Characterization of a novel gamma camera for live source localization in HDR brachytherapy
Johannes Strotmann,
Germany
PD-0506
Abstract
Characterization of a novel gamma camera for live source localization in HDR brachytherapy
Authors: Johannes Strotmann1, Aleyna Sipahi2, Katrin Büsing3, Wolfgang Kunth3, Ndimofor Chofor4, Björn Poppe3, Amol Patil5, Andreas A. Schönfeld4
1Carl von Ossietzky University, University Clinic for Medical Radiation Physics, Oldenburg, Germany; 2Heinrich Heine University, Department of Radiation Oncology, Duesseldorf, Germany; 3University Clinic of Medical Radiation Physics, Medical Campus Pius-Hospital, Oldenburg, Germany; 4Sun Nuclear, A Mirion Medical Company, Research & Development, Melbourne, USA; 5Mirion Technologies, Inc., Research & Development, Meriden, USA
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Purpose or Objective
By combining a visual video camera with a gamma camera, the novel HDR-Vue system provides real-time visualization of the source location in a HDR brachytherapy treatment room. The aim of the present work was to investigate the capabilities of the system for the localization of the HDR source.
Material and Methods
A Ir-192 source (A = 345–239 GBq) was scanned across the 30° by 40° field of view (FOV) of the gamma camera of a prototype HDR Vue system (Mirion Technologies, Atlanta, USA) in a 10 mm grid using a motorized water phantom with a custom-made mounting system. Thereby, camera-to-source distances of 500, 700, and 1000 mm in air, as well as water depths of 30, 50, 100, and 150 mm were investigated at a dwell time of 5 s to mimic clinical scenarios. The mean source position and the corresponding standard deviation were determined based on the recorded video frames, where the water phantom’s coordinate system served as reference. The entire FOV could thus be characterized with regards to localization accuracy of the source in air and in water.
Results
The standard deviation of the detected source position was below 2 mm at the center of the image and increased with increasing source to camera distance, viewing angle and depth in water. An accuracy of better than 10 mm standard deviation across the full FOV is achieved for water depths of up to 50 mm at a source to camera distance of 500 mm. At a depth in water of 120 mm, a 10 mm standard deviation is still achievable within an FOV of 6°.
Conclusion
The HDR-Vue provides real-time localization of the Ir-192 source during the treatment and may benefit the detection of gross errors in HDR brachytherapy, as well as provide useful information for emergency recovery scenarios.