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Nakao M, Ozawa S, Miura H, Yamada K, Hayata M, Hayashi K, Kawahara D, Nakashima T, Ochi Y, Okumura T, Kunimoto H, Kawakubo A, Kusaba H, Nozaki H, Habara K, Tohyama N, Nishio T, Nakamura M, Minemura T, Okamoto H, Ishikawa M, Kurooka M, Shimizu H, Hotta K, Saito M, Nakano M, Tsuneda M, Nagata Y. CT number calibration audit in photon radiation therapy. Med Phys 2024; 51:1571-1582. [PMID: 38112216 DOI: 10.1002/mp.16887] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2023] [Revised: 06/29/2023] [Accepted: 11/26/2023] [Indexed: 12/21/2023] Open
Abstract
BACKGROUND Inadequate computed tomography (CT) number calibration curves affect dose calculation accuracy. Although CT number calibration curves registered in treatment planning systems (TPSs) should be consistent with human tissues, it is unclear whether adequate CT number calibration is performed because CT number calibration curves have not been assessed for various types of CT number calibration phantoms and TPSs. PURPOSE The purpose of this study was to investigate CT number calibration curves for mass density (ρ) and relative electron density (ρe ). METHODS A CT number calibration audit phantom was sent to 24 Japanese photon therapy institutes from the evaluating institute and scanned using their individual clinical CT scan protocols. The CT images of the audit phantom and institute-specific CT number calibration curves were submitted to the evaluating institute for analyzing the calibration curves registered in the TPSs at the participating institutes. The institute-specific CT number calibration curves were created using commercial phantom (Gammex, Gammex Inc., Middleton, WI, USA) or CIRS phantom (Computerized Imaging Reference Systems, Inc., Norfolk, VA, USA)). At the evaluating institute, theoretical CT number calibration curves were created using a stoichiometric CT number calibration method based on the CT image, and the institute-specific CT number calibration curves were compared with the theoretical calibration curve. Differences in ρ and ρe over the multiple points on the curve (Δρm and Δρe,m , respectively) were calculated for each CT number, categorized for each phantom vendor and TPS, and evaluated for three tissue types: lung, soft tissues, and bones. In particular, the CT-ρ calibration curves for Tomotherapy TPSs (ACCURAY, Sunnyvale, CA, USA) were categorized separately from the Gammex CT-ρ calibration curves because the available tissue-equivalent materials (TEMs) were limited by the manufacturer recommendations. In addition, the differences in ρ and ρe for the specific TEMs (ΔρTEM and Δρe,TEM , respectively) were calculated by subtracting the ρ or ρe of the TEMs from the theoretical CT-ρ or CT-ρe calibration curve. RESULTS The mean ± standard deviation (SD) of Δρm and Δρe,m for the Gammex phantom were -1.1 ± 1.2 g/cm3 and -0.2 ± 1.1, -0.3 ± 0.9 g/cm3 and 0.8 ± 1.3, and -0.9 ± 1.3 g/cm3 and 1.0 ± 1.5 for lung, soft tissues, and bones, respectively. The mean ± SD of Δρm and Δρe,m for the CIRS phantom were 0.3 ± 0.8 g/cm3 and 0.9 ± 0.9, 0.6 ± 0.6 g/cm3 and 1.4 ± 0.8, and 0.2 ± 0.5 g/cm3 and 1.6 ± 0.5 for lung, soft tissues, and bones, respectively. The mean ± SD of Δρm for Tomotherapy TPSs was 2.1 ± 1.4 g/cm3 for soft tissues, which is larger than those for other TPSs. The mean ± SD of Δρe,TEM for the Gammex brain phantom (BRN-SR2) was -1.8 ± 0.4, implying that the tissue equivalency of the BRN-SR2 plug was slightly inferior to that of other plugs. CONCLUSIONS Latent deviations between human tissues and TEMs were found by comparing the CT number calibration curves of the various institutes.
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Affiliation(s)
- Minoru Nakao
- Hiroshima High-Precision Radiotherapy Cancer Center, Hiroshima, Japan
- Department of Radiation Oncology, Graduate School of Biomedical & Health Sciences, Hiroshima University, Hiroshima, Japan
- Technical Support Working Group in Hiroshima High-Precision Radiotherapy Cancer Center, Hiroshima, Japan
- Medical Physics Working Group in Japan Clinical Oncology Group - Radiation Therapy Study Group, Tokyo, Japan
| | - Shuichi Ozawa
- Hiroshima High-Precision Radiotherapy Cancer Center, Hiroshima, Japan
- Department of Radiation Oncology, Graduate School of Biomedical & Health Sciences, Hiroshima University, Hiroshima, Japan
- Technical Support Working Group in Hiroshima High-Precision Radiotherapy Cancer Center, Hiroshima, Japan
- Medical Physics Working Group in Japan Clinical Oncology Group - Radiation Therapy Study Group, Tokyo, Japan
| | - Hideharu Miura
- Hiroshima High-Precision Radiotherapy Cancer Center, Hiroshima, Japan
- Department of Radiation Oncology, Graduate School of Biomedical & Health Sciences, Hiroshima University, Hiroshima, Japan
- Technical Support Working Group in Hiroshima High-Precision Radiotherapy Cancer Center, Hiroshima, Japan
| | - Kiyoshi Yamada
- Hiroshima High-Precision Radiotherapy Cancer Center, Hiroshima, Japan
- Technical Support Working Group in Hiroshima High-Precision Radiotherapy Cancer Center, Hiroshima, Japan
| | - Masahiro Hayata
- Hiroshima High-Precision Radiotherapy Cancer Center, Hiroshima, Japan
- Technical Support Working Group in Hiroshima High-Precision Radiotherapy Cancer Center, Hiroshima, Japan
| | - Kosuke Hayashi
- Hiroshima High-Precision Radiotherapy Cancer Center, Hiroshima, Japan
- Technical Support Working Group in Hiroshima High-Precision Radiotherapy Cancer Center, Hiroshima, Japan
| | - Daisuke Kawahara
- Department of Radiation Oncology, Graduate School of Biomedical & Health Sciences, Hiroshima University, Hiroshima, Japan
- Technical Support Working Group in Hiroshima High-Precision Radiotherapy Cancer Center, Hiroshima, Japan
- Medical Physics Working Group in Japan Clinical Oncology Group - Radiation Therapy Study Group, Tokyo, Japan
| | - Takeo Nakashima
- Technical Support Working Group in Hiroshima High-Precision Radiotherapy Cancer Center, Hiroshima, Japan
- Medical Physics Working Group in Japan Clinical Oncology Group - Radiation Therapy Study Group, Tokyo, Japan
- Radiation Therapy Section, Department of Clinical Support, Hiroshima University Hospital, Hiroshima, Japan
| | - Yusuke Ochi
- Technical Support Working Group in Hiroshima High-Precision Radiotherapy Cancer Center, Hiroshima, Japan
- Radiation Therapy Section, Department of Clinical Support, Hiroshima University Hospital, Hiroshima, Japan
| | - Takuro Okumura
- Technical Support Working Group in Hiroshima High-Precision Radiotherapy Cancer Center, Hiroshima, Japan
- Radiation Therapy Section, Department of Clinical Support, Hiroshima University Hospital, Hiroshima, Japan
| | - Haruhide Kunimoto
- Technical Support Working Group in Hiroshima High-Precision Radiotherapy Cancer Center, Hiroshima, Japan
- Radiation Therapy Department, Hiroshima Prefectural Hospital, Hiroshima, Japan
| | - Atsushi Kawakubo
- Technical Support Working Group in Hiroshima High-Precision Radiotherapy Cancer Center, Hiroshima, Japan
- Radiation Therapy Department, Hiroshima City Hiroshima Citizens Hospital, Hiroshima, Japan
| | - Hayate Kusaba
- Technical Support Working Group in Hiroshima High-Precision Radiotherapy Cancer Center, Hiroshima, Japan
- Radiation Therapy Department, Hiroshima City Hiroshima Citizens Hospital, Hiroshima, Japan
| | - Hiroshige Nozaki
- Technical Support Working Group in Hiroshima High-Precision Radiotherapy Cancer Center, Hiroshima, Japan
- Division of Radiology, Hiroshima Red Cross Hospital & Atomic-bomb Survivors Hospital, Hiroshima, Japan
| | - Kosaku Habara
- Technical Support Working Group in Hiroshima High-Precision Radiotherapy Cancer Center, Hiroshima, Japan
- Division of Radiology, Hiroshima Red Cross Hospital & Atomic-bomb Survivors Hospital, Hiroshima, Japan
| | - Naoki Tohyama
- Medical Physics Working Group in Japan Clinical Oncology Group - Radiation Therapy Study Group, Tokyo, Japan
- Division of Medical Physics, Tokyo Bay Makuhari Clinic for Advanced Imaging, Cancer Screening, and High-Precision Radiotherapy, Chiba, Japan
| | - Teiji Nishio
- Medical Physics Working Group in Japan Clinical Oncology Group - Radiation Therapy Study Group, Tokyo, Japan
- Medical Physics Laboratory, Division of Health Science, Graduate School of Medicine, Osaka University, Osaka, Japan
| | - Mitsuhiro Nakamura
- Medical Physics Working Group in Japan Clinical Oncology Group - Radiation Therapy Study Group, Tokyo, Japan
- Department of Radiation Oncology and Image-Applied Therapy, Kyoto University, Kyoto, Japan
- Department of Advanced Medical Physics, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Toshiyuki Minemura
- Medical Physics Working Group in Japan Clinical Oncology Group - Radiation Therapy Study Group, Tokyo, Japan
- Division of Medical Support and Partnership, Institute for Cancer Control, National Cancer Center, Tokyo, Japan
| | - Hiroyuki Okamoto
- Medical Physics Working Group in Japan Clinical Oncology Group - Radiation Therapy Study Group, Tokyo, Japan
- Radiation Safety and Quality Assurance Division, National Cancer Center Hospital, Tokyo, Japan
| | - Masayori Ishikawa
- Medical Physics Working Group in Japan Clinical Oncology Group - Radiation Therapy Study Group, Tokyo, Japan
- Faculty of Health Sciences, Hokkaido University, Hokkaido, Japan
| | - Masahiko Kurooka
- Medical Physics Working Group in Japan Clinical Oncology Group - Radiation Therapy Study Group, Tokyo, Japan
- Department of Radiation Therapy, Tokyo Medical University Hospital, Tokyo, Japan
| | - Hidetoshi Shimizu
- Medical Physics Working Group in Japan Clinical Oncology Group - Radiation Therapy Study Group, Tokyo, Japan
- Department of Radiation Oncology, Aichi Cancer Center Hospital, Aichi, Japan
| | - Kenji Hotta
- Medical Physics Working Group in Japan Clinical Oncology Group - Radiation Therapy Study Group, Tokyo, Japan
- Radiation Safety and Quality Assurance division, National Cancer Center Hospital East, Chiba, Japan
- Particle Therapy Division, Exploratory Oncology Research and Clinical Trial Center, National Cancer Center, Chiba, Japan
| | - Masahide Saito
- Medical Physics Working Group in Japan Clinical Oncology Group - Radiation Therapy Study Group, Tokyo, Japan
- Department of Radiology, University of Yamanashi, Yamanashi, Japan
| | - Masahiro Nakano
- Medical Physics Working Group in Japan Clinical Oncology Group - Radiation Therapy Study Group, Tokyo, Japan
- Department of Radiation Oncology, Kitasato University School of Medicine, Kanagawa, Japan
| | - Masato Tsuneda
- Medical Physics Working Group in Japan Clinical Oncology Group - Radiation Therapy Study Group, Tokyo, Japan
- Graduate School of Medicine, Chiba University, Chiba, Japan
| | - Yasushi Nagata
- Hiroshima High-Precision Radiotherapy Cancer Center, Hiroshima, Japan
- Department of Radiation Oncology, Graduate School of Biomedical & Health Sciences, Hiroshima University, Hiroshima, Japan
- Technical Support Working Group in Hiroshima High-Precision Radiotherapy Cancer Center, Hiroshima, Japan
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Wesolowska P, Slusarczyk-Kacprzyk W, Fillmann M, Kazantsev P, Bulski W. Results of the IAEA supported national end-to-end audit of the IMRT technique in Poland. Phys Med 2023; 116:103168. [PMID: 37984129 DOI: 10.1016/j.ejmp.2023.103168] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/16/2023] [Revised: 10/09/2023] [Accepted: 11/05/2023] [Indexed: 11/22/2023] Open
Abstract
The dosimetry audit services were established in Poland in 1991, since then new audits have been introduced. The recently developed IAEA audit methodology for IMRT H&N treatments was tested nationally. Anthropomorphic SHANE phantom (CIRS) was used to perform measurements in 8 hospitals which voluntarily participated in the study. Each participant had to complete successfully pre-visit activities to take part in an onsite visit. During the visit, auditors together with the local staff, did a CT scan using local protocol, recalculated the plan and verified all the relevant parameters and performed measurements with an ionization chamber and films in SHANE. The adoption of IAEA methodology to the national circumstances was done with no major issues. Participants plans were verified and the results of ionization chamber were all within the 5 % tolerance limit for PTV (max 4,5%) and 7 % for OAR (max 5,3%). Film global gamma results (3 %, 3 mm, 90 % acceptance limit) were within 91,5-99,7% range. The IAEA established acceptance criteria which were achievable for most tests except for CTtoRED conversion curve. The locally performed study allowed establishing new limits. The audit gave interesting results and showed that the procedure is very thorough and capable to identify issues related with suboptimal treatment preparation and delivery. The new limits for CTtoRED conversion curve were adopted for national study. Such an audit gives an opportunity to verify the quality of locally implemented procedures and should be available for Polish hospitals on a daily basis.
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Affiliation(s)
- Paulina Wesolowska
- Department of Medical Physics, Maria Sklodowska-Curie National Research Institute of Oncology, Warsaw, Poland.
| | | | - Marta Fillmann
- Department of Medical Physics, Maria Sklodowska-Curie National Research Institute of Oncology, Warsaw, Poland
| | - Pavel Kazantsev
- Dosimetry Laboratory, Dosimetry and Medical Radiation Physics Section, Division of Human Health, International Atomic Energy Agency, Vienna, Austria
| | - Wojciech Bulski
- Department of Medical Physics, Maria Sklodowska-Curie National Research Institute of Oncology, Warsaw, Poland
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Li C, Zhou L, Deng J, Wu H, Wang R, Wang F, Yao K, Chen C, Niu T, Zhang Y. A generalizable new figure of merit for dose optimization in dual energy cone beam CT scanning protocols. Phys Med Biol 2023; 68:185021. [PMID: 37619587 DOI: 10.1088/1361-6560/acf3cd] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2023] [Accepted: 08/24/2023] [Indexed: 08/26/2023]
Abstract
Objective. This study proposes and evaluates a new figure of merit (FOMn) for dose optimization of Dual-energy cone-beam CT (DE-CBCT) scanning protocols based on size-dependent modeling of radiation dose and multi-scale image quality.Approach. FOMn was defined using Z-score normalization and was proportional to the dose efficiency providing better multi-scale image quality, including comprehensive contrast-to-noise ratio (CCNR) and electron density (CED) for CatPhan604 inserts of various materials. Acrylic annuluses were combined with CatPhan604 to create four phantom sizes (diameters of the long axis are 200 mm, 270 mm, 350 mm, and 380 mm, respectively). DE-CBCT was decomposed using image-domain iterative methods based on Varian kV-CBCT images acquired using 25 protocols (100 kVp and 140 kVp combined with 5 tube currents).Main results. The accuracy of CED was approximately 1% for all protocols, but degraded monotonically with the increased phantom sizes. Combinations of lower voltage + higher current and higher voltage + lower current were optimal protocols balancing CCNR and dose. The most dose-efficient protocols for CED and CCNR were inconsistent, underlining the necessity of including multi-scale image quality in the evaluation and optimization of DE-CBCT. Pediatric and adult anthropomorphic phantom tests confirmed dose-efficiency of FOMn-recommended protocols.Significance. FOMn is a comprehensive metric that collectively evaluates radiation dose and multi-scale image quality for DE-CBCT. The models and data can also serve as lookup tables, suggesting personalized dose-efficient protocols for specific clinical imaging purposes.
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Affiliation(s)
- Chenguang Li
- Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education/Beijing), Department of Radiation Oncology, Peking University Cancer Hospital & Institute, Beijing, 100142, People's Republic of China
- Department of Physics and Astronomy, University of British Columbia, 325-6224 Agricultural Road, Vancouver, BC V6T1Z1, Canada
| | - Li Zhou
- Department of Radiotherapy Physics & Technology, West China Hospital, Sichuan University, No. 37 Guo Xue Xiang, Chengdu, 610041, People's Republic of China
| | - Jun Deng
- Department of Therapeutic Radiology, Yale University School of Medicine, New Haven, CT 06510, United States of America
| | - Hao Wu
- Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education/Beijing), Department of Radiation Oncology, Peking University Cancer Hospital & Institute, Beijing, 100142, People's Republic of China
| | - Ruoxi Wang
- Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education/Beijing), Department of Radiation Oncology, Peking University Cancer Hospital & Institute, Beijing, 100142, People's Republic of China
| | - Fei Wang
- Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education/Beijing), Department of Radiation Oncology, Peking University Cancer Hospital & Institute, Beijing, 100142, People's Republic of China
| | - Kaining Yao
- Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education/Beijing), Department of Radiation Oncology, Peking University Cancer Hospital & Institute, Beijing, 100142, People's Republic of China
| | - Chen Chen
- School of Electronics, Peking University, Beijing, 100871, People's Republic of China
| | - Tianye Niu
- Shenzhen Bay Laboratory, Shenzhen, 518118, People's Republic of China
| | - Yibao Zhang
- Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education/Beijing), Department of Radiation Oncology, Peking University Cancer Hospital & Institute, Beijing, 100142, People's Republic of China
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Diagnosis of Osteoporosis by Quantifying Volumetric Bone Mineral Density of Lumbar Vertebrae Using Abdominal CT Images and Two-Compartment Model. Healthcare (Basel) 2023; 11:healthcare11040556. [PMID: 36833090 PMCID: PMC9957021 DOI: 10.3390/healthcare11040556] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2022] [Revised: 02/04/2023] [Accepted: 02/10/2023] [Indexed: 02/17/2023] Open
Abstract
With the aging population, osteoporosis has become an important public health issue. The purpose of this study was to establish a two-compartment model (TCM) to quantify the volumetric bone mineral density (vBMD) of the lumbar spine using abdominal computed tomography (CT) images. The TCM approach uses water as the bone marrow equivalent and K2HPO4 solution as the cortical bone equivalent. A phantom study was performed to evaluate the accuracy of vBMD estimation at 100 kVp and 120 kVp. The data of 180 patients who underwent abdominal CT imaging and dual-energy X-ray absorptiometry (DXA) within one month were retrospectively collected. vBMD of L1-L4 vertebrae were calculated, and the receiver-operating characteristic curve analysis was performed to establish the diagnostic thresholds for osteoporosis and osteopenia in terms of vBMD. The average difference between the measured vBMD following TCM and the theoretical vBMD of the self-made phantom was 0.2%, and the maximum difference was 0.5%. vBMD of lumbar vertebrae obtained from TCM and aBMD obtained by DXA had a significant positive correlation (r = 0.655 to 0.723). The average diagnostic threshold for osteoporosis was 0.116 g/cm3. The sensitivity, specificity, and accuracy were 95.7%, 75.6.5%, and 80.0%, respectively. The average diagnostic threshold for osteopenia was 0.126 g/cm3. The sensitivity, specificity, and accuracy were 81.3%, 82.5%, and 82.7%, respectively. The aforementioned threshold values were used to perform the diagnostics on a test cohort, and the performance was equivalent to that in the experimental cohort. From the perspective of preventive medicine, opportunistic screening of bone mineral density using abdominal CT images and the TCM approach can facilitate early detection of osteoporosis and osteopenia and, with in-time treatment, slow down their progression.
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Tsunemine S, Ozawa S, Nakao M, Miura H, Saito A, Kawahara D, Onishi Y, Onishi T, Okawa F, Terai A, Hashiguchi T, Yamasaki H, Maruta T, Murakami Y, Nagata Y. Tolerance levels of mass density for adaptive helical tomotherapy using MVCT. JOURNAL OF RADIATION RESEARCH 2022; 64:195-201. [PMCID: PMC9855312 DOI: 10.1093/jrr/rrac071] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/12/2022] [Revised: 12/30/2022] [Indexed: 01/02/2024]
Abstract
Daily dose distributions for adaptive radiotherapy (ART) using helical tomotherapy (HT) are calculated using megavoltage computed tomography (MVCT). Generally, the MVCT number is converted to mass density (MD) using an MD calibration table (MVCT-MD table). The aims of this study are to calculate the tolerance levels of the MD for ART and to evaluate the tolerance levels using clinical patient plans. These tolerance levels of MD were calculated based on the tissue maximum ratio (TMR) of 6MV flattening-filter-free (FFF) beam of HT and the effective tissue thickness data from an International Commission on Radiological Protection 110 phantom data for lung, adipose/muscle and cartilage/spongy-bone. These tolerance levels were determined by considering both the MD causing a dose error of 2% and the variation in MVCT numbers. Subsequently, the stability of the MD values was estimated with the standard deviations (SD) in the MVCT number over 6 months. The dose distribution for clinical patient plans was calculated using the MVCT-MD table with added tolerance levels. These tolerance levels were determined as MD differences causing a dose error of 2%, and were ± 0.049 g/cm3, ± 0.030 g/cm3 and ± 0.049 g/cm3 for lung, adipose/muscle and cartilage/spongy-bone, respectively. The calculated dose distribution errors using the MVCT-MD table added tolerance levels were within 2%. We proposed these tolerance levels in MD for the quality control of the MVCT-MD table.
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Affiliation(s)
- Shogo Tsunemine
- Program of Medicine Doctoral Course, Graduate School of Biomedical and Health Sciences, Hiroshima University, 1-2-3, Kasumi, Minamiku, Hiroshima, 734-8553 Japan
- Department of Radiology, National Hospital Organization Himeji Medical Center, 68, Hommachi, Himeji, Hyogo, 670-8520, Japan
| | - Shuichi Ozawa
- Department of Radiology, National Hospital Organization Himeji Medical Center, 68, Hommachi, Himeji, Hyogo, 670-8520, Japan
- Hiroshima High-Precision Radiotherapy Cancer Center, Hiroshima, 3-2-2, Futabanosato, Higashiku, Hiroshima, 732-0057, Japan
- Department of Radiation Oncology, Graduate School of Biomedical and Health Sciences, Hiroshima University, 1-2-3, Kasumi, Minamiku, Hiroshima, 734-8553 Japan
| | - Minoru Nakao
- Hiroshima High-Precision Radiotherapy Cancer Center, Hiroshima, 3-2-2, Futabanosato, Higashiku, Hiroshima, 732-0057, Japan
- Department of Radiation Oncology, Graduate School of Biomedical and Health Sciences, Hiroshima University, 1-2-3, Kasumi, Minamiku, Hiroshima, 734-8553 Japan
| | - Hideharu Miura
- Hiroshima High-Precision Radiotherapy Cancer Center, Hiroshima, 3-2-2, Futabanosato, Higashiku, Hiroshima, 732-0057, Japan
- Department of Radiation Oncology, Graduate School of Biomedical and Health Sciences, Hiroshima University, 1-2-3, Kasumi, Minamiku, Hiroshima, 734-8553 Japan
| | - Akito Saito
- Department of Radiation Oncology, Graduate School of Biomedical and Health Sciences, Hiroshima University, 1-2-3, Kasumi, Minamiku, Hiroshima, 734-8553 Japan
| | - Daisuke Kawahara
- Department of Radiation Oncology, Graduate School of Biomedical and Health Sciences, Hiroshima University, 1-2-3, Kasumi, Minamiku, Hiroshima, 734-8553 Japan
| | - Yasuhiko Onishi
- Department of Radiology, National Hospital Organization Himeji Medical Center, 68, Hommachi, Himeji, Hyogo, 670-8520, Japan
| | - Takashi Onishi
- Department of Radiology, National Hospital Organization Himeji Medical Center, 68, Hommachi, Himeji, Hyogo, 670-8520, Japan
| | - Fumito Okawa
- Department of Radiology, National Hospital Organization Himeji Medical Center, 68, Hommachi, Himeji, Hyogo, 670-8520, Japan
| | - Atsushi Terai
- Department of Radiology, National Hospital Organization Himeji Medical Center, 68, Hommachi, Himeji, Hyogo, 670-8520, Japan
| | - Taiki Hashiguchi
- Department of Radiology, National Hospital Organization Himeji Medical Center, 68, Hommachi, Himeji, Hyogo, 670-8520, Japan
| | - Hidetoshi Yamasaki
- Department of Radiology, National Hospital Organization Himeji Medical Center, 68, Hommachi, Himeji, Hyogo, 670-8520, Japan
| | - Tsutomu Maruta
- Department of Therapeutic Radiology, National Hospital Organization Himeji Medical Center, 68, Hommachi, Himeji, Hyogo, 670-8520, Japan
| | - Yuji Murakami
- Hiroshima High-Precision Radiotherapy Cancer Center, Hiroshima, 3-2-2, Futabanosato, Higashiku, Hiroshima, 732-0057, Japan
- Department of Radiation Oncology, Graduate School of Biomedical and Health Sciences, Hiroshima University, 1-2-3, Kasumi, Minamiku, Hiroshima, 734-8553 Japan
| | - Yasushi Nagata
- Hiroshima High-Precision Radiotherapy Cancer Center, Hiroshima, 3-2-2, Futabanosato, Higashiku, Hiroshima, 732-0057, Japan
- Department of Radiation Oncology, Graduate School of Biomedical and Health Sciences, Hiroshima University, 1-2-3, Kasumi, Minamiku, Hiroshima, 734-8553 Japan
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Tsunemine S, Ozawa S, Nakao M, Miura H, Saito A, Kawahara D, Onishi Y, Onishi T, Hashiguchi T, Matsumoto Y, Maruta T, Murakami Y, Nagata Y. Influence of different air CT numbers for IVDT on the dose distribution in TomoTherapy MVCT. J Appl Clin Med Phys 2022; 24:e13835. [PMID: 36316723 PMCID: PMC9924119 DOI: 10.1002/acm2.13835] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2022] [Revised: 08/16/2022] [Accepted: 10/10/2022] [Indexed: 11/07/2022] Open
Abstract
This study aims to evaluate the effect of different air computed tomography (CT) numbers of the image value density table (IVDT) on the retrospective dose calculation of head-and-neck (HN) radiotherapy using TomoTherapy megavoltage CT (MVCT) images. The CT numbers of the inside and outside air and each tissue-equivalent plug of the "Cheese" phantom were obtained from TomoTherapy MVCT. Two IVDTs with different air CT numbers were created and applied to MVCT images of the HN anthropomorphic phantom and recalculated by Planned Adaptive to verify dose distribution. We defined the recalculation dose with MVCT images using both inside and outside air of the IVDT as IVDT MVCT inair ${\mathrm{IVDT}}_{\mathrm{MVCT}}^{\mathrm{inair}}$ and IVDT MVCT outair ${\mathrm{IVDT}}_{\mathrm{MVCT}}^{\mathrm{outair}}$ , respectively. Treatment planning doses calculated on kVCT images were compared with those calculated on MVCT images using two different IVDT tables, namely, IVDT MVCT inair ${\mathrm{IVDT}}_{\mathrm{MVCT}}^{\mathrm{inair}}$ and IVDT MVCT outair ${\mathrm{IVDT}}_{\mathrm{MVCT}}^{\mathrm{outair}}$ . The difference between average MVCT numbers ±1 standard deviation on inside and outside air of the calibration phantom was 65 ± 36 HU. This difference in MVCT number of air exceeded the recommendation lung tolerance for dose calculation error of 2%. The dose differences between the planning target volume (PTV): D98% , D50% , D2% and the organ at risk (OAR): Dmax , Dmean recalculated by IVDT MVCT inair ${\mathrm{IVDT}}_{\mathrm{MVCT}}^{\mathrm{inair}}$ and IVDT MVCT outair ${\mathrm{IVDT}}_{\mathrm{MVCT}}^{\mathrm{outair}}$ using MVCT images were a maximum of 0.7% and 1.2%, respectively. Recalculated doses to the PTV and OAR with MVCT showed that IVDT MVCT outair ${\mathrm{IVDT}}_{\mathrm{MVCT}}^{\mathrm{outair}}$ was 0.5%-0.7% closer to the kVCT treatment planning dose than IVDT MVCT inair ${\mathrm{IVDT}}_{\mathrm{MVCT}}^{\mathrm{inair}}$ . This study showed that IVDT MVCT outair ${\mathrm{IVDT}}_{\mathrm{MVCT}}^{\mathrm{outair}}$ was more accurate than IVDT MVCT inair ${\mathrm{IVDT}}_{\mathrm{MVCT}}^{\mathrm{inair}}$ in recalculating the dose HN cases of MVCT using TomoTherapy.
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Affiliation(s)
- Shogo Tsunemine
- Program of Medicine Doctoral CourseGraduate School of Biomedical and Health Sciences, Hiroshima UniversityHiroshimaJapan,Radiation and Proton Therapy CenterShizuoka Cancer CenterShizuokaJapan,Department of RadiologyNational Hospital Organization Himeji Medical CenterHimejiJapan
| | - Shuichi Ozawa
- Department of Therapeutic RadiologyNational Hospital Organization Himeji Medical CenterHimejiJapan,Hiroshima High‐Precision Radiotherapy Cancer CenterHiroshimaJapan,Department of Radiation OncologyGraduate School of Biomedical and Health SciencesHiroshima UniversityHiroshimaJapan
| | - Minoru Nakao
- Hiroshima High‐Precision Radiotherapy Cancer CenterHiroshimaJapan,Department of Radiation OncologyGraduate School of Biomedical and Health SciencesHiroshima UniversityHiroshimaJapan
| | - Hideharu Miura
- Hiroshima High‐Precision Radiotherapy Cancer CenterHiroshimaJapan,Department of Radiation OncologyGraduate School of Biomedical and Health SciencesHiroshima UniversityHiroshimaJapan
| | - Akito Saito
- Department of Radiation OncologyGraduate School of Biomedical and Health SciencesHiroshima UniversityHiroshimaJapan
| | - Daisuke Kawahara
- Department of Radiation OncologyGraduate School of Biomedical and Health SciencesHiroshima UniversityHiroshimaJapan
| | - Yasuhiko Onishi
- Department of RadiologyNational Hospital Organization Himeji Medical CenterHimejiJapan
| | - Takashi Onishi
- Department of RadiologyNational Hospital Organization Himeji Medical CenterHimejiJapan
| | - Taiki Hashiguchi
- Department of RadiologyNational Hospital Organization Himeji Medical CenterHimejiJapan
| | - Yoshihisa Matsumoto
- Department of RadiologyNational Hospital Organization Himeji Medical CenterHimejiJapan
| | - Tsutomu Maruta
- Department of Therapeutic RadiologyNational Hospital Organization Himeji Medical CenterHimejiJapan
| | - Yuji Murakami
- Hiroshima High‐Precision Radiotherapy Cancer CenterHiroshimaJapan,Department of Radiation OncologyGraduate School of Biomedical and Health SciencesHiroshima UniversityHiroshimaJapan
| | - Yasushi Nagata
- Hiroshima High‐Precision Radiotherapy Cancer CenterHiroshimaJapan,Department of Radiation OncologyGraduate School of Biomedical and Health SciencesHiroshima UniversityHiroshimaJapan
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7
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Effect of X-ray beam energy and image reconstruction technique on computed tomography numbers of various tissue equivalent materials. Radiography (Lond) 2021; 27:95-100. [DOI: 10.1016/j.radi.2020.06.017] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2020] [Revised: 06/08/2020] [Accepted: 06/19/2020] [Indexed: 11/23/2022]
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8
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Nierer L, Walter F, Niyazi M, Shpani R, Landry G, Marschner S, von Bestenbostel R, Dinkel D, Essenbach G, Reiner M, Belka C, Corradini S. Radiotherapy in oncological emergencies: fast-track treatment planning. Radiat Oncol 2020; 15:215. [PMID: 32912293 PMCID: PMC7488151 DOI: 10.1186/s13014-020-01657-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Accepted: 08/31/2020] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND AND PURPOSE To report on our clinical experience with a newly implemented workflow for radiotherapy (RT) emergency treatments, which allows for a fast treatment application outside the regular working-hours, and its clinical applicability. METHODS Treatment planning of 18 emergency RT patients was carried out using diagnostic computed tomography (CT) without a dedicated RT simulation CT. The cone-beam CT (CBCT) deviations of the first RT treatment were analyzed regarding setup accuracy. Furthermore, feasibility of the "fast-track" workflow was evaluated with respect to dose deviations caused by different Hounsfield unit (HU) to relative electron density (rED) calibrations and RT treatment couch surface shapes via 3D gamma index analysis of exemplary treatment plans. The dosimetric uncertainty introduced by different CT calibrations was quantified. RESULTS Mean patient setup vs. CBCT isocenter deviations were (0.49 ± 0.44) cm (x), (2.68 ± 1.63) cm (y) and (1.80 ± 1.06) cm (z) for lateral, longitudinal and vertical directions, respectively. Three out of four dose comparisons between the emergency RT plan calculated on the diagnostic CT and the same plan calculated on the treatment planning CT showed clinically acceptable gamma passing rates, when correcting for surface artifacts. The maximum difference of rED was 0.054, while most parts of the CT calibration curves coincided well. CONCLUSION In an emergency RT setting, the use of diagnostic CT data for treatment planning might be time-saving and was shown to be suitable for many cases, considering reproducibility of patient setup, accuracy of initial patient setup and accuracy of dose-calculation.
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Affiliation(s)
- Lukas Nierer
- Department of Radiation Oncology, University Hospital, LMU Munich, Marchioninistr. 15, 81377 Munich, Germany
| | - Franziska Walter
- Department of Radiation Oncology, University Hospital, LMU Munich, Marchioninistr. 15, 81377 Munich, Germany
| | - Maximilian Niyazi
- Department of Radiation Oncology, University Hospital, LMU Munich, Marchioninistr. 15, 81377 Munich, Germany
| | - Roel Shpani
- Department of Radiation Oncology, University Hospital, LMU Munich, Marchioninistr. 15, 81377 Munich, Germany
| | - Guillaume Landry
- Department of Radiation Oncology, University Hospital, LMU Munich, Marchioninistr. 15, 81377 Munich, Germany
| | - Sebastian Marschner
- Department of Radiation Oncology, University Hospital, LMU Munich, Marchioninistr. 15, 81377 Munich, Germany
| | - Rieke von Bestenbostel
- Department of Radiation Oncology, University Hospital, LMU Munich, Marchioninistr. 15, 81377 Munich, Germany
| | - Dominika Dinkel
- Department of Radiation Oncology, University Hospital, LMU Munich, Marchioninistr. 15, 81377 Munich, Germany
| | - Gabriela Essenbach
- Department of Radiation Oncology, University Hospital, LMU Munich, Marchioninistr. 15, 81377 Munich, Germany
| | - Michael Reiner
- Department of Radiation Oncology, University Hospital, LMU Munich, Marchioninistr. 15, 81377 Munich, Germany
| | - Claus Belka
- Department of Radiation Oncology, University Hospital, LMU Munich, Marchioninistr. 15, 81377 Munich, Germany
| | - Stefanie Corradini
- Department of Radiation Oncology, University Hospital, LMU Munich, Marchioninistr. 15, 81377 Munich, Germany
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9
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Jacobsen MC, Thrower SL. Multi-energy computed tomography and material quantification: Current barriers and opportunities for advancement. Med Phys 2020; 47:3752-3771. [PMID: 32453879 PMCID: PMC8495770 DOI: 10.1002/mp.14241] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2019] [Revised: 04/20/2020] [Accepted: 05/07/2020] [Indexed: 12/21/2022] Open
Abstract
Computed tomography (CT) technology has rapidly evolved since its introduction in the 1970s. It is a highly important diagnostic tool for clinicians as demonstrated by the significant increase in utilization over several decades. However, much of the effort to develop and advance CT applications has been focused on improving visual sensitivity and reducing radiation dose. In comparison to these areas, improvements in quantitative CT have lagged behind. While this could be a consequence of the technological limitations of conventional CT, advanced dual-energy CT (DECT) and photon-counting detector CT (PCD-CT) offer new opportunities for quantitation. Routine use of DECT is becoming more widely available and PCD-CT is rapidly developing. This review covers efforts to address an unmet need for improved quantitative imaging to better characterize disease, identify biomarkers, and evaluate therapeutic response, with an emphasis on multi-energy CT applications. The review will primarily discuss applications that have utilized quantitative metrics using both conventional and DECT, such as bone mineral density measurement, evaluation of renal lesions, and diagnosis of fatty liver disease. Other topics that will be discussed include efforts to improve quantitative CT volumetry and radiomics. Finally, we will address the use of quantitative CT to enhance image-guided techniques for surgery, radiotherapy and interventions and provide unique opportunities for development of new contrast agents.
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Affiliation(s)
- Megan C. Jacobsen
- Department of Imaging Physics, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Sara L. Thrower
- Department of Imaging Physics, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
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10
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Nakao M, Ozawa S, Miura H, Yamada K, Habara K, Hayata M, Kusaba H, Kawahara D, Miki K, Nakashima T, Ochi Y, Tsuda S, Seido M, Morimoto Y, Kawakubo A, Nozaki H, Nagata Y. Development of a CT number calibration audit phantom in photon radiation therapy: A pilot study. Med Phys 2020; 47:1509-1522. [PMID: 32026482 PMCID: PMC7216906 DOI: 10.1002/mp.14077] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2019] [Revised: 01/30/2020] [Accepted: 01/31/2020] [Indexed: 01/24/2023] Open
Abstract
PURPOSE In photon radiation therapy, computed tomography (CT) numbers are converted into values for mass density (MD) or relative electron density to water (RED). CT-MD or CT-RED calibration tables are relevant for human body dose calculation in an inhomogeneous medium. CT-MD or CT-RED calibration tables are influenced by patient imaging (CT scanner manufacturer, scanning parameters, and patient size), the calibration process (tissue-equivalent phantom manufacturer, and selection of tissue-equivalent material), differences between tissue-equivalent materials and standard tissues, and the dose calculation algorithm applied; however, a CT number calibration audit has not been established. The purposes of this study were to develop a postal audit phantom, and to establish a CT number calibration audit process. METHODS A conventional stoichiometric calibration conducts a least square fit of the relationships between the MD, material weight, and measured CT number, using two parameters. In this study, a new stoichiometric CT number calibration scheme has been empirically established, using three parameters to harmonize the calculated CT number with the measured CT number for air and lung tissue. In addition, the suitable material set and the minimal number of materials required for stoichiometric CT number calibration were determined. The MDs and elemental weights from the International Commission on Radiological Protection Publication 110 were used as standard tissue data, to generate the CT-MD and CT-RED calibration tables. A small-sized, CT number calibration phantom was developed for a postal audit, and stoichiometric CT number calibration with the phantom was compared to the CT number calibration tables registered in the radiotherapy treatment planning systems (RTPSs) associated with five radiotherapy institutions. RESULTS When a least square fit was performed for the stoichiometric CT number calibration with the three parameters, the calculated CT number showed better agreement with the measured CT number. We established stoichiometric CT number calibration using only two materials because the accuracy of the process was determined not by the number of used materials but by the number of elements contained. The stoichiometric CT number calibration was comparable to the tissue-substitute calibration, with a dose difference less than 1%. An outline of the CT number calibration audit was demonstrated through a multi-institutional study. CONCLUSIONS We established a new stoichiometric CT number calibration method for validating the CT number calibration tables registered in RTPSs. We also developed a CT number calibration phantom for a postal audit, which was verified by the performances of multiple CT scanners located at several institutions. The new stoichiometric CT number calibration has the advantages of being performed using only two materials, and decreasing the difference between the calculated and measured CT numbers for air and lung tissue. In the future, a postal CT number calibration audit might be achievable using a smaller phantom.
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Affiliation(s)
- Minoru Nakao
- Hiroshima High‐Precision Radiotherapy Cancer Center3‐2‐2, Futabanosato, Higashi‐kuHiroshima732‐0057Japan
- Department of Radiation OncologyGraduate School of Biomedical & Health SciencesHiroshima University1‐2‐3 Kasumi, Minami‐kuHiroshima734‐8551Japan
| | - Shuichi Ozawa
- Hiroshima High‐Precision Radiotherapy Cancer Center3‐2‐2, Futabanosato, Higashi‐kuHiroshima732‐0057Japan
- Department of Radiation OncologyGraduate School of Biomedical & Health SciencesHiroshima University1‐2‐3 Kasumi, Minami‐kuHiroshima734‐8551Japan
| | - Hideharu Miura
- Hiroshima High‐Precision Radiotherapy Cancer Center3‐2‐2, Futabanosato, Higashi‐kuHiroshima732‐0057Japan
- Department of Radiation OncologyGraduate School of Biomedical & Health SciencesHiroshima University1‐2‐3 Kasumi, Minami‐kuHiroshima734‐8551Japan
| | - Kiyoshi Yamada
- Hiroshima High‐Precision Radiotherapy Cancer Center3‐2‐2, Futabanosato, Higashi‐kuHiroshima732‐0057Japan
| | - Kosaku Habara
- Hiroshima High‐Precision Radiotherapy Cancer Center3‐2‐2, Futabanosato, Higashi‐kuHiroshima732‐0057Japan
| | - Masahiro Hayata
- Hiroshima High‐Precision Radiotherapy Cancer Center3‐2‐2, Futabanosato, Higashi‐kuHiroshima732‐0057Japan
| | - Hayate Kusaba
- Hiroshima High‐Precision Radiotherapy Cancer Center3‐2‐2, Futabanosato, Higashi‐kuHiroshima732‐0057Japan
| | - Daisuke Kawahara
- Department of Radiation OncologyGraduate School of Biomedical & Health SciencesHiroshima University1‐2‐3 Kasumi, Minami‐kuHiroshima734‐8551Japan
| | - Kentaro Miki
- Department of Radiation OncologyHiroshima University Hospital1‐2‐3 Kasumi, Minami‐kuHiroshima734‐8551Japan
| | - Takeo Nakashima
- Radiation Therapy SectionDepartment of Clinical SupportHiroshima University Hospital1‐2‐3 Kasumi, Minami‐kuHiroshima734‐8551Japan
| | - Yusuke Ochi
- Radiation Therapy SectionDepartment of Clinical SupportHiroshima University Hospital1‐2‐3 Kasumi, Minami‐kuHiroshima734‐8551Japan
| | - Shintaro Tsuda
- Radiation Therapy SectionDepartment of Clinical SupportHiroshima University Hospital1‐2‐3 Kasumi, Minami‐kuHiroshima734‐8551Japan
| | - Mineaki Seido
- Department of RadiologyHiroshima Prefectural Hospital1‐5‐54, Ujinakanda, Minami‐kuHiroshima734‐8530Japan
| | - Yoshiharu Morimoto
- Department of RadiologyHiroshima Prefectural Hospital1‐5‐54, Ujinakanda, Minami‐kuHiroshima734‐8530Japan
| | - Atsushi Kawakubo
- Radiation Therapy DepartmentHiroshima City Hiroshima Citizens Hospital7‐33, Motomachi, Naka‐kuHiroshima730‐8518Japan
| | - Hiroshige Nozaki
- Division of RadiologyHiroshima Red Cross Hospital & Atomic‐bomb Survivors Hospital1‐9‐6, Senda, Naka‐kuHiroshima730‐8619Japan
| | - Yasushi Nagata
- Hiroshima High‐Precision Radiotherapy Cancer Center3‐2‐2, Futabanosato, Higashi‐kuHiroshima732‐0057Japan
- Department of Radiation OncologyGraduate School of Biomedical & Health SciencesHiroshima University1‐2‐3 Kasumi, Minami‐kuHiroshima734‐8551Japan
- Department of Radiation OncologyHiroshima University Hospital1‐2‐3 Kasumi, Minami‐kuHiroshima734‐8551Japan
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Ohno Y. [15. The Quality Management of the Radiation Therapy]. Nihon Hoshasen Gijutsu Gakkai Zasshi 2020; 76:93-103. [PMID: 31956191 DOI: 10.6009/jjrt.2020_jsrt_76.1.93] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Affiliation(s)
- Yoshimi Ohno
- Department of Clinical Practice and Support, Hiroshima University Hospital
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12
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Abstract
PURPOSE The IAEA newly developed "end-to-end" audit methodology for on-site verification of IMRT dose delivery has been carried out in Portugal in 2018. The main goal was to evaluate the physical aspects of the head and neck (H&N) cancer IMRT treatments. This paper presents the national results. METHODS All institutions performing IMRT treatments in Portugal, 20 out of 24, have voluntarily participated in this audit. Following the adopted methodology, a Shoulder, Head and Neck End-to-End phantom (SHANE) - that mimics an H&N region, underwent all steps of an IMRT treatment, according to the local practices. The measurements using an ionization chamber placed inside the SHANE phantom at four reference locations (three in PTVs and one in the spinal cord) and an EBT3 film positioned in a coronal plane were compared with calculated doses. FilmQA Pro software was used for film analysis. RESULTS For ionization chamber measurements, the percent difference was within the specified tolerances of ±5% for PTVs and ±7% for the spinal cord in all participating institutions. Considering film analysis, gamma passing rates were on average 96.9%±2.9% for a criterion of 3%/3 mm, 20% threshold, all above the acceptance limit of 90%. CONCLUSIONS The national results of the H&N IMRT audit showed a compliance between the planned and the delivered doses within the specified tolerances, confirming no major reasons for concern. At the same time the audit identified factors that contributed to increased uncertainties in the IMRT dose delivery in some institutions resulting in recommendations for quality improvement.
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Nakao M, Ozawa S, Yogo K, Miura H, Yamada K, Hosono F, Hayata M, Miki K, Nakashima T, Ochi Y, Kawahara D, Morimoto Y, Yoshizaki T, Nozaki H, Habara K, Nagata Y. Tolerance levels of mass density for CT number calibration in photon radiation therapy. J Appl Clin Med Phys 2019; 20:45-52. [PMID: 31081175 PMCID: PMC6560312 DOI: 10.1002/acm2.12601] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2018] [Revised: 03/22/2019] [Accepted: 04/10/2019] [Indexed: 01/21/2023] Open
Abstract
Computed tomography (CT) data are required to calculate the dose distribution in a patient's body. Generally, there are two CT number calibration methods for commercial radiotherapy treatment planning system (RTPS), namely CT number-relative electron density calibration (CT-RED calibration) and CT number-mass density calibration (CT-MD calibration). In a previous study, the tolerance levels of CT-RED calibration were established for each tissue type. The tolerance levels were established when the relative dose error to local dose reached 2%. However, the tolerance levels of CT-MD calibration are not established yet. We established the tolerance levels of CT-MD calibration based on the tolerance levels of CT-RED calibration. In order to convert mass density (MD) to relative electron density (RED), the conversion factors were determined with adult reference computational phantom data available in the International Commission on Radiological Protection publication 110 (ICRP-110). In order to validate the practicability of the conversion factor, the relative dose error and the dose linearity were validated with multiple RTPSes and dose calculation algorithms for two groups, namely, CT-RED calibration and CT-MD calibration. The tolerance levels of CT-MD calibration were determined from the tolerance levels of CT-RED calibration with conversion factors. The converted RED from MD was compared with actual RED calculated from ICRP-110. The conversion error was within ±0.01 for most standard organs. It was assumed that the conversion error was sufficiently small. The relative dose error difference for two groups was less than 0.3% for each tissue type. Therefore, the tolerance levels for CT-MD calibration were determined from the tolerance levels of CT-RED calibration with the conversion factors. The MD tolerance levels for lung, adipose/muscle, and cartilage/spongy-bone corresponded to ±0.044, ±0.022, and ±0.045 g/cm3 , respectively. The tolerance levels were useful in terms of approving the CT-MD calibration table for clinical use.
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Affiliation(s)
- Minoru Nakao
- Hiroshima High‐Precision Radiotherapy Cancer CenterHiroshimaJapan
- Department of Radiation Oncology, Institute of Biomedical & Health ScienceHiroshima UniversityHiroshimaJapan
| | - Shuichi Ozawa
- Hiroshima High‐Precision Radiotherapy Cancer CenterHiroshimaJapan
- Department of Radiation Oncology, Institute of Biomedical & Health ScienceHiroshima UniversityHiroshimaJapan
| | - Katsunori Yogo
- Department of RadiologyNagoya University Graduate School of MedicineNagoyaJapan
| | - Hideharu Miura
- Hiroshima High‐Precision Radiotherapy Cancer CenterHiroshimaJapan
- Department of Radiation Oncology, Institute of Biomedical & Health ScienceHiroshima UniversityHiroshimaJapan
| | - Kiyoshi Yamada
- Hiroshima High‐Precision Radiotherapy Cancer CenterHiroshimaJapan
| | - Fumika Hosono
- Hiroshima High‐Precision Radiotherapy Cancer CenterHiroshimaJapan
| | - Masahiro Hayata
- Hiroshima High‐Precision Radiotherapy Cancer CenterHiroshimaJapan
| | - Kentaro Miki
- Department of Radiation Oncology, Institute of Biomedical & Health ScienceHiroshima UniversityHiroshimaJapan
| | - Takeo Nakashima
- Radiation Therapy Section, Department of Clinical SupportHiroshima University HospitalHiroshimaJapan
| | - Yusuke Ochi
- Radiation Therapy Section, Department of Clinical SupportHiroshima University HospitalHiroshimaJapan
| | - Daisuke Kawahara
- Radiation Therapy Section, Department of Clinical SupportHiroshima University HospitalHiroshimaJapan
| | | | - Toru Yoshizaki
- Radiation Therapy DepartmentHiroshima City Hiroshima Citizens HospitalHiroshimaJapan
| | - Hiroshige Nozaki
- Division of RadiologyHiroshima Red Cross Hospital & Atomic‐bomb Survivors HospitalHiroshimaJapan
| | - Kosaku Habara
- Division of RadiologyHiroshima Red Cross Hospital & Atomic‐bomb Survivors HospitalHiroshimaJapan
| | - Yasushi Nagata
- Hiroshima High‐Precision Radiotherapy Cancer CenterHiroshimaJapan
- Department of Radiation Oncology, Institute of Biomedical & Health ScienceHiroshima UniversityHiroshimaJapan
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