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Opitz M, Funke F, Darwiche K, Zensen S, Frings M, Salhöfer L, Haubold J, Forsting M, Doerr F, Bölükbas S, Oezkan F, Winantea J, Zellerhoff H, Karpf-Wissel R, Wienker J, Westhölter D, Welsner M, Taube C, Büscher E. First assessment of photon-counting CT for virtual bronchoscopic navigation. Eur Respir J 2025; 65:2402476. [PMID: 39915055 PMCID: PMC11965957 DOI: 10.1183/13993003.02476-2024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2024] [Accepted: 01/09/2025] [Indexed: 04/05/2025]
Abstract
Lung cancer screening (LCS) has been implemented or is in the process of being introduced in several countries worldwide as a strategy to detect lung cancer at an earlier stage, potentially allowing a curable therapeutic approach [1, 2]. Virtual navigation bronchoscopy (VBN) is gaining attention among the available diagnostic tools for evaluating peripheral pulmonary lesions due to its potential to enhance diagnostic accuracy [3]. However, LCS often detects incidental findings that require follow-up imaging, typically using low-dose computed tomography (LDCT) [4]. Virtual bronchoscopic navigation (VBN) with photon-counting CT reduces radiation dose by 83% compared to energy-integrating CT, meeting the threshold for lung cancer screening and the high resolution standards required for accurate VBN https://bit.ly/3BXQ3zj
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Affiliation(s)
- Marcel Opitz
- Institute of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, Essen, Germany marcel.opitz@uk-essen
| | - Faustina Funke
- Division of Interventional Pneumology, Department of Pulmonary Medicine, University Hospital Essen-Ruhrlandklinik, Essen, Germany
- Department of Pulmonary Medicine, University Hospital Essen-Ruhrlandklinik, Essen, Germany
| | - Kaid Darwiche
- Division of Interventional Pneumology, Department of Pulmonary Medicine, University Hospital Essen-Ruhrlandklinik, Essen, Germany
- Department of Pulmonary Medicine, University Hospital Essen-Ruhrlandklinik, Essen, Germany
| | - Sebastian Zensen
- Institute of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, Essen, Germany
| | - Marko Frings
- Institute of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, Essen, Germany
| | - Luca Salhöfer
- Institute of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, Essen, Germany
| | - Johannes Haubold
- Institute of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, Essen, Germany
| | - Michael Forsting
- Institute of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, Essen, Germany
| | - Fabian Doerr
- Department of Thoracic Surgery, West German Cancer Center, University Hospital Essen-Ruhrlandklinik, Essen, Germany
| | - Servet Bölükbas
- Department of Thoracic Surgery, West German Cancer Center, University Hospital Essen-Ruhrlandklinik, Essen, Germany
| | - Filiz Oezkan
- Division of Interventional Pneumology, Department of Pulmonary Medicine, University Hospital Essen-Ruhrlandklinik, Essen, Germany
- Department of Pulmonary Medicine, University Hospital Essen-Ruhrlandklinik, Essen, Germany
| | - Jane Winantea
- Division of Interventional Pneumology, Department of Pulmonary Medicine, University Hospital Essen-Ruhrlandklinik, Essen, Germany
- Department of Pulmonary Medicine, University Hospital Essen-Ruhrlandklinik, Essen, Germany
| | - Hanna Zellerhoff
- Division of Interventional Pneumology, Department of Pulmonary Medicine, University Hospital Essen-Ruhrlandklinik, Essen, Germany
- Department of Pulmonary Medicine, University Hospital Essen-Ruhrlandklinik, Essen, Germany
| | - Rüdiger Karpf-Wissel
- Division of Interventional Pneumology, Department of Pulmonary Medicine, University Hospital Essen-Ruhrlandklinik, Essen, Germany
- Department of Pulmonary Medicine, University Hospital Essen-Ruhrlandklinik, Essen, Germany
| | - Johannes Wienker
- Division of Interventional Pneumology, Department of Pulmonary Medicine, University Hospital Essen-Ruhrlandklinik, Essen, Germany
- Department of Pulmonary Medicine, University Hospital Essen-Ruhrlandklinik, Essen, Germany
| | - Dirk Westhölter
- Department of Pulmonary Medicine, University Hospital Essen-Ruhrlandklinik, Essen, Germany
| | - Matthias Welsner
- Department of Pulmonary Medicine, University Hospital Essen-Ruhrlandklinik, Essen, Germany
| | - Christian Taube
- Department of Pulmonary Medicine, University Hospital Essen-Ruhrlandklinik, Essen, Germany
| | - Erik Büscher
- Division of Interventional Pneumology, Department of Pulmonary Medicine, University Hospital Essen-Ruhrlandklinik, Essen, Germany
- Department of Pulmonary Medicine, University Hospital Essen-Ruhrlandklinik, Essen, Germany
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Chen LG, Kao HW, Wu PA, Sheu MH, Huang LC. Optimal image quality and radiation doses with optimal tube voltages/currents for pediatric anthropomorphic phantom brains. PLoS One 2024; 19:e0306857. [PMID: 39037987 PMCID: PMC11262643 DOI: 10.1371/journal.pone.0306857] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2024] [Accepted: 06/25/2024] [Indexed: 07/24/2024] Open
Abstract
OBJECTIVE Using pediatric anthropomorphic phantoms (APs), we aimed to determine the scanning tube voltage/current combinations that could achieve optimal image quality and avoid excessive radiation exposure in pediatric patients. MATERIALS AND METHODS A 64-slice scanner was used to scan a standard test phantom to determine the volume CT dose indices (CTDIvol), and three pediatric anthropomorphic phantoms (APs) with highly accurate anatomy and tissue-equivalent materials were studied. These specialized APs represented the average 1-year-old, 5-year-old, and 10-year-old children, respectively. The physical phantoms were constructed with brain tissue-equivalent materials having a density of ρ = 1.07 g/cm3, comprising 22 numbered 2.54-cm-thick sections for the 1-year-old, 26 sections for the 5-year-old, and 32 sections for the 10-year-old. They were scanned to acquire brain CT images and determine the standard deviations (SDs), effective doses (EDs), and contrast-to noise ratios (CNRs). The APs were scanned by 21 combinations of tube voltages/currents (80, 100, or 120 kVp/10, 40, 80, 120, 150, 200, or 250 mA) and rotation time/pitch settings of 1 s/0.984:1. RESULTS The optimal tube voltage/current combinations yielding optimal image quality were 80 kVp/80 mA for the 1-year-old AP; 80 kVp/120 mA for the 5-year-old AP; and 80 kVp/150 mA for the 10-year-old AP. Because these scanning tube voltages/currents yielded SDs, respectively, of 12.81, 13.09, and 12.26 HU, along with small EDs of 0.31, 0.34, and 0.31 mSv, these parameters and the induced values were expediently defined as optimal. CONCLUSIONS The optimal tube voltages/currents that yielded optimal brain image quality, SDs, CNRs, and EDs herein are novel and essentially important. Clinical translation of these optimal values may allow CT diagnosis with low radiation doses to children's heads.
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Affiliation(s)
- Li-Guo Chen
- Department of Medical Imaging, Hualien Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, Hualien, Taiwan
| | - Hung-Wen Kao
- Department of Medical Imaging, Hualien Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, Hualien, Taiwan
- Department of Radiology, School of Medicine, Tzu Chi University, Hualien, Taiwan
| | - Ping-An Wu
- Department of Medical Imaging, Hualien Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, Hualien, Taiwan
| | - Ming-Huei Sheu
- Department of Medical Imaging, Hualien Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, Hualien, Taiwan
| | - Li-Chuan Huang
- Department of Medical Imaging, Hualien Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, Hualien, Taiwan
- Department of Medical Imaging and Radiological Sciences, Tzu Chi University of Science and Technology, Hualien, Taiwan
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Takemitsu M, Kudomi S, Takegami K, Uehara T. The effect of a pre-reconstruction process in a filtered back projection reconstruction on an image quality of a low tube voltage computed tomography. Radiol Phys Technol 2024; 17:306-314. [PMID: 38100019 DOI: 10.1007/s12194-023-00764-9] [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: 09/14/2023] [Revised: 11/07/2023] [Accepted: 11/22/2023] [Indexed: 03/01/2024]
Abstract
This study aims to evaluate the effect of pre-reconstruction process for low tube voltage computed tomography (CT) on image quality of filtered back projection (FBP) reconstruction. Small and large quality assurance water phantoms (19 and 33 cm diameter) were scanned on a third-generation dual-source CT with 70 kVp and 120 kVp at various dose levels. Image quality was assessed in terms of the noise power spectrum (NPS) and task-based transfer function (TTF). NPSs and TTFs in the small phantom were comparable between 70 and 120 kVp protocols. In the large phantom, the curves of the NPS changed and the TTF decreased even at the high-dose levels for 70 kVp protocol compared to 120 kVp protocol. Our results indicated that the pre-reconstruction process is performed in low tube voltage CT for large objects even for the FBP reconstruction and has an effect on the image quality.
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Affiliation(s)
- Masaki Takemitsu
- Department of Radiological Technology, Yamaguchi University Hospital, Yamaguchi, 755-8505, Japan.
| | - Shohei Kudomi
- Department of Radiological Technology, Yamaguchi University Hospital, Yamaguchi, 755-8505, Japan
| | - Kazuki Takegami
- Department of Radiological Technology, Yamaguchi University Hospital, Yamaguchi, 755-8505, Japan
| | - Takuya Uehara
- Department of Radiological Technology, Yamaguchi University Hospital, Yamaguchi, 755-8505, Japan
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Feldle P, Grunz JP, Kunz AS, Pannenbecker P, Patzer TS, Pichlmeier S, Sauer ST, Hendel R, Ergün S, Bley TA, Huflage H. Influence of spectral shaping and tube voltage modulation in ultralow-dose computed tomography of the abdomen. BMC Med Imaging 2024; 24:49. [PMID: 38395772 PMCID: PMC10893640 DOI: 10.1186/s12880-024-01228-1] [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: 05/10/2023] [Accepted: 02/14/2024] [Indexed: 02/25/2024] Open
Abstract
PURPOSE Unenhanced abdominal CT constitutes the diagnostic standard of care in suspected urolithiasis. Aiming to identify potential for radiation dose reduction in this frequent imaging task, this experimental study compares the effect of spectral shaping and tube voltage modulation on image quality. METHODS Using a third-generation dual-source CT, eight cadaveric specimens were scanned with varying tube voltage settings with and without tin filter application (Sn 150, Sn 100, 120, 100, and 80 kVp) at three dose levels (3 mGy: standard; 1 mGy: low; 0.5 mGy: ultralow). Image quality was assessed quantitatively by calculation of signal-to-noise ratios (SNR) for various tissues (spleen, kidney, trabecular bone, fat) and subjectively by three independent radiologists based on a seven-point rating scale (7 = excellent; 1 = very poor). RESULTS Irrespective of dose level, Sn 100 kVp resulted in the highest SNR of all tube voltage settings. In direct comparison to Sn 150 kVp, superior SNR was ascertained for spleen (p ≤ 0.004) and kidney tissue (p ≤ 0.009). In ultralow-dose scans, subjective image quality of Sn 100 kVp (median score 3; interquartile range 3-3) was higher compared with conventional imaging at 120 kVp (2; 2-2), 100 kVp (1; 1-2), and 80 kVp (1; 1-1) (all p < 0.001). Indicated by an intraclass correlation coefficient of 0.945 (95% confidence interval: 0.927-0.960), interrater reliability was excellent. CONCLUSIONS In abdominal CT with maximised dose reduction, tin prefiltration at 100 kVp allows for superior image quality over Sn 150 kVp and conventional imaging without spectral shaping.
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Affiliation(s)
- Philipp Feldle
- Department of Diagnostic and Interventional Radiology, University Hospital Würzburg, Oberdürrbacher Straße 6, 97080, Würzburg, Germany
| | - Jan-Peter Grunz
- Department of Diagnostic and Interventional Radiology, University Hospital Würzburg, Oberdürrbacher Straße 6, 97080, Würzburg, Germany
| | - Andreas Steven Kunz
- Department of Diagnostic and Interventional Radiology, University Hospital Würzburg, Oberdürrbacher Straße 6, 97080, Würzburg, Germany
| | - Pauline Pannenbecker
- Department of Diagnostic and Interventional Radiology, University Hospital Würzburg, Oberdürrbacher Straße 6, 97080, Würzburg, Germany
| | - Theresa Sophie Patzer
- Department of Diagnostic and Interventional Radiology, University Hospital Würzburg, Oberdürrbacher Straße 6, 97080, Würzburg, Germany
| | - Svenja Pichlmeier
- Department of Diagnostic and Interventional Radiology, University Hospital Würzburg, Oberdürrbacher Straße 6, 97080, Würzburg, Germany
| | - Stephanie Tina Sauer
- Department of Diagnostic and Interventional Radiology, University Hospital Würzburg, Oberdürrbacher Straße 6, 97080, Würzburg, Germany
| | - Robin Hendel
- Department of Diagnostic and Interventional Radiology, University Hospital Würzburg, Oberdürrbacher Straße 6, 97080, Würzburg, Germany
| | - Süleyman Ergün
- Institute of Anatomy and Cell Biology, University of Würzburg, Koellikerstraße 6, 97070, Würzburg, Germany
| | - Thorsten Alexander Bley
- Department of Diagnostic and Interventional Radiology, University Hospital Würzburg, Oberdürrbacher Straße 6, 97080, Würzburg, Germany
| | - Henner Huflage
- Department of Diagnostic and Interventional Radiology, University Hospital Würzburg, Oberdürrbacher Straße 6, 97080, Würzburg, Germany.
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Park MS, Ha HI, Ahn JH, Lee IJ, Lim HK. Reducing contrast-agent volume and radiation dose in CT with 90-kVp tube voltage, high tube current modulation, and advanced iteration algorithm. PLoS One 2023; 18:e0287214. [PMID: 37319309 PMCID: PMC10270572 DOI: 10.1371/journal.pone.0287214] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2023] [Accepted: 05/31/2023] [Indexed: 06/17/2023] Open
Abstract
Increasing utilization of computed tomography (CT) has raised concerns regarding CT radiation dose and technology has been developed to achieve an appropriate balance between image quality, radiation dose, and the amount of contrast material. This study was planned to evaluate the image quality and radiation dose in pancreatic dynamic computed tomography (PDCT) with 90-kVp tube voltage and reduction of the standard amount of contrast agent, compared with 100-kVp PDCT of the research hospital's convention. Total of 51 patients with both CT protocols were included. The average Hounsfield units (HU) values of the abdominal organs and image noise were measured for objective image quality analysis. Two radiologists evaluated five categories of image qualities such as subjective image noise, visibility of small structure, beam hardening or streak artifact, lesion conspicuity and overall diagnostic performance for subjective image quality analysis. The total amount of contrast agent, radiation dose, and image noise decreased in the low-kVp group, by 24.4%, 31.7%, and 20.6%, respectively (p < 0.001). The intraobserver and interobserver agreements were moderate to substantial (k = 0.4-0.8). The contrast-to-noise ratio (CNR), signal-to-noise ratio (SNR), and figure of merit of the almost organs except psoas muscle in the low-kVp group were significantly higher (p < 0.001). Except for lesion conspicuity, both reviewers judged that subjective image quality of the 90-kVp group was better (p < 0.001). With 90-kVp tube voltage, 25% reduced contrast agent volume with advanced iteration algorithm and high tube current modulation achieved radiation dose reduction of 31.7%, as well as better image quality and diagnostic confidence.
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Affiliation(s)
- Min Su Park
- Department of Radiology, Hallym University Sacred Heart Hospital, Anyang-si, Gyeonggi-do, Republic of Korea
| | - Hong Il Ha
- Department of Radiology, Hallym University Sacred Heart Hospital, Anyang-si, Gyeonggi-do, Republic of Korea
| | - Jhii-Hyun Ahn
- Department of Radiology, Yonsei University Wonju College of Medicine, Wonju Severance Christian Hospital, Wonju, Gangwon-do, Republic of Korea
| | - In Jae Lee
- Department of Radiology, Hallym University Sacred Heart Hospital, Anyang-si, Gyeonggi-do, Republic of Korea
| | - Hyun Kyung Lim
- Department of Radiology, Soonchunhyang University Seoul Hospital, Seoul, Republic of Korea
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Bos D, Zensen S, Opitz MK, Haubold J, Nassenstein K, Kinner S, Schweiger B, Forsting M, Wetter A, Guberina N. Diagnostic reference levels for chest computed tomography in children as a function of patient size. Pediatr Radiol 2022; 52:1446-1455. [PMID: 35378606 PMCID: PMC9271112 DOI: 10.1007/s00247-022-05340-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/21/2021] [Revised: 02/11/2022] [Accepted: 02/25/2022] [Indexed: 11/10/2022]
Abstract
BACKGROUND Radiation exposures from computed tomography (CT) in children are inadequately studied. Diagnostic reference levels (DRLs) can help optimise radiation doses. OBJECTIVE To determine local DRLs for paediatric chest CT performed mainly on modern dual-source, multi-slice CT scanners as a function of patient size. MATERIALS AND METHODS Five hundred thirty-eight chest CT scans in 345 children under 15 years (y) of age (median age: 8 y, interquartile range [IQR]: 4-13 y) performed on four different CT scanners (38% on third-generation and 43% on second-generation dual-source CT) between November 2013 and December 2020 were retrospectively analysed. Examinations were grouped by water-equivalent diameter as a measure of patient size. DRLs for volume CT dose index (CTDIvol) and dose-length product (DLP) were determined for six different patient sizes and compared to national and European DRLs. RESULTS The DRLs for CTDIvol and DLP are determined for each patient size group as a function of water-equivalent diameter as follows: (I) < 13 cm (n = 22; median: age 7 months): 0.4 mGy, 7 mGy·cm; (II) 13 cm to less than 17 cm (n = 151; median: age 3 y): 1.2 mGy, 25 mGy·cm; (III) 17 cm to less than 21 cm (n = 211; median: age 8 y): 1.7 mGy, 44 mGy·cm; (IV) 21 cm to less than 25 cm (n = 97; median: age 14 y): 3.0 mGy, 88 mGy·cm; (V) 25 cm to less than 29 cm (n = 42; median: age 14 y): 4.5 mGy, 135 mGy·cm; (VI) ≥ 29 cm (n = 15; median: age 14 y): 8.0 mGy, 241 mGy·cm. Compared with corresponding age and weight groups, our size-based DRLs for DLP are 54% to 71% lower than national and 23% to 85% lower than European DRLs. CONCLUSION We developed DRLs for paediatric chest CT as a function of patient size with substantially lower values than national and European DRLs. Precise knowledge of size-based DRLs may assist other institutions in further dose optimisation in children.
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Affiliation(s)
- Denise Bos
- Institute of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, University of Duisburg-Essen, Hufelandstraße 55, 45147, Essen, Germany.
| | - Sebastian Zensen
- Institute of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, University of Duisburg-Essen, Hufelandstraße 55, 45147, Essen, Germany
| | - Marcel K Opitz
- Institute of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, University of Duisburg-Essen, Hufelandstraße 55, 45147, Essen, Germany
| | - Johannes Haubold
- Institute of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, University of Duisburg-Essen, Hufelandstraße 55, 45147, Essen, Germany
| | - Kai Nassenstein
- Institute of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, University of Duisburg-Essen, Hufelandstraße 55, 45147, Essen, Germany
| | - Sonja Kinner
- Institute of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, University of Duisburg-Essen, Hufelandstraße 55, 45147, Essen, Germany
| | - Bernd Schweiger
- Institute of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, University of Duisburg-Essen, Hufelandstraße 55, 45147, Essen, Germany
| | - Michael Forsting
- Institute of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, University of Duisburg-Essen, Hufelandstraße 55, 45147, Essen, Germany
| | - Axel Wetter
- Institute of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, University of Duisburg-Essen, Hufelandstraße 55, 45147, Essen, Germany
- Department of Diagnostic and Interventional Radiology, Neuroradiology, Asklepios Klinikum Harburg, Eißendorfer Pferdeweg 52, 21075, Hamburg, Germany
| | - Nika Guberina
- Institute of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, University of Duisburg-Essen, Hufelandstraße 55, 45147, Essen, Germany
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Hasegawa A, Ishihara T, Pan T, Ropp AM, Winkler M, Sneider MB. Impact of pixel value truncation on image quality of low dose chest CT. Med Phys 2022; 49:2979-2994. [PMID: 35235216 DOI: 10.1002/mp.15589] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2021] [Revised: 02/04/2022] [Accepted: 02/25/2022] [Indexed: 11/11/2022] Open
Abstract
PURPOSE In some noisy low-dose CT lung cancer screening images, we noticed that the CT density values of air were increased and the visibility of emphysema was distinctly decreased. By examining histograms of these images, we found that the CT density values were truncated at -1,024 HU. The purpose of this study was to investigate the effect of pixel value truncation on the visibility of emphysema using mathematical models. METHODS AND MATERIALS Assuming CT noise follows a normal distribution, we derived the relationship between the mean CT density value and the standard deviation (SD) when the pixel values below -1,024 HU are truncated and replaced by -1,024 HU. To validate our mathematical model, 20 untruncated phantom CT images were truncated by simulation, and the mean CT density values and SD of air in the images were measured and compared with the theoretical values. In addition, the mean CT density values and SD of air were measured in 100 cases of real clinical images obtained by GE, Siemens, and Philips scanners, respectively, and the agreement with the theoretical values was examined. Next, the contrast-to-noise ratio (CNR) between air (-1,000 HU) and lung parenchyma (-850 HU) was derived from the mathematical model in the presence and absence of truncation as a measure of the visibility of emphysema. In addition, the radiation dose ratios required to obtain the same CNR in the case with and without truncation were also calculated. RESULTS The mathematical model revealed that when the pixel values are truncated, the mean CT density values are proportional to the noise magnitude when the magnitude exceeds a certain level. The mean CT density values and SD measured in the images with pixel values truncated by simulation and in the real clinical images acquired by GE and Philips scanners agreed well with the theoretical values from our mathematical model. In the Siemens images, the measured and theoretical values agreed well when a portion of the truncated values were replaced by random values instead of simply replacing by -1,024 HU. The CNR of air and lung parenchyma was lowered by truncating CT density values compared to that of no truncation. Furthermore, it was found that higher radiation dose was required to obtain the same CNR with truncation as without. As an example, when the noise SD was 60 HU, the radiation dose required for the GE and Philips truncation method was about 1.2 times higher than that without truncation, and that for the Siemens truncation method was about 1.4 times higher. CONCLUSIONS It was demonstrated mathematically that pixel value truncation causes a brightening of the mean CT density value and decreases the CNR of emphysema. Our results indicate that it is advisable to turn off truncation at -1,024 HU, especially when scanning at low and ultra-low radiation doses in the thorax. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Akira Hasegawa
- Department of Radiological Technology, National Cancer Center Japan, Tokyo, 104-0045, Japan.,AlgoMedica, Inc., Sunnyvale, CA, 94085, USA
| | - Toshihiro Ishihara
- Department of Radiological Technology, National Cancer Center Japan, Tokyo, 104-0045, Japan
| | - Tinsu Pan
- Department of Imaging Physics, M.D. Anderson Cancer Center, University of Texas, Houston, TX, 77030, USA
| | - Alan M Ropp
- Department of Radiology and Medical Imaging, University of Virginia Health, Charlottesville, VA, 22908, USA
| | - Michael Winkler
- Department of Radiology and Imaging, Medical College of Georgia at Augusta University, Augusta, GA, 30912, USA
| | - Michael B Sneider
- Department of Radiology and Medical Imaging, University of Virginia Health, Charlottesville, VA, 22908, USA
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Ziegelmayer S, Reischl S, Harder F, Makowski M, Braren R, Gawlitza J. Feature Robustness and Diagnostic Capabilities of Convolutional Neural Networks Against Radiomics Features in Computed Tomography Imaging. Invest Radiol 2022; 57:171-177. [PMID: 34524173 DOI: 10.1097/rli.0000000000000827] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
MATERIALS AND METHODS Imaging phantoms were scanned twice on 3 computed tomography scanners from 2 different manufactures with varying tube voltages and currents. Phantoms were segmented, and features were extracted using PyRadiomics and a pretrained CNN. After standardization the concordance correlation coefficient (CCC), mean feature variance, feature range, and the coefficient of variant were calculated to assess feature robustness. In addition, the cosine similarity was calculated for the vectorized activation maps for an exemplary phantom. For the in vivo comparison, the radiomics and CNN features of 30 patients with hepatocellular carcinoma (HCC) and 30 patients with hepatic colon carcinoma metastasis were compared. RESULTS In total, 851 radiomics features and 256 CNN features were extracted for each phantom. For all phantoms, the global CCC of the CNN features was above 98%, whereas the highest CCC for the radiomics features was 36%. The mean feature variance and feature range was significantly lower for the CNN features. Using a coefficient of variant ≤0.2 as a threshold to define robust features and averaging across all phantoms 346 of 851 (41%) radiomics features and 196 of 256 (77%) CNN features were found to be robust. The cosine similarity was greater than 0.98 for all scanner and parameter variations. In the retrospective analysis, 122 of the 256 CNN (49%) features showed significant differences between HCC and hepatic colon metastasis. DISCUSSION Convolutional neural network features were more stable compared with radiomics features against technical variations. Moreover, the possibility of tumor entity differentiation based on CNN features was shown. Combined with visualization methods, CNN features are expected to increase reproducibility of quantitative image representations. Further studies are warranted to investigate the impact of feature stability on radiological image-based prediction of clinical outcomes.
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Affiliation(s)
- Sebastian Ziegelmayer
- From the Institute of Diagnostic and Interventional Radiology, School of Medicine, Klinikum rechts der Isar, Technical University Munich
| | - Stefan Reischl
- From the Institute of Diagnostic and Interventional Radiology, School of Medicine, Klinikum rechts der Isar, Technical University Munich
| | - Felix Harder
- From the Institute of Diagnostic and Interventional Radiology, School of Medicine, Klinikum rechts der Isar, Technical University Munich
| | - Marcus Makowski
- From the Institute of Diagnostic and Interventional Radiology, School of Medicine, Klinikum rechts der Isar, Technical University Munich
| | | | - Joshua Gawlitza
- From the Institute of Diagnostic and Interventional Radiology, School of Medicine, Klinikum rechts der Isar, Technical University Munich
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Variation in tube voltage for pediatric neck 64VCT: Effect on radiation dose and image quality. PLoS One 2021; 16:e0259772. [PMID: 34767600 PMCID: PMC8589163 DOI: 10.1371/journal.pone.0259772] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2021] [Accepted: 10/27/2021] [Indexed: 11/19/2022] Open
Abstract
Exposure to ionizing radiation can cause cancer, especially in children. In computed tomography (CT), a trade-off exists between the radiation dose and image quality. Few studies have investigated the effect of dose reduction on image quality in pediatric neck CT. We aimed to assess the effect of peak kilovoltage on the radiation dose and image quality in pediatric neck multidetector-row CT. Measurements were made using three phantoms representative of children aged 1, 5, and 10 years, with tube voltages of 80, 100, and 120 kilovoltage peak (kVp); tube current of 10, 40, 80, 120, 150, 200, and 250 mA; and exposure time = 0.5 s (pitch, 0.984:1). Radiation dose estimates were derived from the dose-length product with a 64-multidetector-row CT scanner. Images obtained from the control protocol (120 kVp) were compared with the 80- and 100-kVp protocols. The effective dose (ED) was determined for each protocol and compared with the 120-kVp protocol. Quantitative analysis entailed noise measurements by recording the standard deviation of attenuation for a circular 1-cm2 region of interest placed on homogeneous soft tissue structures in the phantom. The mean noise of the various kVp protocols was compared using the unpaired Student t-test. Reduction of ED was 37.58% and 68.58% for neck CT with 100 kVp and 80 kVp, respectively. The image noise level increased with the decrease in peak kilovoltage. Noise values were higher at 80 kVp at all neck levels, but did not increase at 100 kVp, compared to 120 kVp in the three phantoms. The measured noise difference was the greatest at 80 kVp (absolute increases<2.5 HU). The subjective image quality did not differ among the protocols. Thus, reducing voltage from 120 to 80 kVp for neck CT may achieve ED reduction of 68.58%, without compromising image quality.
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Optimisation of CT scan parameters to increase the accuracy of gross tumour volume identification in brain radiotherapy. JOURNAL OF RADIOTHERAPY IN PRACTICE 2021. [DOI: 10.1017/s1460396920000436] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
AbstractAim:This study aimed to optimise computed tomography (CT) simulation scan parameters to increase the accuracy for gross tumour volume identification in brain radiotherapy. For this purpose, high-contrast scan protocols were assessed.Materials and methods:A CT accreditation phantom (ACR Gammex 464) was used to optimise brain CT scan parameters on a Toshiba Alexion 16-row multislice CT scanner. Dose, tube voltage, tube current–time and CT dose index (CTDI) were varied to create five image quality enhancement (IQE) protocols. They were assessed in terms of contrast-to-noise ratio (CNR), signal-to-noise ratio (SNR) and noise level and compared with a standard clinical protocol. Finally, the ability of the selected protocols to identify low-contrast objects was examined based on a subjective method.Results:Among the five IQE protocols, the one with the highest tube current–time product (250 mA) and lowest tube voltage (100 kVp) showed higher CNR, while another with a tube current–time product of 150 mA and a tube voltage of 135 kVp had improved SNR and lower noise level compared to the standard protocol. In contouring low-contrast objects, the protocol with the highest milliampere and lowest peak kilovoltage exhibited the lowest error rate (1%) compared to the standard protocol (25%).Findings:CT image quality should be optimised using the high-dose parameters created in this study to provide better soft tissue contrast. This could lead to an accurate identification of gross tumour volume recognition in the planning of radiotherapy treatment.
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11
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Zhu Z, Zhao Y, Zhao X, Wang X, Yu W, Hu M, Zhang X, Zhou C. Impact of preset and postset adaptive statistical iterative reconstruction-V on image quality in nonenhanced abdominal-pelvic CT on wide-detector revolution CT. Quant Imaging Med Surg 2021; 11:264-275. [PMID: 33392027 DOI: 10.21037/qims-19-945] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Background Adaptive statistical iterative reconstruction-V technique (ASIR-V) is usually set at different strengths according to the different clinical requirements and scenarios encountered when setting scanning protocols, such as setting a more aggressive tube current reduction (defined as preset ASIR-V). Reconstruction with ASIR-V is useful after scanning using image algorithms to improve image quality (defined as postset ASIR-V). The aim of this study was to investigate the quality of images reconstructed with preset and postset ASIR-V, using the same noncontrast abdominal-pelvic computed tomography (CT) protocols in the same individual on a wide detector CT. Methods We prospectively enrolled 141 patients. The scan protocols in Groups A-E were 0%, 20%, 40%, 60%, and 80% preset ASIR-V, respectively, in the 256 wide-detector row Revolution CT (GE Healthcare, Waukesha, WI, USA). Each group was further divided into 5 subgroups with 0%, 20%, 40%, 60%, and 80% postset ASIR-V, respectively. The 64-detector Discovery 750 HDCT (GE, USA) was used for Group F as a control group, using 0%, 20%, 40%, 60%, and 80% ASIR, respectively. Image noise was measured in the spleen, aorta, and muscle. The CT attenuation and image noise were analyzed using the paired t-test; analysis of variance and post hoc multiple comparisons were made using the Student-Newman-Keuls (SNK) method. Results The CT attenuation in Groups A-F exhibited no significant difference between subgroups in three organs (P>0.05). Only with increasing preset ASIR-V% (Groups A to E), did the image noise decrease, except in Group B in the aorta and muscle (NoiseB > NoiseA, PmuscleA&B=0.233, PaortaA&B=0.796). Only with increasing postset ASIR-V or ASIR% (Groups A and F), did the image noise decrease in the three organs. After preset and postset ASIR-V were combined, with preset ASIR-V% being equal to postset ASIR-V%, the image become similar to the corresponding preset ASIR-V part with the line of postset ASIR-V 0% (baseline of each group). When preset ASIR-V% was greater than the postset ASIR-V%, the image noise was higher than the baseline of each group. When preset ASIR-V% was less than the postset ASIR-V%, the image noise was lower than the baseline of each group. The radiation dose from B to E decreased from 11.2% to 57.1%. The CT dose index volume (CTDIvol) and dose length product (DLP) in Group F were significantly higher than those in Group A. Conclusions Using both preset and postset ASIR-V allows dose reduction, with a potential to improve image quality only when postset ASIR-V% is higher than or equal to preset ASIR-V%. The image quality depends on postset ASIR-V%, whereas the decrease of radiation dose depends on preset ASIR-V%.
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Affiliation(s)
- Zheng Zhu
- Department of Diagnostic Radiology, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Yanfeng Zhao
- Department of Diagnostic Radiology, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Xinming Zhao
- Department of Diagnostic Radiology, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Xiaoyi Wang
- Department of Diagnostic Radiology, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Weijun Yu
- Department of Diagnostic Radiology, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Mancang Hu
- Department of Diagnostic Radiology, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | | | - Chunwu Zhou
- Department of Diagnostic Radiology, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
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Ishiguro A, Sato K, Taura M, Hoshi H. Quantitative evaluation of the effect of changes in effective energy on the image quality in X-ray computed tomography. Phys Eng Sci Med 2020; 43:567-575. [PMID: 32524441 DOI: 10.1007/s13246-020-00857-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2019] [Accepted: 03/09/2020] [Indexed: 10/24/2022]
Abstract
The X-ray effective energy differs for each computed tomography (CT) scanner even at the same tube voltage because of differences in the bow-tie filter and additional filter. Even when scanning with the same tube voltage and dose setting, these differences in effective energy result in different image noise levels. Although this qualitative change is known, the related quantitative changes have not been clarified. In this study, using two CT scanners with the same geometric specifications and detector configurations, we quantitatively assessed the reduction in image noise accompanying the increase in effective energy. We also clarified the fluctuations in CT number. For both CT scanners, the effective energy, the standard deviation (SD) of the noise image when using two water phantoms with diameters of 240 mm and 320 mm, and CT numbers of the sensitometry module were measured. Further, the dose required to obtain the same image noise level in each CT scanner was calculated. The effective energy difference was 5.5 keV to 10.7 keV, and the difference tended to be larger when the scan field of view was larger. The SD differences were 24% and 14% for the 320-mm and 240-mm phantoms, respectively. For converting to the dose required to obtain the same SD, the dose can be reduced by 42% and 24% for the 320-mm and 240-mm phantoms, respectively. The CT number difference of both CT scanners was small. Therefore, higher effective energy contributes to the reduction of image noise.
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Affiliation(s)
- Ayana Ishiguro
- Sendai Open Hospital, 5-22-1 Tsurugaya, Miyagino-ku, Sendai, Miyagi, 983-0824, Japan.
| | - Kazuhiro Sato
- Tohoku University Graduate School of Medicine, 2-1 Seiryo-machi Aoba-ku, Sendai, Miyagi, 980-8575, Japan
| | - Masaaki Taura
- Tohoku Medical and Pharmaceutical University Hospital, 1-12-1 Fukumuro, Miyagino-ku, Sendai, Miyagi, 983-8512, Japan
| | - Hideki Hoshi
- Sendai Open Hospital, 5-22-1 Tsurugaya, Miyagino-ku, Sendai, Miyagi, 983-0824, Japan.,Tohoku University Graduate School of Medicine, 2-1 Seiryo-machi Aoba-ku, Sendai, Miyagi, 980-8575, Japan
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Funama Y. [1. Basic Characteristics of Tube Voltages in X- ray CT Scanner]. Nihon Hoshasen Gijutsu Gakkai Zasshi 2020; 76:1321-1326. [PMID: 33342954 DOI: 10.6009/jjrt.2020_jsrt_76.12.1321] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Affiliation(s)
- Yoshinori Funama
- Department of Medical Radiation Sciences, Faculty of Life Sciences, Kumamoto University
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Anam C, Budi WS, Adi K, Sutanto H, Haryanto F, Ali MH, Fujibuchi T, Dougherty G. Assessment of patient dose and noise level of clinical CT images: automated measurements. JOURNAL OF RADIOLOGICAL PROTECTION : OFFICIAL JOURNAL OF THE SOCIETY FOR RADIOLOGICAL PROTECTION 2019; 39:783-793. [PMID: 31117064 DOI: 10.1088/1361-6498/ab23cc] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
We investigated comparisons between patient dose and noise in pelvic, abdominal, thoracic and head CT images using an automatic method. 113 patient images (37 pelvis, 34 abdominal, 25 thoracic, and 17 head examinations) were retrospectively and automatically examined in this study. Water-equivalent diameter (Dw), size-specific dose estimates (SSDE) and noise were automatically calculated from the center slice for every patient image. The Dw was calculated based on auto-contouring of the patients' edges, and the SSDE was calculated as the product of the volume CT dose index (CTDIvol) extracted from the Digital Imaging and Communications in Medicine (DICOM) header and the size conversion factor based on the Dw obtained from AAPM 204. The noise was automatically measured as a minimum standard deviation in the map of standard deviations. A square region of interest of about 1 cm2 was used in the automated noise measurement. The SSDE values for the pelvis, abdomen, thorax, and head were 21.8 ± 7.3 mGy, 22.0 ± 4.5 mGy, 21.5 ± 4.7 mGy, and 65.1 ± 1.7 mGy, respectively. The SSDEs for the pelvis, abdomen, and thorax increased linearly with increasing Dw, and for the head with constant tube current, the SSDE decreased with increasing Dw. The noise in the pelvis, abdomen, thorax, and head were 5.9 ± 1.5 HU, 5.2 ± 1.4 HU, 4.9 ± 0.8 HU and 3.9 ± 0.2 HU, respectively. The noise levels for the pelvis, abdomen, and thorax of the patients were relatively constant with Dw because of tube current modulation. The noise in the head image was also relatively constant because Dw variations in the head are very small. The automated approach provides a convenient and objective tool for dose optimizations.
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Affiliation(s)
- Choirul Anam
- Department of Physics, Faculty of Mathematics and Natural Sciences, Diponegoro University, Jl. Prof. Soedarto SH, Tembalang, Semarang 50275, Central Java, Indonesia
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Hu X, Ding D, Chu D. Multiple Hidden Markov Model for Pathological Vessel Segmentation. BIOMED RESEARCH INTERNATIONAL 2018; 2018:9868215. [PMID: 30643827 PMCID: PMC6311274 DOI: 10.1155/2018/9868215] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/27/2018] [Revised: 09/12/2018] [Accepted: 11/28/2018] [Indexed: 11/27/2022]
Abstract
One of the obstacles that prevent the accurate delineation of vessel boundaries is the presence of pathologies, which results in obscure boundaries and vessel-like structures. Targeting this limitation, we present a novel segmentation method based on multiple Hidden Markov Models. This method works with a vessel axis + cross-section model, which constrains the classifier around the vessel. The vessel axis constraint gives our method the potential to be both physiologically accurate and computationally effective. Focusing on pathological vessels, we reap the benefits of the redundant information embedded in multiple vessel-specific features and the good statistical properties coming with Hidden Markov Model, to cover the widest possible spectrum of complex situations. The performance of our method is evaluated on synthetic complex-structured datasets, where we achieve a 91% high overlap ratio. We also validate the proposed method on a real challenging case, segmentation of pathological abdominal arteries. The performance of our method is promising, since our method yields better results than two state-of-the-art methods on both synthetic datasets and real clinical datasets.
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Affiliation(s)
- Xin Hu
- School of Computer Science and Technology, Harbin Institute of Technology at Weihai, Weihai 264209, China
| | - Deqiong Ding
- School of Computer Science and Technology, Harbin Institute of Technology, Harbin 150001, China
| | - Dianhui Chu
- School of Computer Science and Technology, Harbin Institute of Technology at Weihai, Weihai 264209, China
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16
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Nagayama Y, Oda S, Nakaura T, Tsuji A, Urata J, Furusawa M, Utsunomiya D, Funama Y, Kidoh M, Yamashita Y. Radiation Dose Reduction at Pediatric CT: Use of Low Tube Voltage and Iterative Reconstruction. Radiographics 2018; 38:1421-1440. [DOI: 10.1148/rg.2018180041] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Affiliation(s)
- Yasunori Nagayama
- From the Department of Diagnostic Radiology, Graduate School of Medical Sciences (Y.N., S.O., T.N., D.U., M.K., Y.Y.), and Department of Medical Physics, Faculty of Life Sciences (Y.F.), Kumamoto University, 1-1-1 Honjo, Chuo-ku, Kumamoto 860-8556, Japan; and Department of Radiology, Kumamoto City Hospital, Kumamoto, Japan (Y.N., A.T., J.U., M.F.)
| | - Seitaro Oda
- From the Department of Diagnostic Radiology, Graduate School of Medical Sciences (Y.N., S.O., T.N., D.U., M.K., Y.Y.), and Department of Medical Physics, Faculty of Life Sciences (Y.F.), Kumamoto University, 1-1-1 Honjo, Chuo-ku, Kumamoto 860-8556, Japan; and Department of Radiology, Kumamoto City Hospital, Kumamoto, Japan (Y.N., A.T., J.U., M.F.)
| | - Takeshi Nakaura
- From the Department of Diagnostic Radiology, Graduate School of Medical Sciences (Y.N., S.O., T.N., D.U., M.K., Y.Y.), and Department of Medical Physics, Faculty of Life Sciences (Y.F.), Kumamoto University, 1-1-1 Honjo, Chuo-ku, Kumamoto 860-8556, Japan; and Department of Radiology, Kumamoto City Hospital, Kumamoto, Japan (Y.N., A.T., J.U., M.F.)
| | - Akinori Tsuji
- From the Department of Diagnostic Radiology, Graduate School of Medical Sciences (Y.N., S.O., T.N., D.U., M.K., Y.Y.), and Department of Medical Physics, Faculty of Life Sciences (Y.F.), Kumamoto University, 1-1-1 Honjo, Chuo-ku, Kumamoto 860-8556, Japan; and Department of Radiology, Kumamoto City Hospital, Kumamoto, Japan (Y.N., A.T., J.U., M.F.)
| | - Joji Urata
- From the Department of Diagnostic Radiology, Graduate School of Medical Sciences (Y.N., S.O., T.N., D.U., M.K., Y.Y.), and Department of Medical Physics, Faculty of Life Sciences (Y.F.), Kumamoto University, 1-1-1 Honjo, Chuo-ku, Kumamoto 860-8556, Japan; and Department of Radiology, Kumamoto City Hospital, Kumamoto, Japan (Y.N., A.T., J.U., M.F.)
| | - Mitsuhiro Furusawa
- From the Department of Diagnostic Radiology, Graduate School of Medical Sciences (Y.N., S.O., T.N., D.U., M.K., Y.Y.), and Department of Medical Physics, Faculty of Life Sciences (Y.F.), Kumamoto University, 1-1-1 Honjo, Chuo-ku, Kumamoto 860-8556, Japan; and Department of Radiology, Kumamoto City Hospital, Kumamoto, Japan (Y.N., A.T., J.U., M.F.)
| | - Daisuke Utsunomiya
- From the Department of Diagnostic Radiology, Graduate School of Medical Sciences (Y.N., S.O., T.N., D.U., M.K., Y.Y.), and Department of Medical Physics, Faculty of Life Sciences (Y.F.), Kumamoto University, 1-1-1 Honjo, Chuo-ku, Kumamoto 860-8556, Japan; and Department of Radiology, Kumamoto City Hospital, Kumamoto, Japan (Y.N., A.T., J.U., M.F.)
| | - Yoshinori Funama
- From the Department of Diagnostic Radiology, Graduate School of Medical Sciences (Y.N., S.O., T.N., D.U., M.K., Y.Y.), and Department of Medical Physics, Faculty of Life Sciences (Y.F.), Kumamoto University, 1-1-1 Honjo, Chuo-ku, Kumamoto 860-8556, Japan; and Department of Radiology, Kumamoto City Hospital, Kumamoto, Japan (Y.N., A.T., J.U., M.F.)
| | - Masafumi Kidoh
- From the Department of Diagnostic Radiology, Graduate School of Medical Sciences (Y.N., S.O., T.N., D.U., M.K., Y.Y.), and Department of Medical Physics, Faculty of Life Sciences (Y.F.), Kumamoto University, 1-1-1 Honjo, Chuo-ku, Kumamoto 860-8556, Japan; and Department of Radiology, Kumamoto City Hospital, Kumamoto, Japan (Y.N., A.T., J.U., M.F.)
| | - Yasuyuki Yamashita
- From the Department of Diagnostic Radiology, Graduate School of Medical Sciences (Y.N., S.O., T.N., D.U., M.K., Y.Y.), and Department of Medical Physics, Faculty of Life Sciences (Y.F.), Kumamoto University, 1-1-1 Honjo, Chuo-ku, Kumamoto 860-8556, Japan; and Department of Radiology, Kumamoto City Hospital, Kumamoto, Japan (Y.N., A.T., J.U., M.F.)
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Masuda T, Funama Y, Kiguchi M, Osawa K, Suzuki S, Oku T, Sugisawa K, Shouji T, Awai K. Relationship between the radiation doses at nonenhanced CT studies using different tube voltages and automatic tube current modulation during anthropomorphic phantoms of young children. J Appl Clin Med Phys 2017; 18:232-243. [PMID: 28984023 PMCID: PMC5689931 DOI: 10.1002/acm2.12192] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2016] [Revised: 07/10/2017] [Accepted: 08/10/2017] [Indexed: 11/14/2022] Open
Abstract
To compare the radiation dose and image noise of nonenhanced CT scans performed at 80, 100, and 120 kVp with tube current modulation (TCM) we used anthropomorphic phantoms of newborn, 1‐year‐old, and 5‐year‐old children. The noise index was set at 12. The image noise in the center of the phantoms at the level of the chest and abdomen was measured within a circumscribed region of interest. We measured the doses in individual tissues or organs with radio‐photoluminescence glass dosimeters for each phantom. Various tissues or organs were assigned and the radiation dose was calculated based on the international commission on radiological protection definition. With TCM the respective radiation dose at tube voltages of 80, 100, and 120 was 29.71, 31.60, and 33.79 mGy for the newborn, 32.00, 36.79, and 39.48 mGy for the 1‐year‐old, and 32.78, 38.11, and 40.85 mGy for the 5‐year‐old phantom. There were no significant differences in the radiation dose among the tube voltages and phantoms (P > 0.05). Our comparison of the radiation dose using anthropomorphic phantoms of young children showed that the radiation dose of nonenhanced CT performed at different tube voltages with TCM was not significantly different.
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Affiliation(s)
- Takanori Masuda
- Department of Radiological Technology, Tsuchiya General Hospital, Naka-ku, Japan.,Department of Diagnostic Radiology, Graduate School of Biomedical Sciences, Hiroshima University, Hiroshima, Japan
| | - Yoshinori Funama
- Department of Medical Physics, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan
| | - Masao Kiguchi
- Department of Diagnostic Radiology, Graduate School of Biomedical Sciences, Hiroshima University, Hiroshima, Japan
| | - Kazuaki Osawa
- Department of Radiological Technology, Saiseikai Chuwa Hospital, Nara, Japan
| | - Syouichi Suzuki
- Department of Diagnostic Radiology, Fujita Health University School of Health Science, Aichi, Japan
| | - Takayuki Oku
- Department of Radiological Technology, Tsuchiya General Hospital, Naka-ku, Japan
| | - Koichi Sugisawa
- Department of Diagnostic Radiology, Keio University School, Tokyo, Japan
| | - Tomokazu Shouji
- Department of Radiology, Jikei University Kashiwa Hospital, Chiba, Japan
| | - Kazuo Awai
- Department of Diagnostic Radiology, Graduate School of Biomedical Sciences, Hiroshima University, Hiroshima, Japan
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Zidek J, Vojtova L, Abdel-Mohsen AM, Chmelik J, Zikmund T, Brtnikova J, Jakubicek R, Zubal L, Jan J, Kaiser J. Accurate micro-computed tomography imaging of pore spaces in collagen-based scaffold. JOURNAL OF MATERIALS SCIENCE. MATERIALS IN MEDICINE 2016; 27:110. [PMID: 27153826 DOI: 10.1007/s10856-016-5717-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2015] [Accepted: 04/09/2016] [Indexed: 06/05/2023]
Abstract
In this work we have used X-ray micro-computed tomography (μCT) as a method to observe the morphology of 3D porous pure collagen and collagen-composite scaffolds useful in tissue engineering. Two aspects of visualizations were taken into consideration: improvement of the scan and investigation of its sensitivity to the scan parameters. Due to the low material density some parts of collagen scaffolds are invisible in a μCT scan. Therefore, here we present different contrast agents, which increase the contrast of the scanned biopolymeric sample for μCT visualization. The increase of contrast of collagenous scaffolds was performed with ceramic hydroxyapatite microparticles (HAp), silver ions (Ag(+)) and silver nanoparticles (Ag-NPs). Since a relatively small change in imaging parameters (e.g. in 3D volume rendering, threshold value and μCT acquisition conditions) leads to a completely different visualized pattern, we have optimized these parameters to obtain the most realistic picture for visual and qualitative evaluation of the biopolymeric scaffold. Moreover, scaffold images were stereoscopically visualized in order to better see the 3D biopolymer composite scaffold morphology. However, the optimized visualization has some discontinuities in zoomed view, which can be problematic for further analysis of interconnected pores by commonly used numerical methods. Therefore, we applied the locally adaptive method to solve discontinuities issue. The combination of contrast agent and imaging techniques presented in this paper help us to better understand the structure and morphology of the biopolymeric scaffold that is crucial in the design of new biomaterials useful in tissue engineering.
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Affiliation(s)
- Jan Zidek
- CEITEC-Central European Institute of Technology, Brno University of Technology, Purkynova 123, 61200, Brno, Czech Republic.
| | - Lucy Vojtova
- CEITEC-Central European Institute of Technology, Brno University of Technology, Purkynova 123, 61200, Brno, Czech Republic
- SCITEG, a.s., Brno, Czech Republic
| | - A M Abdel-Mohsen
- CEITEC-Central European Institute of Technology, Brno University of Technology, Purkynova 123, 61200, Brno, Czech Republic
- Textile Research Division, National Research Centre, El-Buhouth St, P.O. Box 12311, Cairo, Egypt
| | - Jiri Chmelik
- Institute of Biomedical Engineering, FEEC, Brno University of Technology, Technicka 12, 61600, Brno, Czech Republic
| | - Tomas Zikmund
- CEITEC-Central European Institute of Technology, Brno University of Technology, Purkynova 123, 61200, Brno, Czech Republic
| | - Jana Brtnikova
- CEITEC-Central European Institute of Technology, Brno University of Technology, Purkynova 123, 61200, Brno, Czech Republic
| | - Roman Jakubicek
- Institute of Biomedical Engineering, FEEC, Brno University of Technology, Technicka 12, 61600, Brno, Czech Republic
| | - Lukas Zubal
- CEITEC-Central European Institute of Technology, Brno University of Technology, Purkynova 123, 61200, Brno, Czech Republic
| | - Jiri Jan
- Institute of Biomedical Engineering, FEEC, Brno University of Technology, Technicka 12, 61600, Brno, Czech Republic
| | - Jozef Kaiser
- CEITEC-Central European Institute of Technology, Brno University of Technology, Purkynova 123, 61200, Brno, Czech Republic
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Shimonobo T, Funama Y, Utsunomiya D, Nakaura T, Oda S, Kiguchi M, Masuda T, Sakabe D, Yamashita Y, Awai K. Low-tube-voltage selection for non-contrast-enhanced CT: Comparison of the radiation dose in pediatric and adult phantoms. Phys Med 2016; 32:197-201. [DOI: 10.1016/j.ejmp.2015.12.005] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/29/2015] [Revised: 11/30/2015] [Accepted: 12/11/2015] [Indexed: 11/30/2022] Open
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20
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Iterative reconstruction technique with reduced volume CT dose index: diagnostic accuracy in pediatric acute appendicitis. Pediatr Radiol 2015; 45:181-7. [PMID: 24996812 PMCID: PMC4308578 DOI: 10.1007/s00247-014-3109-7] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/27/2014] [Revised: 05/13/2014] [Accepted: 06/22/2014] [Indexed: 10/25/2022]
Abstract
BACKGROUND Iterative reconstruction technique has been proposed as a means of reducing patient radiation dose in pediatric CT. Yet, the effect of such reductions on diagnostic accuracy has not been thoroughly evaluated. OBJECTIVE This study compares accuracy of diagnosing pediatric acute appendicitis using contrast-enhanced abdominopelvic CT scans performed with traditional pediatric weight-based protocols and filtered back projection reconstruction vs. a filtered back projection/iterative reconstruction technique blend with reduced volume CT dose index (CTDIvol). MATERIALS AND METHODS Results of pediatric contrast-enhanced abdominopelvic CT scans done for pain and/or suspected appendicitis were reviewed in two groups: A, 192 scans performed with the hospital's established weight-based CT protocols and filtered back projection reconstruction; B, 194 scans performed with iterative reconstruction technique and reduced CTDIvol. Reduced CTDIvol was achieved primarily by reductions in effective tube current-time product (mAseff) and tube peak kilovoltage (kVp). CT interpretation was correlated with clinical follow-up and/or surgical pathology. CTDIvol, size-specific dose estimates (SSDE) and performance characteristics of the two CT techniques were then compared. RESULTS Between groups A and B, mean CTDIvol was reduced by 45%, and mean SSDE was reduced by 46%. Sensitivity, specificity and diagnostic accuracy were 96%, 97% and 96% in group A vs. 100%, 99% and 99% in group B. CONCLUSION Accuracy in diagnosing pediatric acute appendicitis was maintained in contrast-enhanced abdominopelvic CT scans that incorporated iterative reconstruction technique, despite reductions in mean CTDIvol and SSDE by nearly half as compared to the hospital's traditional weight-based protocols.
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Museyko O, Heinemann A, Krause M, Wulff B, Amling M, Püschel K, Glüer CC, Kalender W, Engelke K. A low-radiation exposure protocol for 3D QCT of the spine. Osteoporos Int 2014; 25:983-92. [PMID: 24142100 DOI: 10.1007/s00198-013-2544-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/02/2013] [Accepted: 09/30/2013] [Indexed: 10/26/2022]
Abstract
SUMMARY Cadaver and phantom measurements and simulations confirmed that radiation exposure in 3D QCT of the spine can be reduced if 80 kV instead of 120 kV protocols are used; 120 mAs and slice thicknesses of 1-1.3 mm should be usable but obese patient will require higher milliampere-second settings. PURPOSE To develop a low-radiation exposure CT acquisition protocol for 3D QCT of the thoracolumbar spine. METHODS Twenty-six cadavers were scanned with a standard protocol of 120 kV, 100 mAs and with a low-dose protocol using 90 kV, 150 mAs. The scan range included the vertebrae T6 to L4. Each vertebra was segmented and the integral volume and BMD of the total vertebral body were determined. Effective dose values were estimated. The impact of milliampere-second reduction on image quality was simulated by adding noise. RESULTS One hundred ninety-six vertebrae were analyzed. Integral volume as well as integral BMD correlated significantly (p < 0.001) between standard and low-dose protocols (volume, r (2) = 0.991, residual root mean square (RMS) error, 0.77 cm(3); BMD, r (2) = 0.985, RMS error, 4.21 mg/cm(3)). The slope significantly differed from 1 for integral BMD but not for volume hinting at residual field inhomogeneity differences between the two voltage settings that could be corrected by cross-calibration. Compared to the standard protocol, effective dose was reduced by over 50 % in the low-dose protocol. Adding noise in the 90 kV images to simulate a reduction from 150 to 100 mAs did not affect the results for integral volume or BMD. CONCLUSIONS For 3D QCT of the spine, depending on scanner type, 80 or 90 kV instead of 120 kV protocols may be considered as an important option to reduce radiation exposure; 120 mAs and slice thicknesses of 1-1.5 mm are usable if segmentation is robust to noise. In obese patients, higher milliampere-second settings will be required.
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Affiliation(s)
- O Museyko
- Institute of Medical Physics (IMP), University of Erlangen-Nuremberg, Henkestr. 91, 91052, Erlangen, Germany,
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