title: First Steps Toward Ultrasound-Based Motion Compensation for Imaging and Therapy: Calibration with an Optical System and 4D PET Imaging.
abstract: Target motion, particularly in the abdomen, due to respiration or patient movement is still a challenge in many diagnostic and therapeutic processes. Hence, methods to detect and compensate this motion are required. Diagnostic ultrasound (US) represents a non-invasive and dose-free alternative to fluoroscopy, providing more information about internal target motion than respiration belt or optical tracking. The goal of this project is to develop an US-based motion tracking for real-time motion correction in radiation therapy and diagnostic imaging, notably in 4D positron emission tomography (PET). In this work, a workflow is established to enable the transformation of US tracking data to the coordinates of the treatment delivery or imaging system - even if the US probe is moving due to respiration. It is shown that the US tracking signal is equally adequate for 4D PET image reconstruction as the clinically used respiration belt and provides additional opportunities in this concern. Furthermore, it is demonstrated that the US probe being within the PET field of view generally has no relevant influence on the image quality. The accuracy and precision of all the steps in the calibration workflow for US tracking-based 4D PET imaging are found to be in an acceptable range for clinical implementation. Eventually, we show in vitro that an US-based motion tracking in absolute room coordinates with a moving US transducer is feasible.
authors.affiliation: Mediri GmbH , Heidelberg , Germany.
authors.forename: Julia
authors.initials: J
authors.lastname: Schwaab
authors.affiliation: Department of Radiation Oncology, Heidelberg Ion-Beam Therapy Center (HIT), Heidelberg University Hospital , Heidelberg , Germany.
authors.forename: Christopher
authors.initials: C
authors.lastname: Kurz
authors.affiliation: Mediri GmbH , Heidelberg , Germany.
authors.forename: Cristina
authors.initials: C
authors.lastname: Sarti
authors.affiliation: Mediri GmbH , Heidelberg , Germany.
authors.forename: André
authors.initials: A
authors.lastname: Bongers
authors.affiliation: Siemens Healthcare AG , Zurich , Switzerland.
authors.forename: Frédéric
authors.initials: F
authors.lastname: Schoenahl
authors.affiliation: GSI Helmholtzzentrum für Schwerionenforschung , Darmstadt , Germany ; Strahlenklinik, Erlangen University Hospital , Erlangen , Germany.
authors.forename: Christoph
authors.initials: C
authors.lastname: Bert
authors.affiliation: Department of Radiation Oncology, Heidelberg Ion-Beam Therapy Center (HIT), Heidelberg University Hospital , Heidelberg , Germany.
authors.forename: Jürgen
authors.initials: J
authors.lastname: Debus
authors.affiliation: Department of Radiation Oncology, Heidelberg Ion-Beam Therapy Center (HIT), Heidelberg University Hospital , Heidelberg , Germany ; Department of Experimental Physics - Medical Physics, Ludwig-Maximilian-University , Munich , Germany.
authors.forename: Katia
authors.initials: K
authors.lastname: Parodi
authors.affiliation: Mediri GmbH , Heidelberg , Germany ; Fraunhofer MEVIS , Bremen , Germany.
authors.forename: Jürgen Walter
authors.initials: JW
authors.lastname: Jenne
keywords: 4D PET imaging; ultrasound calibration; ultrasound imaging; ultrasound in PET/CT; ultrasound-based motion compensation