Combination of dual-energy computed tomography and iterative metal artefact reduction to increase general quality of imaging for radiotherapy patients with high dense materials. Phantom study |
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| Institution: | 1. Department of Medical Physics, Greater Poland Cancer Centre, Poznań, Poland;2. Department of Technical Physics, Poznan University of Technology, Poznań, Poland;3. Medical Physics & Clinical Engineering, Nottingham University Hospitals NHS Trust, Nottingham, UK;4. School of Medicine, University of Nottingham, Nottingham, UK;5. Department of Electroradiology, Poznań University of Medical Sciences, Poznań, Poland;1. Graduate School of Health Sciences, Kumamoto University, 4-24-1 Kuhonji, Chuo-ku, Kumamoto 862-0976, Japan;2. Department of Health Sciences, Faculty of Life Sciences, Kumamoto University, 4-24-1 Kuhonji, Chuo-ku, Kumamoto 862-0976, Japan;1. Medical Physics, San Raffaele Hospital Scientific Institute, Milan, Italy;2. Radiotherapy, San Raffaele Hospital Scientific Institute, Milan, Italy;1. Department of Radiation Oncology, Medical University Vienna, Austria;2. Division of Radiation Therapy, Department of Diagnostic and Therapeutic Radiology, Faculty of Medicine Ramathibodi Hospital, Mahidol University, Bangkok, Thailand;3. University of Applied Science Wiener, Neustadt, Austria;4. MedAustron Ion Therapy Center, Wiener Neustadt, Austria;1. Nagoya University Graduate School of Medicine, 1-1-20, Daikominami, Higashi-ku, Nagoya, Japan;2. National Cancer Center Hospital East, Department of Radiological Technology, 6-5-1 Kashiwanoha, Kashiwa, Japan;3. National Institutes for Quantum and Radiological Science and Technology, Center for Advanced Radiation Emergency Medicine, Department of Radiation Measurement and Dose Assessment, 4-9-1 Anagawa, Inage-ku, Chiba, Japan;4. National Cancer Center Hospital East, Department of Medical Informatics, 6-5-1 Kashiwanoha, Kashiwa, Japan;5. Canon Medical Systems Corporation, 1385 Shimoishigami, Otawara, Tochigi, Japan;1. Department of Medical Physics in Radiation Oncology, German Cancer Research Center Heidelberg, Germany;2. Department of Medical Physics in Radiology, German Cancer Research Center Heidelberg, Germany;3. Department of Radiation Oncology, University of Heidelberg, Germany;4. Department of Radiotherapy, German Cancer Research Center Heidelberg, Germany;5. Department of Radiotherapy and Oncology, Clinical Center Vivantes Neukoelln;6. Department of Radiooncology, Ortenau Klinikum Offenburg-Gengenbach, Germany;1. School of Science, RMIT University, Melbourne, Australia;2. The European Synchrotron Radiation Facility, ID17 Biomedical Beamline, Grenoble, France;3. Inserm UA7 STROBE, Grenoble Alps University, Grenoble, France;4. Swansea University Medical School, Singleton Park, Swansea, United Kingdom;5. Radiation Oncology, Alfred Hospital, Melbourne, Australia;6. School of Health and Biomedical Sciences, RMIT University, Melbourne, Australia;7. Physical Sciences, Peter MacCallum Cancer Centre, Melbourne, Australia;8. Australian Nuclear Science and Technology Organisation (ANSTO), Australian Synchrotron, Clayton, Australia;9. Department of Obstetrics and Gynaecology, University of Melbourne, Royal Women’s Hospital, Melbourne, Australia;10. Australian Radiation Protection and Nuclear Safety Agency (ARPANSA), Melbourne, Australia;11. Radiation Analytics, Brisbane, Australia |
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| Abstract: | PurposeTo evaluate the use of pseudo-monoenergetic reconstructions (PMR) from dual-energy computed tomography, combined with the iterative metal artefact reduction (iMAR) method.MethodsPseudo-monoenergetic CT images were obtained using the dual-energy mode on the Siemens Somatom Definition AS scanner. A range of PMR combinations (70–130 keV) were used with and without iMAR. A Virtual Water? phantom was used for quantitative assessment of error in the presence of high density materials: titanium, alloys 330 and 600. The absolute values of CT number differences (AD) and normalised standard deviations (NSD) were calculated for different phantom positions. Image quality was assessed using an anthropomorphic pelvic phantom with an embedded hip prosthesis. Image quality was scored blindly by five observers.ResultsAD and NSD values revealed differences in CT number errors between tested sets. AD and NSD were reduced in the vicinity of metal for images with iMAR (p < 0.001 for AD/NSD). For ROIs away from metal, with and without iMAR, 70 keV PMR and pCT AD values were lower than for the other reconstructions (p = 0.039). Similarly, iMAR NSD values measured away from metal were lower for 130 keV and 70 keV PMR (p = 0.002). Image quality scores were higher for 70 keV and 130 keV PMR with iMAR (p = 0.034).ConclusionThe use of 70 keV PMR with iMAR allows for significant metal artefact reduction and low CT number errors observed in the vicinity of dense materials. It is therefore an attractive alternative to high keV imaging when imaging patients with metallic implants, especially in the context of radiotherapy planning. |
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| Keywords: | Metal artefact reduction Dual energy CT iMAR Quality of CT images Imaging for radiation therapy |
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