Comparison of three differently shaped ROIs in free breathing breast radiotherapy setup using surface guidance with AlignRT

Marko Laaksomaa, Torsten Moser, Julia Kritz, Kiira Pynnönen, Maija Rossi

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Background: Setup accuracy within adjuvant radiotherapy of breast cancer treated in free breathing is well studied, but a comparison of the typical regions of interest (ROI) used in surface guided radiation therapy (SGRT) does not exist. The aim of this study was to estimate the setup accuracy obtained with differently shaped ROIs in SGRT. Materials and methods: A total of 573 orthogonal image pairs were analyzed from free breathing breast patients in two groups: positioning using AlignRT® surface guidance system (Group A, n = 20), and setup using conventional laser and tattoo setup (Group L, n = 20). For SGRT, three different setup ROIs were used: a Breast-shaped, O-shaped and T-shaped (B-O and T-ROI). We evaluated the isocenter-, rotation-, pitch and arm position accuracy and residual errors for the chest wall and shoulder joint in kV orthogonal and tangential setup images with laser or SGRT-based setup. Results: Less isocenter variance was found in Group A than in Group L. Rotations and posture errors were larger in group L than in Group A (p ≤ 0.05). Rotation error was smaller with T-shaped ROI than with O-or B-shape (p = 0.01–0.04). Conclusion: Setup with AlignRT® improves reproducibility compared to laser setup. Between the different ROI shapes only small differences were found in the patient posture or the isocenter position in the images. The T-ROI is recommended to set up the chest wall bony structure and an additional B-ROI may be used to fine-tune the soft tissue accuracy

Original languageEnglish
Pages (from-to)545-552
Number of pages8
JournalReports of Practical Oncology and Radiotherapy
Issue number4
Publication statusPublished - 2021
Publication typeA1 Journal article-refereed


  • breast
  • patient positioning
  • region of interest
  • surface-guided radiotherapy

Publication forum classification

  • Publication forum level 0

ASJC Scopus subject areas

  • Oncology


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