Rudi Apolle1, Stefan Brückner2, Susanne Frosch3, Maximilian Rehm3, Julia Thiele4, Chiara Valentini4, Fabian Lohaus4, Jana Babatz2, Daniela E Aust5, Jochen Hampe2, Esther G C Troost6. 1. Helmholtz-Zentrum Dresden - Rossendorf, Institute of Radiooncology - OncoRay, Germany; OncoRay - National Center for Radiation Research in Oncology, Faculty of Medicine and University Hospital Carl Gustav Carus, Technische Universität Dresden, Helmholtz-Zentrum Dresden - Rossendorf, Germany. Electronic address: rudi.apolle1@oncoray.de. 2. Department of Internal Medicine I, University Hospital Carl Gustav Carus, Dresden, Germany. 3. Department of Radiotherapy and Radiation Oncology, Faculty of Medicine and University Hospital Carl Gustav Carus, Technische Universität Dresden, Germany. 4. OncoRay - National Center for Radiation Research in Oncology, Faculty of Medicine and University Hospital Carl Gustav Carus, Technische Universität Dresden, Helmholtz-Zentrum Dresden - Rossendorf, Germany; Department of Radiotherapy and Radiation Oncology, Faculty of Medicine and University Hospital Carl Gustav Carus, Technische Universität Dresden, Germany. 5. Institute for Pathology and Tumour and Normal Tissue Bank of the University Cancer Center (UCC), University Hospital Carl Gustav Carus, Medical Faculty, Technische Universität Dresden, Germany. 6. Helmholtz-Zentrum Dresden - Rossendorf, Institute of Radiooncology - OncoRay, Germany; OncoRay - National Center for Radiation Research in Oncology, Faculty of Medicine and University Hospital Carl Gustav Carus, Technische Universität Dresden, Helmholtz-Zentrum Dresden - Rossendorf, Germany; Department of Radiotherapy and Radiation Oncology, Faculty of Medicine and University Hospital Carl Gustav Carus, Technische Universität Dresden, Germany; German Cancer Consortium (DKTK), Partner Site Dresden, and German Cancer Research Center (DKFZ), Heidelberg, Germany; National Center for Tumor Diseases (NCT), Partner Site Dresden, Germany: German Cancer Research Center (DKFZ), Heidelberg, Germany; Faculty of Medicine and University Hospital Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany, and; Helmholtz Association / Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Dresden, Germany.
Abstract
BACKGROUND AND PURPOSE: Oesophageal mobility relative to bony anatomy is a major source of geometrical uncertainty in proton radiotherapy of oesophageal carcinoma. To mitigate this uncertainty we investigated the use of implanted fiducial markers for direct target verification in terms of safety, visibility, and stability. MATERIALS AND METHODS: A total of 19 helical gold markers were endoscopically implanted in ten patients. Their placement at the proximal and distal tumour borders was compared to tumour demarcations derived from [18F]Fluorodeoxyglucose positron emission tomography, their visibility quantified via the contrast-to-noise ratio on daily orthogonal X-ray imaging, and their mobility relative to bony anatomy analysed by means of retrospective triangulation. RESULTS: Marker implantation proceeded without complications, but the distal tumour border could not be reached in two patients. Marker locations corresponded reasonably well with metabolic tumour edges (mean: 5.4 mm more distally). Marker visibility was limited but mostly sufficient (mean contrast-to-noise ratio: 1.5), and sixteen markers (84%) remained in situ until the end of treatment. Overall, marker excursions from their planned position were larger than 5(10) mm in 59(17)% of all analysed fractions. On one occasion severe target displacement was only identified via markers and was corrected before treatment delivery. CONCLUSION: Implanted helical gold fiducial markers are a safe and reliable method of providing target-centric positioning verification in proton beam therapy of oesophageal carcinoma.
BACKGROUND AND PURPOSE: Oesophageal mobility relative to bony anatomy is a major source of geometrical uncertainty in proton radiotherapy of oesophageal carcinoma. To mitigate this uncertainty we investigated the use of implanted fiducial markers for direct target verification in terms of safety, visibility, and stability. MATERIALS AND METHODS: A total of 19 helical gold markers were endoscopically implanted in ten patients. Their placement at the proximal and distal tumour borders was compared to tumour demarcations derived from [18F]Fluorodeoxyglucose positron emission tomography, their visibility quantified via the contrast-to-noise ratio on daily orthogonal X-ray imaging, and their mobility relative to bony anatomy analysed by means of retrospective triangulation. RESULTS: Marker implantation proceeded without complications, but the distal tumour border could not be reached in two patients. Marker locations corresponded reasonably well with metabolic tumour edges (mean: 5.4 mm more distally). Marker visibility was limited but mostly sufficient (mean contrast-to-noise ratio: 1.5), and sixteen markers (84%) remained in situ until the end of treatment. Overall, marker excursions from their planned position were larger than 5(10) mm in 59(17)% of all analysed fractions. On one occasion severe target displacement was only identified via markers and was corrected before treatment delivery. CONCLUSION: Implanted helical gold fiducial markers are a safe and reliable method of providing target-centric positioning verification in proton beam therapy of oesophageal carcinoma.
Authors: Melissa Thomas; Robin De Roover; Schalk van der Merwe; Maarten Lambrecht; Gilles Defraene; Karin Haustermans Journal: Clin Transl Radiat Oncol Date: 2020-11-05