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Røhme LAG, Homme THF, Johansen ECK, Schulz A, Aaløkken TM, Johansson E, Johansen S, Mussmann B, Brunborg C, Eikvar LK, Martinsen ACT. Image quality and radiation doses in abdominal CT: A multicenter study. Eur J Radiol 2024; 178:111642. [PMID: 39079322 DOI: 10.1016/j.ejrad.2024.111642] [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: 03/23/2024] [Revised: 06/18/2024] [Accepted: 07/22/2024] [Indexed: 08/18/2024]
Abstract
PURPOSE To benchmark image quality and corresponding radiation doses for acute abdominal CT examination across different laboratories and CT manufacturers. METHOD An anthropomorphic phantom was scanned once with local abdominal CT protocols at 40 CT scanners, from four vendors, in thirty-three sites. Quantitative image quality was evaluated by CNR and SNR in the liver and kidney parenchyma. Qualitative image quality was assessed by visual grading analysis performed by three experienced radiologists using a five-point Likert scale to score thirteen image quality criteria. The CTDIvol was recorded for each scan. Pearson's correlation coefficient was calculated for the continuous variables, and the intraclass correlation coefficient was used to investigate interrater reliability between the radiologists. RESULTS CTDIvol ranged from 3.5 to 12 mGy (median 5.3 mGy, third quartile 6.7 mGy). SNR in liver parenchyma ranged from 4.4 to 14.4 (median 8.5), and CNR ranged from 2.7 to 11.2 (median 6.1). A weak correlation was found between CTDIvol and CNR (r = 0.270, p = 0.092). Variations in CNR across scanners at the same dose level CTDIvol were observed. No significant difference in CTDIvol or CNR was found based on scanner installation year. The oldest scanners had a 15 % higher median CTDIvol and a 12 % lower median CNR. The ICC showed acceptable agreement for all dose groups: low (ICC=0.889), medium (ICC=0.767), high (ICC=0.847), and in low (ICC=0.803) and medium (ICC=0.811) CNR groups. CONCLUSION There was large variation in radiation dose and image quality across the different CT scanners. Interestingly, the weak correlation between CTDIvol and CNR indicates that higher doses do not consistently improve CNR, indicating a need for systematic assessment and optimization of image quality and radiation doses for the abdominal CT examination.
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Affiliation(s)
- Linn Andrea Gjerberg Røhme
- Department of Life Sciences and Health, Faculty of Health Science, Oslo Metropolitan University Oslo, Norway.
| | - Tora Hilde Fjeld Homme
- Department of Life Sciences and Health, Faculty of Health Science, Oslo Metropolitan University Oslo, Norway.
| | | | - Anselm Schulz
- Department of Radiology and Nuclear Medicine, Oslo University Hospital, Norway; Institute of Clinical Medicine, University of Oslo, Oslo, Norway.
| | - Trond Mogens Aaløkken
- Institute of Clinical Medicine, University of Oslo, Oslo, Norway; Department of Radiology and Nuclear Medicine, Oslo University Hospital Rikshospitalet, Oslo, Norway.
| | - Ellen Johansson
- Department of Radiology, Drammen Hospital, Vestre Viken Hospital Trust, Norway.
| | - Safora Johansen
- Department of Life Sciences and Health, Faculty of Health Science, Oslo Metropolitan University Oslo, Norway; Department of Cancer Treatment, Oslo University Hospital, Oslo, Norway; Health and Social Science Cluster, Singapore Institute of Technology, Singapore.
| | - Bo Mussmann
- Department of Life Sciences and Health, Faculty of Health Science, Oslo Metropolitan University Oslo, Norway; Department of Radiology, Odense University Hospital, Odense, Denmark; Research and Innovation Unit of Radiology, University of Southern Denmark, Odense, Denmark.
| | - Cathrine Brunborg
- Oslo Centre for Biostatistics and Epidemiology, Research Support Services, Oslo University Hospital, Oslo, Norway.
| | - Lars Kristian Eikvar
- Department of Medicine and Health Services, The South-Eastern Norway Health Authority, Hamar, Norway.
| | - Anne Catrine T Martinsen
- Department of Life Sciences and Health, Faculty of Health Science, Oslo Metropolitan University Oslo, Norway; Centre for Research and Innovation, Sunnaas Rehabilitation Hospital, Bjornemyr, Norway.
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Karout L, Kalra MK. Survey of CT radiation doses and iodinated contrast medium administration: an international multicentric study. Eur Radiol 2024:10.1007/s00330-024-11017-7. [PMID: 39181948 DOI: 10.1007/s00330-024-11017-7] [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: 01/03/2024] [Revised: 06/24/2024] [Accepted: 07/15/2024] [Indexed: 08/27/2024]
Abstract
OBJECTIVE To assess the relationship between intravenous iodinated contrast media (ICM) administration usage and radiation doses for contrast-enhanced (CE) CT of head, chest, and abdomen-pelvis (AP) in international, multicenter settings. METHODS Our international (n = 16 countries), multicenter (n = 43 sites), and cross-sectional (ConRad) study had two parts. Part 1: Redcap survey with questions on information related to CT and ICM manufacturer/brand and respective protocols. Part 2: Information on 3,258 patients (18-96 years; M:F 1654:1604) who underwent CECT for a routine head (n = 456), chest (n = 528), AP (n = 599), head CT angiography (n = 539), pulmonary embolism (n = 599), and liver CT examinations (n = 537) at 43 sites across five continents. The following information was recorded: hospital name, patient age, gender, body mass index [BMI], clinical indications, scan parameters (number of scan phases, kV), IV-contrast information (concentration, volume, flow rate, and delay), and dose indices (CTDIvol and DLP). RESULTS Most routine chest (58.4%) and AP (68.7%) CECT exams were performed with 2-4 scan phases with fixed scan delay (chest 71.4%; AP 79.8%, liver CECT 50.7%) following ICM administration. Most sites did not change kV across different patients and scan phases; most CECT protocols were performed at 120-140 kV (83%, 1979/2685). There were no significant differences between radiation doses for non-contrast (CTDIvol 24 [16-30] mGy; DLP 633 [414-702] mGy·cm) and post-contrast phases (22 [19-27] mGy; 648 [392-694] mGy·cm) (p = 0.142). Sites that used bolus tracking for chest and AP CECT had lower CTDIvol than sites with fixed scan delays (p < 0.001). There was no correlation between BMI and CTDIvol (r2 ≤ - 0.1 to 0.1, p = 0.931). CONCLUSION Our study demonstrates up to ten-fold variability in ICM injection protocols and radiation doses across different CT protocols. The study emphasizes the need for optimizing CT scanning and contrast protocols to reduce unnecessary contrast and radiation exposure to patients. CLINICAL RELEVANCE STATEMENT The wide variability and lack of standardization of ICM media and radiation doses in CT protocols suggest the need for education and optimization of contrast usage and scan factors for optimizing image quality in CECT. KEY POINTS There is a lack of patient-centric CT protocol optimization taking into consideration mainly patients' size. There is a lack of correlation between ICM volume and CT radiation dose across CT protocol. A ten-fold variation in iodine-load for the same CT protocol in sites suggests a lack of standardization.
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Affiliation(s)
- Lina Karout
- Massachusetts General Hospital, Boston, MA, USA
| | - Mannudeep K Kalra
- Faculty of Applied Medical, Jordan University of Science and Technology, Irbid, Jordan.
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Jiang Y, Jiang J, Li J, Hui Q, Tang J, Wang G, Zhang Y, Ma C. Enhancing acute stroke assessment: evaluating the clinical utility of the "Real" one-stop-shop scan protocol combining brain computed tomography perfusion and head-and-neck computed tomography angiography using a 512-slice detector computed tomography scanner. Clin Radiol 2024:S0009-9260(24)00413-6. [PMID: 39198108 DOI: 10.1016/j.crad.2024.07.023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2024] [Revised: 07/26/2024] [Accepted: 07/30/2024] [Indexed: 09/01/2024]
Abstract
AIM To assess the efficiency and diagnostic value of the "real" one-stop-shop protocol integrating the computed tomography angiography (CTA) sequence of the head and neck into the computed tomography perfusion (CTP) acquisition using a 512-slice detector CT scanner in patients who suffered from acute ischemic stroke. MATERIALS AND METHODS This prospective study included 100 patients suspected of acute ischemic stroke. The patients were randomly divided into two groups: the control group (n=50) who underwent the traditional protocol (brain CTP and head-and-neck CTA examination separately) and the experimental group (n=50) who underwent a one-stop-shop protocol (combined brain CT perfusion and head-and-neck CTA, the CTA triggering time determined by a low-dose test bolus injection). The examination time, contrast-agent dosage, radiation dose, postprocessing time, and image quality were compared between the two groups. RESULTS Compared to the control group, the experimental group had a significantly lower total iodine contrast-agent dosage (80 vs. 100 ml, P<0.001) and shorter scan time (3.23 [3.13, 3.35] vs. 2.32 [2.17, 2.45] min, P<0.001). Additionally, the radiation dose exposure was lower in the experimental group than in the control group (5129.00 [5173, 5232] vs. 4681.35 [4555.12, 4822.95] mGy-cm, P<0.001). No statistically significant differences were observed between the two groups in terms of postprocessing time, head-and-neck CTA, and CTP imaging quality. CONCLUSION The one-stop-shop protocol enables effective detection of lesions, providing clear visualization of the location and degree of stenosis in the head-and-neck vessels. It achieves this with lower costs in scan time, contrast-agent dosage, and radiation dose compared to the traditional protocol and is thus worth considering as the first examination for patients who suffer from acute ischemic stroke.
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Affiliation(s)
- Y Jiang
- Department of Radiology, Deyang People's Hospital, 173# Taishan Bei Road, Jingyang District, Deyang, 618000, Sichuan, China
| | - J Jiang
- Department of Radiology, Deyang People's Hospital, 173# Taishan Bei Road, Jingyang District, Deyang, 618000, Sichuan, China
| | - J Li
- Department of Thyroid and Breast Surgery, General Hospital of Western Theater Command of Chinese People's Liberation Army, Chengdu, Sichuan, China
| | - Q Hui
- Department of Radiology, Deyang People's Hospital, 173# Taishan Bei Road, Jingyang District, Deyang, 618000, Sichuan, China
| | - J Tang
- Department of Radiology, Deyang People's Hospital, 173# Taishan Bei Road, Jingyang District, Deyang, 618000, Sichuan, China
| | - G Wang
- CT Business Unit, Neusoft Medical System Company, Shenyang, China
| | - Y Zhang
- Department of Radiology, Deyang People's Hospital, 173# Taishan Bei Road, Jingyang District, Deyang, 618000, Sichuan, China
| | - C Ma
- Department of Radiology, Deyang People's Hospital, 173# Taishan Bei Road, Jingyang District, Deyang, 618000, Sichuan, China.
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Girsa D, Kremenova K, Lukavsky J, Sukupova L, Malikova H. Comparison of dose length product and image quality of a biphasic whole-body polytrauma CT protocol with and without the automatic tube voltage selection. Biomed Pap Med Fac Univ Palacky Olomouc Czech Repub 2024. [PMID: 38445394 DOI: 10.5507/bp.2024.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/07/2024] Open
Abstract
BACKGROUND AND AIMS A significant source of man-made radiation is now linked to medical devices especially X-ray imaging based ones like CT scans which expose the body to cumulative ionizing radiation and thus attendant cancer risks. The aim of this study was to determine whether using a combination of Automatic Tube Current Modulation (ATCM) and Automatic Tube Voltage Selection (ATVS) during two-phase whole-body CT (2PWBCT) examinations would reduce the radiation dose while preserving the image quality. PATIENTS AND METHODS This was a prospective, observational, single-centre study of 127 adult patients who had undergone the 2PWBCT polytraumatic protocol. All were examined on a Somatom Drive scanner (Siemens). The patients were divided into two groups: ATCM only (42 patients) and ATCM +ATVS (85 patients). Patients' arm positions during examination and the examination dose length product (DLP) values were recorded, as well the standard deviations (SD) of the density in reference areas on CT scans for the image quality assessment. The DLP values and image quality in the groups were compared using ANOVA. RESULTS Mean Total DLP (in mGy*cm): ATCM only: 3337 +/-797, ATCM+ATVS: 3402 +/-830; P=0.674. No effect of arm position (P=0.586). Mean density SD values in reference areas (in HU) in ATCM only: 49 +/-45, 15 +/-6, 9 +/-2, 12 +/-4, 10 +/-3, in ATCM+ATVS: 48 +/-45, 17 +/-6, 11 +/-3, 15 +/-6, 12 +/-4. SD values was higher in ATCM+ATVS group (P<0.001). CONCLUSION Combination of ATVS and ATCM in polytraumatic 2PWBCT leads to no significant radiation load reduction compared with ATCM only but does lead to a slight degradation of image quality. The radiation load is significantly reduced if the patient has their arms behind the head when scanning, regardless of the activation of ATVS.
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Affiliation(s)
- David Girsa
- Department of Radiology and Nuclear Medicine, Third Faculty of Medicine, Charles University in Prague and Faculty Hospital Kralovske Vinohrady; Second Faculty of Medicine, Charles University in Prague, Czech Republic
| | - Karin Kremenova
- Department of Radiology and Nuclear Medicine, Third Faculty of Medicine, Charles University in Prague and Faculty Hospital Kralovske Vinohrady, Prague, Czech Republic
| | - Jiri Lukavsky
- Institute of Psychology, Czech Academy of Sciences, 110 00 Prague, Czech Republic; Department of Psychology, Faculty of Arts, Charles University in Prague, Czech Republic
| | - Lucie Sukupova
- Director's Department, Institute for Clinical and Experimental Medicine, Prague, Czech Republic
| | - Hana Malikova
- Department of Radiology and Nuclear Medicine, Third Faculty of Medicine, Charles University in Prague and Faculty Hospital Kralovske Vinohrady; Second Faculty of Medicine, Charles University in Prague, Czech Republic
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Masuda T, Nakaura T, Funama Y, Sato T, Masuda S, Gotanda R, Arao K, Imaizumi H, Arao S, Ono A, Hiratsuka J, Awai K. RADIATION DOSE REDUCTION AT LOW TUBE VOLTAGE WITH CORONARY ARTERY BYPASS GRAFT COMPUTED TOMOGRAPHY ANGIOGRAPHY BASED ON THE CONTRAST NOISE RATIO INDEX. RADIATION PROTECTION DOSIMETRY 2023; 199:527-532. [PMID: 36881907 DOI: 10.1093/rpd/ncad049] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/10/2022] [Revised: 02/08/2023] [Accepted: 02/10/2023] [Indexed: 06/18/2023]
Abstract
To compare the radiation dose and diagnostic ability of the 100-kVp protocol, based on the contrast noise ratio (CNR) index, during coronary artery bypass graft (CABG) vessels with those of the 120-kVp protocol. For the 120-kVp scans (150 patients), the targeted image level was set at 25 Hounsfield units (HU) (CNR120 = iodine contrast/25 HU). For the 100-kVp scans (150 patients), the targeted noise level was set at 30 HU to obtain the same CNR as in the 120-kVp scans (i.e. using 1.2-fold higher iodine contrast, CNR100 = 1.2 × iodine contrast/(1.2 × 25 HU) = CNR120). We compared the CNRs, radiation doses, detection of CABG vessels and visualisation scores of the scans acquired at 120 and 100 kVp, respectively. At the same CNR, the 100-kVp protocol may help reduce the radiation dose by ⁓30% compared with the 120-kVp protocol, without degradation of diagnostic ability during CABG.
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Affiliation(s)
- Takanori Masuda
- Department of Radiological Technology, Faculty of Health Science and Technology, Kawasaki University of Medical Welfare, 288, Matsushima, Kurashiki, Okayama 701-0193, Japan
| | - Takeshi Nakaura
- Department of Diagnostic Radiology, Graduate School of Medical Sciences, Kumamoto University, 1-1-1 Honjo, Kumamoto 860-8556, Japan
| | - Yoshinori Funama
- Department of Medical Physics, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan
| | - Tomoyasu Sato
- Department of Diagnostic Radiology, Tsuchiya General Hospital, Nakajima-cho 3-30, Naka-ku, Hiroshima 730-8655, Japan
| | - Shouko Masuda
- Department of Radiological Technology, Kawamura clinic Otemachi, Naka-ku, Hiroshima 730-0051, Japan
| | - Rumi Gotanda
- Department of Radiological Technology, Faculty of Health Science and Technology, Kawasaki University of Medical Welfare, 288, Matsushima, Kurashiki, Okayama 701-0193, Japan
| | - Keiko Arao
- Department of Radiological Technology, Faculty of Health Science and Technology, Kawasaki University of Medical Welfare, 288, Matsushima, Kurashiki, Okayama 701-0193, Japan
| | - Hiromasa Imaizumi
- Department of Radiological Technology, Faculty of Health Science and Technology, Kawasaki University of Medical Welfare, 288, Matsushima, Kurashiki, Okayama 701-0193, Japan
| | - Shinichi Arao
- Department of Radiological Technology, Faculty of Health Science and Technology, Kawasaki University of Medical Welfare, 288, Matsushima, Kurashiki, Okayama 701-0193, Japan
| | - Atsushi Ono
- Department of Radiological Technology, Faculty of Health Science and Technology, Kawasaki University of Medical Welfare, 288, Matsushima, Kurashiki, Okayama 701-0193, Japan
| | - Junichi Hiratsuka
- Department of Radiological Technology, Faculty of Health Science and Technology, Kawasaki University of Medical Welfare, 288, Matsushima, Kurashiki, Okayama 701-0193, Japan
| | - Kazuo Awai
- Department of Diagnostic Radiology, Graduate School of Biomedical Sciences, Hiroshima University, Hiroshima, Japan
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Tao S, Gong H, Michalak G, McCollough C, Leng S, Hu Y. Technical note: Evaluation of Artificial 120-kilovolt computed tomography images for radiation therapy applications. Med Phys 2022; 49:3683-3691. [PMID: 35394074 DOI: 10.1002/mp.15592] [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: 09/03/2021] [Revised: 02/25/2022] [Accepted: 02/28/2022] [Indexed: 11/09/2022] Open
Abstract
PURPOSE The purpose of this work is to evaluate the scaled CT number accuracy of an artificial 120 kV reconstruction technique based on phantom experiments in the context of radiation therapy planning. METHODS An abdomen-shaped electron density phantom was scanned on a clinical CT scanner capable of artificial 120 kV reconstruction using different tube potentials from 70 kV to 150 kV. A series of tissue equivalent phantom inserts (lung, adipose, breast, solid water, liver, inner bone, 30%/50% CaCO3, cortical bone) were placed inside the phantom. Images were reconstructed using a conventional quantitative reconstruction kernel as well as the artificial 120 kV reconstruction kernel. Scaled CT numbers of inserts were measured from images acquired at different kVs and compared with those acquired at 120 kV, which were deemed as the ground truth. The relative error was quantified as the percentage deviation of scaled CT numbers acquired at different tube potentials from their ground truth values acquired at 120 kV. RESULTS Scaled CT numbers measured from images reconstructed using the conventional reconstruction demonstrated a strong kV-dependence. The relative error in scaled CT number ranged from 0.6% (liver insert) to 31.1% (cortical bone insert). The artificial 120 kV reconstruction reduced the kV-dependence, especially for bone tissues. The relative error in scaled CT number was reduced to 0.4% (liver insert) and 2.6% (30% CaCO3 insert) using this technique. When tube potential selection was limited to the range of 90 kV to 150 kV, the relative error was further restrained to <1.2% for all tissue types. CONCLUSION Phantom results demonstrated that using the artificial 120 kV technique, it was feasible to acquire raw projection data at a desired tube potential and then reconstruct images with scaled CT numbers comparable to those obtained directly at 120 kV. In radiotherapy applications, this technique may allow optimization of tube potential without complicating clinical workflow by eliminating the necessity of maintaining multiple sets of CT calibration curves. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Shengzhen Tao
- Department of Radiology, Mayo Clinic, Jacksonville, FL, USA
| | - Hao Gong
- Department of Radiology, Mayo Clinic, Rochester, MN, USA
| | | | | | - Shuai Leng
- Department of Radiology, Mayo Clinic, Rochester, MN, USA
| | - Yanle Hu
- Department of Radiation Oncology, Mayo Clinic, Phoenix, AZ, USA
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The Image Quality and Diagnostic Performance of CT with Low-Concentration Iodine Contrast (240 mg Iodine/mL) for the Abdominal Organs. Diagnostics (Basel) 2022; 12:diagnostics12030752. [PMID: 35328304 PMCID: PMC8947528 DOI: 10.3390/diagnostics12030752] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2022] [Revised: 03/11/2022] [Accepted: 03/17/2022] [Indexed: 11/17/2022] Open
Abstract
Purpose: To evaluate the difference between CT examinations using 240 mgI/mL contrast material (CM) and 320 mgI/mL CM in the contrast enhancement of the abdominal organs and the diagnostic performance for focal hepatic lesions. Materials and methods: This retrospective study included 422 CT examinations, using 240 mgI/mL iohexol (Group A, 206 examinations) and 320 mgI/mL ioversol (Group B, 216 examinations), performed between April 2019 and May 2020. Two CT scanners (single-source CT (machine A) and dual-source CT (machine B)) were used to obtain CT images. Two radiologists independently drew regions of interest (ROIs) in the liver, pancreas, spleen, kidney, aorta, portal vein, and paraspinal muscle. The signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated for each organ. They evaluated the degree of subjective enhancement of the organs and detected/differentiated focal hepatic lesions. Results: The SNR, CNR, and subjective enhancement of most organs were significantly higher in Group B than in Group A (p < 0.05). The sensitivity and specificity for cysts and malignancy were higher than 85.0% in both groups. The sensitivity for hemangioma was lower in Group B (<75%) than in Group A. In Group A, the SNR and CNR were significantly higher in most organs with machine B than with machine A. Conclusion: Although the SNR and CNR of the abdominal organs were lower with 240 mgI/mL CM than with 320 mgI/mL CM, 240 mgI/mL CM was feasible for evaluating the liver. A CT scanner with more advanced specifications may be beneficial for examinations with 240 mgI/mL CM by using lower tube voltage.
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Tao S, Sheedy E, Bruesewitz M, Weber N, Williams K, Halaweish A, Schmidt B, Williamson E, McCollough C, Leng S. Technical Note: kV-independent coronary calcium scoring: A phantom evaluation of score accuracy and potential radiation dose reduction. Med Phys 2021; 48:1307-1314. [PMID: 33332626 DOI: 10.1002/mp.14663] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2020] [Revised: 12/04/2020] [Accepted: 12/08/2020] [Indexed: 11/10/2022] Open
Abstract
PURPOSE To determine the accuracy of CT number and calcium score of a kV-independent technique based on an artificial 120 kV reconstruction, and its potential to reduce radiation dose. METHODS Anthropomorphic chest phantoms were scanned on a third-generation dual-source CT system equipped with the artificial 120 kV reconstruction. First, a phantom module containing a 20-mm diameter hydroxyapatite (HA) insert was scanned inside the chest phantoms at different tube potentials (70-140 kV) to evaluate calcium CT number accuracy. Next, three small HA inserts (diameter/length = 5 mm) were inserted into a pork steak and scanned inside the phantoms to evaluate calcium score accuracy at different kVs. Finally, the same setup was scanned using automatic exposure control (AEC) at 120 kV, and then with automatic kV selection (auto-kV). Phantoms were also scanned at 120 kV using a size-dependent mA chart. CT numbers of soft tissue and calcium were measured from different kV images. Calcium score of each small HA insert was measured using commercial software. RESULTS The CT number difference from 120 kV was small with tube potentials from 90 to 140 kV for both soft tissue and calcium (maximal difference of 4/5 HU, respectively). Consistent calcium scores were obtained from images of different kVs compared to 120 kV, with a relative difference <8%. Auto-kV provided a 25-34% dose reduction compared to AEC alone. CONCLUSION A kV-independent calcium scoring technique can produce artificial 120 kV images with consistent soft tissue and calcium CT numbers compared to standard 120 kV examinations. When coupled with auto-kV, this technique can reduce radiation by 25-34% compared to that with AEC alone, while providing consistent calcium scores as that of standard 120 kV examinations.
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Affiliation(s)
- Shengzhen Tao
- Department of Radiology, Mayo Clinic, Jacksonville, FL, USA
| | - Emily Sheedy
- Department of Radiology, Mayo Clinic, Rochester, MN, USA
| | | | - Nikkole Weber
- Department of Radiology, Mayo Clinic, Rochester, MN, USA
| | - Kyle Williams
- Department of Radiology, Mayo Clinic, Rochester, MN, USA
| | | | - Bernhard Schmidt
- Siemens Healthineers, Siemensstraße 1, Forchheim, 91301, Germany
| | | | | | - Shuai Leng
- Department of Radiology, Mayo Clinic, Rochester, MN, USA
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Tailoring Contrast Media Protocols to Varying Tube Voltages in Vascular and Parenchymal CT Imaging: The 10-to-10 Rule. Invest Radiol 2020; 55:673-676. [PMID: 32898358 DOI: 10.1097/rli.0000000000000682] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The latest technical developments in CT have created the possibility for individualized scan protocols at variable kV settings. Lowering tube voltages closer to the K-edge of iodine increases attenuation. However, the latter is also influenced by patient characteristics such as total body weight. To maintain a robust contrast enhancement throughout the patient population in both vascular and parenchymal CT scans, one must adapt the contrast media administration protocols to both the selected kV setting and patient body habitus. This article proposes a simple rule of thumb for how to adapt the contrast media protocol to any kV setting: the 10-to-10 rule.
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10
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Tanaka H, Igami T, Shimoyama Y, Ebata T, Yokoyama Y, Mori K, Nagino M. New method for the assessment of perineural invasion from perihilar cholangiocarcinoma. Surg Today 2020; 51:136-143. [PMID: 32623582 DOI: 10.1007/s00595-020-02071-x] [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: 06/07/2020] [Accepted: 06/19/2020] [Indexed: 01/01/2023]
Abstract
PURPOSE Perineural invasion (PN) is often found in perihilar cholangiocarcinoma. New procedure was developed to assess PN around the right hepatic artery (RHA) using dual-energy computed tomography (DECT). METHODS Thirty patients with perihilar cholangiocarcinoma who underwent DECT before biliary drainage were retrospectively reviewed. Mask images, i.e., the periarterial layer (PAL) around the RHA and superior mesenteric artery (SMA), were made from late arterial phase DECT. The mean CT number of the PAL was measured. RESULTS Twenty patients with PN around the RHA were classified into the PN (+) group. The remaining 10 patients without PN and other 26 patients with other diseases that are never accompanied with PN were classified into the PN (-) group. The PAL ratio (the CT number of the PAL around the RHA relative to that around the SMA) was calculated. Both the mean CT number of the PAL around the RHA and the PAL ratio were significantly higher in the PN (+) group than in the PN (-) group. According to an ROC analysis, the predictive ability of the PAL ratio was superior. Using the cutoff value of the PAL ratio 1.009, a diagnosis of PN around the RHA was made with approximately 75% accuracy. CONCLUSIONS Assessment with CT number of the PAL reconstructed from DECT images is an easy and objective method to diagnose PN.
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Affiliation(s)
- Hiroshi Tanaka
- Division of Surgical Oncology, Department of Surgery, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya, 466-8550, Japan
| | - Tsuyoshi Igami
- Division of Surgical Oncology, Department of Surgery, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya, 466-8550, Japan.
| | - Yoshie Shimoyama
- Department of Pathology and Clinical Laboratories, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Tomoki Ebata
- Division of Surgical Oncology, Department of Surgery, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya, 466-8550, Japan
| | - Yukihiro Yokoyama
- Division of Surgical Oncology, Department of Surgery, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya, 466-8550, Japan
| | - Kensaku Mori
- Graduate School of Informatics, Nagoya University, Nagoya, Japan.,Information Strategy Office, Information and Communications, Nagoya University, Nagoya, Japan
| | - Masato Nagino
- Division of Surgical Oncology, Department of Surgery, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya, 466-8550, Japan
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Choi MH, Lee YJ, Jung SE. A LESSON FROM AUTOMATIC TUBE VOLTAGE SELECTION: FEASIBILITY OF 100 kVp IN PORTAL VENOUS PHASE ABDOMINAL CT. RADIATION PROTECTION DOSIMETRY 2020; 188:424-431. [PMID: 31998958 DOI: 10.1093/rpd/ncz302] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Revised: 10/17/2019] [Accepted: 12/23/2019] [Indexed: 06/10/2023]
Abstract
PURPOSE To evaluate the relationship between ATVS-recommended tube voltage and patient body habitus and to compare radiation dose and diagnostic performance between fixed 120-kVp and ATVS protocols in portal venous phase abdomen CT. METHODS A total of 907 portal venous phase abdominal CTs were evaluated. Radiation dose in the ATVS protocol was compared according to tube voltage (80, 100 or 120 kVp). Quantitative image analysis and diagnostic performance were compared between 81 pairs of CT using ATVS and fixed 120-kVp protocols. RESULTS Most CT examinations with ATVS were performed with 80 or 100 kVp. The average reduction rate of radiation dose in the ATVS protocol was 15.4%. There was no significant difference in diagnostic performance (p = 0.388) between ATVS and fixed 120-kVp protocols. CONCLUSIONS In conclusion, ATVS frequently selected 80 or 100 kVp for portal venous phase abdominal CT without impairing the diagnostic performance, even with filtered back projection.
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Affiliation(s)
- Moon Hyung Choi
- Department of Radiology, Eunpyeong St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea
- Catholic Smart Imaging Center, Eunpyeong St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea
- Department of Radioogy, Seoul St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea
| | - Young Joon Lee
- Department of Radiology, Eunpyeong St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea
- Catholic Smart Imaging Center, Eunpyeong St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea
- Department of Radioogy, Seoul St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea
| | - Seung Eun Jung
- Department of Radiology, Eunpyeong St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea
- Catholic Smart Imaging Center, Eunpyeong St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea
- Department of Radioogy, Seoul St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea
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12
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Tang S, Liu X, He L, Zhou Y, Cheng Z. Application of ASiR in combination with noise index in the chest CT examination of preschool-age children. Radiol Med 2019; 124:467-477. [DOI: 10.1007/s11547-018-00983-w] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2018] [Accepted: 12/20/2018] [Indexed: 12/26/2022]
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13
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Kaasalainen T, Mäkelä T, Kortesniemi M. The effect of vertical centering and scout direction on automatic tube voltage selection in chest CT: a preliminary phantom study on two different CT equipments. Eur J Radiol Open 2018; 6:24-32. [PMID: 30619916 PMCID: PMC6298908 DOI: 10.1016/j.ejro.2018.12.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2018] [Revised: 12/11/2018] [Accepted: 12/11/2018] [Indexed: 12/11/2022] Open
Abstract
Purpose To determine the effect of patient's vertical off-centering and scout direction on the function of automatic tube voltage selection (ATVS) and tube current modulation (TCM) in chest computed tomography (CT). Methods Chest phantom was scanned with Siemens and GE CT systems using three clinical chest CT protocols exploiting ATVS and a fixed 120 kVp chest protocol. The scans were performed at five vertical positions of the phantom (-6 to +6 cm from the scanner isocenter). The effects of scout direction (posterior-to-anterior, anterior-to-posterior, and lateral) and vertical off-centering on the function of ATVS and TCM were studied by examining changes in selected voltage, radiation dose (volume CT dose index, CTDIvol), and image noise and contrast. Results Both scout direction and vertical off-centering affected ATVS. The effect differed between the vendors for the studied geometry, demonstrating differences in technical approaches. The greatest observed increase in CTDIvol due to off-centering was 91%. Anterior-to-posterior scout produced highest doses at the uppermost table position, whereas posterior-to-anterior scout produced highest doses at the lowermost table position. Dose varied least using lateral scouts. Vertical off-centering impacted image noise and contrast due to the combined effect of ATVS, TCM, structural noise, and bowtie filters. Conclusions Patient vertical off-centering and scout direction affected substantially the CTDIvol and image quality in chest CT examinations. Vertical off-centering caused variation also in the selected tube voltage. The function of ATVS and TCM methods differ significantly between the CT vendors, resulting in differences in CTDIvol and image noise characteristics.
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Affiliation(s)
- Touko Kaasalainen
- HUS Medical Imaging Center, Helsinki University Central Hospital, Finland.,Department of Physics, University of Helsinki, Finland
| | - Teemu Mäkelä
- HUS Medical Imaging Center, Helsinki University Central Hospital, Finland.,Department of Physics, University of Helsinki, Finland
| | - Mika Kortesniemi
- HUS Medical Imaging Center, Helsinki University Central Hospital, Finland.,Department of Physics, University of Helsinki, Finland
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14
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Masuda T, Funama Y, Nakaura T, Tahara M, Yamashita Y, Kiguchi M, Imada N, Sato T, Awai K. Radiation Dose Reduction with a Low-Tube Voltage Technique for Pediatric Chest Computed Tomographic Angiography Based on the Contrast-to-Noise Ratio Index. Can Assoc Radiol J 2018; 69:390-396. [DOI: 10.1016/j.carj.2018.05.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2017] [Revised: 03/08/2018] [Accepted: 05/16/2018] [Indexed: 10/28/2022] Open
Abstract
Introduction The aim of this study was to evaluate the radiation dose and image quality at low tube-voltage pediatric chest computed tomographic angiography (CTA) that applies the same contrast-to-noise ratio (CNR) index as the standard tube voltage technique. Materials and Methods Contrast-enhanced chest CTA scans of 100 infants were acquired on a 64-row multidetector computed tomography (MDCT) scanner. In the retrospective study, we evaluated 50 images acquired at 120 kVp; the image noise level was set at 25 Hounsfield units. In the prospective study, we used an 80-kVp protocol; the image noise level was 40 Hounsfield units because the iodine contrast was 1.6 times higher than on 120-kVp scans; the CNR was as in the 120-kVp protocol. We compared the CT number, image noise, CT dose index volume (CTDIvol), and the dose-length product on scans acquired with the 2 protocols. A diagnostic radiologist and a pediatric cardiologist visually evaluated all CTA images. Results The mean CTDIvol and the mean dose-length product were 0.5 mGy and 7.8 mGy-cm for 80- and 1.2 mGy and 20.8 mGy-cm for 120-kVp scans, respectively ( P < .001). The mean CTDIvol was 42% lower at 80 kVp than at 120 kVp, and there was no significant difference in the visual scores assigned to the CTA images ( P = .28). Conclusions With the CNR index being the same at 80-kVp and 120-kVp imaging, the radiation dose delivered to infants subjected to chest CTA can be reduced without degradation of the image quality.
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Affiliation(s)
- Takanori Masuda
- Department of Radiological Technology, Tsuchiya General Hospital, Hiroshima, Japan
- Department of Diagnostic Radiology, Graduate School of Biomedical Sciences, Hiroshima University, Hiroshima, Japan
| | - Yoshinori Funama
- Department of Medical Physics, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan
| | - Takeshi Nakaura
- Department of Diagnostic Radiology, Graduate School of Medical Sciences, Kumamoto University, Kumamoto, Japan
| | - Masahiro Tahara
- Department of Pediatric Cardiology, Tsuchiya General Hospital, Hiroshima, Japan
| | - Yukari Yamashita
- Department of Radiological Technology, Tsuchiya General Hospital, Hiroshima, Japan
| | - Masao Kiguchi
- Department of Diagnostic Radiology, Graduate School of Biomedical Sciences, Hiroshima University, Hiroshima, Japan
| | - Naoyuki Imada
- Department of Radiological Technology, Tsuchiya General Hospital, Hiroshima, Japan
| | - Tomoyasu Sato
- Department of Diagnostic Radiology, Tsuchiya General Hospital, Hiroshima, Japan
| | - Kazuo Awai
- Department of Diagnostic Radiology, Graduate School of Biomedical Sciences, Hiroshima University, Hiroshima, Japan
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15
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Prospective evaluation of ultra-low-dose contrast-enhanced 100-kV abdominal computed tomography with tin filter: effect on radiation dose reduction and image quality with a third-generation dual-source CT system. Eur Radiol 2018; 29:2107-2116. [PMID: 30324392 DOI: 10.1007/s00330-018-5750-2] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2018] [Revised: 08/19/2018] [Accepted: 09/11/2018] [Indexed: 12/16/2022]
Abstract
OBJECTIVES To investigate the radiation dose exposure, image quality, and diagnostic performance of enhanced 100-kVp abdominopelvic single-energy CT protocol with tin filter (TF). METHODS Ninety-three consecutive patients referred for a single-phase enhanced abdominopelvic CT were prospectively included after informed consent. They underwent in addition to a standard protocol (SP) an acquisition with TF. Both examinations were performed on a third-generation dual-source CT system (DSCT), in single energy, using automatic tube current modulation, identical pitch, and identical level of iterative reconstruction. Radiation metrics were compared. Size-specific dose estimates (SSDE), contrast to noise ratio (CNR), and figure of merit (FOM) were calculated. Diagnostic confidence for the assessment of a predetermined list of abdominal lesions was rated by two independent readers. RESULTS The mean dose of the TF protocol was significantly lower (CDTI 1.56 ± 0.43 mGy vs. 8.13 ± 3.32, p < 0.001; SSDE 9.94 ± 3.08 vs. 1.93 ± 0.39, p < 0.001), with an effective dose close to 1 mSv (1.14 mSv ± 0.34; p < 0.001). TF group exhibited non-significant lower liver CNR (2.76 vs. 3.03, p = 0.56) and was more dose efficient (FOM 10.6 vs. 2.49/mSv, p < 0.001) in comparison to SP. The mean diagnostic confidence for visceral, bone, and peritoneal tumors was equivalent between both groups. CONCLUSIONS Enhanced 100-kVp abdominopelvic CT acquired after spectral shaping with tin filtration can achieve similar diagnostic performance and CNR compared to a standard CT protocol, while reducing the radiation dose by 81%. KEY POINTS • 100-kVp spectral filtration enables enhanced abdominal CT with high-dose efficiency. • The radiation dose reaches the 1-mSv range. • Predetermined abdominopelvic lesions can be assessed without impairing on diagnostic confidence.
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16
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Masuda T, Funama Y, Nakaura T, Satou T, Okimoto T, Yamashita Y, Imada N, Awai K. Radiation Dose Reduction at Low Tube Voltage CCTA Based on the CNR Index. Acad Radiol 2018; 25:1298-1304. [PMID: 29599007 DOI: 10.1016/j.acra.2018.01.019] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2017] [Revised: 01/18/2018] [Accepted: 01/19/2018] [Indexed: 01/04/2023]
Abstract
RATIONALE AND OBJECTIVES We compared the radiation dose and diagnostic accuracy on 120- and 100-kVp coronary computed tomography angiography (CCTA) scans whose contrast-to-noise ratio (CNR) was the same. MATERIALS AND METHODS We studied 1311 coronary artery segments from 100 patients. For 120-kVp scans, the targeted image level was set at 25 Hounsfield units (HU). For 100-kVp scans, the targeted noise level was set at 30 HU to obtain the same CNR as at 120 kVp. We compared the CNR and the radiation dose on scans acquired at 120 and 100 kVp. Invasive coronary angiography (ICA) images were evaluated by an interventional coronary angiography specialist, and CCTA images were evaluated by a radiologist. Coronary artery disease was defined as a luminal narrowing ≧50% for ICA and CCTA. With ICA considered the gold standard, the diagnostic accuracy (sensitivity, specificity, positive predictive value, and negative predictive value) was analyzed on both 120- and 100-kVp CCTA images. We also compared the diagnostic accuracy for area under the receiver operating characteristic curve of the ICA and CCTA performed at 120 and 100 kVp. Two blinded observers visually evaluated the septal branch. RESULTS The mean dose-length product was 48% lower at 100 kVp than at 120 kVp (P < .01). Under the 120-kVp CCTA protocol, the area under the curve, 95% confidence interval, sensitivity, specificity, positive predictive value, and negative predictive value were 0.94%, 0.91%-0.96%, 94.0%, 93.0%, 82.3%, and 98.1%, respectively; at 100 kVp these values were 0.94%, 0.92%-0.97%, 96.1%, 92.0%, 85.2%, and 98.0%, respectively. Area under the receiver operating characteristic curve analysis revealed no significant difference in diagnostic accuracy between the two protocols (P = .87). CONCLUSIONS At the same CNR, the 100-kVp CCTA protocol may help to reduce the radiation dose by approximately 50% compared to the 120-kVp protocol without degradation of diagnostic accuracy.
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17
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Best Protocol for Combined Contrast-Enhanced Thoracic and Abdominal CT for Lung Cancer: A Single-Institution Randomized Crossover Clinical Trial. AJR Am J Roentgenol 2018; 210:1226-1234. [DOI: 10.2214/ajr.17.19185] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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18
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Euler A, Obmann MM, Szucs-Farkas Z, Mileto A, Zaehringer C, Falkowski AL, Winkel DJ, Marin D, Stieltjes B, Krauss B, Schindera ST. Comparison of image quality and radiation dose between split-filter dual-energy images and single-energy images in single-source abdominal CT. Eur Radiol 2018; 28:3405-3412. [DOI: 10.1007/s00330-018-5338-x] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2017] [Revised: 01/09/2018] [Accepted: 01/17/2018] [Indexed: 12/25/2022]
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19
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Goo HW. Comparison of Chest Pain Protocols for Electrocardiography-Gated Dual-Source Cardiothoracic CT in Children and Adults: The Effect of Tube Current Saturation on Radiation Dose Reduction. Korean J Radiol 2018; 19:23-31. [PMID: 29353996 PMCID: PMC5768502 DOI: 10.3348/kjr.2018.19.1.23] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2017] [Accepted: 07/04/2017] [Indexed: 11/17/2022] Open
Abstract
Objective To compare radiation doses between conventional and chest pain protocols using dual-source retrospectively electrocardiography (ECG)-gated cardiothoracic computed tomography (CT) in children and adults and assess the effect of tube current saturation on radiation dose reduction. Materials and Methods This study included 104 patients (16.6 ± 7.7 years, range 5–48 years) that were divided into two groups: those with and those without tube current saturation. The estimated radiation doses of retrospectively ECG-gated spiral cardiothoracic CT were compared between conventional, uniphasic, and biphasic chest pain protocols acquired with the same imaging parameters in the same patients by using paired t tests. Dose reduction percentages, patient ages, volume CT dose index values, and tube current time products per rotation were compared between the two groups by using unpaired t tests. A p value < 0.05 was considered significant. Results The volume CT dose index values of the biphasic chest pain protocol (10.8 ± 3.9 mGy) were significantly lower than those of the conventional protocol (12.2 ± 4.7 mGy, p < 0.001) and those of the uniphasic chest pain protocol (12.9 ± 4.9 mGy, p < 0.001). The dose-saving effect of biphasic chest pain protocol was significantly less with a saturated tube current (4.5 ± 10.2%) than with unsaturated tube current method (14.8 ± 11.5%, p < 0.001). In 76 patients using 100 kVp, patient age showed no significant differences between the groups with and without tube current saturation in all protocols (p > 0.05); the groups with tube current saturation showed significantly higher volume CT dose index values (p < 0.01) and tube current time product per rotation (p < 0.001) than the groups without tube current saturation in all protocols. Conclusion The radiation dose of dual-source retrospectively ECG-gated spiral cardiothoracic CT can be reduced by approximately 15% by using the biphasic chest pain protocol instead of the conventional protocol in children and adults if radiation dose parameters are further optimized to avoid tube current saturation.
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Affiliation(s)
- Hyun Woo Goo
- Department of Radiology and Research Institute of Radiology, University of Ulsan College of Medicine, Asan Medical Center, Seoul 05505, Korea
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20
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Qurashi A, Rainford L, Ajlan A, Khashoggi K, Ashkar L, Al-Raddadi M, Al-Ghamdi M, Al-Thobaiti M, Foley S. Optimal abdominal CT protocol for obese patients. Radiography (Lond) 2017; 24:e1-e12. [PMID: 29306386 DOI: 10.1016/j.radi.2017.08.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2017] [Revised: 08/03/2017] [Accepted: 08/07/2017] [Indexed: 01/15/2023]
Abstract
INTRODUCTION This study investigated the impact of different protocols on radiation dose and image quality for obese patients undergoing abdominal CT examinations. METHODS Five abdominal/pelvis CT protocols employed across three scanners from a single manufacturer in a single centre used a variety of parameters (kV: 100/120, reference mAs: 150/190/218/250/300, image reconstruction: filtered back projection (FBP)/iterative (IR)). The routine protocol employed 300 reference mAs and 120 kV. Data sets resulting from obese patient examinations (n = 42) were assessed for image quality using visual grading analysis by three experienced radiologists. Objective assessment (noise, signal/contrast-noise ratios) and radiation dose was compared to determine optimal protocols for prospective testing on a further sample of patients (n = 47) for scanners using FBP and IR techniques. RESULTS Compared to the routine protocol, mean radiation dose was reduced by 60% when using 100 kV and SAFIRE technique strength 3 (p = 0.001). Reduction of up to 30% in radiation dose was noted for the FBP protocol: 120 kV and 190 reference mAs (p = 0.008). Subjective and objective image quality for both protocols were comparable to that of the routine protocol (p > 0.05). An overall improvement in image quality with increasing strength of SAFIRE was noted. Upon clinical implementation of the optimal dose protocols, local radiology consensus deemed image quality to be acceptable for the participating obese patient cohort. CONCLUSION Radiation dose for obese patients can be optimised whilst maintaining image quality. Where iterative reconstruction is available relatively low kV and quality reference mAs are also viable for imaging obese patients at 30-60% lower radiation doses.
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Affiliation(s)
- A Qurashi
- Radiography and Diagnostic Imaging, School of Medicine, University College Dublin, Ireland; Faculty of Applied Medical Sciences, Taibah University, Madinah, Saudi Arabia.
| | - L Rainford
- Radiography and Diagnostic Imaging, School of Medicine, University College Dublin, Ireland
| | - A Ajlan
- King Abdulaziz University, Jeddah, Saudi Arabia
| | - K Khashoggi
- King Abdulaziz University, Jeddah, Saudi Arabia
| | - L Ashkar
- King Abdulaziz University, Jeddah, Saudi Arabia
| | | | - M Al-Ghamdi
- King Abdulaziz Hospital, Jeddah, Saudi Arabia
| | | | - S Foley
- Radiography and Diagnostic Imaging, School of Medicine, University College Dublin, Ireland
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21
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Wortman JR, Landman W, Fulwadhva UP, Viscomi SG, Sodickson AD. CT angiography for acute gastrointestinal bleeding: what the radiologist needs to know. Br J Radiol 2017; 90:20170076. [PMID: 28362508 DOI: 10.1259/bjr.20170076] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Acute gastrointestinal (GI) bleeding is a common cause of both emergency department visits and hospitalizations in the USA and can have a high morbidity and mortality if not treated rapidly. Imaging is playing an increasing role in both the diagnosis and management of GI bleeding. In particular, CT angiography (CTA) is a promising initial test for acute GI bleeding as it is universally available, can be performed rapidly and may provide diagnostic information to guide management. The purpose of this review was to provide an overview of the uses of imaging in the diagnosis and management of acute GI bleeding, with a focus on CTA.
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Affiliation(s)
- Jeremy R Wortman
- 1 Department of Radiology, Brigham and Women's Hospital, Boston, MA, USA.,2 Division of Emergency Radiology, Harvard Medical School, Boston, MA, USA
| | - Wendy Landman
- 1 Department of Radiology, Brigham and Women's Hospital, Boston, MA, USA.,2 Division of Emergency Radiology, Harvard Medical School, Boston, MA, USA
| | - Urvi P Fulwadhva
- 1 Department of Radiology, Brigham and Women's Hospital, Boston, MA, USA.,2 Division of Emergency Radiology, Harvard Medical School, Boston, MA, USA
| | - Salvatore G Viscomi
- 1 Department of Radiology, Brigham and Women's Hospital, Boston, MA, USA.,3 Department of Radiology, Cape Cod Hospital, Hyannis, MA, USA
| | - Aaron D Sodickson
- 1 Department of Radiology, Brigham and Women's Hospital, Boston, MA, USA.,2 Division of Emergency Radiology, Harvard Medical School, Boston, MA, USA
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22
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Masuda T, Funama Y, Kiguchi M, Imada N, Oku T, Sato T, Awai K. Radiation dose reduction based on CNR index with low-tube voltage scan for pediatric CT scan: experimental study using anthropomorphic phantoms. SPRINGERPLUS 2016; 5:2064. [PMID: 27995041 PMCID: PMC5133217 DOI: 10.1186/s40064-016-3715-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/09/2016] [Accepted: 11/21/2016] [Indexed: 12/13/2022]
Abstract
Background To figure out the relationship between image noise and contrast noise ratio (CNR) at different tube voltages, using anthropomorphic new-born and 1-year-old phantoms, and to discuss the feasibility of radiation dose reduction, based on the obtained CNR index from image noise. We performed helical scans of the anthropomorphic new-born and 1-year-old phantoms. The CT numbers of the simulated aorta and image noise of the simulated mediastinum were measured; then CNR was calculated on 80, 100, and 120-kVp images reconstructed with filtered back projection (FBP) and iterative reconstruction (IR). We also measured the center and surface dose in the case of CNR of 14 using radio-photoluminescence glass dosimeters. Results The CT number of the simulated aorta was increased with decreasing tube voltage from 120 to 80 kVp (362.5–535.1 HU for the new-born, 358.9–532.6 HU for the 1-year-old). At CNR of 14, the center dose was 0.4, 0.6 and 0.9 mGy at FBP and 0.5, 0.6 and 0.9 mGy at IR and with the new-born phantom acquired at 80, 100 and 120 kVp, respectively. The center dose for FBP image was reduced by 56% at 80 kVp, 34% at 100 kVp for the new-born and 36% at 80 kVp, 22% at 100 kVp for the 1-year-old compared with that at 120 kVp. We obtained a relationship between image noise and CNR at different tube voltages using the anthropomorphic new-born and 1-year-old phantoms. Conclusion The use of index of CNR with low-tube voltage may achieve further radiation dose reduction in pediatric CT examination.
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Affiliation(s)
- Takanori Masuda
- Department of Radiological Technology, Tsuchiya General Hospital, Nakajima-cho 3-30, Naka-ku, Hiroshima, 730-8655 Japan ; Department of Diagnostic Radiology, Graduate School of Biomedical Sciences, Hiroshima University, Hiroshima, Japan
| | - Yoshinori Funama
- Department of Medical Physics, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan
| | - Masao Kiguchi
- Department of Diagnostic Radiology, Graduate School of Biomedical Sciences, Hiroshima University, Hiroshima, Japan
| | - Naoyuki Imada
- Department of Radiological Technology, Tsuchiya General Hospital, Nakajima-cho 3-30, Naka-ku, Hiroshima, 730-8655 Japan
| | - Takayuki Oku
- Department of Radiological Technology, Tsuchiya General Hospital, Nakajima-cho 3-30, Naka-ku, Hiroshima, 730-8655 Japan
| | - Tomoyasu Sato
- Department of Diagnostic Radiology, Tsuchiya General Hospital, Nakajima-cho 3-30, Naka-ku, Hiroshima, 730-8655 Japan
| | - Kazuo Awai
- Department of Diagnostic Radiology, Graduate School of Biomedical Sciences, Hiroshima University, Hiroshima, Japan
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23
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Cumulative radiation exposure from imaging procedures and associated lifetime cancer risk for patients with lymphoma. Sci Rep 2016; 6:35181. [PMID: 27748377 PMCID: PMC5066222 DOI: 10.1038/srep35181] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2016] [Accepted: 09/26/2016] [Indexed: 12/16/2022] Open
Abstract
The aim of this study was to systematically evaluate the cumulative radiation exposure and the associated lifetime-cancer-risk from diagnostic imaging in patients with Hodgkin-lymphoma-(HL) or diffuse-large-B-cell-lymphoma (DLBCL). 99 consecutive patients (53-males) diagnosed with HL or DLBCL were included in the study and followed. Based on the imaging reports, organ and effective-doses-(ED) were calculated individually for each patient and the excess lifetime risks were estimated. The average ED in the first year after diagnosis was significantly different for men (59 ± 33 mSv) and women (744 ± 33 mSv)-(p < 0.05). The mean cumulative ED in each of the following 5 years was 16 ± 16 mSv without significant differences between men and women-(p > 0.05). Over all years, more than 90% of the ED resulted from CT. The average cumulative radiation risk estimated for the first year was significantly lower for men (0.76 ± 0.41%) as compared to women (1.28 ± 0.54%)-(p < 0.05). The same was found for each of the subsequent 5-years (men-0.18 ± 0.17%; women-0.28 ± 0.25%)-(p < 0.05). In conclusion, for HL and DLBCL patients investigated in this study, a cumulative radiation risk of about 1 excess cancer per 100 patients is estimated for diagnostic imaging procedures performed during both the first year after diagnosis and a follow-up period of 5 years.
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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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Manual adjustment of tube voltage from 120 to 100 kVp during abdominal CT in patients with body weights ≤75 kg: assessment of image quality and radiation dose in a prospective, randomised trial. Clin Radiol 2016; 71:615.e1-6. [DOI: 10.1016/j.crad.2016.02.014] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2016] [Revised: 02/05/2016] [Accepted: 02/14/2016] [Indexed: 11/22/2022]
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Lamba R, Corwin MT, Fananapazir G. Practical dose reduction tips for abdominal interventional procedures using CT-guidance. Abdom Radiol (NY) 2016; 41:743-53. [PMID: 26920005 DOI: 10.1007/s00261-016-0670-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Reducing the radiation dose should be an endeavor not only for diagnostic CT exams but also for interventional procedures using CT-guidance. Given that interventional procedures vary in scope and complexity, there is greater variability in radiation doses delivered during CT procedures. The goal in an interventional procedure is simply to advance the interventional instruments into the target lesions, and as such diagnostic level doses are not required and only narrow scan range scans need to be acquired. Adherence to the principles outlined in this article will allow such procedures to be performed with reduced radiation doses.
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Affiliation(s)
- Ramit Lamba
- Department of Radiology, University of California Davis Medical Center, 4860 Y Street, Sacramento, CA, 95817, USA.
| | - Michael T Corwin
- Department of Radiology, University of California Davis Medical Center, 4860 Y Street, Sacramento, CA, 95817, USA
| | - Ghaneh Fananapazir
- Department of Radiology, University of California Davis Medical Center, 4860 Y Street, Sacramento, CA, 95817, USA
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Boos J, Aissa J, Lanzman RS, Heusch P, Schimmöller L, Schleich C, Thomas C, Antoch G, Kröpil P. CT angiography of the aorta using 80 kVp in combination with sinogram-affirmed iterative reconstruction and automated tube current modulation: Effects on image quality and radiation dose. J Med Imaging Radiat Oncol 2016; 60:187-93. [DOI: 10.1111/1754-9485.12425] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2015] [Accepted: 11/04/2015] [Indexed: 01/16/2023]
Affiliation(s)
- Johannes Boos
- Department of Diagnostic and Interventional Radiology; Medical Faculty; University Dusseldorf; Dusseldorf Germany
| | - Joel Aissa
- Department of Diagnostic and Interventional Radiology; Medical Faculty; University Dusseldorf; Dusseldorf Germany
| | - Rotem S Lanzman
- Department of Diagnostic and Interventional Radiology; Medical Faculty; University Dusseldorf; Dusseldorf Germany
| | - Philipp Heusch
- Department of Diagnostic and Interventional Radiology; Medical Faculty; University Dusseldorf; Dusseldorf Germany
| | - Lars Schimmöller
- Department of Diagnostic and Interventional Radiology; Medical Faculty; University Dusseldorf; Dusseldorf Germany
| | - Christoph Schleich
- Department of Diagnostic and Interventional Radiology; Medical Faculty; University Dusseldorf; Dusseldorf Germany
| | - Christoph Thomas
- Department of Diagnostic and Interventional Radiology; Medical Faculty; University Dusseldorf; Dusseldorf Germany
| | - Gerald Antoch
- Department of Diagnostic and Interventional Radiology; Medical Faculty; University Dusseldorf; Dusseldorf Germany
| | - Patric Kröpil
- Department of Diagnostic and Interventional Radiology; Medical Faculty; University Dusseldorf; Dusseldorf Germany
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Automated tube voltage selection in thoracoabdominal computed tomography at high pitch using a third-generation dual-source scanner: image quality and radiation dose performance. Invest Radiol 2015; 50:352-60. [PMID: 25591129 DOI: 10.1097/rli.0000000000000133] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
OBJECTIVES The objective of this study was to evaluate the radiation dose and image quality performance of thoracoabdominal examinations with an automated tube voltage selection (tube voltage adaptation), tube current modulation, and high pitch using a third-generation dual-source computed tomography (CT) compared intraindividually with 120-kV examinations with tube current modulation with special attention on clinically relevant lesions in the liver, the lungs, and extrahepatic soft tissues. MATERIALS AND METHODS This study was approved by the institutional review board. Computed tomography of the body was performed using a third-generation dual-source system in 95 patients (mean body mass index, 25 kg/m²; range, 18-35 kg/m²). For 49 of these patients, all calculated tube settings and resulting dose values were recorded for each of the 12 gradual contrast weightings of the tube voltage adaptation algorithm. Spiral CT was performed for all patients with an intermediate weighting (grade 7) in a portal venous phase at 120 reference kV, 180 reference mAs, and pitch of 1.55. Objective image quality was assessed on the basis of contrast-to-noise ratio. Subjective image quality was assessed on the basis of clarity and sharpness of anatomical and pathological structures as well as interfering beam hardening and spiral and motion artifacts (heart, lungs, diaphragm). Previous examinations on a 64-slice scanner served as reference. RESULTS All examinations were rated good or excellent for clinical diagnosis. Automated tube voltage selection resulted in significantly lower effective radiation dose (9.5 mSv) compared with the reference (12.0 mSv; P < 0.01). Contrast-to-noise ratio and image quality of soft tissue lesions were significantly increased (P < 0.01). Motion artifacts were significantly reduced (P < 0.01). CONCLUSIONS Automated tube voltage adaptation combined with high-pitch protocols allows for a substantial radiation dose reduction while substantially increasing the image quality, even at large-volume exposure.
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Seyal AR, Arslanoglu A, Abboud SF, Sahin A, Horowitz JM, Yaghmai V. CT of the Abdomen with Reduced Tube Voltage in Adults: A Practical Approach. Radiographics 2015; 35:1922-39. [PMID: 26473536 DOI: 10.1148/rg.2015150048] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Recent innovations in computed tomographic (CT) hardware and software have allowed implementation of low tube voltage imaging into everyday CT scanning protocols in adults. CT at a low tube voltage setting has many benefits, including (a) radiation dose reduction, which is crucial in young patients and those with chronic medical conditions undergoing serial CT examinations for disease management; and (b) higher contrast enhancement. For the latter, increased attenuation of iodinated contrast material improves the evaluation of hypervascular lesions, vascular structures, intestinal mucosa in patients with bowel disease, and CT urographic images. Additionally, the higher contrast enhancement may provide diagnostic images in patients with renal dysfunction receiving a reduced contrast material load and in patients with suboptimal peripheral intravenous access who require a lower contrast material injection rate. One limitation is that noisier images affect image quality at a low tube voltage setting. The development of denoising algorithms such as iterative reconstruction has made it possible to perform CT at a low tube voltage setting without compromising diagnostic confidence. Other potential pitfalls of low tube voltage CT include (a) photon starvation artifact in larger patients, (b) accentuation of streak artifacts, and (c) alteration of the CT attenuation value, which may affect evaluation of lesions on the basis of conventional enhancement thresholds. CT of the abdomen with a low tube voltage setting is an excellent radiation reduction technique when properly applied to imaging of select patients in the appropriate clinical setting.
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Affiliation(s)
- Adeel R Seyal
- From the Department of Radiology, Northwestern University-Feinberg School of Medicine, 676 N Saint Clair St, Suite 800, Chicago, IL 60611
| | - Atilla Arslanoglu
- From the Department of Radiology, Northwestern University-Feinberg School of Medicine, 676 N Saint Clair St, Suite 800, Chicago, IL 60611
| | - Samir F Abboud
- From the Department of Radiology, Northwestern University-Feinberg School of Medicine, 676 N Saint Clair St, Suite 800, Chicago, IL 60611
| | - Azize Sahin
- From the Department of Radiology, Northwestern University-Feinberg School of Medicine, 676 N Saint Clair St, Suite 800, Chicago, IL 60611
| | - Jeanne M Horowitz
- From the Department of Radiology, Northwestern University-Feinberg School of Medicine, 676 N Saint Clair St, Suite 800, Chicago, IL 60611
| | - Vahid Yaghmai
- From the Department of Radiology, Northwestern University-Feinberg School of Medicine, 676 N Saint Clair St, Suite 800, Chicago, IL 60611
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Effects of automatic tube potential selection on radiation dose index, image quality, and lesion detectability in pediatric abdominopelvic CT and CTA: a phantom study. Eur Radiol 2015; 26:157-66. [DOI: 10.1007/s00330-015-3817-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2014] [Revised: 04/20/2015] [Accepted: 04/21/2015] [Indexed: 11/26/2022]
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Ramirez-Giraldo JC, Fuld M, Grant K, Primak AN, Flohr T. New Approaches to Reduce Radiation While Maintaining Image Quality in Multi-Detector-Computed Tomography. CURRENT RADIOLOGY REPORTS 2015. [DOI: 10.1007/s40134-014-0084-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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