Shingo Ohira1, Hayate Washio2, Masashi Yagi3, Tsukasa Karino2, Kenji Nakamura4, Yoshihiro Ueda2, Masayoshi Miyazaki2, Masahiko Koizumi5, Teruki Teshima2. 1. Department of Radiation Oncology, Osaka International Cancer Institute, Osaka, Japan; Department of Medical Physics and Engineering, Osaka University Graduate School of Medicine, Suita, Japan. Electronic address: oohira-si@mc.pref.osaka.jp. 2. Department of Radiation Oncology, Osaka International Cancer Institute, Osaka, Japan. 3. Department of Carbon Ion Radiotherapy, Osaka University Graduate School of Medicine, Suita, Japan. 4. Department of Radiology, Nakakawachi Medical Center of Acute Medicine, Higashi-Osaka, Japan. 5. Department of Medical Physics and Engineering, Osaka University Graduate School of Medicine, Suita, Japan.
Abstract
PURPOSE: Assess the accuracy for quantitative measurements of electron density relative to water (ρe/ρe,w), effective atomic number (Zeff) and stopping power ratio relative to water (SPRw) using a dual-layer computed tomography (DLCT) system. METHODS AND MATERIALS: A tissue characterization phantom was scanned using DLCT with varying scanning parameters (i.e., tube voltage, rotation time, CTDIvol, and scanning mode) and different reference materials. Then, electron density ρe/ρe,w and atomic number Zeff images were reconstructed, and their values were determined for each reference materials. Based on these two values, SPRw was calculated. Finally, the percent error (PE) against the theoretical values was calculated for reference materials. RESULTS: Significant linear relationships (p < 0.001) were observed between the measured and theoretical ρe/ρe,w (r = 1.000), Zeff (r = 0.989) and SPRw (r = 1.000) values. The PE for each reference material varied from -2.0 to 1.2% (mean, <0.1%) for electron density ρe/ρe,w, from -6.4 to 8.0% (mean, -2.0%) for atomic number Zeff, and from -2.0 to 1.9% (mean, 0.3%) for stopping power ratio SPRw. The mean PE of ρe/ρe,w (<0.1%), Zeff (<-2.5%) and SPRw (<0.4%) was verified across the variation of scanning parameters (p > 0.85). CONCLUSIONS: DLCT provides a reasonable accuracy in the measurements of ρe/ρe,w, Zeff and SPRw, and could enhance radiotherapy treatment planning and the subsequent outcomes.
PURPOSE: Assess the accuracy for quantitative measurements of electron density relative to water (ρe/ρe,w), effective atomic number (Zeff) and stopping power ratio relative to water (SPRw) using a dual-layer computed tomography (DLCT) system. METHODS AND MATERIALS: A tissue characterization phantom was scanned using DLCT with varying scanning parameters (i.e., tube voltage, rotation time, CTDIvol, and scanning mode) and different reference materials. Then, electron density ρe/ρe,w and atomic number Zeff images were reconstructed, and their values were determined for each reference materials. Based on these two values, SPRw was calculated. Finally, the percent error (PE) against the theoretical values was calculated for reference materials. RESULTS: Significant linear relationships (p < 0.001) were observed between the measured and theoretical ρe/ρe,w (r = 1.000), Zeff (r = 0.989) and SPRw (r = 1.000) values. The PE for each reference material varied from -2.0 to 1.2% (mean, <0.1%) for electron density ρe/ρe,w, from -6.4 to 8.0% (mean, -2.0%) for atomic number Zeff, and from -2.0 to 1.9% (mean, 0.3%) for stopping power ratio SPRw. The mean PE of ρe/ρe,w (<0.1%), Zeff (<-2.5%) and SPRw (<0.4%) was verified across the variation of scanning parameters (p > 0.85). CONCLUSIONS: DLCT provides a reasonable accuracy in the measurements of ρe/ρe,w, Zeff and SPRw, and could enhance radiotherapy treatment planning and the subsequent outcomes.
Authors: Friderike K Longarino; Antonia Kowalewski; Thomas Tessonnier; Stewart Mein; Benjamin Ackermann; Jürgen Debus; Andrea Mairani; Wolfram Stiller Journal: Front Oncol Date: 2022-04-20 Impact factor: 5.738
Authors: Friderike K Longarino; Thomas Tessonnier; Stewart Mein; Semi B Harrabi; Jürgen Debus; Wolfram Stiller; Andrea Mairani Journal: J Appl Clin Med Phys Date: 2021-11-01 Impact factor: 2.102