A Tool to Automatically Analyze Electromagnetic Tracking Data from High Dose Rate Brachytherapy of Breast Cancer Patients
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1,2,5 Th. I. Götz, 2 G. Lahmer, 2 V. Strnad, 2 Ch. Bert, 5 B. Hensel, 3 A. M. Tomé and 1 E. W. Lang,
1 CIML, Biophysics, University of Regensburg, 93040 Regensburg, Germany
2 Department of Radiation Oncology, Universitätsklinikum Erlangen,
Friedrich-Alexander-Universität Erlangen-Nürnberg 91054 Erlangen, Germany
3 IEETA, DETI, Universidade de Aveiro, 3810-193 Aveiro, Portugal
5 Center for Medical Physics and Engineering,
University of Erlangen-Nuremberg, 91052 Erlangen, Germany
email: theresa.goetz@biologie.uni-regensburg.de
During High Dose Rate Brachytherapy (HDR-BT) the spatial position
of the radiation source inside catheters implanted into a female breast
is determined via electromagnetic tracking (EMT). Dwell poistions and
dwell times of the radiation source are established, relative to the pa-
tient's anatomy, from an initial X-ray-CT-image. During the irradiation
treatment, catheter displacements can occur due to patient movements.
The current study develops an automatic analysis tool of EMT data sets
recorded with a solenoid sensor to assure concordance of the source move-
ment with the treatment plan. The tool combines machine learning tech-
niques such as multi-dimensional scaling (MDS), ensemble empirical mode
decomposition (EEMD), singular spectrum analysis (SSA) and particle
lter (PF) to precisely detect and quantify any mismatch between the
treatment plan and actual EMT measurements. We demonstrate that
movement artifacts as well as technical signal distortions can be removed
automatically and reliably, resulting in artifact-free reconstructed signals.
This is a prerequisite for a highly accurate determination of any deviations
of dwell positions from the treatment plan.
