Time and frequency to observe fiducial markers in MLC-modulated fields during prostate IMRT/VMAT beam delivery |
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| Institution: | 1. Radiation Oncology Department, 3rd Affiliated Hospital of Qiqihar Medical University, Qiqihar, China;2. Radiation Oncology Department, Fox Chase Cancer Center, Philadelphia, PA, United States;1. Medical Imaging Department, School of Health Sciences, University of Management & Technology, Lahore, Pakistan;2. Medical Physics Oncology Department, Combined Military Hospital, Rawalpindi, Pakistan;3. Radiotherapy Oncology Department, San Bortolo Hospital, Vicenza, Italy;4. Medical Physics Department, San Bortolo Hospital, Vicenza, Italy;1. Helmholtz-Zentrum Dresden – Rossendorf, Institute of Radiooncology – OncoRay, Germany;2. 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;3. Department of Internal Medicine I, University Hospital Carl Gustav Carus, Dresden, Germany;4. 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. German Cancer Consortium (DKTK), Partner Site Dresden, and German Cancer Research Center (DKFZ), Heidelberg, Germany;7. 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;1. Department of Radiological Technology, Keio University Hospital, 35 Shinanomachi, Shinjuku, Tokyo 160 8582, Japan;2. Division of Health Sciences, Graduate School of Medical Science, Kanazawa University, 5-11-80 Kodatsuno, Kanazawa 920 0942, Japan;3. Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, 5-11-80 Kodatsuno, Kanazawa, Ishikawa 920 0942, Japan;4. Department of Diagnostic Radiology, Shizuoka Cancer Center, 1007 Shimonagakubo, Nagaizumi, Sunto, Shizuoka 411 8777, Japan;5. Department of Radiological Technologist, Osaka College of High Technology, 1-2-43 Miyahara, Osaka Yodogawa, Osaka 532 0003, Japan;6. Department of Radiology, Tokyo Metropolitan Health and Medical Treatment Corporation Toshima Hospital, 33-1 Sakaecho, Itabashi, Tokyo 173 0015, Japan;7. Department of Diagnostic Radiology, Keio University School of Medicine, 35, Shinanomachi, Shinjuku, Tokyo 160 8582, Japan;1. Istituto Nazionale di Fisica Nucleare, Sezione di Catania, Italy;2. MIFT Department, University of Messina, Italy;3. Section of Radiological Sciences, Department of Biomedical and Dental Sciences and Morphofunctional Imaging, University of Messina, Italy;1. School of Physics and Astronomy, The University of Manchester, Manchester M13 9PL, United Kingdom;2. The Cockcroft Institute, Daresbury Science and Innovation Campus, Warrington WA4 4AD, United Kingdom;3. Paul Scherrer Institute, 5232 Villigen, Switzerland |
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| Abstract: | ObjectiveThis work investigates the time and frequency to observe fiducial markers in MLC-modulated fields during intensity-modulated radiotherapy (IMRT) and volumetric-modulated arc therapy (VMAT) beam delivery for real-time prostate localization.MethodsThirty seven prostate patients treated with IMRT or VMAT were included in this retrospective study. DRR images were generated for all MLC segments/control points using the TPS. The MLC leaf pattern of each control point was overlaid on the DRR, and the number of fiducials within the MLC opening was analyzed. EPID images of fiducials in a pelvic phantom were obtained to demonstrate the fiducial visibility during modulated beam delivery.ResultsGold fiducials were visible on EPID images. The probability of seeing a number of fiducials within the MLC opening was analyzed. At least one fiducial was visible during 42 ± 2% and 52 ± 2% beam-on time for IMRT of the prostate with and without lymph nodes, and during 81 ± 4% and 80 ± 5% beam-on time for VMAT of the prostate with and without lymph nodes, respectively. The mean time interval to observe at least one fiducial was 8.4 ± 0.7 and 5.9 ± 0.5 s for IMRT of the prostate with and without the lymph nodes, respectively, and 1.6 ± 0.1 s for VMAT prostate patients. The estimated potential dosimetric uncertainty was 7% and 2% for IMRT and VMAT, respectively.ConclusionsOur results demonstrated that the time and frequency to observe fiducial markers in MLC-modulated fields during IMRT/VMAT beam delivery were adequate for real-time prostate localization. The beam’s eye view fiducial positions could be used for intrafractional target monitoring and motion correction in prostate radiotherapy. |
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| Keywords: | EPID DRR Fiducial markers Intrafraction organ motion Real-time target localization IMRT VMAT |
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