Real-time 2D/3D registration using kV-MV image pairs for tumor motion tracking in image guided radiotherapy

Hugo Furtado*, Elisabeth Steiner, Markus Stock, Dietmar Georg, Wolfgang Birkfellner

*Corresponding author for this work

Research output: Journal article (peer-reviewed)Journal article

25 Citations (Scopus)


Intra-fractional respiratory motion during radiotherapy leads to a larger planning target volume (PTV). Real-time tumor motion tracking by two-dimensional (2D)/3D registration using on-board kilo-voltage (kV) imaging can allow for a reduction of the PTV though motion along the imaging beam axis cannot be resolved using only one projection image. We present a retrospective patient study investigating the impact of paired portal mega-voltage (MV) and kV images on registration accuracy. Material and methods. We used data from 10 patients suffering from non-small cell lung cancer (NSCLC) undergoing stereotactic body radiation therapy (SBRT) lung treatment. For each patient we acquired a planning computed tomography (CT) and sequences of kV and MV images during treatment. We compared the accuracy of motion tracking in six degrees-of-freedom (DOF) using the anterior-posterior (AP) kV sequence or the sequence of kV-MV image pairs. Results. Motion along cranial-caudal direction could accurately be extracted when using only the kV sequence but in AP direction we obtained large errors. When using kV-MV pairs, the average error was reduced from 2.9 mm to 1.5 mm and the motion along AP was successfully extracted. Mean registration time was 188 ms. Conclusion. Our evaluation shows that using kV-MV image pairs leads to improved motion extraction in six DOF and is suitable for real-time tumor motion tracking with a conventional LINAC.

Original languageEnglish
Pages (from-to)1464-1471
Number of pages8
JournalActa Oncologica
Issue number7
Publication statusPublished - Oct 2013
Externally publishedYes

ASJC Scopus subject areas

  • Hematology
  • Oncology
  • Radiology, Nuclear Medicine and Imaging


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