Target position reproducibility in left-breast irradiation with deep inspiration breath-hold using multiple optical surface control points

Aurora Fassi, Giovanni B Ivaldi, Paola Tabarelli de Fatis, Marco Liotta, Ilaria Meaglia, Patrizia Porcu, Lea Regolo, Marco Riboldi, Guido Baroni

Research output: Contribution to journalArticlepeer-review

Abstract

The aim of this study was to investigate the use of 3D optical localization of multiple surface control points for deep inspiration breath-hold (DIBH) guidance in left-breast radiotherapy treatments. Ten left-breast cancer patients underwent whole-breast DIBH radiotherapy controlled by the Real-time Position Management (RPM) system. The reproducibility of the tumor bed (i.e., target) was assessed by the position of implanted clips, acquired through in-room kV imaging. Six to eight passive fiducials were positioned on the patients' thoraco-abdominal surface and localized intrafractionally by means of an infrared 3D optical tracking system. The point-based registration between treatment and planning fiducials coordinates was applied to estimate the interfraction variations in patients' breathing baseline and to improve target reproducibility. The RPM-based DIBH control resulted in a 3D error in target reproducibility of 5.8 ± 3.4 mm (median value ± interquartile range) across all patients. The reproducibility errors proved correlated with the interfraction baseline variations, which reached 7.7 mm for the single patient. The contribution of surface fiducials registration allowed a statistically significant reduction (p < 0.05) in target localization errors, measuring 3.4 ± 1.7 mm in 3D. The 3D optical monitoring of multiple surface control points may help to optimize the use of the RPM system for improving target reproducibility in left-breast DIBH irradiation, providing insights on breathing baseline variations and increasing the robustness of external surrogates for DIBH guidance.

Original languageEnglish
Pages (from-to)35-43
Number of pages9
JournalJournal of Applied Clinical Medical Physics
Volume19
Issue number4
DOIs
Publication statusPublished - Jul 2018

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