Ion beam tracking using ultrasound motion detection. Issue 4 (20th March 2014)

• Record Type: Journal Article
• Authors: Prall, M.; Kaderka, R.; Saito, N.; Graeff, C.; Bert, C.; Durante, M.; Parodi, K.; Schwaab, J.; Sarti, C.; Jenne, J.
• Is Part Of: Medical physics. Volume 41:Issue 4(2014)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2014-03-20
• Subjects: Ultrasonography -- Therapeutic applications, including brachytherapy -- Robotics -- Reconstruction; biomedical ultrasonics -- image reconstruction -- medical image processing -- medical robotics -- motion compensation -- neural nets -- phantoms -- radiation therapy -- tumours -- ultrasonic therapy; motion detection -- diagnostic ultrasound -- hadron therapy -- moving tumors; Diagnosis using ultrasonic, sonic or infrasonic waves -- Radiation therapy -- Ultrasound therapy -- Biological material, e.g. blood, urine; Haemocytometers -- Digital computing or data processing equipment or methods, specially adapted for specific applications -- Image data processing or generation, in general -- Analysis of motion; Ultrasonography -- Rubber -- Motion detection -- Medical imaging -- Tracking devices -- Computer software -- Ion beams -- Cancer -- Robotics -- Heavy ion beams; Medical physics -- Periodicals; Medical physics; Geneeskunde; Natuurkunde; Toepassingen; Biophysics; Periodicals; Periodicals; Electronic journals; 610.153
• DOI: 10.1118/1.4868459
• Languages: English
• ISSNs: 0094-2405

Abstract

Abstract : Purpose: : The use of motion mitigation techniques such as tracking and gating in particle therapy requires real‐time knowledge of tumor position with millimeter precision. The aim of this phantom‐based study was to evaluate the option of diagnostic ultrasound (US) imaging (sonography) as real‐time motion detection method for scanned heavy ion beam irradiation of moving targets. Methods: : For this pilot experiment, a tumor surrogate was moved inside a water bath along two‐dimensional trajectories. A rubber ball was used for this purpose. This ball was moved by a robotic arm in two dimensions lateral to the heavy ion beam. Trajectories having a period of 3 s and peak to peak amplitude of 20 mm were used. Square radiation fields of 3 × 3 cm 2 were irradiated on radiosensitive films with a 200 MeV/u beam of calcium ions having a FWHM of 6 mm. Pencil beam scanning and beam tracking were employed. The films were attached on the robotic arm and thus moved with the rubber ball. The position of the rubber ball was continuously measured by a US tracking system (Mediri GmbH, Heidelberg) and sent to the GSI therapy control system (TCS). This position was used as tracking vector. Position reconstruction from the US tracking system and data communication introduced a delay leading to a position error of several millimeters. An artificial neural network (ANN) was implemented in the TCS to predict motion from US measurements and thus to compensate for the delay. Results: : Using ANN delay compensation and large motion amplitudes, the authors could produce irradiation patterns with a few percent inhomogeneity and about 1 mm geometrical conformity. Conclusions: : This pilot experiment suggests that diagnostic US should be further investigated as dose‐free, high frame‐rate, and model‐independent motion detection method for scanning heavy ion beam irradiation of moving targets.