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Masuda T, Kiguchi M, Fujioka C, Oku T, Ishibashi T, Katsunuma Y, Yoshitake T, Abe S, Awai K. Comparison of pediatric lens scattered dose measurements between axial 40-mm and helical 160-mm detector width computed tomography scan modes. Pediatr Radiol 2024; 54:1197-1204. [PMID: 38769141 DOI: 10.1007/s00247-024-05947-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/31/2023] [Revised: 05/06/2024] [Accepted: 05/06/2024] [Indexed: 05/22/2024]
Abstract
BACKGROUND Reports comparing field lens doses between helical scans with a 40-mm detector width and axial scans with a 160-mm detector width using different computed tomography (CT) scanners are currently scarce. OBJECTIVE To compare scatter doses for lenses between a helical scan with a 40-mm detector width and an axial scan with a 160-mm detector width when using different CT scanners in the context of pediatric chest examinations. MATERIALS AND METHODS Two different CT machines were used: Revolution CT (GE Healthcare, Waukesha, WI) with a 256-row, 0.625-mm multidetector; and Aquilion ONE GENESIS Edition (Canon Medical Systems, Otawara, Japan) with a 320-row, 0.5-mm multidetector. Three pediatric anthropomorphic phantoms were used, with optically stimulated luminescence dosimeters (OSLDs) placed on the left and right lenses. The scatter dose values measured by the OSLDs were compared between a helical scan with a 40-mm detector width and an axial scan with a 160-mm detector width during pediatric chest CT examinations. RESULTS Median equivalent doses for the helical and axial scans were 0.12 and 0.12 mSv/mGy for the newborn, 0.17 and 0.16 mSv/mGy for the 1-year-old, and 0.18 and 0.15 mSv/mGy for the 5-year-old, respectively, when using the Revolution CT. With the Revolution CT, no significant differences were observed in the scatter doses between helical and axial scans in the newborn and 1-year-old phantoms. However, the lens scatter dose for the helical scan was approximately 20-35% higher than that for the axial scan in the 5-year-old phantom (P<0.01). The median equivalent doses of eye lenses for the helical and axial scans were 0.12 and 0.07 mSv/mGy for the newborn, 0.07 and 0.05 mSv/mGy for the 1-year-old, and 0.14 and 0.12 mSv/mGy for the 5-year-old, respectively, when using the Aquilion ONE. With the Aquilion ONE, lens scatter doses for the helical scan were approximately 70%, 40%, and 30% higher in the newborn, 1-year-old, and 5-year-old phantoms, respectively, than those for the axial scan (P<0.01). CONCLUSIONS When using the Aquilion ONE, lens scatter doses for the helical scan were significantly higher in all three phantoms than those for the axial scan. In contrast, when using the Revolution CT, the lens scatter dose for the helical scan was significantly higher in the 5-year-old phantom than that for the axial scan. These results suggest that although scattered doses may vary with respect to the CT scanner and body size, they are generally lower in the case of axial scans.
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Affiliation(s)
- Takanori Masuda
- Department of Radiological Technology, Faculty of Health Science and Technology, Kawasaki University of Medical Welfare, 288, Matsushima, Kurashiki, 701-0193, Okayama, Japan.
| | - Masao Kiguchi
- Department of Radiology, Hiroshima University, Hiroshima, Japan
| | - Chikako Fujioka
- Department of Radiology, Hiroshima University, Hiroshima, Japan
| | - Takayuki Oku
- Department of Radiological Technologist, Tsuchiya General Hospital, Hiroshima, Japan
| | - Toru Ishibashi
- Department of Radiological Technologist, Tsuchiya General Hospital, Hiroshima, Japan
| | - Yasushi Katsunuma
- Department of Radiological Technology, Tokai University Oiso Hospital, Kanagawa, Japan
| | | | - Shuji Abe
- Department of Radiological Technology, Osaka College of High Technology, Osaka, Japan
| | - Kazuo Awai
- Department of Diagnostic Radiology, Hiroshima University, Hiroshima, Japan
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Nagamoto K, Watanabe R, Kawachino T, Ohishi Y, Yamamoto A, Moritake T, Nihei SI, Kamochi M, Kunugita N. CONTRIBUTION OF ORGAN-BASED TUBE CURRENT MODULATION TO THE REDUCTION OF LENS EXPOSURE DOSE IN HEAD 4D CT IMAGING: A PHANTOM STUDY. RADIATION PROTECTION DOSIMETRY 2022; 198:1377-1386. [PMID: 36062449 DOI: 10.1093/rpd/ncac179] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2022] [Revised: 07/04/2022] [Accepted: 08/02/2022] [Indexed: 06/15/2023]
Abstract
The purpose of this study was to evaluate the effectiveness of organ effect modulation (OEM) in reducing the lens dose in 4D computed tomography (CT) of the head in volume-acquisition (NVA) mode. Six radiophotoluminescent dosemeters were placed on the head of a RANDO phantom. The doses absorbed by the organs and image noise change rate were determined. The lens doses without OEM (i.e. in the OEMoff case) were higher than those with the same target standard deviation and volume-computed tomography dose index (CTDIvol) as in the OEMoff case (p < 0.01). The image noise change rate was 11%. OEM reduced the lens dose during head 4D CT imaging in the NVA mode by 18%. Furthermore, the feasibility of lens dose reduction while ensuring sufficient image quality was confirmed under the condition in which OEM was employed with the same CTDIvol as in the OEMoff case.
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Affiliation(s)
- Keisuke Nagamoto
- Department of Radiology, Hospital of the University of Occupational and Environmental Health, Japan, 1-1 Iseigaoka, Yahatanishi-Ku, Kitakyushu, Fukuoka, Japan
| | - Ryo Watanabe
- Department of Radiology, Hospital of the University of Occupational and Environmental Health, Japan, 1-1 Iseigaoka, Yahatanishi-Ku, Kitakyushu, Fukuoka, Japan
| | - Tomonori Kawachino
- Department of Radiology, Hospital of the University of Occupational and Environmental Health, Japan, 1-1 Iseigaoka, Yahatanishi-Ku, Kitakyushu, Fukuoka, Japan
| | - Yoshitaka Ohishi
- Department of Radiology, Hospital of the University of Occupational and Environmental Health, Japan, 1-1 Iseigaoka, Yahatanishi-Ku, Kitakyushu, Fukuoka, Japan
| | - Aina Yamamoto
- Department of Radiology, Hospital of the University of Occupational and Environmental Health, Japan, 1-1 Iseigaoka, Yahatanishi-Ku, Kitakyushu, Fukuoka, Japan
| | - Takashi Moritake
- Department of Radiation Regulatory Research Group, National Institute of Radiological Sciences, Quantum Life and Medical Science Directorate, National Institute for Quantum and Radiological Science and Technology, 4-9-1 Anagawa, Inage-ku, Chiba, Japan
| | - Shun-Ichi Nihei
- Intensive Care Unit, Hospital of the University of Occupational and Environmental Health, Japan, 1-1 Iseigaoka, Yahatanishi-ku, Kitakyushu, Fukuoka, Japan
| | - Masayuki Kamochi
- Intensive Care Unit, Hospital of the University of Occupational and Environmental Health, Japan, 1-1 Iseigaoka, Yahatanishi-ku, Kitakyushu, Fukuoka, Japan
| | - Naoki Kunugita
- Department of Occupational and Community Health Nursing School of Health Sciences, University of Occupational and Environmental Health, Japan, 1-1 Iseigaoka, Yahatanishi-Ku, Kitakyushu, Fukuoka, Japan
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Young HM, Sun Park CK, Chau OW, Lee TY, Gaede S. Technical Note: Volumetric computed tomography for radiotherapy simulation and treatment planning. J Appl Clin Med Phys 2021; 22:295-302. [PMID: 34240548 PMCID: PMC8364284 DOI: 10.1002/acm2.13336] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2021] [Revised: 04/07/2021] [Accepted: 05/29/2021] [Indexed: 11/21/2022] Open
Abstract
Purpose For lung and liver tumors requiring radiotherapy, motion artifacts are common in 4D‐CT images due to the small axial field‐of‐view (aFOV) of conventional CT scanners. This may negatively impact contouring and dose calculation accuracy and could lead to a geographic miss during treatment. Recent advancements in volumetric CT (vCT) enable an aFOV up to 160 mm in a single rotation, which may reduce motion artifacts. However, the impact of large aFOV on CT number required for dose calculation needs to be evaluated before clinical implementation. The objective of this study was to determine the utility of a 256‐slice vCT scanner for 4D‐CT simulation by evaluating image quality and generating relative electron density (RED) curves. Methods Images were acquired on a 256‐slice GE Revolution CT scanner with 40 mm, 80 mm, 120 mm, 140 mm, and 160 mm aFOV. Image quality was assessed by evaluating CT number linearity, uniformity, noise, and low‐contrast resolution. The relationship between each quality metric and aFOV was assessed. Results CT number linearity, uniformity, noise, and low‐contrast resolution were within the expected range for each image set, except CT number in Teflon and Delrin, which were underestimated. Spearman correlation coefficient (ρ) showed that the CT number for Teflon (ρ = 1.0, p = 0.02), Delrin (ρ = 1.0, p = 0.02), and air (ρ = 1.0, p = 0.02) was significantly related to aFOV, while all other measurements were not. The measured deviations from expected values were not clinically significant. Conclusion These results suggest that vCT can be used for CT simulation for radiation treatment planning.
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Affiliation(s)
- Heather M Young
- Department of Medical Biophysics, University of Western Ontario, London, Canada.,London Regional Cancer Program, London, Canada.,Robarts Research Institute, University of Western Ontario, London, Canada
| | - Claire Keun Sun Park
- Department of Medical Biophysics, University of Western Ontario, London, Canada.,Robarts Research Institute, University of Western Ontario, London, Canada
| | - Oi-Wai Chau
- Department of Medical Biophysics, University of Western Ontario, London, Canada.,London Regional Cancer Program, London, Canada
| | - Ting-Yim Lee
- Department of Medical Biophysics, University of Western Ontario, London, Canada.,Robarts Research Institute, University of Western Ontario, London, Canada.,Lawson Health Research Institute, London, Canada
| | - Stewart Gaede
- Department of Medical Biophysics, University of Western Ontario, London, Canada.,London Regional Cancer Program, London, Canada.,Lawson Health Research Institute, London, Canada
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Sako K, Matsubara K, Matsumoto M. [An Evaluation of Radiation Dose for Wide Volume Scan during Chest CT]. Nihon Hoshasen Gijutsu Gakkai Zasshi 2021; 77:284-292. [PMID: 33746176 DOI: 10.6009/jjrt.2021_jsrt_77_3.284] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
PURPOSE A volume scan can cover a range of 160 mm with a single gantry rotation. It can be performed sequentially (a wide volume [WV] scan) to cover more than 160 mm, and volume Xact+ (Xact+) can be used when volume scan is done to extend the reconstruction area. The purpose of this study was to investigate the dose distribution and organ doses for a WV scan during chest CT. METHOD We arranged radiophotoluminescence glass dosimeters (RPLDs) linearly on the surface and inside of the phantom to evaluate the dose distribution along the z-axis. We also placed RPLDs at the lens, thyroid, and breast positions to evaluate organ doses. We performed WV and helical scans and WV scan using Xact+. RESULT The absorbed doses increased at the borders of the volume scans, and dose peaks were observed there. The organ doses for the WV scan outside the acquisition range were lower than those for the helical scan. The organ doses inside the acquisition range changed by the locations of borders. CONCLUSION The WV scan increases the absorbed doses at the overlapping scanned regions, which can be reduced by using Xact+.
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Affiliation(s)
- Kenji Sako
- Department of Radiological Technology, Kizawa Memorial Hospital
| | - Kosuke Matsubara
- Department of Quantum Medical Technology, Faculty of Health Sciences, Institute of Medical Pharmaceutical and Health Sciences, Kanazawa University
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Kobayashi M, Haba T, Suzuki S, Nishihara Y, Asada Y, Minami K. Evaluation of exposure dose in fetal computed tomography using organ-effective modulation. Phys Eng Sci Med 2020; 43:1195-1206. [PMID: 32926394 PMCID: PMC7749874 DOI: 10.1007/s13246-020-00921-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2020] [Accepted: 08/19/2020] [Indexed: 11/28/2022]
Abstract
Organ-effective modulation (OEM) is a computed tomography scanning technique that reduces the exposure dose to organs at risk. Ultrasonography is commonly used for prenatal imaging, but its reliability is reported to be limited. Radiography and computed tomography (CT) are reliable but pose risk of radiation exposure to the pregnant woman and her fetus. Although there are many reports on the exposure dose associated with fetal CT scans, no reports exist on OEM use in fetal CT scans. We measured the basic characteristics of organ-effective modulation (X-ray output modulation angle, maximum X-ray output modulation rate, total X-ray output modulation rate, and noise modulation) and used them in a Monte Carlo simulation to evaluate the effect of this technique on fetal CT scans in terms of image quality and exposure dose to the pregnant woman and fetus. Using ImPACT MC software, Monte Carlo simulations of OEMON and OEMOFF were run on 8 cases involving fetal CT scans. We confirmed that the organ-effective modulation X-ray output modulation angle was 160°; the X-ray output modulation rate increased with increasing tube current; and no modulation occurred at tube currents of 80 mA or below. Our findings suggest that OEM has only a minimal effect in reducing organ exposure in pregnant women; therefore, it should be used on the anterior side (OEMON,front) to reduce the exposure dose to the fetus.
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Affiliation(s)
- Masanao Kobayashi
- Graduate School of Medical Sciences, Fujita Health University, 1-98 Dengakugakubo, Kutsukake-cho, Toyoake, Aichi Japan
| | - Tomonobu Haba
- Graduate School of Medical Sciences, Fujita Health University, 1-98 Dengakugakubo, Kutsukake-cho, Toyoake, Aichi Japan
| | - Sayaka Suzuki
- Department of Radiology, Fujita Health University Hospital, 1-98 Dengakugakubo, Kutsukake-cho, Toyoake, Aichi Japan
| | - Yusei Nishihara
- Department of Radiology, Fujita Health University Hospital, 1-98 Dengakugakubo, Kutsukake-cho, Toyoake, Aichi Japan
| | - Yasuki Asada
- Graduate School of Medical Sciences, Fujita Health University, 1-98 Dengakugakubo, Kutsukake-cho, Toyoake, Aichi Japan
| | - Kazuyuki Minami
- Graduate School of Medical Sciences, Fujita Health University, 1-98 Dengakugakubo, Kutsukake-cho, Toyoake, Aichi Japan
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Conzelmann J, Schwarz FB, Hamm B, Scheel M, Jahnke P. Development of a method to create uniform phantoms for task-based assessment of CT image quality. J Appl Clin Med Phys 2020; 21:201-208. [PMID: 32721106 PMCID: PMC7497917 DOI: 10.1002/acm2.12974] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2019] [Revised: 06/13/2020] [Accepted: 06/18/2020] [Indexed: 12/22/2022] Open
Abstract
Purpose To develop a customized method to produce uniform phantoms for task‐based assessment of CT image quality. Methods Contrasts between polymethyl methacrylate (PMMA) and fructose solutions of different concentrations (240, 250, 260, 280, 290, 300, 310, 320, 330, and 340 mg/mL) were calculated. A phantom was produced by laser cutting PMMA slabs to the shape of a patient’s neck. An opening of 10 mm diameter was cut into the left parapharyngeal space. An angioplasty balloon was inserted and filled with the fructose solutions to simulate low‐contrast lesions. The phantom was scanned with six tube currents. Images were reconstructed with filtered back projection (FBP) and adaptive iterative dose reduction 3D (AIDR 3D). Calculated and measured contrasts were compared. The phantom was evaluated in a detectability experiment using images with 4 and 20 HU lesion contrast. Results Low‐contrast lesions of 4, 9, 11, 13, 18, 20, 24, 30, 35, and 37 HU contrast were simulated. Calculated and measured contrasts correlated excellently (r = 0.998; 95% confidence interval: 0.991 to 1). The mean ± SD difference was 0.41 ± 2.32 HU (P < 0.0001). Detection accuracy and reader confidence were 62.9 ± 18.2% and 1.58 ± 0.68 for 4 HU lesion contrast and 99.6 ± 1.3% and 4.27 ± 0.92 for 20 HU lesion contrast (P < 0.0001), confirming that the method produced lesions at the threshold of detectability. Conclusion A cost‐effective and flexible approach was developed to create uniform phantoms with low‐contrast signals. The method should facilitate access to customized phantoms for task‐based image quality assessment.
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Affiliation(s)
- Juliane Conzelmann
- Department of Radiology, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin Institute of Health, Berlin, Germany
| | - Felix Benjamin Schwarz
- Department of Radiology, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin Institute of Health, Berlin, Germany
| | - Bernd Hamm
- Department of Radiology, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin Institute of Health, Berlin, Germany
| | - Michael Scheel
- Department of Neuroradiology, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin Institute of Health, Berlin, Germany
| | - Paul Jahnke
- Department of Radiology, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin Institute of Health, Berlin, Germany
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