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Schoen JH, Burdette JH, West TG, Geer CP, Lipford ME, Sachs JR. Savings in CT Net Scan Energy Consumption: Assessment Using Dose Report Metrics and Comparison With Savings in Idle State Energy Consumption. AJR Am J Roentgenol 2024; 222:e2330189. [PMID: 37937836 DOI: 10.2214/ajr.23.30189] [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] [Indexed: 11/09/2023]
Abstract
BACKGROUND. CT scanners' net scan state (i.e., image acquisition period) represents a potential target for energy savings through protocol adjustments. However, gauging CT energy savings is difficult without installing costly energy monitors. OBJECTIVE. The purpose of this article was to assess correlations between CT dose report metrics and energy consumption during the system net scan state and to compare theoretic energy savings from matching percentage reductions in energy consumption during net scan and idle system states. METHODS. Current sensors were installed on a single CT scanner. A phantom was scanned at varying kilovoltage settings and effective tube current-rotation time settings. A retrospective assessment was performed in 32 patients (mean age, 61.2 ± 17.9 [SD] years; 17 men, 15 women) who underwent 32 single-energy noncontrast abdominopelvic CT examinations from September 22, 2021, to September 27, 2021, on the same scanner. Correlations between dose report metrics and net scan energy consumption were assessed in the phantom and clinical scans, and equations were generated to derive net scan energy consumption from DLP. An additional retrospective assessment was performed in 1355 patients (mean age, 59.3 ± 16.9 years; 663 men, 692 women) who underwent 1728 single-energy noncontrast abdominopelvic CT examinations from January 1, 2021, through December 31, 2021, on the same scanner to estimate net scan energy consumption per examination. This information was integrated with literature-derived values to compare estimated annual national energy savings resulting from 20% reductions in net scan and idle state energy consumption. RESULTS. Net scan energy consumption in the phantom scans showed high linear correlation with DLP (R2 = 0.87), and, in the clinical scans, high linear correlation with CTDIvol (R2 = 0.89) and very high linear correlation with DLP (R2 = 0.92). When combining mean DLP in examinations performed in the 1-year interval, an equation relating DLP and net scan energy consumption and literature values estimated that annual national energy savings was 14.9 times greater (40,437,870 kWh/2,704,000 kWh) by targeting the idle state rather than net scan state. CONCLUSION. CT net scan energy savings can be inferred from reductions in dose report metrics. However, targeting net scan energy consumption has modest impact relative to targeting idle state energy consumption. CLINICAL IMPACT. Environmental sustainability efforts should target the idle state energy consumption of CT.
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Affiliation(s)
- Julia H Schoen
- Department of Radiology, Wake Forest School of Medicine, One Medical Center Blvd, Winston-Salem, NC 27157
| | - Jonathan H Burdette
- Department of Radiology, Wake Forest School of Medicine, One Medical Center Blvd, Winston-Salem, NC 27157
| | - Thomas G West
- Department of Radiology, Wake Forest School of Medicine, One Medical Center Blvd, Winston-Salem, NC 27157
| | - Carol P Geer
- Department of Radiology, Wake Forest School of Medicine, One Medical Center Blvd, Winston-Salem, NC 27157
| | - Megan E Lipford
- Department of Radiology, Wake Forest School of Medicine, One Medical Center Blvd, Winston-Salem, NC 27157
| | - Jeffrey R Sachs
- Department of Radiology, Wake Forest School of Medicine, One Medical Center Blvd, Winston-Salem, NC 27157
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Yilmaz B, Guo X, Schimmel M, Abou-Ayash S. Effect of industrial scanner and framework material interaction on the marginal gaps of CAD-CAM complete arch implant frameworks. J Prosthet Dent 2023; 130:723-730. [PMID: 34998580 DOI: 10.1016/j.prosdent.2021.10.013] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2021] [Revised: 10/18/2021] [Accepted: 10/18/2021] [Indexed: 12/27/2022]
Abstract
STATEMENT OF PROBLEM Structured-light and computed tomography industrial scanners have been used as reference scanners to measure marginal gaps between implants and superstructures. However, the effect of framework material on the scanners' ability to detect gaps and on precision has not yet been evaluated. PURPOSE The purpose of this in vitro study was to investigate the interaction between the industrial scanner and framework material on measured marginal gaps of implant-supported fixed complete arch frameworks made from titanium and polymethylmethacrylate and on the precision of scans. MATERIAL AND METHODS A completely edentulous maxillary model with 4 implants and multiunit abutments at the first molar and canine sites was digitized by using a laboratory scanner. Implant-supported frameworks were milled from titanium and polymethylmethacrylate (n=5). Each framework was secured on the left molar site abutment. The marginal gaps between the frameworks and abutment sites without a screw were measured by using an industrial structured-light scanner and an industrial computed tomography scanner. The effect of the scanner, the framework material, and their interaction on measured gaps was analyzed by applying linear regressions and weighted least square methods. The F-statistics was used with Bonferroni corrections for precision analysis (α=.05). RESULTS No significant effect of scanner, material, or their interaction was found on the marginal gaps at the canine sites. The titanium framework gaps detected by using the computed tomography scanner were greater than those detected by using the structured-light scanner at the right molar site (estimated difference in means=0.054 mm; P=.003) and overall (estimated difference in means=0.023 mm; P=.033). The structured-light scanner's precision was higher than that of the computed tomography scanner when titanium frameworks were scanned (P=.001). The computed tomography scanner's precision was higher when scanning polymethylmethacrylate frameworks than when scanning titanium frameworks (P=.03). CONCLUSIONS Framework material and industrial scanner interaction affected the measured gaps. The computed tomography scanner detected greater marginal gaps with low precision when scanning titanium frameworks than the structured-light scanner. The sample size, the use of only 2 types of materials, and a laboratory scanner to obtain the computer-aided design file should be considered when interpreting the results.
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Affiliation(s)
- Burak Yilmaz
- Associate Professor, Department of Reconstructive Dentistry and Gerodontology, School of Dental Medicine, University of Bern, Bern, Switzerland; Associate Professor, Department of Restorative, Preventive and Pediatric Dentistry, School of Dental Medicine, University of Bern, Bern, Switzerland; Adjunct Professor, Division of Restorative and Prosthetic Dentistry, The Ohio State University College of Dentistry, Columbus, Ohio
| | - Xiaohan Guo
- PhD student, Division of Biostatistics, College of Public Health, The Ohio State University, Columbus, Ohio
| | - Martin Schimmel
- Department Head, Department of Reconstructive Dentistry and Gerodontology, University of Bern, Bern, Switzerland; Senior Lecturer, Extra muros, Division of Gerodontology and Removable Prosthodontics, University Clinics of Dental Medicine, University of Geneva, Geneva, Switzerland
| | - Samir Abou-Ayash
- Senior Lecturer and Head of the Section of Digital Implant and Reconstructive Dentistry, Department of Reconstructive Dentistry and Gerodontology, University of Bern, Bern, Switzerland.
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Bohang SAM, Sohaimi N. An Overview on the Alignment of Radiation Protection in Computed Tomography with Maqasid al-Shari'ah in the Context of al-Dharuriyat. Malays J Med Sci 2023; 30:60-72. [PMID: 37425388 PMCID: PMC10325131 DOI: 10.21315/mjms2023.30.3.5] [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: 07/26/2021] [Accepted: 01/08/2022] [Indexed: 07/11/2023] Open
Abstract
The increasing utilisation of computed tomography (CT) in the medical field has raised a greater concern regarding the radiation-induced health effects as CT imposes high radiation risks on the exposed individual. Adherence to radiation protection measures in CT as endorsed by regulatory bodies; justification, optimisation and dose limit, is essential to minimise radiation risks. Islam values every human being and Maqasid al-Shari'ah helps to protect human beings through its sacred principles which aim to fulfil human beings' benefits (maslahah) and prevent mischief (mafsadah). Alignment of the concept of radiation protection in CT within the framework of al-Dharuriyat; protection of faith or religion (din), protection of life (nafs), protection of lineage (nasl), protection of intellect ('aql) and protection of property (mal) is essential. This strengthens the concept and practices of radiation protection in CT among radiology personnel, particularly Muslim radiographers. The alignment provides supplementary knowledge towards the integration of knowledge fields between Islamic worldview and radiation protection in medical imaging, particularly in CT. This paper is hoped to set a benchmark for future studies on the integration of knowledge between the Islamic worldview and radiation protection in medical imaging in terms of other classifications of Maqasid al-Shari'ah; al-Hajiyat and al-Tahsiniyat.
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Affiliation(s)
- Siti Aisyah Munirah Bohang
- Department of Diagnostic Imaging and Radiotherapy, Kulliyyah of Allied Health Sciences, International Islamic University Malaysia, Pahang, Malaysia
| | - Norhanna Sohaimi
- Department of Diagnostic Imaging and Radiotherapy, Kulliyyah of Allied Health Sciences, International Islamic University Malaysia, Pahang, Malaysia
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Lenfant M, Comby PO, Guillen K, Galissot F, Haioun K, Thay A, Chevallier O, Ricolfi F, Loffroy R. Deep Learning-Based Reconstruction vs. Iterative Reconstruction for Quality of Low-Dose Head-and-Neck CT Angiography with Different Tube-Voltage Protocols in Emergency-Department Patients. Diagnostics (Basel) 2022; 12:1287. [PMID: 35626442 PMCID: PMC9142122 DOI: 10.3390/diagnostics12051287] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2022] [Revised: 05/18/2022] [Accepted: 05/19/2022] [Indexed: 11/20/2022] Open
Abstract
Objective: To compare the image quality of computed tomography angiography of the supra-aortic arteries (CTSA) at different tube voltages in low doses settings with deep learning-based image reconstruction (DLR) vs. hybrid iterative reconstruction (H-IR). Methods: We retrospectively reviewed 102 patients who underwent CTSA systematically reconstructed with both DLR and H-IR. We assessed the image quality both quantitatively and qualitatively at 11 arterial segmental levels and 3 regional levels. Radiation-dose parameters were recorded and the effective dose was calculated. Eighty-six patients were eligible for analysis Of these patients, 27 were imaged with 120 kVp, 30 with 100 kVp, and 29 with 80 kVp. Results: The effective dose in 120 kVp, 100 kVp and 80 kVp was 1.5 ± 0.4 mSv, 1.1 ± 0.3 mSv and 0.68 ± 0.1 mSv, respectively (p < 0.01). Comparing 80 kVp + DLR vs. 120 and 100 kVp + H-IR CT scans, the mean overall arterial attenuation was about 64% and 34% higher (625.9 ± 118.5 HU vs. 382.3 ± 98.6 HU and 468 ± 118.5 HU; p < 0.01) without a significant difference in terms of image noise (17.7 ± 4.9 HU vs. 17.5 ± 5.2; p = 0.7 and 18.1 ± 5.4; p = 0.3) and signal-to-ratio increased by 59% and 33%, respectively (37.9 ± 12.3 vs. 23.8 ± 9.7 and 28.4 ± 12.5). This protocol also provided superior image quality in terms of qualitative parameters, compared to standard-kVp protocols with H-IR. Highest subjective image-quality grades for vascular segments close to the aorta were obtained with the 100 kVp + DLR protocol. Conclusions: DLR significantly reduced image noise and improved the overall image quality of CTSA with both low and standard tube voltages and at all vascular segments. CT that was acquired with 80 kVp and reconstructed with DLR yielded better overall image quality compared to higher kVp values with H-IR, while reducing the radiation dose by half, but it has limitations for arteries that are close to the aortic arch.
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Affiliation(s)
- Marc Lenfant
- Department of Neuroradiology and Emergency Radiology, François-Mitterrand University Hospital, 14 Rue 7 Paul Gaffarel, BP 77908, 21079 Dijon, France; (M.L.); (P.-O.C.); (F.G.); (F.R.)
- Imaging and Artificial Vision (ImViA) Laboratory-EA 7535, University of Bourgogne/Franche-Comté, 9 10 Avenue Alain Savary, BP 47870, 21078 Dijon, France; (K.G.); (O.C.)
| | - Pierre-Olivier Comby
- Department of Neuroradiology and Emergency Radiology, François-Mitterrand University Hospital, 14 Rue 7 Paul Gaffarel, BP 77908, 21079 Dijon, France; (M.L.); (P.-O.C.); (F.G.); (F.R.)
- Imaging and Artificial Vision (ImViA) Laboratory-EA 7535, University of Bourgogne/Franche-Comté, 9 10 Avenue Alain Savary, BP 47870, 21078 Dijon, France; (K.G.); (O.C.)
| | - Kevin Guillen
- Imaging and Artificial Vision (ImViA) Laboratory-EA 7535, University of Bourgogne/Franche-Comté, 9 10 Avenue Alain Savary, BP 47870, 21078 Dijon, France; (K.G.); (O.C.)
- Department of Vascular and Interventional Radiology, Image-Guided Therapy Center, François-Mitterrand 13 University Hospital, 14 Rue Paul Gaffarel, BP 77908, 21079 Dijon, France
| | - Felix Galissot
- Department of Neuroradiology and Emergency Radiology, François-Mitterrand University Hospital, 14 Rue 7 Paul Gaffarel, BP 77908, 21079 Dijon, France; (M.L.); (P.-O.C.); (F.G.); (F.R.)
| | - Karim Haioun
- Computed Tomography Division, Canon Medical Systems France, 24 Quai Gallieni, 92150 Suresnes, France; (K.H.); (A.T.)
| | - Anthony Thay
- Computed Tomography Division, Canon Medical Systems France, 24 Quai Gallieni, 92150 Suresnes, France; (K.H.); (A.T.)
| | - Olivier Chevallier
- Imaging and Artificial Vision (ImViA) Laboratory-EA 7535, University of Bourgogne/Franche-Comté, 9 10 Avenue Alain Savary, BP 47870, 21078 Dijon, France; (K.G.); (O.C.)
- Department of Vascular and Interventional Radiology, Image-Guided Therapy Center, François-Mitterrand 13 University Hospital, 14 Rue Paul Gaffarel, BP 77908, 21079 Dijon, France
| | - Frédéric Ricolfi
- Department of Neuroradiology and Emergency Radiology, François-Mitterrand University Hospital, 14 Rue 7 Paul Gaffarel, BP 77908, 21079 Dijon, France; (M.L.); (P.-O.C.); (F.G.); (F.R.)
| | - Romaric Loffroy
- Imaging and Artificial Vision (ImViA) Laboratory-EA 7535, University of Bourgogne/Franche-Comté, 9 10 Avenue Alain Savary, BP 47870, 21078 Dijon, France; (K.G.); (O.C.)
- Department of Vascular and Interventional Radiology, Image-Guided Therapy Center, François-Mitterrand 13 University Hospital, 14 Rue Paul Gaffarel, BP 77908, 21079 Dijon, France
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Bielecka M, Bielecki A, Obuchowicz R, Piórkowski A. Universal Measure for Medical Image Quality Evaluation Based on Gradient Approach. LECTURE NOTES IN COMPUTER SCIENCE 2020. [PMCID: PMC7303719 DOI: 10.1007/978-3-030-50423-6_30] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
In this paper, a new universal measure of medical images quality is proposed. The measure is based on the analysis of the image by using gradient methods. The number of isolated peaks in the examined image, as a function of the threshold value, is the basis of the assessment of the image quality. It turns out that for higher quality images the curvature of the graph of the said function has a higher value for lower threshold values. On the basis of the observed property, a new method of no-reference image quality assessment has been created. The experimental verification confirmed the method efficiency. The correlation between the arrangement depending on the image quality done by an expert and by using the proposed method is equal to 0.74. This means that the proposed method gives a correlation of higher than the best methods described in the literature. The proposed measure is useful to maximize the image quality while minimizing the time of medical examination.
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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: 0.3] [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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Abstract
Significant anxiety has been expressed by some over the radiation risks associated with computed tomography (CT), particularly when it applies to a screening examination such as CT colonography. These theoretic risks are far outweighed by the significant benefits colorectal cancer screening offers. Regardless of how significant the theoretic risk of CT radiation is in the older population, the ALARA principle maintains that radiation dose should be reduced to As Low As Reasonably Achievable. This article will discuss various strategies that may be utilized to reduce radiation dose and mitigate any increase in image noise that may occur.
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Affiliation(s)
- Kevin J Chang
- Department of Radiology, Newton-Wellesley Hospital, Brown University Alpert Medical School, 2014 Washington Street, Newton, MA 02462, USA.
| | - Judy Yee
- Department of Radiology, Montefiore Medical Center, Albert Einstein College of Medicine, 111 East 210th Street, Bronx, NY 10467, USA
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Assessment of Radiation Dose and Image Quality of Multidetector Computed Tomography. IRANIAN JOURNAL OF RADIOLOGY 2018. [DOI: 10.5812/iranjradiol.59554] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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Yee J, McFarland E. Extracolonic findings and radiation at CT colonography: what the referring provider needs to know. Abdom Radiol (NY) 2018; 43:554-565. [PMID: 29450613 DOI: 10.1007/s00261-018-1461-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
A better understanding of the risks and benefits of extracolonic findings and radiation dose will aid in the safe and proper implementation of CT colonography in clinical practice. The majority of extracolonic findings in screening patients are benign and can be ignored by referring physicians. Radiologists also need to be responsible in reporting extracolonic findings. Referring providers must be knowledgeable about the theoretic risks and controversies regarding the use of ionizing radiation. Screening CT colonography imparts a low-level of radiation to patients that is equivalent or less than annual background dose.
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Affiliation(s)
- Judy Yee
- Department of Radiology, Albert Einstein College of Medicine, Montefiore Medical Center, 111 East 210th St, Bronx, NY, 10467, USA.
| | - Elizabeth McFarland
- SSM St. Joseph Health Center, 300 Capitol Drive, St. Charles, MO, 63301, USA
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Ngo AV, Winant AJ, Lee EY, Phillips GS. Strategies for Reducing Radiation Dose in CT for Pediatric Patients: How We Do It. Semin Roentgenol 2018; 53:124-131. [PMID: 29861004 DOI: 10.1053/j.ro.2018.02.003] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Anh-Vu Ngo
- Department of Radiology, Seattle Children's Hospital, University of Washington School of Medicine, Seattle, WA
| | - Abbey J Winant
- Department of Radiology, Boston Children's Hospital, Harvard Medical School, Boston, MA
| | - Edward Y Lee
- Departments of Radiology and Medicine, Pulmonary Division, Boston Children's Hospital and Harvard Medical School, Boston, MA
| | - Grace S Phillips
- Department of Radiology, Seattle Children's Hospital, University of Washington School of Medicine, Seattle, WA.
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Zheng X, Nardi L, Murray M. Size effect on dose output in phantoms of x-ray tubes in medical x-ray imaging. Biomed Phys Eng Express 2017. [DOI: 10.1088/2057-1976/aa88f2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Zheng X. PATIENT SIZE BASED GUIDING EQUATIONS FOR AUTOMATIC mAs AND kVp SELECTIONS IN GENERAL MEDICAL X-RAY PROJECTION RADIOGRAPHY. RADIATION PROTECTION DOSIMETRY 2017; 174:545-550. [PMID: 27574322 DOI: 10.1093/rpd/ncw246] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2016] [Accepted: 07/27/2016] [Indexed: 06/06/2023]
Abstract
A patient size based guiding equation for the automatic selections of mAs and peak voltage kVp in general medical X-ray projection radiography was derived from the first principles of dose and image quality optimization. Under various specific conditions of constant patient size d, kVp or mAs, this equation leads to various longstanding 'rules of thumbs' currently being employed in clinical practice. For automatic mAs control, this work suggests that the current level of dose to patient in X-ray radiography should be halved without compromise image quality. Further studies on the dependence of the absorbed dose on the patient's thickness are required in general X-ray projection radiography.
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Affiliation(s)
- Xiaoming Zheng
- Medical Radiation Science, School of Dentistry and Health Sciences, Faculty of Science, Charles Sturt University, Wagga Wagga, New South Wales2678, Australia
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Bujila R, Fransson A, Poludniowski G. Practical approaches to approximating MTF and NPS in CT with an example application to task-based observer studies. Phys Med 2016; 33:16-25. [PMID: 28003136 DOI: 10.1016/j.ejmp.2016.10.016] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/31/2016] [Revised: 09/07/2016] [Accepted: 10/19/2016] [Indexed: 01/20/2023] Open
Abstract
PURPOSE To investigate two methods of approximating the Modulation Transfer Function (MTF) and Noise Power Spectrum (NPS) in computed tomography (CT) for a range of scan parameters, from limited image acquisitions. METHODS The two methods consist of 1) using a linear systems approach to approximate the NPS for different filtered backprojection (FBP) kernels with a filter function derived from the kernel ratio of determined MTFs and 2) using an empirical fitted model to approximate the MTF and NPS. In both cases a scaling function accounts for variations in mAs and kV. The two methods of approximating the MTF/NPS are further investigated by comparing image quality figure of merits (FOM) d' and AUC calculated using approximations of the MTF/NPS and MTF/NPS that have been determined for different mAs/kV levels and reconstruction kernels. RESULTS The greatest RMSE for NPS approximated for a range of mAs/kVp/convolution kernels using both methods and compared to determined NPS was 0.05 of the peak value. The RMSE for FOM with the kernel ratio method were at most 0.1 for d' and 0.01 for the AUC. Using the empirical model method, the RMSE for FOM were at most 0.02 for d' and 0.001 for the AUC. CONCLUSIONS The two methods proposed in this paper can provide a convenient way of approximating the MTF and NPS for use in, among other things, mathematical observer studies. Both methods require a relatively small number of direct determinations of NPS from scan acquisitions to model the NPS/MTF for arbitrary mAs and kV.
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Affiliation(s)
- Robert Bujila
- Medical Radiation Physics and Nuclear Medicine, Karolinska University Hospital, SE-17176 Stockholm, Sweden; Department of Physics, Royal Institute of Technology, SE-106 91 Stockholm, Sweden.
| | - Annette Fransson
- Medical Radiation Physics and Nuclear Medicine, Karolinska University Hospital, SE-17176 Stockholm, Sweden
| | - Gavin Poludniowski
- Medical Radiation Physics and Nuclear Medicine, Karolinska University Hospital, SE-17176 Stockholm, Sweden
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Breast dose reduction for chest CT by modifying the scanning parameters based on the pre-scan size-specific dose estimate (SSDE). Eur Radiol 2016; 27:2267-2274. [DOI: 10.1007/s00330-016-4618-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2016] [Revised: 09/12/2016] [Accepted: 09/22/2016] [Indexed: 01/20/2023]
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Optimizing CT technique to reduce radiation dose: effect of changes in kVp, iterative reconstruction, and noise index on dose and noise in a human cadaver. Radiol Phys Technol 2016; 10:180-188. [DOI: 10.1007/s12194-016-0382-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2016] [Revised: 09/21/2016] [Accepted: 09/25/2016] [Indexed: 10/20/2022]
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Schmid AI, Uder M, Lell MM. Reaching for better image quality and lower radiation dose in head and neck CT: advanced modeled and sinogram-affirmed iterative reconstruction in combination with tube voltage adaptation. Dentomaxillofac Radiol 2016; 46:20160131. [PMID: 27540625 DOI: 10.1259/dmfr.20160131] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
OBJECTIVES The aim of this study was to evaluate image quality and radiation dose in low-dose head and neck CT comparing two different commercially available iterative reconstruction algorithms: sinogram-affirmed iterative reconstruction (SAFIRE) and advanced modeled iterative reconstruction (ADMIRE) with fixed and automated tube voltage adaptation (TVA). METHODS CT examinations of 103 patients were analysed. 58 patients were examined on a single-source CT at fixed tube voltage of 120 kV and reconstructed with filtered back projection (FBP) and SAFIRE (Strength Level 3). 45 patients were examined in a single-source mode on a dual-source CT with automated TVA and reconstructed with FBP and ADMIRE (Strength Levels 2 and 3). Image noise was calculated in seven anatomical volumes of interest. Subjective evaluation of the CT images was performed using a four-grade scale. RESULTS Mean CT numbers of FBP and the corresponding iterative reconstruction did not differ significantly (p = 0.74-0.99). Image noise was lower with both iterative reconstruction techniques than with FBP (SAFIRE 3: -22.3%; ADMIRE 2: -14.9%; ADMIRE 3: -24.2%; all p < 0.05); hence, the signal-to-noise ratio and the contrast-to-noise values were higher. Subjective image quality revealed a more favourable result for the iterative reconstruction. ADMIRE 3 in combination with automated TVA showed 14.4% (p < 0.05) less image noise with a 7.5% lower radiation dose than SAFIRE 3 with fixed tube voltage. CONCLUSIONS Higher image quality at lower radiation dose can be achieved using ADMIRE in combination with automated TVA.
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Affiliation(s)
- Andrea I Schmid
- 1 Department of Radiology, University Hospital Erlangen, Friedrich-Alexander-University Erlangen-Nürnberg (FAU), Germany
| | - Michael Uder
- 1 Department of Radiology, University Hospital Erlangen, Friedrich-Alexander-University Erlangen-Nürnberg (FAU), Germany.,2 Imaging Science Institute (ISI) Erlangen, Department of Radiology, Friedrich-Alexander-University Erlangen-Nürnberg (FAU), Germany
| | - Michael M Lell
- 1 Department of Radiology, University Hospital Erlangen, Friedrich-Alexander-University Erlangen-Nürnberg (FAU), Germany.,3 Department of Radiology and Nuclear Medicine, Klinikum Nürnberg, Germany, Paracelsus Medical University
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One-mSv CT colonography: Effect of different iterative reconstruction algorithms on radiologists' performance. Eur J Radiol 2016; 85:641-8. [PMID: 26860679 DOI: 10.1016/j.ejrad.2015.12.030] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2015] [Revised: 12/22/2015] [Accepted: 12/29/2015] [Indexed: 12/24/2022]
Abstract
PURPOSE To analyze the effect of different reconstruction algorithms on image noise and radiologists' performance at ultra-low dose CT colonography (CTC) in human subjects. MATERIALS AND METHODS This retrospective study had institutional review board approval, with waiver of the need to obtain informed consent. CTC and subsequent colonoscopy were performed at the same day in 28 patients. CTC was scanned at the supine/prone positions using 120/100kVp and fixed 10mAs, and reconstructed using filtered back projection (FBP), adaptive statistical iterative reconstruction (ASIR), and model-based IR (Veo) algorithms. Size-specific dose estimates (SSDE) and effective radiation doses were recorded. Image noise was compared among the three datasets using repeated measures analysis of variance (ANOVA). Per-polyp sensitivity and figure-of-merits were compared among the datasets using the McNemar test and jackknife alternative free-response receiver operating characteristic (JAFROC) analysis, respectively, by one novice and one expert reviewer in CTC. RESULTS Mean SSDE and effective radiation dose of CTC were 1.732mGy and 1.002mSv, respectively. Mean image noise at supine/prone position datasets was significantly lowest with Veo (17.2/13.3), followed by ASIR (52.4/38.9) and FBP (69.9/50.8) (P<0.0001). Forty-two polyps in 25 patients were reference polyps. For both readers, per-polyp sensitivity of all 42 polyps was highest with Veo reconstruction (81.0%, 64.3%), followed by ASIR (73.8%, 54.8%) and FBP (57.1%, 50.0%) with statistical significance between Veo and FBP for reader 1 (P=0.002). JAFROC analysis revealed that the figure-of-merit for the detection of polyps was highest with Veo (0.917, 0.786), followed by ASIR (0.881, 0.750) and FBP (0.750, 0.746) with statistical significances between Veo or ASIR and FBP for reader 1 (P<0.05). CONCLUSION One-mSv CTC was not feasible using the standard FBP algorithm. However, diagnostic performance expressed as per-polyp sensitivity and figures-of-merit can be improved with the application of IR algorithms, particularly Veo.
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Image Quality and Radiation Dose of CT Coronary Angiography with Automatic Tube Current Modulation and Strong Adaptive Iterative Dose Reduction Three-Dimensional (AIDR3D). PLoS One 2015; 10:e0142185. [PMID: 26599111 PMCID: PMC4657884 DOI: 10.1371/journal.pone.0142185] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2014] [Accepted: 10/19/2015] [Indexed: 02/07/2023] Open
Abstract
Purpose To investigate image quality and radiation dose of CT coronary angiography (CTCA) scanned using automatic tube current modulation (ATCM) and reconstructed by strong adaptive iterative dose reduction three-dimensional (AIDR3D). Methods Eighty-four consecutive CTCA patients were collected for the study. All patients were scanned using ATCM and reconstructed with strong AIDR3D, standard AIDR3D and filtered back-projection (FBP) respectively. Two radiologists who were blinded to the patients' clinical data and reconstruction methods evaluated image quality. Quantitative image quality evaluation included image noise, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR). To evaluate image quality qualitatively, coronary artery is classified into 15 segments based on the modified guidelines of the American Heart Association. Qualitative image quality was evaluated using a 4-point scale. Radiation dose was calculated based on dose-length product. Results Compared with standard AIDR3D, strong AIDR3D had lower image noise, higher SNR and CNR, their differences were all statistically significant (P<0.05); compared with FBP, strong AIDR3D decreased image noise by 46.1%, increased SNR by 84.7%, and improved CNR by 82.2%, their differences were all statistically significant (P<0.05 or 0.001). Segments with diagnostic image quality for strong AIDR3D were 336 (100.0%), 486 (96.4%), and 394 (93.8%) in proximal, middle, and distal part respectively; whereas those for standard AIDR3D were 332 (98.8%), 472 (93.7%), 378 (90.0%), respectively; those for FBP were 217 (64.6%), 173 (34.3%), 114 (27.1%), respectively; total segments with diagnostic image quality in strong AIDR3D (1216, 96.5%) were higher than those of standard AIDR3D (1182, 93.8%) and FBP (504, 40.0%); the differences between strong AIDR3D and standard AIDR3D, strong AIDR3D and FBP were all statistically significant (P<0.05 or 0.001). The mean effective radiation dose was (2.55±1.21) mSv. Conclusion Compared with standard AIDR3D and FBP, CTCA with ATCM and strong AIDR3D could significantly improve both quantitative and qualitative image quality.
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Kidoh M, Utsunomiya D, Oda S, Funama Y, Yuki H, Nakaura T, Kai N, Nozaki T, Yamashita Y. Validity of the size-specific dose estimate in adults undergoing coronary CT angiography: comparison with the volume CT dose index. Int J Cardiovasc Imaging 2015; 31 Suppl 2:205-11. [PMID: 26440660 DOI: 10.1007/s10554-015-0782-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/21/2015] [Accepted: 09/30/2015] [Indexed: 11/25/2022]
Abstract
Size-specific dose estimate (SSDE) takes into account the patient size but remains to be fully validated for adult coronary computed tomography angiography (CCTA). We investigated the appropriateness of SSDE for accurate estimation of patient dose by comparing the SSDE and the volume CT dose index (CTDIvol) in adult CCTA. This prospective study received institutional review board approval, and informed consent was obtained from each patient. We enrolled 37 adults who underwent CCTA with a 320-row CT. High-sensitivity metal oxide semiconductor field effect transistor dosimeters were placed on the anterior chest. CTDIvol reported by the scanner based on a 32-cm phantom was recorded. We measured chest diameter to convert CTDIvol to SSDE. Using linear regression, we then correlated SSDE with the mean measured skin dose. We also performed linear regression analyses between the skin dose/CTDIvol and the body mass index (BMI), and the skin dose/SSDE and BMI. There was a strong linear correlation (r = 0.93, P < 0.001) between SSDE (mean 37 ± 22 mGy) and mean skin dose (mean 17.7 ± 10 mGy). There was a moderate negative correlation between the skin dose/CTDIvol and BMI (r = 0.45, P < 0.01). The skin dose/SSDE was not affected by BMI (r = 0.06, P > 0.76). SSDE yields a more accurate estimation of the radiation dose without estimation errors attributable to the body size of adult patients undergoing CCTA.
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Affiliation(s)
- Masafumi Kidoh
- Department of Diagnostic Radiology, Faculty of Life Sciences, Kumamoto University, 1-1-1, Honjo, Kumamoto, 860-8556, Japan.
| | - Daisuke Utsunomiya
- Department of Diagnostic Radiology, Faculty of Life Sciences, Kumamoto University, 1-1-1, Honjo, Kumamoto, 860-8556, Japan
| | - Seitaro Oda
- Department of Diagnostic Radiology, Faculty of Life Sciences, Kumamoto University, 1-1-1, Honjo, Kumamoto, 860-8556, Japan
| | - Yoshinori Funama
- Department of Medical Physics, Faculty of Life Sciences, Kumamoto University, 1-1-1, Honjo, Kumamoto, 860-8556, Japan
| | - Hideaki Yuki
- Department of Diagnostic Radiology, Faculty of Life Sciences, Kumamoto University, 1-1-1, Honjo, Kumamoto, 860-8556, Japan
| | - Takeshi Nakaura
- Department of Diagnostic Radiology, Faculty of Life Sciences, Kumamoto University, 1-1-1, Honjo, Kumamoto, 860-8556, Japan
| | - Noriyuki Kai
- Department of Diagnostic Radiology, Faculty of Life Sciences, Kumamoto University, 1-1-1, Honjo, Kumamoto, 860-8556, Japan
| | - Takeshi Nozaki
- Department of Diagnostic Radiology, Faculty of Life Sciences, Kumamoto University, 1-1-1, Honjo, Kumamoto, 860-8556, Japan
| | - Yasuyuki Yamashita
- Department of Diagnostic Radiology, Faculty of Life Sciences, Kumamoto University, 1-1-1, Honjo, Kumamoto, 860-8556, Japan
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Chang K, Heisler M, Mahesh M, Baird G, Mayo-Smith W. CT colonography at low tube potential: using iterative reconstruction to decrease noise. Clin Radiol 2015; 70:981-8. [DOI: 10.1016/j.crad.2015.05.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2014] [Revised: 03/24/2015] [Accepted: 05/12/2015] [Indexed: 01/15/2023]
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Nowik P, Bujila R, Poludniowski G, Fransson A. Quality control of CT systems by automated monitoring of key performance indicators: a two-year study. J Appl Clin Med Phys 2015. [PMID: 26219012 PMCID: PMC5690007 DOI: 10.1120/jacmp.v16i4.5469] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
The purpose of this study was to develop a method of performing routine periodical quality controls (QC) of CT systems by automatically analyzing key performance indicators (KPIs), obtainable from images of manufacturers' quality assurance (QA) phantoms. A KPI pertains to a measurable or determinable QC parameter that is influenced by other underlying fundamental QC parameters. The established KPIs are based on relationships between existing QC parameters used in the annual testing program of CT scanners at the Karolinska University Hospital in Stockholm, Sweden. The KPIs include positioning, image noise, uniformity, homogeneity, the CT number of water, and the CT number of air. An application (MonitorCT) was developed to automatically evaluate phantom images in terms of the established KPIs. The developed methodology has been used for two years in clinical routine, where CT technologists perform daily scans of the manufacturer's QA phantom and automatically send the images to MonitorCT for KPI evaluation. In the cases where results were out of tolerance, actions could be initiated in less than 10 min. 900 QC scans from two CT scanners have been collected and analyzed over the two‐year period that MonitorCT has been active. Two types of errors have been registered in this period: a ring artifact was discovered with the image noise test, and a calibration error was detected multiple times with the CT number test. In both cases, results were outside the tolerances defined for MonitorCT, as well as by the vendor. Automated monitoring of KPIs is a powerful tool that can be used to supplement established QC methodologies. Medical physicists and other professionals concerned with the performance of a CT system will, using such methods, have access to comprehensive data on the current and historical (trend) status of the system such that swift actions can be taken in order to ensure the quality of the CT examinations, patient safety, and minimal disruption of service PACS numbers: 87.57.C‐, 87.57.N‐, 87.57.Q‐
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Shen H, Liang D, Luo M, Duan C, Cai W, Zhu S, Qiu J, Li W. Pilot study on image quality and radiation dose of CT colonography with adaptive iterative dose reduction three-dimensional. PLoS One 2015; 10:e0117116. [PMID: 25635839 PMCID: PMC4311968 DOI: 10.1371/journal.pone.0117116] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2014] [Accepted: 12/17/2014] [Indexed: 12/19/2022] Open
Abstract
Objective To investigate image quality and radiation dose of CT colonography (CTC) with adaptive iterative dose reduction three-dimensional (AIDR3D). Methods Ten segments of porcine colon phantom were collected, and 30 pedunculate polyps with diameters ranging from 1 to 15 mm were simulated on each segment. Image data were acquired with tube voltage of 120 kVp, and current doses of 10 mAs, 20 mAs, 30 mAs, 40 mAs, 50 mAs, respectively. CTC images were reconstructed using filtered back projection (FBP) and AIDR3D. Two radiologists blindly evaluated image quality. Quantitative evaluation of image quality included image noise, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR). Qualitative image quality was evaluated with a five-score scale. Radiation dose was calculated based on dose-length product. Ten volunteers were examined supine 50 mAs with FBP and prone 20 mAs with AIDR3D, and image qualities were assessed. Paired t test was performed for statistical analysis. Results For 20 mAs with AIDR3D and 50 mAs with FBP, image noise, SNRs and CNRs were (16.4 ± 1.6) HU vs. (16.8 ± 2.6) HU, 1.9 ± 0.2 vs. 1.9 ± 0.4, and 62.3 ± 6.8 vs. 62.0 ± 6.2, respectively; qualitative image quality scores were 4.1 and 4.3, respectively; their differences were all not statistically significant. Compared with 50 mAs with FBP, radiation dose (1.62 mSv) of 20 mAs with AIDR3D was decreased by 60.0%. There was no statistically significant difference in image noise, SNRs, CNRs and qualitative image quality scores between prone 20 mAs with AIDR3D and supine 50 mAs with FBP in 10 volunteers, the former reduced radiation dose by 61.1%. Conclusion Image quality of CTC using 20 mAs with AIDR3D could be comparable to standard 50 mAs with FBP, radiation dose of the former reduced by about 60.0% and was only 1.62 mSv.
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Affiliation(s)
- Hesong Shen
- Department of Radiology, The Sixth Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Dan Liang
- Department of Radiology, The Sixth Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Mingyue Luo
- Department of Radiology, The Sixth Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong, China
- * E-mail:
| | - Chaijie Duan
- Research Center of Biomedical Engineering, Graduate School at Shenzhen, Tsinghua University, Shenzhen, Guangdong, China
| | - Wenli Cai
- Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts, United States of America
| | - Shanshan Zhu
- Department of Radiology, The Sixth Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Jianping Qiu
- Department of Radiology, The Sixth Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Wenru Li
- Department of Radiology, The Sixth Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong, China
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Shin CI, Kim SH, Lee ES, Lee DH, Hwang EJ, Chung SY, Lee JM, Han JK, Choi BI. Ultra-low peak voltage CT colonography: effect of iterative reconstruction algorithms on performance of radiologists who use anthropomorphic colonic phantoms. Radiology 2014; 273:759-71. [PMID: 25010640 DOI: 10.1148/radiol.14140192] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
PURPOSE To analyze the effect of a decrease in computed tomographic (CT) colonographic voltage, from 100 and 120 kVp to 80 kVp and reconstructed with filtered back projection ( FBP filtered back projection ), on radiation dose, image noise, and diagnostic performance in anthropomorphic phantoms and to assess the effect of iterative reconstruction ( IR iterative reconstruction ) algorithms on radiologists' performance for 80-kVp CT colonography. MATERIALS AND METHODS Seven colon phantoms with 68 simulated polyps (≥6 mm) were scanned at three peak voltage settings (80, 100, 120 kVp) and 10 mAs. Images were reconstructed by using FBP filtered back projection , hybrid statistic-based IR iterative reconstruction , and knowledge-based IR iterative reconstruction algorithms. Effective radiation dose, image noise, and per-polyp sensitivity were recorded and compared by two reviewers with Friedman test, repeated measures analysis of variance, and McNemar test. RESULTS Median size-specific dose estimate and effective radiation dose of 80-kVp CT colonography was 0.231 mGy and 0.167 mSv, respectively, which was lower than with 100- and 120-kVp CT colonography, with significant difference between 80 and 120 kVp (P = .0005). Image noise (202.0 HU) at 80-kVp FBP filtered back projection CT colonography was significantly higher than at 100-kVp FBP filtered back projection (139.1 HU) and 120-kVp FBP filtered back projection (120.4 HU) (P < .0001). Per-polyp sensitivity (reviewer 1, 14.7% [10 of 68]; reviewer 2, 7.4% [five of 68]) at 80-kVp FBP filtered back projection was significantly lower than at 100-kVp FBP filtered back projection (reviewer 1, 57.4% [39 of 68]; reviewer 2, 39.7% [27 of 68]) and 120-kVp FBP filtered back projection (reviewer 1, 85.3% [58 of 68]; reviewer 2, 83.8% [57 of 68]) (P < .0001). With statistic-based IR iterative reconstruction , image noise at 80 kVp decreased significantly (52.8% [106.7 HU of 202.0 HU]) compared with that at 80-kVp FBP filtered back projection (P < .0001), but per-polyp sensitivity (reviewer 1, 79.4% [54 of 68]; reviewer 2, 66.2% [45 of 68]) at 80-kVp statistic-based IR iterative reconstruction remained significantly lower than at 100-kVp statistic-based IR iterative reconstruction (reviewer 1, 95.6% [65 of 68]; reviewer 2, 86.8% [59 of 68]) (P = .001) and 120-kVp statistic-based IR iterative reconstruction (reviewer 1, 98.5% [67 of 68]; reviewer 2, 89.7% [61 of 68]) (P < .001). For knowledge-based IR iterative reconstruction , per-polyp sensitivity at 80 kVp was improved to 98.5% (67 of 68) and 94.1% (64 of 68), not significantly different from that at 100 kVp (reviewer 1, 100% [68 of 68]; reviewer 2, 95.6% [65 of 68]) and 120 kVp (reviewer 1, 100% [68 of 68]; reviewer 2, 95.6% [65 of 68]) (P > .999). CONCLUSION A decrease in tube voltage to 80 kVp caused reduction in radiation dose (0.166 mSv) with deterioration in image noise and per-polyp sensitivity. By using a knowledge-based IR iterative reconstruction algorithm, radiologists' performance of 80-kVp CT colonography was acceptable and on par with that at 100- or 120-kVp CT colonography.
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Affiliation(s)
- Cheong-Il Shin
- From the Department of Radiology (C.I.S., S.H.K., E.S.L., D.H.L., E.J.H., J.M.L., J.K.H., B.I.C.), Institute of Radiation Medicine (S.H.K., J.M.L., J.K.H., B.I.C.), and Healthcare System Gangnam Center (S.Y.C.), Seoul National University Hospital, 101 Daehangno, Jongno-gu, Seoul 110-744, Korea
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Abstract
Patients, referring physicians, the media, and government agencies have all expressed concern over the risks of medical radiation, particularly as it relates to CT. This concern is particularly paramount when associated with a screening examination such as CT colonography. These theoretical risks must be weighed realistically against the substantial benefits of colon cancer screening as well as against the risks inherent in the major alternative screening option, optical colonoscopy. When put into perspective, the risk-benefit ratio is highly in favor of the performance of CT colonography. Nevertheless, in following the ALARA principle, there is an ever increasing armamentarium of options that can be employed in the pursuit of CT radiation dose reduction, all of which can be used in many synergistic combinations allowing for dose reduction while simultaneously preserving image quality and minimizing image noise. After a brief tutorial on estimating radiation dose, various strategies will be discussed including reductions in tube current and tube voltage as well as the use of automatic dose modulation and iterative reconstruction. Other practical considerations will also be reviewed including proper patient isocentering, optimization of colonic insufflation to minimize additional decubitus scans, proper choice of scan volumes to avoid overranging, and variation of slice thickness and window width to minimize perceived image noise. Finally, a strategy for how to incrementally introduce these methods as well as a way to compare dose reduction efforts across institutions throughout the country will be offered.
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Chang KJ, Caovan DB, Grand DJ, Huda W, Mayo-Smith WW. Reducing radiation dose at CT colonography: decreasing tube voltage to 100 kVp. Radiology 2012; 266:791-800. [PMID: 23264348 DOI: 10.1148/radiol.12120134] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
PURPOSE To assess the effect of a decrease in tube voltage from 120 kVp to 100 kVp on dose, contrast-to-noise ratio (CNR), and three-dimensional (3D) image quality in patients undergoing computed tomographic (CT) colonography as well as to determine how these changes are affected by patient size. MATERIALS AND METHODS This HIPAA-compliant and institutional review board-approved retrospective study included 63 consecutive patients who underwent CT colonography and who waived informed consent. Scanning was performed with patients in the supine (120 kVp) and prone (100 kVp) positions, with other parameters unchanged. Volume CT dose index (CTDI(vol)), dose-length product (DLP), image noise, attenuation of selected materials, and CNR were compared with the Wilcoxon matched-pairs signed rank test. Two readers blinded to tube voltage independently assessed 3D endoluminal image quality. The k coefficients were calculated for interobserver agreement. Average image quality ratings were compared with the Wilcoxon signed rank test. All recorded data were stratified by patient anteroposterior diameter to determine effects of patient size. RESULTS Decreasing tube voltage from 120 to 100 kVp resulted in a 20% decrease in CTDI(vol) (P < .001) and a 16% decrease in DLP (P < .001). Image noise increased by 32% (P < .001). Mean attenuation of tagged fluid increased from 395 to 487 HU (P < .001). There was no change in mean CNR of tagged fluid (17.1 at 120 kVp, 16.8 at 100 kVp; P = .37), regardless of patient size. The 3D image quality decreased slightly from a median score of 5 out of 5 to 4 out of 5 (P < .001). There was substantial interobserver agreement. CONCLUSION A decrease in tube voltage from 120 to 100 kVp results in a significant decrease in radiation dose but only a minimal decrease in 3D image quality at all patient sizes. © RSNA, 2012.
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Affiliation(s)
- Kevin J Chang
- Department of Diagnostic Imaging, Warren Alpert Medical School of Brown University, Rhode Island Hospital, 593 Eddy St, Providence, RI 02903, USA.
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Martin CJ, Huda W. Intercomparison of patient CTDI surveys in three countries. RADIATION PROTECTION DOSIMETRY 2012; 153:431-440. [PMID: 22927650 DOI: 10.1093/rpd/ncs123] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The results of large-scale computed tomography (CT) patient dose surveys from the USA, UK and Germany undertaken during the period 1999-2001 were reviewed. The mean values for volume-weighted CT dose index (CTDI(vol)) and dose length product (DLP) were extracted. For head CT examinations, the reported values for the three surveys were similar with a mean CTDI(vol) of 59±6 mGy and a mean DLP of 760±90 mGy cm. For the body, the values for CTDI(vol) in the USA (21±5 mGy) were nearly double those in the European countries (12±2 mGy). Average head CTDI(vol) values are comparable with the diagnostic reference levels (DRLs) recommended by the European Commission and the UK Health Protection Agency, but lower than the value of 75 mGy, which is currently used in the USA. DRLs for abdominal imaging are nearly a factor of 2 lower in the UK (14 mGy) than in other parts of the European Community and the USA (25 mGy).
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Affiliation(s)
- Colin J Martin
- Department of Clinical Physics and Bio-Engineering, Gartnavel Royal Hospital, Health Physics, West House, Glasgow, UK.
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Zanotti-Fregonara P, Koroscil TM, Mantil J, Satter M. Radiation dose to the fetus from [(18)F]-FDG administration during the second trimester of pregnancy. HEALTH PHYSICS 2012; 102:217-219. [PMID: 22217594 PMCID: PMC3253299 DOI: 10.1097/hp.0b013e318226ebb4] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The authors estimated the fetal radiation dose from [(18)F]-FDG in a rare case of a woman who underwent a PET/CT scan during the second trimester of pregnancy. The patient, a 27-y-old female with a paraganglioma, received 181.3 MBq [(18)F]-FDG. From the concentrations of radioactivity measured on the images, the time-integrated activity coefficients of the fetus and the placenta were derived. The time-integrated activity coefficients of the mother's organs were taken from the standard values of ICRP publication 106. The final fetal dose was calculated using the 6-mo pregnant model of the OLINDA/EXM software. The fetus showed an overall low and homogeneous [(18)F]-FDG uptake, with an average concentration of 2.41 kBq cm(-3). The uptake in the placenta was generally higher (average concentration = 3.69 kBq cm(-3)). The estimated time-integrated activity coefficients were 0.0130 and 0.0058 Bq h Bq(-1) for the fetus and the placenta, respectively. The final average dose to the fetus was 1.97 × 10(-2) mGy MBq(-1) (3.6 mGy in this patient who received 181.3 MBq). Therefore, the dose to the fetus from [(18)F]-FDG administration during the second trimester of pregnancy is low. When medically indicated, pregnancy should not be a categorical basis for withholding [(18)F]-FDG PET scans.
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Affiliation(s)
- Paolo Zanotti-Fregonara
- Molecular Imaging Branch, National Institute of Mental Health (NIMH), National Institutes of Health (NIH), Bethesda, MD 20892-2035, USA.
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Radiation dose in 320-detector-row CT coronary angiography: Prospective ECG triggering combined with multi-segment reconstruction. RADIAT MEAS 2011. [DOI: 10.1016/j.radmeas.2011.07.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Cohen MD. Searching for the holy grail: the pretense and fallacy of measuring CT radiation exposure in an individual patient. Radiology 2011; 260:306-7; author reply 307-8. [PMID: 21697314 DOI: 10.1148/radiol.11110191] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Huda W, Magill D, Spampinato MV. Technical Note: Estimating absorbed doses to the thyroid in CT. Med Phys 2011; 38:3108-13. [DOI: 10.1118/1.3592022] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Huda W, Mettler FA. Volume CT Dose Index and Dose-Length Product Displayed during CT: What Good Are They? Radiology 2011; 258:236-42. [DOI: 10.1148/radiol.10100297] [Citation(s) in RCA: 152] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
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