obtained on thin-slice CTs between cases with and without ground glass opacity. In cases without ground glass opacity there was a tendency for ITV2 to have a smaller volume than ITV1. Conclusions: Combined use of slow CT and thin-slice CT in delineation of ITV contours appeared to be useful in making adjustments for obscured tumor images caused by respiratory movement.

Original languageEnglish
Pages (from-to)443-449
Number of pages7
JournalRadiotherapy and Oncology
Issue number3
Publication statusPublished - 2007 Dec 1



  • Lung cancer
  • Slow CT
  • Stereotactic radiotherapy
  • Target volume delineation

ASJC Scopus subject areas

  • Hematology
  • Oncology
  • Radiology Nuclear Medicine and imaging

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