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Safari A, Rafie P, Taeb S, Najafi M, Mortazavi SMJ. Development of Lead-Free Materials for Radiation Shielding in Medical Settings: A Review. J Biomed Phys Eng 2024; 14:229-244. [PMID: 39027711 PMCID: PMC11252547 DOI: 10.31661/jbpe.v0i0.2404-1742] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2024] [Accepted: 05/20/2024] [Indexed: 07/20/2024]
Abstract
Radiation protection is an essential issue in diagnostic radiology to ensure the safety of patients, healthcare professionals, and the general public. Lead has traditionally been used as a shielding material due to its high atomic number, high density, and effectiveness in attenuating radiation. However, some concerns related to the long-term health effects of toxicity, environmental disease as well as heavy weight of lead have led to the search for alternative lead-free shielding materials. Leadfree multilayered polymer composites and non-lead nano-composite shields have been suggested as effective shielding materials to replace conventional lead-based and single metal shields. Using several elements with high density and atomic number, such as bismuth, barium, gadolinium, and tungsten, offer significant enhancements in the shielding ability of composites. This review focuses on the development and use of lead-free materials for radiation shielding in medical settings. It discusses the drawbacks of traditional lead shielding, such as toxicity, weight, and recycling challenges, and highlights the benefits of lead-free alternatives.
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Affiliation(s)
- Arash Safari
- Department of Radiology, School of Paramedical Sciences, Shiraz University of Medical Sciences, Shiraz, Iran
- Ionizing and Non-ionizing Radiation Protection Research Center (INIRPRC), Shiraz University of Medical Sciences, Shiraz, Iran
| | - Payman Rafie
- Department of Nuclear Engineering, School of Mechanical Engineering, Shiraz University, Shiraz, Iran
| | - Shahram Taeb
- Department of Radiology, School of Paramedical Sciences, Guilan University of Medical Sciences, Rasht, Iran
| | - Masoud Najafi
- Department of Radiology and Nuclear Medicine, School of Paramedical Sciences, Kermanshah University of Medical Science, Kermanshah, Iran
| | - Seyed Mohammad Javad Mortazavi
- Ionizing and Non-ionizing Radiation Protection Research Center (INIRPRC), Shiraz University of Medical Sciences, Shiraz, Iran
- Department of Medical Physics and Engineering, School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran
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Chamberlin JH, Smith CD, Maisuria D, Parrish J, van Swol E, Mah E, Emrich T, Schoepf UJ, Varga-Szemes A, O'Doherty J, Munden RF, Tipnis SV, Baruah D, Kabakus IM. Ultra-high-resolution photon-counting detector computed tomography of the lungs: Phantom and clinical assessment of radiation dose and image quality. Clin Imaging 2023; 104:110008. [PMID: 37862910 DOI: 10.1016/j.clinimag.2023.110008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2023] [Revised: 09/28/2023] [Accepted: 10/12/2023] [Indexed: 10/22/2023]
Abstract
PURPOSE Photon-counting-detector computed tomography (PCD-CT) offers enhanced noise reduction, spatial resolution, and image quality in comparison to energy-integrated-detectors CT (EID-CT). These hypothesized improvements were compared using PCD-CT ultra-high (UHR) and standard-resolution (SR) scan-modes. METHODS Phantom scans were obtained with both EID-CT and PCD-CT (UHR, SR) on an adult body-phantom. Radiation dose was measured and noise levels were compared at a minimum achievable slice thickness of 0.5 mm for EID-CT, 0.2 mm for PCD-CT-UHR and 0.4 mm for PCD-CT-SR. Signal-to-noise ratios (SNR) and contrast-to-noise ratios (CNR) were calculated for five tissue densities. Additionally, data from 25 patients who had PCD-CT of chest were reconstructed at 1 mm and 0.2 mm (UHR) slice-thickness and compared quantitatively (SNR) and qualitatively (noise, quality, sharpness, bone details). RESULTS Phantom PCD-CT-UHR and PCD-CT-SR scans had similar measured radiation dose (16.0mGy vs 15.8 mGy). Phantom PCD-CT-SR (0.4 mm) had lower noise level in comparison to EID-CT (0.5 mm) (9.0HU vs 9.6HU). PCD-CT-UHR (0.2 mm) had slightly higher noise level (11.1HU). Phantom PCD-CT-SR (0.4 mm) had higher SNR in comparison to EID-CT (0.5 mm) while achieving higher resolution (Bone 115 vs 96, Acrylic 14 vs 14, Polyethylene 11 vs 10). SNR was slightly lower across all densities for PCD-CT UHR (0.2 mm). Interestingly, CNR was highest in the 0.2 mm PCD-CT group; PCD-CT CNR was 2.45 and 2.88 times the CNR for 0.5 mm EID-CT for acrylic and poly densities. Clinical comparison of SNR showed predictably higher SNR for 1 mm (30.3 ± 10.7 vs 14.2 ± 7, p = 0.02). Median subjective ratings were higher for 0.2 mm UHR vs 1 mm PCD-CT for nodule contour (4.6 ± 0.3 vs 3.6 ± 0.1, p = 0.02), bone detail (5 ± 0 vs 4 ± 0.1, p = 0.001), image quality (5 ± 0.1 vs 4.6 ± 0.4, p = 0.001), and sharpness (5 ± 0.1 vs 4 ± 0.2). CONCLUSION Both UHR and SR PCD-CT result in similar radiation dose levels. PCD-CT can achieve higher resolution with lower noise level in comparison to EID-CT.
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Affiliation(s)
- Jordan H Chamberlin
- Department of Radiology and Radiological Science, Divisions of Cardiovascular and Thoracic Imaging, Medical University of South Carolina, Charleston, SC 29407, USA
| | - Carter D Smith
- Department of Radiology and Radiological Science, Divisions of Cardiovascular and Thoracic Imaging, Medical University of South Carolina, Charleston, SC 29407, USA
| | - Dhruw Maisuria
- Department of Radiology and Radiological Science, Divisions of Cardiovascular and Thoracic Imaging, Medical University of South Carolina, Charleston, SC 29407, USA
| | - Joe Parrish
- Department of Radiology and Radiological Science, Divisions of Cardiovascular and Thoracic Imaging, Medical University of South Carolina, Charleston, SC 29407, USA
| | - Elizabeth van Swol
- Department of Radiology and Radiological Science, Divisions of Cardiovascular and Thoracic Imaging, Medical University of South Carolina, Charleston, SC 29407, USA
| | - Eugene Mah
- Department of Radiology and Radiological Science, Division of Medical Physics, Medical University of South Carolina, Charleston, SC 29407, USA
| | - Tilman Emrich
- Department of Radiology and Radiological Science, Divisions of Cardiovascular and Thoracic Imaging, Medical University of South Carolina, Charleston, SC 29407, USA
| | - U Joseph Schoepf
- Department of Radiology and Radiological Science, Divisions of Cardiovascular and Thoracic Imaging, Medical University of South Carolina, Charleston, SC 29407, USA
| | - Akos Varga-Szemes
- Department of Radiology and Radiological Science, Divisions of Cardiovascular and Thoracic Imaging, Medical University of South Carolina, Charleston, SC 29407, USA
| | - Jim O'Doherty
- Department of Radiology and Radiological Science, Divisions of Cardiovascular and Thoracic Imaging, Medical University of South Carolina, Charleston, SC 29407, USA; Siemens Medical Solutions, Malvern, PA, USA
| | - Reginald F Munden
- Department of Radiology and Radiological Science, Divisions of Cardiovascular and Thoracic Imaging, Medical University of South Carolina, Charleston, SC 29407, USA
| | - Sameer V Tipnis
- Department of Radiology and Radiological Science, Division of Medical Physics, Medical University of South Carolina, Charleston, SC 29407, USA
| | - Dhiraj Baruah
- Department of Radiology and Radiological Science, Divisions of Cardiovascular and Thoracic Imaging, Medical University of South Carolina, Charleston, SC 29407, USA
| | - Ismail M Kabakus
- Department of Radiology and Radiological Science, Divisions of Cardiovascular and Thoracic Imaging, Medical University of South Carolina, Charleston, SC 29407, USA.
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Wrazidlo R, Walder L, Estler A, Gutjahr R, Schmidt B, Faby S, Fritz J, Nikolaou K, Horger M, Hagen F. Radiation Dose Reduction in Contrast-Enhanced Abdominal CT: Comparison of Photon-Counting Detector CT with 2nd Generation Dual-Source Dual-Energy CT in an oncologic cohort. Acad Radiol 2023; 30:855-862. [PMID: 35760710 DOI: 10.1016/j.acra.2022.05.021] [Citation(s) in RCA: 19] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2022] [Revised: 05/30/2022] [Accepted: 05/30/2022] [Indexed: 11/28/2022]
Abstract
RATIONAL AND OBJECTIVES Comparison of radiation dose and image quality in routine abdominal and pelvic contrast-enhanced computed tomography (CECT) between a photon-counting detector CT (PCD-CT) and a dual energy dual source CT (DSCT). MATERIALS AND METHODS 70 oncologic patients (mean age 66 ± 12 years, 29 females) were prospectively enrolled between November 2021 and February 2022. Abdominal CECT were clinically indicated and performed first on a 2nd-generation DSCT and at follow-up on a 1st-generation dual-source PCD-CT. The same contrast media (Imeron 350, Bracco imaging) and pump protocol was used for both scans. For both scanners, polychromatic images were reconstructed with 3mm slice thickness and comparable kernel (I30f[DSCT] and Br40f[PCD-CT]); for PCD-CT data from all counted events above the lowest energy threshold at 20 keV ("T3D") were used. Results were compared in terms of radiation dose metrics of CT dose index (CTDIvol), dose length product (DLP) and size-specific dose estimation (SSDE), objective and subjective measurements of image quality were scored by two emergency radiologists including lesion conspicuity. RESULTS Median time interval between the scans was 4 months (IQR: 3-6). CNRvessel and SNRvessel of T3D reconstructions from PCD-CT were significantly higher than those of DSCT (all, p < 0.05). Qualitative image noise analysis from PCD-CT and DSCT yielded a mean of 4 each. Lesion conspicuity was rated significantly higher in PCD-CT (Q3 strength) compared to DSCT images. CTDI, DLP and SSDE mean values for PCD-CT and DSCT were 7.98 ± 2.56 mGy vs. 14.11 ± 2.92 mGy, 393.13 ± 153.55 mGy*cm vs. 693.61 ± 185.76 mGy*cm and 9.98 ± 2.41 vs. 14.63 ± 1.63, respectively, translating to a dose reduction of around 32% (SSDE). CONCLUSION PCD-CT enables oncologic abdominal CT with a significantly reduced dose while keeping image quality similar to 2nd-generation DSCT.
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Affiliation(s)
- Robin Wrazidlo
- Department of Diagnostic and Interventional Radiology, Eberhard-Karls-University, 72076 Tübingen, Germany (R.W., L.W., A.E., K.N., M.H., F.H.); Siemens Healthcare GmbH, 91052 Erlangen, Germany (R.G., B.S., S.F.); NYU Grossman School of Medicine, Department of Radiology, New York, NY 10016, USA (J.F.)
| | - Lukas Walder
- Department of Diagnostic and Interventional Radiology, Eberhard-Karls-University, 72076 Tübingen, Germany (R.W., L.W., A.E., K.N., M.H., F.H.); Siemens Healthcare GmbH, 91052 Erlangen, Germany (R.G., B.S., S.F.); NYU Grossman School of Medicine, Department of Radiology, New York, NY 10016, USA (J.F.)
| | - Arne Estler
- Department of Diagnostic and Interventional Radiology, Eberhard-Karls-University, 72076 Tübingen, Germany (R.W., L.W., A.E., K.N., M.H., F.H.); Siemens Healthcare GmbH, 91052 Erlangen, Germany (R.G., B.S., S.F.); NYU Grossman School of Medicine, Department of Radiology, New York, NY 10016, USA (J.F.)
| | - Ralf Gutjahr
- Department of Diagnostic and Interventional Radiology, Eberhard-Karls-University, 72076 Tübingen, Germany (R.W., L.W., A.E., K.N., M.H., F.H.); Siemens Healthcare GmbH, 91052 Erlangen, Germany (R.G., B.S., S.F.); NYU Grossman School of Medicine, Department of Radiology, New York, NY 10016, USA (J.F.)
| | - Bernhard Schmidt
- Department of Diagnostic and Interventional Radiology, Eberhard-Karls-University, 72076 Tübingen, Germany (R.W., L.W., A.E., K.N., M.H., F.H.); Siemens Healthcare GmbH, 91052 Erlangen, Germany (R.G., B.S., S.F.); NYU Grossman School of Medicine, Department of Radiology, New York, NY 10016, USA (J.F.)
| | - Sebastian Faby
- Department of Diagnostic and Interventional Radiology, Eberhard-Karls-University, 72076 Tübingen, Germany (R.W., L.W., A.E., K.N., M.H., F.H.); Siemens Healthcare GmbH, 91052 Erlangen, Germany (R.G., B.S., S.F.); NYU Grossman School of Medicine, Department of Radiology, New York, NY 10016, USA (J.F.)
| | - Jan Fritz
- Department of Diagnostic and Interventional Radiology, Eberhard-Karls-University, 72076 Tübingen, Germany (R.W., L.W., A.E., K.N., M.H., F.H.); Siemens Healthcare GmbH, 91052 Erlangen, Germany (R.G., B.S., S.F.); NYU Grossman School of Medicine, Department of Radiology, New York, NY 10016, USA (J.F.)
| | - Konstantin Nikolaou
- Department of Diagnostic and Interventional Radiology, Eberhard-Karls-University, 72076 Tübingen, Germany (R.W., L.W., A.E., K.N., M.H., F.H.); Siemens Healthcare GmbH, 91052 Erlangen, Germany (R.G., B.S., S.F.); NYU Grossman School of Medicine, Department of Radiology, New York, NY 10016, USA (J.F.)
| | - Marius Horger
- Department of Diagnostic and Interventional Radiology, Eberhard-Karls-University, 72076 Tübingen, Germany (R.W., L.W., A.E., K.N., M.H., F.H.); Siemens Healthcare GmbH, 91052 Erlangen, Germany (R.G., B.S., S.F.); NYU Grossman School of Medicine, Department of Radiology, New York, NY 10016, USA (J.F.).
| | - Florian Hagen
- Department of Diagnostic and Interventional Radiology, Eberhard-Karls-University, 72076 Tübingen, Germany (R.W., L.W., A.E., K.N., M.H., F.H.); Siemens Healthcare GmbH, 91052 Erlangen, Germany (R.G., B.S., S.F.); NYU Grossman School of Medicine, Department of Radiology, New York, NY 10016, USA (J.F.)
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Estler A, Nikolaou K, Schönberg SO, Bamberg F, Froelich MF, Tollens F, Verloh N, Weiss J, Horger M, Hagen F. Is There Still a Role for Two-Phase Contrast-Enhanced CT and Virtual Monoenergetic Images in the Era of Photon-Counting Detector CT? Diagnostics (Basel) 2023; 13:diagnostics13081454. [PMID: 37189555 DOI: 10.3390/diagnostics13081454] [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: 01/30/2023] [Revised: 04/14/2023] [Accepted: 04/16/2023] [Indexed: 05/17/2023] Open
Abstract
BACKGROUND To compare the diagnostic characteristics between arterial phase imaging versus portal venous phase imaging, applying polychromatic T3D images and low keV virtual monochromatic images using a 1st generation photon-counting CT detector, of CT in patients with hepatocellular carcinoma (HCC). METHODS Consecutive patients with HCC, with a clinical indication for CT imaging, were prospectively enrolled. Virtual monoenergetic images (VMI) were reconstructed at 40 to 70 keV for the PCD-CT. Two independent, blinded radiologists counted all hepatic lesions and quantified their size. The lesion-to-background ratio was quantified for both phases. SNR and CNR were determined for T3D and low VMI images; non-parametric statistics were used. RESULTS Among 49 oncologic patients (mean age 66.9 ± 11.2 years, eight females), HCC was detected in both arterial and portal venous scans. The signal-to-noise ratio, the CNR liver-to-muscle, the CNR tumor-to-liver, and CNR tumor-to-muscle were 6.58 ± 2.86, 1.40 ± 0.42, 1.13 ± 0.49, and 1.53 ± 0.76 in the arterial phase and 5.93 ± 2.97, 1.73 ± 0.38, 0.79 ± 0.30, and 1.36 ± 0.60 in the portal venous phase with PCD-CT, respectively. There was no significant difference in SNR between the arterial and portal venous phases, including between "T3D" and low keV images (p > 0.05). CNRtumor-to-liver differed significantly between arterial and portal venous contrast phases (p < 0.005) for both "T3D" and all reconstructed keV levels. CNRliver-to-muscle and CNRtumor-to-muscle did not differ in either the arterial or portal venous contrast phases. CNRtumor-to-liver increased in the arterial contrast phase with lower keV in addition to SD. In the portal venous contrast phase, CNRtumor-to-liver decreased with lower keV; whereas, CNRtumor-to-muscle increased with lower keV in both arterial and portal venous contrast phases. CTDI and DLP mean values for the arterial upper abdomen phase were 9.03 ± 3.59 and 275 ± 133, respectively. CTDI and DLP mean values for the abdominal portal venous phase were 8.75 ± 2.99 and 448 ± 157 with PCD-CT, respectively. No statistically significant differences were found concerning the inter-reader agreement for any of the (calculated) keV levels in either the arterial or portal-venous contrast phases. CONCLUSIONS The arterial contrast phase imaging provides higher lesion-to-background ratios of HCC lesions using a PCD-CT; especially, at 40 keV. However, the difference was not subjectively perceived as significant.
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Affiliation(s)
- Arne Estler
- Department of Diagnostic and Interventional Radiology, University of Tuebingen, Hoppe-Seyler-Str. 3, 72076 Tuebingen, Germany
| | - Konstantin Nikolaou
- Department of Diagnostic and Interventional Radiology, University of Tuebingen, Hoppe-Seyler-Str. 3, 72076 Tuebingen, Germany
| | - Stefan O Schönberg
- Department of Radiology and Nuclear Medicine, University Medical Centre Mannheim, Medical Faculty Mannheim, University of Heidelberg, 68167 Mannheim, Germany
| | - Fabian Bamberg
- Department of Diagnostic and Interventional Radiology, Medical Center University of Freiburg, 79106 Freiburg, Germany
| | - Matthias F Froelich
- Department of Radiology and Nuclear Medicine, University Medical Centre Mannheim, Medical Faculty Mannheim, University of Heidelberg, 68167 Mannheim, Germany
| | - Fabian Tollens
- Department of Radiology and Nuclear Medicine, University Medical Centre Mannheim, Medical Faculty Mannheim, University of Heidelberg, 68167 Mannheim, Germany
| | - Niklas Verloh
- Department of Diagnostic and Interventional Radiology, Medical Center University of Freiburg, 79106 Freiburg, Germany
| | - Jakob Weiss
- Department of Diagnostic and Interventional Radiology, Medical Center University of Freiburg, 79106 Freiburg, Germany
| | - Marius Horger
- Department of Diagnostic and Interventional Radiology, University of Tuebingen, Hoppe-Seyler-Str. 3, 72076 Tuebingen, Germany
| | - Florian Hagen
- Department of Diagnostic and Interventional Radiology, University of Tuebingen, Hoppe-Seyler-Str. 3, 72076 Tuebingen, Germany
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Hagen F, Walder L, Fritz J, Gutjahr R, Schmidt B, Faby S, Bamberg F, Schoenberg S, Nikolaou K, Horger M. Image Quality and Radiation Dose of Contrast-Enhanced Chest-CT Acquired on a Clinical Photon-Counting Detector CT vs. Second-Generation Dual-Source CT in an Oncologic Cohort: Preliminary Results. Tomography 2022; 8:1466-1476. [PMID: 35736867 PMCID: PMC9227736 DOI: 10.3390/tomography8030119] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2022] [Revised: 05/14/2022] [Accepted: 05/30/2022] [Indexed: 11/16/2022] Open
Abstract
Our aim was to compare the image quality and patient dose of contrast-enhanced oncologic chest-CT of a first-generation photon-counting detector (PCD-CT) and a second-generation dual-source dual-energy CT (DSCT). For this reason, one hundred consecutive oncologic patients (63 male, 65 ± 11 years, BMI: 16−42 kg/m2) were prospectively enrolled and evaluated. Clinically indicated contrast-enhanced chest-CT were obtained with PCD-CT and compared to previously obtained chest-DSCT in the same individuals. The median time interval between the scans was three months. The same contrast media protocol was used for both scans. PCD-CT was performed in QuantumPlus mode (obtaining full spectral information) at 120 kVp. DSCT was performed using 100 kV for Tube A and 140 kV for Tube B. “T3D” PCD-CT images were evaluated, which emulate conventional 120 keV polychromatic images. For DSCT, the convolution algorithm was set at I31f with class 1 iterative reconstruction, whereas comparable Br40 kernel and iterative reconstruction strengths (Q1 and Q3) were applied for PCD-CT. Two radiologists assessed image quality using a five-point Likert scale and performed measurements of vessels and lung parenchyma for signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and in the case of pulmonary metastases tumor-to-lung parenchyma contrast ratio. PCD-CT CNRvessel was significantly higher than DSCT CNRvessel (all, p < 0.05). Readers rated image contrast of mediastinum, vessels, and lung parenchyma significantly higher in PCD-CT than DSCT images (p < 0.001). Q3 PCD-CT CNRlung_parenchyma was significantly higher than DSCT CNRlung_parenchyma and Q1 PCD-CT CNRlung_parenchyma (p < 0.01). The tumor-to-lung parenchyma contrast ratio was significantly higher on PCD-CT than DSCT images (0.08 ± 0.04 vs. 0.03 ± 0.02, p < 0.001). CTDI, DLP, SSDE mean values for PCD-CT and DSCT were 4.17 ± 1.29 mGy vs. 7.21 ± 0.49 mGy, 151.01 ± 48.56 mGy * cm vs. 288.64 ± 31.17 mGy * cm and 4.23 ± 0.97 vs. 7.48 ± 1.09, respectively. PCD-CT enables oncologic chest-CT with a significantly reduced dose while maintaining image quality similar to a second-generation DSCT for comparable protocol settings.
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Affiliation(s)
- Florian Hagen
- Department of Diagnostic and Interventional Radiology, Eberhard-Karls-University, Hoppe-Seyler-Str. 3, 72070 Tübingen, Germany; (F.H.); (K.N.); (M.H.)
| | - Lukas Walder
- Department of Diagnostic and Interventional Radiology, Eberhard-Karls-University, Hoppe-Seyler-Str. 3, 72070 Tübingen, Germany; (F.H.); (K.N.); (M.H.)
- Correspondence: ; Tel.: +49-07071-29-68622
| | - Jan Fritz
- NYU Grossman School of Medicine, Department of Radiology, New York, NY 10016, USA;
| | - Ralf Gutjahr
- Siemens Healthcare GmbH, 91052 Erlangen, Germany; (R.G.); (B.S.); (S.F.)
| | - Bernhard Schmidt
- Siemens Healthcare GmbH, 91052 Erlangen, Germany; (R.G.); (B.S.); (S.F.)
| | - Sebastian Faby
- Siemens Healthcare GmbH, 91052 Erlangen, Germany; (R.G.); (B.S.); (S.F.)
| | - Fabian Bamberg
- Department of Radiology, Albert-Ludwigs-University Freiburg, 79106 Freiburg, Germany;
| | - Stefan Schoenberg
- Department of Radiology, University of Mannheim, 68167 Mannheim, Germany;
| | - Konstantin Nikolaou
- Department of Diagnostic and Interventional Radiology, Eberhard-Karls-University, Hoppe-Seyler-Str. 3, 72070 Tübingen, Germany; (F.H.); (K.N.); (M.H.)
| | - Marius Horger
- Department of Diagnostic and Interventional Radiology, Eberhard-Karls-University, Hoppe-Seyler-Str. 3, 72070 Tübingen, Germany; (F.H.); (K.N.); (M.H.)
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Hagen F, Hofmann J, Wrazidlo R, Gutjahr R, Schmidt B, Faby S, Nikolaou K, Horger M. Image quality and dose exposure of contrast-enhanced abdominal CT on a 1st generation clinical dual-source photon-counting detector CT in obese patients vs. a 2nd generation dual-source dual energy integrating detector CT. Eur J Radiol 2022; 151:110325. [DOI: 10.1016/j.ejrad.2022.110325] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Revised: 04/11/2022] [Accepted: 04/13/2022] [Indexed: 01/15/2023]
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Shim J, Chung YE, Jeong HW, Lee Y. Feasibility Study of Dose Modulation for Reducing Radiation Dose with Arms-Down Patient Position in Abdominal Computed Tomography. Diagnostics (Basel) 2022; 12:diagnostics12020323. [PMID: 35204414 PMCID: PMC8871179 DOI: 10.3390/diagnostics12020323] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2022] [Revised: 01/25/2022] [Accepted: 01/25/2022] [Indexed: 11/16/2022] Open
Abstract
This study was carried out to demonstrate whether the radiation dose for patients in arms-down position can be reduced without affecting the diagnosis on abdominal computed tomography (CT). The patients were divided into two groups: group A, which included patients with arms-down position using dose modulation on, and group B, which included patients with arms-down position using dose modulation turned off. Quantitative evaluation was compared using Hounsfield units, standard deviation, and signal-to-noise ratio of the four regions. The qualitative evaluation was assessed for overall image quality, subjective image noise, and beam hardening artifacts. Dose evaluation for CT dose index (CTDI) and dose length product (DLP) was compared by comparing the CT images with dose modulation turned on and off. In the quantitative and qualitative evaluation, there was no statistically significant difference between groups A and B (p > 0.05). In the dose evaluation, the CT images with dose modulation turned off had significantly lower CTDI and DLP than the CT images with dose modulation turned on (p < 0.05). Our results suggest that, for the GE Revolution EVO CT scanner, turning off dose modulation and increasing the tube voltage can reduce the radiation dose for patients with the arms-down position without affecting the diagnosis. This study did not consider the change of tube potential according to the use of dose modulation, and we plan to conduct additional research in the future.
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Affiliation(s)
- Jina Shim
- Department of Diagnostic Radiology, Severance Hospital, 50-1, Yonsei-ro, Seodaemun-gu, Seoul 03722, Korea;
| | - Yong Eun Chung
- Department of Radiology, Yonsei University Health System, Yonsei University College of Medicine, 50-1, Yonsei-ro, Seodaemun-gu, Seoul 03722, Korea;
| | - Hyun-Woo Jeong
- Department of Biomedical Engineering, Eulji University, 553, Sanseong-daero, Sujeong-gu, Seongnam-si 13135, Gyeonggi-do, Korea
- Correspondence: (H.-W.J.); (Y.L.); Tel.: +82-31-740-7135 (H.-W.J.); +82-32-820-4362 (Y.L.)
| | - Youngjin Lee
- Department of Radiological Science, Gachon University, 191, Hambakmoero, Yeonsu-gu, Incheon 21936, Korea
- Correspondence: (H.-W.J.); (Y.L.); Tel.: +82-31-740-7135 (H.-W.J.); +82-32-820-4362 (Y.L.)
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Papadakis AE, Damilakis J. Technical Note: Evaluating automatic tube current modulation in CT using the standard CTDI dosimetry phantom. Med Phys 2020; 48:659-666. [PMID: 33098127 DOI: 10.1002/mp.14551] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Revised: 10/08/2020] [Accepted: 10/15/2020] [Indexed: 12/11/2022] Open
Abstract
PURPOSE To assess the utility of the standard body CTDI phantom in characterizing the operation scheme of tube current modulation (TCM) systems in CT. METHODS The body CDTI phantom was used to characterize two TCM systems: TCM1 and TCM2 , implemented in scanners from different vendors. The phantom was aligned at the gantry isocenter in two configurations. In configuration A, the facet planes of the phantom were parallel to the patient table, while in configuration B they were vertical to the patient table and parallel to the patient's long axis. Acquisitions were performed using the routine abdominal examination protocol. mA(z) profiles were recorded from images' DICOM header. The water equivalent diameter (dw ) and oval ratio (OR) were calculated as a function of z-axis location. Image noise was defined as the standard deviation (SD) of the mean Hounsfield unit value measured in a region of interest at the center of the phantom's image. Regression analysis was performed to modulated mA and SD vs dw and OR. The spatial concordance between the change in phantom size and change in mA (SCmA ) was calculated as the percent difference in the slope of mA(z) change between the 1st and 2nd half of the phantom. The corresponding spatial concordance between the change in phantom size and change in image noise (SCnoise ) was calculated. RESULTS Modulated mA(z) along the z-axis did not substantially differentiate between configurations A and B. Correlation between ln(mA) and OR was found to be higher compared to correlation between ln(mA) and dw . SCmA was 48% for TCM1 and 33% for TCM2 . The corresponding SCnoise was 29% for TCM1 and 16% for TCM2 . CONCLUSION Apart from routine CT dosimetry evaluations, the standard CTDI phantom positioned in configuration A or B may additionally be used by medical physicists to evaluate the performance of TCM operational characteristics.
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Affiliation(s)
- Antonios E Papadakis
- Medical Physics Department, University Hospital of Heraklion, Stavrakia, Crete, 71110, Greece
| | - John Damilakis
- Medical Physics Department, University of Crete, Stavrakia, Crete, 71110, Greece
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Perisinakis K, Ntoufas N, Velivassaki M, Tzedakis A, Myronakis M, Hatzidakis A, Damilakis J. Effect of scan projection radiography coverage on tube current modulation in pediatric and adult chest CT. Z Med Phys 2020; 30:259-270. [PMID: 32513526 DOI: 10.1016/j.zemedi.2020.05.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2019] [Revised: 04/22/2020] [Accepted: 05/03/2020] [Indexed: 11/30/2022]
Abstract
PURPOSE To investigate the effect of scan projection radiography (SPR) coverage on tube current modulation in pediatric and adult thoracic CT examinations. METHODS Sixty pediatric and 60 adult chest CT examinations were retrospectively studied to determine the incidence rate of examinations involving SPRs that did not include the entire image volume (IV) or the entire primarily exposed body volume (PEBV). The routine chest CT acquisition procedure on a modern 64-slice CT system was imitated on five anthropomorphic phantoms of different size. SPRs of varying length were successively acquired. The same IV was prescribed each time and the computed tube current modulation plan was recorded. The SPR boundaries were altered symmetrically by several steps of ±10mm with respect to the IV boundaries. RESULTS The upper IV boundary was found to be excluded from SPR in 52% of pediatric and 40% adult chest CT examinations. The corresponding values for the lower boundary were 15% and 20%, respectively. The computed tube current modulation was found to be considerably affected when the SPR did not encompass the entire IV. SPR deficit of 3cm was found to induce up to 46% increase in the computed tube current value to be applied during the first tube rotations over lung apex. CONCLUSIONS The tube current modulation mechanism functions properly only if the IV set by the operator is entirely included in the localizing SPR image. Operators should cautiously set the SPR boundaries to avoid partial exclusion of prescribed IV from SPRs and thus achieve optimum tube current modulation.
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Affiliation(s)
- Kostas Perisinakis
- University of Crete, Medical School, Department of Medical Physics, 71003 Heraklion, Crete, Greece; University Hospital of Heraklion, Department of Medical Physics, P.O. Box 1352, 71110 Heraklion, Crete, Greece.
| | - Nikos Ntoufas
- University of Crete, Medical School, Department of Medical Physics, 71003 Heraklion, Crete, Greece
| | - Mary Velivassaki
- University Hospital of Heraklion, Department of Medical Physics, P.O. Box 1352, 71110 Heraklion, Crete, Greece
| | - Antonis Tzedakis
- University Hospital of Heraklion, Department of Medical Physics, P.O. Box 1352, 71110 Heraklion, Crete, Greece
| | - Marios Myronakis
- University of Crete, Medical School, Department of Medical Physics, 71003 Heraklion, Crete, Greece; Brigham and Women's Hospital, Dana-Farber Cancer Institute, Harvard Medical School
| | - Adam Hatzidakis
- University of Crete, Medical School, Department of Radiology, Heraklion, Crete, Greece
| | - John Damilakis
- University of Crete, Medical School, Department of Medical Physics, 71003 Heraklion, Crete, Greece; University Hospital of Heraklion, Department of Medical Physics, P.O. Box 1352, 71110 Heraklion, Crete, Greece
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Rogalla P, Paravasthu M, Farrell C, Kandel S. Helical CT with variable target noise levels for dose reduction in chest, abdomen and pelvis CT. Eur Radiol 2018; 28:3922-3928. [DOI: 10.1007/s00330-018-5315-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2017] [Revised: 12/31/2017] [Accepted: 01/05/2018] [Indexed: 01/16/2023]
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Inkoom S, Papadakis AE, Raissaki M, Perisinakis K, Schandorf C, Fletcher JJ, Damilakis J. PAEDIATRIC NECK MULTIDETECTOR COMPUTED TOMOGRAPHY: THE EFFECT OF BISMUTH SHIELDING ON THYROID DOSE AND IMAGE QUALITY. RADIATION PROTECTION DOSIMETRY 2017; 173:361-373. [PMID: 26891787 DOI: 10.1093/rpd/ncw007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2015] [Accepted: 01/01/2016] [Indexed: 06/05/2023]
Abstract
This study investigated the effect of bismuth shielding on thyroid dose and image quality in paediatric neck multidetector computed tomography (MDCT) performed with fixed tube current (FTC) and automatic exposure control (AEC). Four paediatric anthropomorphic phantoms representing the equivalent newborn, 1-, 5- and 10-y-old child were subjected to neck CT using a 16-slice MDCT system. Each scan was performed without and with single- and double-layered bismuth shield placed on the skin surface above the thyroid. Scans were repeated with cotton spacers of 1, 2 and 3 cm thick placed between the skin and shield, to study the effect of skin-to-shielding distance on image noise. Thyroid dose was measured with thermoluminescent dosemeters. The location of the thyroid within the phantom slices was determined by anthropometric data from patients' CT examinations whose body stature closely matched the phantoms. Effective dose (E) was estimated using the dose-length product (DLP) method. Image quality of resulted CT images was assessed through the image noise. Activation of AEC was found to decrease the thyroid dose by 46 % to the 10-y-old phantom subjected to neck CT. When FTC technique is used, single- and double-layered bismuth shielding was found to reduce the thyroid dose to the same phantom by 35 and 47 %, respectively. The corresponding reductions in AEC-activated scans were 60 and 66 %, respectively. Elevation of shields by 1-, 2- and 3-cm cotton spacers decreased the image noise by 69, 87 and 92 %, respectively, for single-layered FTC, without considerably affecting the thyroid dose. AEC was more effective in thyroid dose reduction than in-plane bismuth shields. Application of cotton spacers had no significant impact on thyroid dose, but significantly decreased the image noise.
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Affiliation(s)
- Stephen Inkoom
- Department of Medical Physics, Faculty of Medicine, University of Crete, P.O. Box 2208, 71003 Iraklion, Crete, Greece
| | - Antonios E Papadakis
- Department of Medical Physics, University Hospital of Heraklion, P. O. Box 1352, Heraklion 71110, Crete, Greece
| | - Maria Raissaki
- Department of Radiology, Faculty of Medicine, University of Crete, Iraklion 71003, Crete, Greece
| | - Kostas Perisinakis
- Department of Medical Physics, University Hospital of Heraklion, P. O. Box 1352, Heraklion 71110, Crete, Greece
| | - Cyril Schandorf
- School of Nuclear and Allied Sciences, University of Ghana, Atomic Campus, P. O. Box AE 1, Atomic, Accra, Ghana
| | - John J Fletcher
- Department of Applied Physics, Faculty of Applied Sciences, University for Development Studies, Navrongo Campus, Navrongo, Ghana
| | - John Damilakis
- Department of Medical Physics, University Hospital of Heraklion, P. O. Box 1352, Heraklion 71110, Crete, Greece
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Martin CJ, Sookpeng S. Setting up computed tomography automatic tube current modulation systems. JOURNAL OF RADIOLOGICAL PROTECTION : OFFICIAL JOURNAL OF THE SOCIETY FOR RADIOLOGICAL PROTECTION 2016; 36:R74-R95. [PMID: 27485613 DOI: 10.1088/0952-4746/36/3/r74] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Automatic tube current modulation (ATCM) on CT scanners can yield significant reductions in patient doses. Modulation is based on x-ray beam attenuation in body tissues obtained from scan projection radiographs (SPRs) and aims to maintain the same level of image quality throughout a scan. Noise level is important in judging image quality, but tissues in larger patients exhibit higher contrast resulting from the presence of fat. CT scanner manufacturers use different metrics to assess image quality. Some employ a simple measure of image noise, while others adopt a measure related to a reference image that accepts higher noise levels in more attenuating parts with higher contrast. At the present time there is no standard method for testing ATCM. This paper reviews the operation of different ATCM systems, considers options for testing, and sets out a framework that could be used for optimizing clinical protocols. If dose and image quality can be established for a reference phantom, the modulation performed by ATCM systems can be characterised using anatomical phantoms or geometrical elliptical phantoms which may be conical or include sections of varying dimension. For scanners using a reference image or mAs, selection of the image quality reference determines other factors. However, for scanners using a noise reference, a higher noise level should be selected for larger patients to avoid high doses, and the operator should ensure that appropriate limits are set for mA modulation. Other factors that need to be considered include the SPRs used to plan the ATCM and image thickness. Users should be aware of the mode of operation of the ATCM system on their CT scanner, and be familiar with the effects of changing different protocol parameters. The behaviour of ATCM systems should be established through testing of each CT scanner with suitable phantoms during commissioning.
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Affiliation(s)
- C J Martin
- Health Physics, Department of Clinical Physics, University of Glasgow, Gartnavel Royal Hospital, Glasgow, G12 0XH, UK
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Tsai HY, Lo CC, Yeh SH, Lee MY, Chen TR. Ambient and Personal Effective Dose Assessment at the International Arrival Hall of Taichung Airport in Taiwan. ARCHIVES OF ENVIRONMENTAL & OCCUPATIONAL HEALTH 2015; 70:265-271. [PMID: 24456008 DOI: 10.1080/19338244.2013.879565] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Ambient monitor and phantom studies were carried out in the international arrival hall of Taichung Airport, Taiwan. A total of 172 thermoluminescent dosimeters (TLDs) were used for ambient monitoring. The sites of the export conveyor, the outward face of the x-ray scanning chamber, and the x-ray image monitor were assessed as low-radiation areas because the possible annual effective doses were 0.12, 0.39, and 0.16 mSv, all less than 1 mSv per year. In addition, a phantom filled with 126 TLDs was used to simulate a 10-year-old child being exposed by the x-ray baggage scanner. The effective dose was evaluated as 3.39 ± 0.33 μSv/scan, using the tissue weighting factor of the International Commission on Radiological Protection (ICRP) 103 report. This figure is a useful reference should a person be accidentally scanned by the x-ray baggage scanner.
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Affiliation(s)
- Hui-Yu Tsai
- a Department of Medical Imaging and Radiological Sciences , Chang Gung University , Taoyuan , Taiwan
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Abdominal CT during pregnancy: a phantom study on the effect of patient centring on conceptus radiation dose and image quality. Eur Radiol 2014; 25:911-21. [DOI: 10.1007/s00330-014-3505-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2014] [Revised: 09/06/2014] [Accepted: 11/13/2014] [Indexed: 12/15/2022]
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Papadakis AE, Perisinakis K, Damilakis J. Automatic exposure control in CT: the effect of patient size, anatomical region and prescribed modulation strength on tube current and image quality. Eur Radiol 2014; 24:2520-31. [DOI: 10.1007/s00330-014-3309-4] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2014] [Revised: 04/25/2014] [Accepted: 07/03/2014] [Indexed: 10/25/2022]
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Yamauchi-Kawaura C, Yamauchi M, Imai K, Ikeda M, Aoyama T. Image quality and age-specific dose estimation in head and chest CT examinations with organ-based tube-current modulation. RADIATION PROTECTION DOSIMETRY 2013; 157:193-205. [PMID: 23734058 DOI: 10.1093/rpd/nct137] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
The purpose of this study was to investigate the effects of an organ-based tube-current modulation (OBTCM) system on image quality and age-specific dose in head and chest CT examinations. Image noise, contrast-to-noise ratio (CNR) and image entropy were assessed using statistical and entropy analyses. Radiation doses for newborn, 6-y-old child and adult phantoms were measured with in-phantom dosimetry systems. The quality of CT images obtained with OBTCM was not different from that obtained without OBTCM. In head CT scans, the eye lens dose decreased by 20-33 % using OBTCM. In chest CT scans, breast dose decreased by 5-32 % using OBTCM. Posterior skin dose, however, increased by 11-20 % using OBTCM in head and chest CT scans. The reduction of effective dose using OBTCM was negligibly small. Detailed image quality and dose information provided in this study can be effectively used for OBTCM application.
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Affiliation(s)
- C Yamauchi-Kawaura
- Department of Radiological Sciences, Graduate School of Medicine, Nagoya University, 1-1-20 Daikominami, Higashi-ku, Nagoya 461-8673, Japan
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Calzado Cantera A, Hernández-Girón I, Salvadó Artells M, Rodríguez González R. [State of the art and future trends in technology for computed tomography dose reduction]. RADIOLOGIA 2013; 55 Suppl 2:9-16. [PMID: 24211196 DOI: 10.1016/j.rx.2013.08.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2013] [Revised: 07/19/2013] [Accepted: 08/21/2013] [Indexed: 10/26/2022]
Abstract
The introduction of helical and multislice acquisitions in CT scanners together with decreased image reconstruction times has had a tremendous impact on radiological practice. Technological developments in the last 10 to 12 years have enabled very high quality images to be obtained in a very short time. Improved image quality has led to an increase in the number of indications for CT. In parallel to this development, radiation exposure in patients has increased considerably. Concern about the potential health risks posed by CT imaging, reflected in diverse initiatives and actions by official organs and scientific societies, has prompted the search for ways to reduce radiation exposure in patients without compromising diagnostic efficacy. To this end, good practice guidelines have been established, special applications have been developed for scanners, and research has been undertaken to optimize the clinical use of CT. Noteworthy technical developments incorporated in scanners include the different modes of X-ray tube current modulation, automatic selection of voltage settings, selective organ protection, adaptive collimation, and iterative reconstruction. The appropriate use of these tools to reduce radiation doses requires thorough knowledge of how they work.
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Affiliation(s)
- A Calzado Cantera
- Departamento de Radiología y Medicina Física, Universidad Complutense, Madrid, España.
| | - I Hernández-Girón
- Departamento de Radiología y Medicina Física, Universidad Complutense, Madrid, España; Departamento de Ciencias Médicas Básicas, Universitat Rovira i Virgili, Reus, España
| | - M Salvadó Artells
- Departamento de Ciencias Médicas Básicas, Universitat Rovira i Virgili, Reus, España
| | - R Rodríguez González
- Departamento de Radiología y Medicina Física, Universidad Complutense, Madrid, España; Servicio de Radiología, Hospital Clínico San Carlos, Madrid, España
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Stratis A, Molfetas M, Panagiotakis N, Louizi A, Kottou S. Accuracy of CT dose monitor values: a multicentric study. RADIATION PROTECTION DOSIMETRY 2013; 158:285-289. [PMID: 24026901 DOI: 10.1093/rpd/nct223] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Four hundred and ninety-five adult patients in 16 medical centres participated in this study aiming to investigate the congruence between the volume CT dose index (CTDIvol) monitor values and measured ones during common CT procedures, performed by 20 systems. Tube output CTDIair measurements were carried out on single and multislice scanners for any kV, slice thickness, mA and FOV combination used. The maximum/minimum ratio of measured CTDIvol values found to be 3.1, 3.5, 7.4, 7.5, 4.2, 11.3 and 5.5 for head base, head cerebrum, thorax, abdomen, pelvis, cervical spine and lumbar spine protocols, respectively. The mean divergence between the measured and displayed CTDIvol values was 4.2, 3.5, -1.0, 2.7, 4.9, -3.9 and -2.8 % for protocols as mentioned above, respectively. From the perspective of the number of detector rows of the scanners, the mean divergence was -6.7, -6.0, 0.8, -1.1, -0.4, -1.9, -5.3, 5.2 and 10.1 % for single, dual, 4, 6, 16, 24, 64, 128 and dual source 256-slice systems, respectively.
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Affiliation(s)
- A Stratis
- Medical Physics Department, Medical School, University of Athens, Athens, Greece
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Effect of x-ray tube parameters and iodine concentration on image quality and radiation dose in cerebral pediatric and adult CT angiography: a phantom study. Invest Radiol 2013; 48:192-9. [PMID: 23344518 DOI: 10.1097/rli.0b013e31827efc17] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
OBJECTIVES The aim of the present phantom study was to investigate the effect of x-ray tube parameters and iodine concentration on image quality and radiation dose in cerebral computed tomographic (CT) angiographic examinations of pediatric and adult individuals. MATERIALS AND METHODS Four physical anthropomorphic phantoms that represent the average individual as neonate, 1-year-old, 5-year-old, and 10-year-old children and the RANDO phantom that simulates the average adult individual were used. Cylindrical vessels were bored along the brain-equivalent plugs of each physical phantom. To simulate the brain vasculature, vessels of 0.6, 1, 2, and 3 mm in diameter were created. These vessels were filled with contrast medium (CM) solutions at different iodine concentrations, that is, 5.6, 4.2, 2.7, and 1.4 mg I/mL. The phantom heads were scanned at 120, 100, and 80 kV. The applied quality reference tube current-time product values ranged from a minimum of 45 to a maximum of 680. The CT acquisitions were performed on a 16-slice CT scanner using the automatic exposure control system. Image quality was evaluated on the basis of image noise and contrast-to-noise ratio (CNR) between the contrast-enhanced iodinated vessels and the unenhanced regions of interest. Dose reduction was calculated as the percentage difference of the CT dose index value at the quality reference tube current-time product and the CT dose index at the mean modulated tube current-time product. RESULTS Image noise that was measured using the preset tube current-time product settings varied significantly among the different phantoms (P < 0.0001). Hounsfield unit number of iodinated vessels was linearly related to CM concentration (r² = 0.907) and vessel diameter (r² = 0.918). The Hounsfield unit number of iodinated vessels followed a decreasing trend from the neonate phantom to the adult phantom at all kilovoltage settings. For the same image noise level, a CNR improvement of up to 69% and a dose reduction of up to 61% may be achieved when CT acquisition is performed at 80 kV compared with 120 kV. For the same CNR, a reduction by 25% of the administered CM concentration may be achieved when CT acquisition is performed at 80 kV compared with 120 kV. CONCLUSIONS In cerebral CT angiographic studies, appropriate adjustment of the preset tube current-time product settings is required to achieve the same image noise level among participants of different age. Cerebral CT angiography at 80 kV significantly improves CNR and significantly reduces radiation dose. Moreover, at 80 kV, a considerable reduction of the administered amount of the CM may be reached, thus reducing potential risks for contrast-induced nephropathy.
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Verdun FR, Alamo L, Miéville FA, Gudinchet F. Radiation Dose Management in Pediatric CT. CURRENT RADIOLOGY REPORTS 2013. [DOI: 10.1007/s40134-012-0002-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Stratis A, Kottou S, Molfetas M, Xirafi I, Delis H, Panayiotakis G. The effect of a combined tube current modulation system on dose delivered to patients undergoing thoracic and abdominal CT with a 128-slice scanner. RADIATION PROTECTION DOSIMETRY 2013; 153:206-211. [PMID: 23173217 DOI: 10.1093/rpd/ncs301] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Combined tube current modulation techniques (such as Care Dose4D used in this study) during computed tomography (CT) procedures bring together the benefits of the angular and z-axis modulation techniques, measuring X-ray attenuation profile in the z-axis together with the data from the perpendicular x-y direction with a sophisticated algorithm. The purpose of this study was to investigate the radiation dose, in terms of computed tomography dose index (CTDI(vol)), delivered to patients during thoracic and abdominal CT using this technique and compare it with the corresponding CTDI(vol) of the fixed tube current CT technique. The results revealed a 5-32% dose reduction for chest CT and a dose reduction of 7.6-60% for the three-sequence abdominal CT scan of normal and overweight patients. In the case of obese patients a 15.4-18.7% dose increase for chest CT and a (-1.5) - (26.3)% dose increase for the three-stage abdominal examinations for females and males, respectively, was revealed.
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Affiliation(s)
- A Stratis
- Department of Medical Physics, School of Medicine, University of Patras, Patras 26500, Greece.
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Van der Molen AJ, Joemai RMS, Geleijns J. Performance of longitudinal and volumetric tube current modulation in a 64-slice CT with different choices of acquisition and reconstruction parameters. Phys Med 2011; 28:319-26. [PMID: 22061446 DOI: 10.1016/j.ejmp.2011.10.005] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/07/2011] [Revised: 10/08/2011] [Accepted: 10/11/2011] [Indexed: 10/15/2022] Open
Abstract
Aim of the study was to evaluate the performance of a tube current modulation (TCM) system ((SURE)Exposure 3D). On a 64 detector-row CT scanner (Aquilion 64, Toshiba), performance of fixed tube current, longitudinal TCM, and volumetric TCM acquisitions were assessed. A homogeneous cone-shaped phantom and an anthropomorphic phantom were used. Tube current and noise profiles were quantitatively analysed by box and whisker plots when phantom size, acquisition, and reconstruction parameters were varied. At similar median noise, fixed tube current scanning showed a noise range of 16.8-38.3 HU, while longitudinal TCM showed a range of 19.4-31.4 HU and volumetric TCM showed an even lower range of 20.7-28.7 HU. When acquisitions resulting in similar image quality (noise) were compared, the use of volumetric compared to longitudinal TCM resulted in a variable radiation dose reduction up to 6.6%. In conclusion, (SURE)Exposure 3D resulted in more uniform image quality at a lower dose. Volumetric TCM shows improved results over longitudinal TCM.
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Affiliation(s)
- Aart J Van der Molen
- Department of Radiology C-2S, Leiden University Medical Center, Albinusdreef 2, NL-2333 ZA Leiden, The Netherlands.
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Bartolac S, Graham S, Siewerdsen J, Jaffray D. Fluence field optimization for noise and dose objectives in CT. Med Phys 2011; 38 Suppl 1:S2. [PMID: 21978114 DOI: 10.1118/1.3574885] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Affiliation(s)
- Steven Bartolac
- Department of Medical Biophysics, University of Toronto, Toronto, Ontario M5G 2M9, Canada.
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Yu L, Bruesewitz MR, Thomas KB, Fletcher JG, Kofler JM, McCollough CH. Optimal Tube Potential for Radiation Dose Reduction in Pediatric CT: Principles, Clinical Implementations, and Pitfalls. Radiographics 2011; 31:835-48. [PMID: 21571660 DOI: 10.1148/rg.313105079] [Citation(s) in RCA: 155] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Affiliation(s)
- Lifeng Yu
- Department of Radiology, Mayo Clinic College of Medicine, 200 First St SW, Rochester, MN 55905, USA.
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Raissaki M, Perisinakis K, Damilakis J, Gourtsoyiannis N. Eye-lens bismuth shielding in paediatric head CT: artefact evaluation and reduction. Pediatr Radiol 2010; 40:1748-54. [PMID: 20552187 DOI: 10.1007/s00247-010-1715-6] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/07/2010] [Revised: 03/25/2010] [Accepted: 04/14/2010] [Indexed: 11/26/2022]
Abstract
BACKGROUND CT scans of the brain, sinuses and petrous bones performed as the initial imaging test for a variety of indications have the potential to expose the eye-lens, considered among the most radiosensitive human tissues, to a radiation dose. There are several studies in adults discussing the reduction of orbital dose resulting from the use of commercially available bismuth-impregnated latex shields during CT examinations of the head. OBJECTIVE To evaluate bismuth shielding-induced artefacts and to provide suggestions for optimal eye-lens shielding in paediatric head CT. MATERIALS AND METHODS A bismuth shield was placed over the eyelids of 60 consecutive children undergoing head CT. Images were assessed for the presence and severity of artefacts with regard to eye-shield distance and shield wrinkling. An anthropomorphic paediatric phantom and thermoluminescence dosimeters (TLDs) were used to study the effect of eye lens-to-shield distance on shielding efficiency. RESULTS Shields were tolerated by 56/60 children. Artefacts were absent in 45% of scans. Artefacts on orbits, not affecting and affecting orbit evaluation were noted in 39% and 14% of scans, respectively. Diagnostically insignificant artefacts on intracranial structures were noted in 1 case (2%) with shield misplacement. Mean eye-lens-to-shield distance was 8.8 mm in scans without artefacts, and 4.3 mm and 2.2 mm in scans with unimportant and diagnostically important artefacts, respectively. Artefacts occurred in 8 out of 9 cases with shield wrinkling. Dose reduction remained unchanged for different shield-to-eye distances. CONCLUSION Bismuth shielding-related artefacts occurring in paediatric head CT are frequent, superficial and diagnostically insignificant when brain pathology is assessed. Shields should be placed 1 cm above the eyes when orbital pathology is addressed. Shield wrinkling should be avoided.
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Affiliation(s)
- Maria Raissaki
- Department of Radiology, University Hospital of Heraklion, University of Crete, Faculty of Medicine, Stavrakia, Voutes, PO Box 2208, 71003 Heraklion, Crete, Greece.
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van Straten M, Deak P, Shrimpton PC, Kalender WA. The effect of angular and longitudinal tube current modulations on the estimation of organ and effective doses in x-ray computed tomography. Med Phys 2010; 36:4881-9. [PMID: 19994496 DOI: 10.1118/1.3231948] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
PURPOSE Tube current modulation (TCM) is one of the recent developments in multislice CT that has proven to reduce the patient radiation dose without affecting the image quality. Presently established methods and published coefficients for estimating organ doses from the dose measured free in air on the axis of rotation or in the CT dose index (CTDI) dosimetry phantoms do not take into account this relatively new development in CT scanner design and technology. Based on these organ dose coefficients effective dose estimates can be made. The estimates are not strictly valid for CT scanning protocols utilizing TCM. In this study, the authors investigated the need to take TCM into account when estimating organ and effective dose values. METHODS A whole-body adult anthropomorphic phantom (Alderson Rando) was scanned with a multislice CT scanner (Somatom Definition, Siemens, Forchheim, Germany) utilizing TCM (CareDose4D). Tube voltage was 120 kV, beam collimation 19.2 mm, and pitch 1. A voxelized patient model was used to define the tissues and organs in the phantom. Tube current values as a function of tube angle were obtained from the raw data for each individual tube rotation of the scan. These values were used together with the Monte Carlo dosimetry tool IMPACTMC (VAMP GmbH, Erlangen, Germany) to calculate organ dose values both with and without account of TCM. Angular and longitudinal modulations were investigated separately. Finally, corresponding effective dose conversion coefficients were determined for both cases according to the updated 2007 recommendations of the ICRP. RESULTS TCM amplitude was greatest in the shoulder and pelvic regions. Consequently, dose distributions and organ dose values for particular cross sections changed considerably when taking angular modulation into account. The effective dose conversion coefficients were up to 11% lower for a single rotation in the shoulder region and 17% lower in the pelvis when taking angular TCM into account. In the head, neck, thorax, and upper abdominal regions, conversion coefficients changed similarly by only 5% or less. Conversion coefficients for estimating effective doses for scans of complete regions, e.g., chest or abdomen, were approximately 8% lower when taking angular and longitudinal TCMs into account. CONCLUSIONS The authors conclude that for accurate organ and effective dose estimates in individual cross sections in the shoulder or pelvic regions, the angular tube current modulation should be taken into account. In general, using the average of the modulated tube current causes an overestimation of the effective dose.
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Affiliation(s)
- Marcel van Straten
- Institute of Medical Physics, University Erlangen-Nürnberg, Henkestrasse 91, 91052 Erlangen, Germany.
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Brisse HJ, Robilliard M, Savignoni A, Pierrat N, Gaboriaud G, De Rycke Y, Neuenschwander S, Aubert B, Rosenwald JC. Assessment of organ absorbed doses and estimation of effective doses from pediatric anthropomorphic phantom measurements for multi-detector row CT with and without automatic exposure control. HEALTH PHYSICS 2009; 97:303-314. [PMID: 19741359 DOI: 10.1097/hp.0b013e3181ad00ed] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
This study was designed to measure organ absorbed doses from multi-detector row computed tomography (MDCT) on pediatric anthropomorphic phantoms, calculate the corresponding effective doses, and assess the influence of automatic exposure control (AEC) in terms of organ dose variations. Four anthropomorphic phantoms (phantoms represent the equivalent of a newborn, 1-, 5-, and 10-y-old child) were scanned with a four-channel MDCT coupled with a z-axis-based AEC system. Two CT torso protocols were compared: a first protocol without AEC and constant tube current-time product and a second protocol with AEC using age-adjusted noise indices. Organ absorbed doses were monitored by thermoluminescent dosimeters (LiF: Mg, Cu, P). Effective doses were calculated according to the tissue weighting factors of the International Commission on Radiological Protection (). For fixed mA acquisitions, organ doses normalized to the volume CT dose index in a 16-cm head phantom (CTDIvol16) ranged from 0.6 to 1.5 and effective doses ranged from 8.4 to 13.5 mSv. For the newborn-equivalent phantom, the AEC-modulated scan showed almost no significant dose variation compared to the fixed mA scan. For the 1-, 5- and 10-y equivalent phantoms, the use of AEC induced a significant dose decrease on chest organs (ranging from 61 to 31% for thyroid, 37 to 21% for lung, 34 to 17% for esophagus, and 39 to 10% for breast). However, AEC also induced a significant dose increase (ranging from 28 to 48% for salivary glands, 22 to 51% for bladder, and 24 to 70% for ovaries) related to the high density of skull base and pelvic bones. These dose increases should be considered before using AEC as a dose optimization tool in children.
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Effective dose and image quality evaluations of an automatic CT tube current modulation system with an anthropomorphic phantom. Eur J Radiol 2009; 72:181-7. [DOI: 10.1016/j.ejrad.2008.06.027] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2008] [Revised: 06/04/2008] [Accepted: 06/25/2008] [Indexed: 11/19/2022]
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Radiation Dose for Body CT Protocols: Variability of Scanners at One Institution. AJR Am J Roentgenol 2009; 193:1141-7. [PMID: 19770340 DOI: 10.2214/ajr.09.2330] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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Brisse HJ, Brenot J, Pierrat N, Gaboriaud G, Savignoni A, De Rycke Y, Neuenschwander S, Aubert B, Rosenwald JC. The relevance of image quality indices for dose optimization in abdominal multi-detector row CT in children: experimental assessment with pediatric phantoms. Phys Med Biol 2009; 54:1871-92. [PMID: 19265204 DOI: 10.1088/0031-9155/54/7/002] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
This study assessed and compared various image quality indices in order to manage the dose of pediatric abdominal MDCT protocols and to provide guidance on dose reduction. PMMA phantoms representing average body diameters at birth, 1 year, 5 years, 10 years and 15 years of age were scanned in a four-channel MDCT with a standard pediatric abdominal CT protocol. Image noise (SD, standard deviation of CT number), noise derivative (ND, derivative of the function of noise with respect to dose) and contrast-to-noise ratio (CNR) were measured. The 'relative' low-contrast detectability (rLCD) was introduced as a new quantity to adjust LCD to the various phantom diameters on the basis of the LCD(1%) assessed in a Catphan phantom and a constant central absorbed dose. The required variations of CTDIvol(16) with respect to phantom size were analyzed in order to maintain each image quality index constant. The use of a fixed SD or CNR level leads to major dose ratios between extreme patient sizes (factor 22.7 to 44 for SD, 31.7 to 51.5 for CNR(2.8%)), whereas fixed ND and rLCD result in acceptable dose ratios ranging between factors of 2.9 and 3.9 between extreme phantom diameters. For a 5-9 mm rLCD1(%), adjusted ND values range between -0.84 and -0.11 HU mGy(-1). Our data provide guidance on dose reduction on the basis of patient dimensions and the required rLCD (e.g., to get a constant 7 mm rLCD(1%) for abdominal diameters of 10, 13, 16, 20 and 25 cm, tube current-time product should be adjusted in order to obtain CTDIvol(16) values of 6.2, 7.2, 8.8, 11.6 and 17.7 mGy, respectively).
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Affiliation(s)
- H J Brisse
- Imaging Department, Institut Curie, 26 rue d'Ulm 75005 Paris, France.
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Effective dose estimation in whole-body multislice CT in paediatric trauma patients. Pediatr Radiol 2009; 39:245-52. [PMID: 19148630 DOI: 10.1007/s00247-008-1091-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/17/2007] [Revised: 07/07/2008] [Accepted: 10/19/2008] [Indexed: 10/24/2022]
Abstract
BACKGROUND The number of multislice CT (MSCT) scans performed in polytraumatized children has increased rapidly. There is growing concern regarding the radiation dose in MSCT and its long-term consequences, especially in children. OBJECTIVE To determine the effective dose to polytraumatized children who undergo whole-body MSCT. MATERIALS AND METHODS A total of 51 traumatized children aged 0-16 years underwent a polytrauma protocol CT scan between November 2004 and August 2006 at our institution. The effective dose was calculated retrospectively by a computer program (CT-Expo 1.5, Hannover, Germany). RESULTS The mean effective dose was 20.8 mSv (range 8.6-48.9 mSv, SD +/- 7.9 mSv). There was no statistically significant difference in the effective dose between male and female patients. CONCLUSION Whole-body MSCT is a superior diagnostic tool in polytraumatized children with 20.8 mSv per patient being a justified mean effective dose. In a potentially life-threatening situation whole-body MSCT provides the clinicians with relevant information to initiate life-saving therapy. Radiologists should use special paediatric protocols that include dose-saving mechanisms to keep the effective dose as low as possible. Further studies are needed to examine and advance dose-saving strategies in MSCT, especially in children.
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Papadakis AE, Perisinakis K, Damilakis J. Automatic exposure control in pediatric and adult multidetector CT examinations: A phantom study on dose reduction and image quality. Med Phys 2008; 35:4567-76. [DOI: 10.1118/1.2977535] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
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Pan X, Siewerdsen J, La Riviere PJ, Kalender WA. Anniversary paper. Development of x-ray computed tomography: the role of medical physics and AAPM from the 1970s to present. Med Phys 2008; 35:3728-39. [PMID: 18777932 PMCID: PMC3910137 DOI: 10.1118/1.2952653] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2008] [Revised: 06/09/2008] [Accepted: 06/09/2008] [Indexed: 01/17/2023] Open
Abstract
The AAPM, through its members, meetings, and its flagship journal Medical Physics, has played an important role in the development and growth of x-ray tomography in the last 50 years. From a spate of early articles in the 1970s characterizing the first commercial computed tomography (CT) scanners through the "slice wars" of the 1990s and 2000s, the history of CT and related techniques such as tomosynthesis can readily be traced through the pages of Medical Physics and the annals of the AAPM and RSNA/AAPM Annual Meetings. In this article, the authors intend to give a brief review of the role of Medical Physics and the AAPM in CT and tomosynthesis imaging over the last few decades.
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Affiliation(s)
- Xiaochuan Pan
- Department of Radiology, University of Chicago, Chicago, Illinois 60637, USA.
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Brink M, Deunk J, Dekker HM, Kool DR, Edwards MJR, van Vugt AB, Blickman JG. Added Value of Routine Chest MDCT After Blunt Trauma: Evaluation of Additional Findings and Impact on Patient Management. AJR Am J Roentgenol 2008; 190:1591-1598. [DOI: 10.2214/ajr.07.3277] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/30/2023]
Affiliation(s)
- Monique Brink
- Department of Diagnostic Imaging, Radboud University Nijmegen Medical Centre, Internal number (Huispost) 667, Geert Groote plein 10, 6500 HB Nijmegen, The Netherlands
| | - Jaap Deunk
- Department of Surgery, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
| | - Helena M. Dekker
- Department of Diagnostic Imaging, Radboud University Nijmegen Medical Centre, Internal number (Huispost) 667, Geert Groote plein 10, 6500 HB Nijmegen, The Netherlands
| | - Digna R. Kool
- Department of Diagnostic Imaging, Radboud University Nijmegen Medical Centre, Internal number (Huispost) 667, Geert Groote plein 10, 6500 HB Nijmegen, The Netherlands
| | - Michael J. R. Edwards
- Department of Surgery, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
| | - Arie B. van Vugt
- Department of Surgery, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
| | - Johan G. Blickman
- Department of Diagnostic Imaging, Radboud University Nijmegen Medical Centre, Internal number (Huispost) 667, Geert Groote plein 10, 6500 HB Nijmegen, The Netherlands
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