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Sookpeng S, Martin CJ. A PHANTOM EVALUATION OF THE USE OF CT AUTOMATIC TUBE CURRENT MODULATION WITH LOW TUBE POTENTIALS FOR IODINATED CONTRAST STUDIES. RADIATION PROTECTION DOSIMETRY 2022; 198:188-195. [PMID: 35224645 DOI: 10.1093/rpd/ncac023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2021] [Revised: 10/29/2021] [Accepted: 02/08/2022] [Indexed: 06/14/2023]
Abstract
This paper aimed to investigate effects of different tube voltage and image quality settings on radiation dose and image quality for patients undergoing computed tomography iodinated contrast studies using automatic tube current modulation system and to recommend settings to achieve improved radiation dose and image quality values. A Pagoda phantom with an additional rod of iodine contrast was scanned using different tube voltages and noise index (NI) settings. Size-specific dose estimate (SSDE) and image quality (noise, contrast, contrast-to-noise ratio (CNR) and figure of merit (FOM)) were analysed. Values of SSDE were maintained with similar NI settings. Contrast and CNR were higher for lower tube voltage settings. Better FOM values can be achieved with higher NI settings with the lower kVs. To achieve better CNR and SSDE compared with the standard setting of 120 kV, a 80 kV with an NI setting of 15 was recommended.
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Affiliation(s)
- Supawitoo Sookpeng
- Department of Radiological Technology, Faculty of Allied Health Sciences, Naresuan University, Phitsanulok 65000, Thailand
| | - Colin J Martin
- Department of Clinical Physics and Bioengineering, University of Glasgow, Gartnavel Royal Hospital, Glasgow G12 0XH, UK
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Sookpeng S, Martin CJ, Krisanachinda A. Effects of tube potential selection together with computed tomography automatic tube current modulation on CT imaging performance. JOURNAL OF RADIOLOGICAL PROTECTION : OFFICIAL JOURNAL OF THE SOCIETY FOR RADIOLOGICAL PROTECTION 2021; 41:809-831. [PMID: 33657533 DOI: 10.1088/1361-6498/abebb4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2020] [Accepted: 03/03/2021] [Indexed: 06/12/2023]
Abstract
The effects of tube potential selection with a computed tomography (CT) automatic tube current modulation (ATCM) system on radiation dose and image quality have been investigated on a Canon CT scanner. The use of different values of tube voltage for imaging, and the appropriate settings of the ATCM system, were evaluated. The custom-made phantom consisted of three sections of different sizes with inserts of various materials. It was scanned using tube potentials of 80-140 kV and different image quality ATCM settings. CTDIvoland image quality in terms of noise, contrast, and contrast-to-noise ratio (CNR) for air, polyethylene (PE), acrylic, polyoxymethylene (POM) and polyvinylchloride (PVC) were analysed. A figure of merit (FOM) was estimated by combining CNR and CTDIvol. CTDIvolvalues were similar for all values of tube voltage and individual image quality ATCM settings when tube current was not restricted by the maximum value. The contrasts were independent of ATCM image quality setting, but CNR increased at the higher image quality level as image noise decreased. Both contrast and CNR decreased with increasing tube voltage for PVC and PE, but increased for POM and acrylic. PVC was the only insert material for which there was a significant improvement in contrast at lower tube potentials. FOM indicated that standard (SD = 10) and low dose (SD = 12.5) ATCM settings might be appropriate. The optimum tube voltage settings for imaging the PVC was 80-100 kV, but not for the lower contrast POM and acrylic, for which the standard tube voltage setting of 120 kV was better. The tube potential should be carefully set to gain radiological protection optimisation and keep the radiation dose as low as possible. Results indicate that 100 kV is likely to be appropriate for imaging small and medium-sized Thai patients when iodine contrast is used.
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Affiliation(s)
- S Sookpeng
- Department of Radiological Technology, Faculty of Allied Health Sciences, Naresuan University, Phitsanulok, Thailand
| | - C J Martin
- Department of Clinical Physics and Bio-engineering, University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - A Krisanachinda
- Department of Radiology, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand
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Anam C, Sutanto H, Adi K, Budi WS, Muhlisin Z, Haryanto F, Matsubara K, Fujibuchi T, Dougherty G. Development of a computational phantom for validation of automated noise measurement in CT images. Biomed Phys Eng Express 2020; 6. [PMID: 35135906 DOI: 10.1088/2057-1976/abb2f8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2020] [Accepted: 08/26/2020] [Indexed: 11/11/2022]
Abstract
The purpose of this study was to develop a computational phantom for validation of automatic noise calculations applied to all parts of the body, to investigate kernel size in determining noise, and to validate the accuracy of automatic noise calculation for several noise levels. The phantom consisted of objects with a very wide range of HU values, from -1000 to +950. The incremental value for each object was 10 HU. Each object had a size of 15 × 15 pixels separated by a distance of 5 pixels. There was no dominant homogeneous part in the phantom. The image of the phantom was then degraded to mimic the real image quality of CT by convolving it with a point spread function (PSF) and by addition of Gaussian noise. The magnitude of the Gaussian noises was varied (5, 10, 25, 50, 75 and 100 HUs), and they were considered as the ground truth noise (NG). We also used a computational phantom with added actual noise from a CT scanner. The phantom was used to validate the automated noise measurement based on the average of the ten smallest standard deviations (SD) from the standard deviation map (SDM). Kernel sizes from 3 × 3 up to 27 × 27 pixels were examined in this study. A computational phantom for automated noise calculations validation has been successfully developed. It was found that the measured noise (NM) was influenced by the kernel size. For kernels of 15 × 15 pixels or smaller, the NMvalue was much smaller than the NG. For kernel sizes from 17 × 17 to 21 × 21 pixels, the NMvalue was about 90% of NG. And for kernel sizes of 23 × 23 pixels and above, NMis greater than NG. It was also found that even with small kernel sizes the relationship between NMand NGis linear with R2more than 0.995. Thus accurate noise levels can be automatically obtained even with small kernel sizes without any concern regarding the inhomogeneity of the object.
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Affiliation(s)
- Choirul Anam
- Department of Physics, Faculty of Sciences and Mathematics, Diponegoro University, Jl. Prof. Soedarto SH, Tembalang, Semarang 50275, Central Java, Indonesia
| | - Heri Sutanto
- Department of Physics, Faculty of Sciences and Mathematics, Diponegoro University, Jl. Prof. Soedarto SH, Tembalang, Semarang 50275, Central Java, Indonesia
| | - Kusworo Adi
- Department of Physics, Faculty of Sciences and Mathematics, Diponegoro University, Jl. Prof. Soedarto SH, Tembalang, Semarang 50275, Central Java, Indonesia
| | - Wahyu Setia Budi
- Department of Physics, Faculty of Sciences and Mathematics, Diponegoro University, Jl. Prof. Soedarto SH, Tembalang, Semarang 50275, Central Java, Indonesia
| | - Zaenul Muhlisin
- Department of Physics, Faculty of Sciences and Mathematics, Diponegoro University, Jl. Prof. Soedarto SH, Tembalang, Semarang 50275, Central Java, Indonesia
| | - Freddy Haryanto
- Department of Physics, Faculty of Mathematics and Natural Sciences, Bandung Institute of Technology, Bandung, West Java, Indonesia
| | - Kosuke Matsubara
- Department of Quantum Medical Technology, Faculty of Health Sciences, Institute of Medical Pharmaceutical and Health Sciences, Kanazawa University, Kanazawa, Japan
| | - Toshioh Fujibuchi
- Department of Health Sciences, Faculty of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
| | - Geoff Dougherty
- Department of Applied Physics and Medical Imaging, California State University Channel Islands, Camarillo, CA 93012, United States of America
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Sookpeng S, Martin CJ, Krisanachinda A. Design and use of a phantom for testing and comparing the performance of computed tomography automatic tube current modulation systems. JOURNAL OF RADIOLOGICAL PROTECTION : OFFICIAL JOURNAL OF THE SOCIETY FOR RADIOLOGICAL PROTECTION 2020; 40:753-773. [PMID: 32303017 DOI: 10.1088/1361-6498/ab8a56] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Automatic tube current modulation (ATCM) is now available on all computed tomography (CT) scanners, but there is no standard phantom for testing its operation. For this study, a phantom comprising five elliptical sections of varying diameters in the shape of a pagoda has been made to represent the range of sizes for patients in Thailand and the Far East. ATCM performance can be evaluated in terms of how tube current and image noise vary with changes in the sizes of the sections. Additional rods of different materials with similar properties to human tissues have been inserted to allow the measurement of contrast-to-noise ratios (CNRs) for assessment of image quality. The phantom has been used to test and compare the performance of CT ATCM systems for the major four CT scanner vendors. The results showed that the ATCM systems of Toshiba and GE CT scanners maintained image noise and CNR within narrower ranges by varying tube current aggressively along the scan length, and commencing modulation before the high attenuation sections are reached. In contrast, the ATCM systems of Philips and Siemens scanners adjusted the tube current within narrower ranges, allowed larger variations in image noise and CNR, and commenced modulation at the start of sections with higher attenuation. The phantom can be used to confirm functionality of the system for acceptance testing, as well as providing information on the tradeoff between radiation dose and image quality when setting up clinical protocols during commissioning of new CT scanners. The phantom can also be used on a routine basis to check that performance is maintained, and could be used in the future for selecting protocol settings to give required values of CNR or adjusting protocol settings on different CT scanners to provide similar levels of clinical performance.
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Affiliation(s)
- S Sookpeng
- Department of Radiological Technology, Faculty of Allied Health Sciences, Naresuan University, Phitsanulok, Thailand. Author to whom any correspondence should be addressed
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Yurt A, Haliloğlu RÇ, Özsoykal İ, Şişman G, Ada E. Baş-Boyun BT Anjiyografi’de Otomatik Tüp Akımı Modülasyon Sisteminin Hasta Dozu ve Görüntü Kalitesi Üzerine Etkisi. DICLE MEDICAL JOURNAL 2019. [DOI: 10.5798/dicletip.661208] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Tube Current Reduction in CT Angiography: How Low Can We Go in Imaging of Patients With Suspected Acute Stroke? AJR Am J Roentgenol 2019; 213:410-416. [DOI: 10.2214/ajr.18.20954] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Maamoun I, Khalil MM. Assessment of iterative image reconstruction on kidney and liver donors: Potential role of adaptive iterative dose reduction 3D (AIDR 3D) technology. Eur J Radiol 2018; 109:124-129. [PMID: 30527293 DOI: 10.1016/j.ejrad.2018.10.020] [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: 05/12/2018] [Revised: 09/30/2018] [Accepted: 10/19/2018] [Indexed: 02/02/2023]
Abstract
OBJECTIVE The aim of this study was to evaluate the radiation exposure levels in two different types of subjects including liver and kidney donors in diagnostic assessment of transplant operation and also the significance of dose reduction on total effective dose. MATERIALS AND METHODS A number of Sixty subjects (40 males and 20 females, average age of 35 ± 10 years) were randomly prospectively recruited and equally divided into two distinct groups namely kidney donors (KD, 24 M and 6 F) and liver donors (LD, 21 M and 9 female). Kidney donors were divided into full dose (KFD, n = 20) group and low dose (KLD, n = 10) group. They had undergone dynamic renal scan using Tc99 m-DTPA, CT renal angiography and x-ray plain radiograph. Liver donors were divided into full dose (LFD, n = 20) and low dose (LLD, n = 10) groups and performed CT liver volumetry. The CT dose index (CTDIvol), dose length product (DLP), total milli-ampere product time mAs, effective dose and image noise index were measured in all subjects of kidney and liver donors comparing full dose and low dose protocols. RESULTS In comparison of all subjects of kidney donor groups (KFD vs KLD), the parameters (mAs = 16386.8 ± 3140.7 vs 2830.286 ± 831.676), (CTDIvol = 183.19 ± 32.58 mGy vs. 45.5 ± 13.3 mGy), DLP = 2884 ± 859.0 mGy.cm vs. 1437.5 ± 399 mGy.cm) and (effective dose = 49.0 ± 9.0 mSv vs. 18.9 mSv±5.7 mSv) were significant, p < 0.0005. Statistical evaluation of liver donors groups (LFD vs LLD) showed that (mAs = 14348.8 ± 4571.8 vs 3123.357 ± 794.5), (CTDIvol = 333.6 ± 59.5 mGy vs. 51.4 ± 13 mGy), (DLP = 3268.3 ± 604.3 mGy.cm vs 1260.5 ± 404.6 mGy.cm) and (effective dose = 43.3 mSv±12.9 mSv vs. 21.6 ± 5.9 mSv) are statistically significant, p < 0.0005. Nevertheless, the comparative evaluation of the image quality noise index of KFD vs KLD groups and LFD vs LLD showed a no statistical significance p > 0.05. CONCLUSION Renal and liver donors bear a relatively significant radiation dose due to diagnostic evaluation and patient management. The CT iterative reconstruction using AIDR3D proved very valuable tool in dose reduction such that it can reduce 37% in kidney donors and 48% in liver donors while able to maintain an acceptable image quality. Monitoring of those subjects on the clinical and radiobiological levels are recommended.
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Affiliation(s)
- I Maamoun
- Department of Intensive Care, Nuclear Cardiology Unit, Faculty of Medicine, Cairo University, Cairo, Egypt
| | - Magdy M Khalil
- Department of Physics, Faculty of Science, Helwan University, Cairo, Egypt.
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Cai W, Hu C, Hu S, Wang X, Gong J, Zhang W, Shi D, Cheng B. Feasibility study of iterative model reconstruction combined with low tube voltage, low iodine load, and low iodine delivery rate in craniocervical CT angiography. Clin Radiol 2017; 73:217.e1-217.e6. [PMID: 29066028 DOI: 10.1016/j.crad.2017.09.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Revised: 05/18/2017] [Accepted: 09/20/2017] [Indexed: 12/11/2022]
Abstract
AIM To investigate the feasibility of iterative model reconstruction (IMR) combined with low tube voltage, low iodine load, and low iodine deliver rate in craniocervical computed tomography angiography (CTA). MATERIALS AND METHODS Sixty patients were randomly divided into two groups (n=30 for each): group A: 120 kVp, 50 ml of iopromide at a flow rate of 5 ml/s; filtered back projection (FBP) reconstruction; group B: 80 kVp, 30 ml of iohexol at 4.5 ml/s; hybrid iterative reconstruction (HIR) for group B1 and IMR for group B2. CT attenuation values, image noise, signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), subjective image quality, effective dose (ED), iodine load, and iodine delivery rate (IDR) were compared. RESULTS CT attenuation values of the arteries were higher in groups B1 and B2 than group A. The SNR and CNR were higher, while image noise was lower, for group B2 compared with groups B1 and A. The best subjective image quality was obtained with group B2. ED, iodine load, and IDR reduction of 69.6%, 51.4%, 27%, respectively, was obtained in group B compared with group A. CONCLUSION IMR combined with 80 kVp and 30 ml of iohexol at a flow rate of 4.5 ml/s for craniocervical CTA can reduce ED, iodine load, and IDR, while improving image quality.
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Affiliation(s)
- W Cai
- Department of Radiology, First Affiliated Hospital of Soochow University, Suzhou, Jiangsu, China; Department of Radiology, Second Affiliated Hospital of Soochow University, Suzhou, Jiangsu, China
| | - C Hu
- Department of Radiology, First Affiliated Hospital of Soochow University, Suzhou, Jiangsu, China.
| | - S Hu
- Department of Radiology, First Affiliated Hospital of Soochow University, Suzhou, Jiangsu, China
| | - X Wang
- Department of Radiology, First Affiliated Hospital of Soochow University, Suzhou, Jiangsu, China
| | - J Gong
- Department of Radiology, Second Affiliated Hospital of Soochow University, Suzhou, Jiangsu, China
| | - W Zhang
- Department of Radiology, Second Affiliated Hospital of Soochow University, Suzhou, Jiangsu, China
| | - D Shi
- Department of Radiology, Second Affiliated Hospital of Soochow University, Suzhou, Jiangsu, China
| | - B Cheng
- Department of Radiology, West China Second University Hospital of Sichuan University, Chengdu, Sichuan, China
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Hu X, Ma L, Zhang J, Li Z, Shen Y, Hu D. Use of pulmonary CT angiography with low tube voltage and low-iodine-concentration contrast agent to diagnose pulmonary embolism. Sci Rep 2017; 7:12741. [PMID: 29038563 PMCID: PMC5643383 DOI: 10.1038/s41598-017-13077-w] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2017] [Accepted: 09/18/2017] [Indexed: 12/26/2022] Open
Abstract
Pulmonary CT angiography (CTPA) is regarded as the preferred imaging method in diagnosing pulmonary embolism (PE). Considering the harm of radiation exposure and the side effect of iodinated contrast agent, CTPA protocol with low tube voltage and low dose of contrast agent became research hotspot in last decade. The present study evaluates the image quality, radiation dose, positive rate of PE and the location of PE with a CTPA protocol using low tube voltage (80 kVp) and low-iodine-concentration contrast agent (270 mg I/ml) in patients suspected of PE compared to a conventional CTPA protocol (120 kVp, 350 mg I/ml). The results showed that 80 kVp CTPA protocol with 40 ml 270 mg I/ml achieved equally subjective image quality and a positive rate for diagnosing PE, though the quantitative image quality was reduced compared to the 120 kVp CTPA protocol with 40 ml 350 mg I/ml administered, with a 63.6% decrease in radiation dose and a 22.9% reduction in iodine content of contrast agent. Our results document that CTPA protocol with low tube voltage and low iodine concentration of contrast agent is satisfied to the clinical application.
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Affiliation(s)
- Xuemei Hu
- Department of Radiology, Tongji Hospital Affiliated to Tongji Medical College of Huazhong University of Science and Technology, Wuhan, China
| | - Liya Ma
- Department of Radiology, Tongji Hospital Affiliated to Tongji Medical College of Huazhong University of Science and Technology, Wuhan, China
| | - Jinhua Zhang
- Department of Radiology, Tongji Hospital Affiliated to Tongji Medical College of Huazhong University of Science and Technology, Wuhan, China
| | - Zhen Li
- Department of Radiology, Tongji Hospital Affiliated to Tongji Medical College of Huazhong University of Science and Technology, Wuhan, China
| | - Yaqi Shen
- Department of Radiology, Tongji Hospital Affiliated to Tongji Medical College of Huazhong University of Science and Technology, Wuhan, China.
| | - Daoyu Hu
- Department of Radiology, Tongji Hospital Affiliated to Tongji Medical College of Huazhong University of Science and Technology, Wuhan, China
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Braad PEN, Andersen T, Hansen SB, Høilund-Carlsen PF. Strategies for CT tissue segmentation for Monte Carlo calculations in nuclear medicine dosimetry. Med Phys 2016; 43:6507. [DOI: 10.1118/1.4967267] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Image Quality and Radiation Dose for Prospectively Triggered Coronary CT Angiography: 128-Slice Single-Source CT versus First-Generation 64-Slice Dual-Source CT. Sci Rep 2016; 6:34795. [PMID: 27752040 PMCID: PMC5067634 DOI: 10.1038/srep34795] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2016] [Accepted: 09/19/2016] [Indexed: 12/02/2022] Open
Abstract
This study sought to compare the image quality and radiation dose of coronary computed tomography angiography (CCTA) from prospectively triggered 128-slice CT (128-MSCT) versus dual-source 64-slice CT (DSCT). The study was approved by the Medical Ethics Committee at Tongji Medical College of Huazhong University of Science and Technology. Eighty consecutive patients with stable heart rates lower than 70 bpm were enrolled. Forty patients were scanned with 128-MSCT, and the other 40 patients were scanned with DSCT. Two radiologists independently assessed the image quality in segments (diameter >1 mm) according to a three-point scale (1: excellent; 2: moderate; 3: insufficient). The CCTA radiation dose was calculated. Eighty patients with 526 segments in the 128-MSCT group and 544 segments in the DSCT group were evaluated. The image quality 1, 2 and 3 scores were 91.6%, 6.9% and 1.5%, respectively, for the 128-MSCT group and 97.6%, 1.7% and 0.7%, respectively, for the DSCT group, and there was a statistically significant inter-group difference (P ≤ 0.001). The effective doses were 3.0 mSv in the 128-MSCT group and 4.5 mSv in the DSCT group (P ≤ 0.001). Compared with DSCT, CCTA with prospectively triggered 128-MSCT had adequate image quality and a 33.3% lower radiation dose.
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How Much Is the Dose Varying between Follow-Up CT-Examinations Performed on the Same Scanner with the Same Imaging Protocol? PLoS One 2016; 11:e0152961. [PMID: 27050659 PMCID: PMC4822887 DOI: 10.1371/journal.pone.0152961] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2015] [Accepted: 03/22/2016] [Indexed: 12/12/2022] Open
Abstract
Purpose To investigate the dose variation between follow-up CT examinations, when a patient is examined several times on the same scanner with the identical scan protocol which comprised automated exposure control. Material and Methods This retrospective study was approved by the local ethics committee. The volume computed tomography dose index (CTDIvol) and the dose-length-product (DLP) were recorded for 60 cancer patients (29 male, 31 female, mean age 60.1 years), who received 3 follow-up CT examinations each composed of a non-enhanced scan of the liver (LI-CT) and a contrast-enhanced scan of chest (CH-CT) and abdomen (AB-CT). Each examination was performed on the same scanner (Siemens Definition FLASH) equipped with automated exposure control (CARE Dose 4D and CARE KV) using the identical scan protocol. Results The median percentage difference in DLP between follow-up examinations was 9.6% for CH-CT, 10.3% for LI-CT, and 10.1% for AB-CT; the median percentage difference in CTDIvol 8.3% for CH-CT, 7.4% for LI-CT and 7.7% for AB-CT (p<0.0001 for all values). The maximum difference in DLP between follow-up examinations was 67.5% for CH-CT, 50.8% for LI-CT and 74.3% for AB-CT; the maximum difference in CTDIvol 62.9% for CH-CT, 47.2% for LI-CT, and 49% for AB-CT. Conclusion A significant variance in the radiation dose occurs between follow-up CT examinations when the same CT scanner and the identical imaging protocol are used in combination with automated exposure control.
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Impact of the scout view orientation on the radiation exposure and image quality in thoracic and abdominal CT. Eur Radiol 2016; 26:4072-4079. [PMID: 26943131 DOI: 10.1007/s00330-016-4285-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2015] [Revised: 01/24/2016] [Accepted: 02/16/2016] [Indexed: 10/22/2022]
Abstract
OBJECTIVES To assess the impact of the scout view orientation on radiation exposure and image quality in thoracoabdominal CT, when automated tube voltage selection (ATVS) and automated tube current modulation (ATCM) are used in combination with scan planning on a single scout view. METHODS Fifty patients underwent two thoracoabdominal CT examinations, one planned on an anteroposterior scout view, one planned on a lateral scout view. Both examinations included contrast-enhanced imaging of chest (CH) and abdomen (AB) and non-contrast-enhanced imaging of the liver (LI). For all examinations the same imaging protocol was used on the same dual-source CT scanner. The radiation exposure was recorded and objective as well as visual image quality was assessed for all examinations. RESULTS The median dose-length product was significantly lower in scans planned on a lateral scout view (CH: 179 vs. 218 mGy*cm, LI: 148 vs. 178 mGy*cm, AB: 324 vs. 370 mGy*cm, p < 0.0001). Objective image quality was marginal lower in scans planned on a lateral scout view, whereas the visual image quality was rated as equal. CONCLUSION At the tested radiation doses, the orientation of the scout view has a significant impact on the radiation exposure but no clinically relevant impact on the image quality. KEY POINTS • The scout view orientation has a significant impact on the radiation exposure. • The scout view orientation has no clinically relevant impact on image quality. • A lateral scout view should be preferred with regard to radiation exposure.
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Effect of an arm traction device on image quality and radiation exposure during neck computed tomography. Eur J Radiol 2016; 85:68-72. [PMID: 26724651 DOI: 10.1016/j.ejrad.2015.11.008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2015] [Revised: 10/28/2015] [Accepted: 11/03/2015] [Indexed: 11/23/2022]
Abstract
OBJECTIVE To retrospectively determine the effect of an arm traction device on image quality and radiation exposure during a neck computed tomography (CT) scan. MATERIALS AND METHODS Standard neck CT examinations with an automatic tube current modulation technique were compared for two groups (intervention group: patients with an arm traction device, n=45; control group: no particular positioning optimization, n=45). Image quality was the primary outcome and was assessed using image noise and the streak artifact. The secondary outcome was radiation exposure, which was measured by the volume CT dose index (CTDIvol) and dose-length product. Potential confounders, including the effective diameter of the neck and scan length, were also assessed. RESULTS Image noise and the streak artifact at the lower neck and the supraclavicular fossa were significantly improved in the intervention group compared with the control group (p<0.001). There was a significant decrease in the CTDIvol in the intervention group versus the control group (p=0.042). DLP showed a tendency toward a decrease in the intervention group that was non-significant (p=0.106). The effective diameter and scan length showed no statistical difference between the two groups. CONCLUSION An arm traction device improves the image quality in the lower neck and the supraclavicular fossa during a neck CT. Application of this device also reduces the tendency for radiation exposure.
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Chun M, Choi YH, Kim JH. Automated measurement of CT noise in patient images with a novel structure coherence feature. Phys Med Biol 2015; 60:9107-22. [DOI: 10.1088/0031-9155/60/23/9107] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
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Wallace AN, Vyhmeister R, Bagade S, Chatterjee A, Hicks B, Ramirez-Giraldo JC, McKinstry RC. Evaluation of the use of automatic exposure control and automatic tube potential selection in low-dose cerebrospinal fluid shunt head CT. Neuroradiology 2015; 57:639-44. [PMID: 25779098 DOI: 10.1007/s00234-015-1508-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2014] [Accepted: 03/02/2015] [Indexed: 11/24/2022]
Abstract
INTRODUCTION Cerebrospinal fluid shunts are primarily used for the treatment of hydrocephalus. Shunt complications may necessitate multiple non-contrast head CT scans resulting in potentially high levels of radiation dose starting at an early age. A new head CT protocol using automatic exposure control and automated tube potential selection has been implemented at our institution to reduce radiation exposure. The purpose of this study was to evaluate the reduction in radiation dose achieved by this protocol compared with a protocol with fixed parameters. METHODS A retrospective sample of 60 non-contrast head CT scans assessing for cerebrospinal fluid shunt malfunction was identified, 30 of which were performed with each protocol. The radiation doses of the two protocols were compared using the volume CT dose index and dose length product. The diagnostic acceptability and quality of each scan were evaluated by three independent readers. RESULTS The new protocol lowered the average volume CT dose index from 15.2 to 9.2 mGy representing a 39 % reduction (P < 0.01; 95 % CI 35-44 %) and lowered the dose length product from 259.5 to 151.2 mGy/cm representing a 42 % reduction (P < 0.01; 95 % CI 34-50 %). The new protocol produced diagnostically acceptable scans with comparable image quality to the fixed parameter protocol. CONCLUSION A pediatric shunt non-contrast head CT protocol using automatic exposure control and automated tube potential selection reduced patient radiation dose compared with a fixed parameter protocol while producing diagnostic images of comparable quality.
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Affiliation(s)
- Adam N Wallace
- Mallinckrodt Institute of Radiology, Barnes Jewish Hospital, St. Louis, MO, USA
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Potential for Radiation Dose Savings in Abdominal and Chest CT Using Automatic Tube Voltage Selection in Combination With Automatic Tube Current Modulation. AJR Am J Roentgenol 2014; 203:292-9. [DOI: 10.2214/ajr.13.11628] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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18
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Luo S, Zhang LJ, Meinel FG, Zhou CS, Qi L, McQuiston AD, Schoepf UJ, Lu GM. Low tube voltage and low contrast material volume cerebral CT angiography. Eur Radiol 2014; 24:1677-85. [PMID: 24792591 DOI: 10.1007/s00330-014-3184-z] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2013] [Revised: 03/13/2014] [Accepted: 04/09/2014] [Indexed: 12/01/2022]
Abstract
OBJECTIVES To evaluate the image quality, radiation dose and diagnostic accuracy of low kVp and low contrast material volume cerebral CT angiography (CTA) in intracranial aneurysm detection. METHODS One hundred twenty patients were randomly divided into three groups (n = 40 for each): Group A, 70 ml iodinated contrast agent/120 kVp; group B, 30 ml/100 kVp; group C, 30 ml/80 kVp. The CT numbers, noise, signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were measured in the internal carotid artery (ICA) and middle cerebral artery (MCA). Subjective image quality was evaluated. For patients undergoing DSA, diagnostic accuracy of CTA was calculated with DSA as reference standard and compared. RESULTS CT numbers of ICA and MCA were higher in groups B and C than in group A (P < 0.01). SNR and CNR in groups A and B were higher than in group C (both P < 0.05). There was no difference in subjective image quality among the three groups (P = 0.939). Diagnostic accuracy for aneurysm detection among these groups had no statistical difference (P = 1.00). Compared with group A, the radiation dose of groups B and C was decreased by 45% and 74%. CONCLUSION Cerebral CTA at 100 or 80 kVp using 30 ml contrast agent can obtain diagnostic image quality with a low radiation dose while maintaining the same diagnostic accuracy for aneurysm detection. KEY POINTS • Cerebral CTA is feasible using 100/80 kVp and 30 ml contrast agent. • This approach obtains diagnostic image quality with 45-74% radiation dose reduction. • Diagnostic accuracy for intracranial aneurysm detection seems not to be compromised.
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Affiliation(s)
- Song Luo
- Department of Medical Imaging, Jinling Hospital, Medical School of Nanjing University, Nanjing, Jiangsu, 210002, China
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19
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Ibrahim M, Parmar H, Christodoulou E, Mukherji S. Raise the bar and lower the dose: current and future strategies for radiation dose reduction in head and neck imaging. AJNR Am J Neuroradiol 2014; 35:619-24. [PMID: 23449649 DOI: 10.3174/ajnr.a3473] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
SUMMARY Technologic advances in CT have generated a dramatic increase in the number of CT studies, with a resultant increase in the radiation dose related to CT scanning. Such increase in radiation dose is becoming a concern for the radiology community, especially with increasing public awareness of the dose burden related to examinations. To cope with the increase in CT-related radiation exposure, it is becoming necessary to optimize CT imaging protocols and apply radiation dose reduction techniques to ensure the best imaging with the lowest radiation dose.
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Affiliation(s)
- M Ibrahim
- From the University of Michigan Health System, Ann Arbor, Michigan
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20
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Sookpeng S, Martin CJ, Gentle DJ, Lopez-Gonzalez MR. Relationships between patient size, dose and image noise under automatic tube current modulation systems. JOURNAL OF RADIOLOGICAL PROTECTION : OFFICIAL JOURNAL OF THE SOCIETY FOR RADIOLOGICAL PROTECTION 2014; 34:103-123. [PMID: 24334678 DOI: 10.1088/0952-4746/34/1/103] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Automatic tube current modulation (ATCM) systems are now used for the majority of CT scans. The principles of ATCM operation are different in CT scanners from different manufacturers. Toshiba and GE scanners base the current modulation on a target noise setting, while Philips and Siemens scanners use reference image and reference mAs concepts respectively. Knowledge of the relationships between patient size, dose and image noise are important for CT patient dose optimisation. In this study, the CT patient doses were surveyed for 14 CT scanners from four different CT scanner manufacturers. The patient cross sectional area, the tube current modulation and the image noise from the CT images were analysed using in-house software. The Toshiba and GE scanner results showed that noise levels are relatively constant but tube currents are dependent on patient size. As a result of this there is a wide range in tube current values across different patient sizes, and doses for large patients are significantly higher in these scanners. In contrast, in the Philips and Siemens scanners, tube currents are less dependent on patient size, the range in tube current is narrower, and the doses for larger patients are not as high. Image noise is more dependent on the patient size.
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Affiliation(s)
- S Sookpeng
- Health Physics, Gartnavel Royal Hospital, 1055 Great Western Road, Glasgow G12 0XH, UK. Department of Clinical Physics, University of Glasgow, Glasgow G12 8QQ, UK
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Hybrid Iterative Reconstruction Algorithm Improves Image Quality in Craniocervical CT Angiography. AJR Am J Roentgenol 2013; 201:W861-6. [DOI: 10.2214/ajr.13.10701] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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22
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Liao Y, Lai N, Tyan Y, Chuang K, Tsai H. Automatic tube current modulation for volume scan in a 320-detector row CT scanner. RADIAT MEAS 2013. [DOI: 10.1016/j.radmeas.2013.04.012] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Siegelman JRQW, Gress DA. Radiology stewardship and quality improvement: the process and costs of implementing a CT radiation dose optimization committee in a medium-sized community hospital system. J Am Coll Radiol 2013; 10:416-22. [PMID: 23491153 DOI: 10.1016/j.jacr.2012.12.008] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2012] [Accepted: 12/05/2012] [Indexed: 12/20/2022]
Abstract
PURPOSE The aims of this study were to measure the effectiveness of a multidisciplinary CT dose optimization committee and estimate its costs and to describe a radiation stewardship quality improvement initiative in one CT department at a medium-sized community hospital system that used a participatory design committee methodology. METHODS A CT dose optimization committee was conceived, funded, and formed, consisting of the following stakeholders: radiologists, technologists, consultant medical physicists, and an administrator. Volume CT dose index (CTDIvol) and repeat rate were monitored for 1 month, for one scan type, during which iterative protocol adjustments were made through committee interaction. Effects on repeat rate and CTDIvol were quantified and benchmarked against national diagnostic reference levels after retrospective medical record review of 100 consecutive patients before and after the intervention. Labor hours were reported and wage resources estimated. RESULTS Over 3 months, the committee met in person twice and exchanged 128 e-mails in establishing a process for protocol improvement and measurement of success. Repeat rate was reduced from 13% (13 of 100) to 0% (0 of 100). Scans meeting the ACR reference level for CTDIvol (75 mGy) improved by 34% (38 of 100 before, 51 of 100 after; Fisher's exact 2-tailed P = .09), and those meeting ACR pass/fail criterion (80 mGy) improved by 29% (58 of 100 before, 75 of 100 after; Fisher's exact 2-tailed P = .01). Committee evolution and work, and protocol development and implementation, required 57 person-hours, at an estimated labor cost of $12,488. CONCLUSIONS An efficient process was established as a proof of concept for the use of a multidisciplinary committee to reduce patient radiation dose, repeat rate, and variability in image quality. The committee and process ultimately improved the quality of patient care, fostered a culture of safety and ongoing quality improvement, and calculated costs for such an endeavor.
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Affiliation(s)
- Jenifer R Q W Siegelman
- Norwich Diagnostic Imaging at The William W. Backus Hospital, Norwich, Connecticut 06360, USA.
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24
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Organ-Based Dose Current Modulation and Thyroid Shields: Techniques of Radiation Dose Reduction for Neck CT. AJR Am J Roentgenol 2012; 198:1132-8. [DOI: 10.2214/ajr.11.7445] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Radiation Exposure and Image Quality of Normal Computed Tomography Brain Images Acquired With Automated and Organ-Based Tube Current Modulation Multiband Filtering and Iterative Reconstruction. Invest Radiol 2012; 47:202-7. [DOI: 10.1097/rli.0b013e31823a86d5] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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26
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Sun G, Ding J, Lu Y, Li M, Li L, Li GY, Zhang XP. Comparison of standard- and low-tube voltage 320-detector row volume CT angiography in detection of intracranial aneurysms with digital subtraction angiography as gold standard. Acad Radiol 2012; 19:281-8. [PMID: 22206609 DOI: 10.1016/j.acra.2011.11.004] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2011] [Revised: 10/15/2011] [Accepted: 11/08/2011] [Indexed: 12/22/2022]
Abstract
RATIONALE AND OBJECTIVES The aim of this study was to prospectively assess the effect of low-tube voltage (80 kVp) 320-detector row volume computed tomographic (CT) angiography (L-VCTA) in the detection of intracranial aneurysms, with three-dimensional (3D) spin digital subtraction angiography (DSA) as the gold standard. MATERIALS AND METHODS Forty-eight patients with clinically suspected subarachnoid hemorrhages were divided into two groups. One group underwent L-VCTA and DSA, while the other group underwent conventional-tube voltage (120 kVp) volume CT angiography (C-VCTA) and DSA. Vascular enhancement, image quality, detection accuracy of aneurysms, and radiation dose were compared between the two groups. RESULTS For objective image quality, the L-VCTA group had higher mean vessel attenuation, correlated with higher image noise and lower signal-to-noise ratio, than the C-VCTA group. For subjective image quality, there were no significant differences between the two groups regarding scores for arterial enhancement, depiction of small arterial detail, interference of venous structures, and overall image quality scores. The mean effective dose for the L-VCTA group was significantly lower than for the C-VCTA group (0.56 ± 0.25 vs 1.84 ± 0.002 mSv), with a reduction of radiation dose of 69.73%. With 3D DSA as the reference standard, the sensitivity, specificity, and accuracy in the L-VCTA and C-VCTA groups were 94.12%, 100%, 94.4% and 100%, 100%, and 100%, respectively. In both groups, there were significant correlations for maximum aneurysm diameter measurements between volume CT angiography and 3D DSA; no statistical difference in the mean maximum diameter of each aneurysm was measured between volume CT angiography and 3D DSA. CONCLUSIONS L-VCTA is helpful in detecting intracranial aneurysms, with results similar to those of 3D DSA, but at a lower radiation dose than C-VCTA.
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Affiliation(s)
- Gang Sun
- Department of Medical Imaging, Jinan Military General Hospital, China.
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The influence of chest wall tissue composition in determining image noise during cardiac CT. AJR Am J Roentgenol 2012; 197:1328-34. [PMID: 22109286 DOI: 10.2214/ajr.11.6816] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
OBJECTIVE The purpose of this article is to determine the influence of chest wall composition on image quality in cardiac CT. MATERIALS AND METHODS A retrospective study of 100 consecutive patients referred for CT coronary artery calcium assessment was performed. Image noise (Hounsfield units) was measured by prescribing a region of interest in the descending thoracic aorta. Image noise was correlated with conventional patient biometric parameters, including body weight, body mass index (BMI), and anteroposterior and lateral thoracic diameters, and with novel patient biometric parameters, including total chest wall soft tissue, chest wall fat, and chest wall muscle and bone. The linear correlation coefficient was used to indicate the strength of the association. RESULTS A strong correlation was noted between BMI and image noise in men (r = 0.66), but the strongest relationships were observed in larger women (BMI ≥ 25), who had more chest wall fat than muscle and very strong correlations between image noise, chest wall fat (r = 0.82), and total chest wall soft tissue (r = 0.85). CONCLUSION Chest wall composition has a significant correlation with image noise for cardiac CT. Therefore, strategies that target radiation dose reduction should incorporate adaptation to chest wall composition. These determinations become more significant given the current obesity epidemic.
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Lee S, Yoon SW, Yoo SM, Ji YG, Kim KA, Kim SH, Lee JT. Comparison of image quality and radiation dose between combined automatic tube current modulation and fixed tube current technique in CT of abdomen and pelvis. Acta Radiol 2011; 52:1101-6. [PMID: 21903869 DOI: 10.1258/ar.2011.100295] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
BACKGROUND Tube current is an important determinant of radiation dose and image quality in X-ray-based examination. The combined automatic tube current modulation technique (ATCM) enables automatic adjustment of the tube current in various planes (x-y and z) based on the size and attenuation of the body area scanned. PURPOSE To compare image quality and radiation dose of the ATCM with those of a fixed tube current technique (FTC) in CT of the abdomen and pelvis performed with a 16-slice multidetector row CT. MATERIAL AND METHODS We reviewed 100 patients in whom initial and follow-up CT of the abdomen and pelvis were performed with FTC and ATCM. All acquisition parameters were identical in both techniques except for tube current. We recorded objective image noise in liver parenchyma, subjective image noise and diagnostic acceptability by using a five-point scale, radiation dose, and body mass index (BMI, kg/m(2)). Data were analyzed with parametric and non-parametric statistical tests. RESULTS There was no significant difference in image noise and diagnostic acceptability between two techniques. All subjects had acceptable subjective image noise in both techniques. The significant reduction in radiation dose (45.25% reduction) was noted with combined ATCM (P < 0.001). There was a significant linear statistical correlation between BMI and dose reduction (r = -0.78, P < 0.05). CONCLUSION The ATCM for CT of the abdomen and pelvis substantially reduced radiation dose while maintaining diagnostic image quality. Patients with lower BMI showed more reduction in radiation dose.
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Affiliation(s)
- Sanghee Lee
- Department of Radiology and Center for Imaging Science, Samsung Medical Center, Sungkyunkwan University School of Medicine
| | - Sang-Wook Yoon
- Department of Diagnostic Radiology, CHA Bundang Medical Center, CHA University
| | - Seung-Min Yoo
- Department of Diagnostic Radiology, CHA Bundang Medical Center, CHA University
| | - Young Geon Ji
- Preventive Medicine, CHA Bundang Medical Center, CHA University, Korea
| | - Kyoung Ah Kim
- Department of Diagnostic Radiology, CHA Bundang Medical Center, CHA University
| | - Sang Heum Kim
- Department of Diagnostic Radiology, CHA Bundang Medical Center, CHA University
| | - Jong Tae Lee
- Department of Diagnostic Radiology, CHA Bundang Medical Center, CHA University
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Yamamoto H, Kuwayama N, Hayashi N, Kubo M, Endo S. Usefulness of computed tomography angiography for the detection of high-risk aortas for carotid artery stenting. Neurol Med Chir (Tokyo) 2011; 51:756-61. [PMID: 22123477 DOI: 10.2176/nmc.51.756] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
This study evaluated the usefulness of computed tomography (CT) angiography for the detection of high-risk aortas for carotid artery stenting (CAS). We investigated changes in the treatment method and modifications of endovascular techniques according to the information from CT angiography. CT angiography using three-dimensional and multi-planar reconstruction was performed in 43 consecutive patients with carotid artery stenoses intended to undergo CAS. Two neurosurgeons evaluated the images and estimated the risk and difficulties of CAS. CT angiography clearly depicted the entire aorta, the supra-aortic vessels, and the ilio-femoral arteries in all patients. Abnormal vascular findings were found in 17 patients. High-risk aortic lesions for CAS were detected in 5 patients, including thick aortic plaques with thrombi in 2. We changed the treatment strategy from CAS to carotid endarterectomy (CEA) in these 2 patients. CT angiograms proved very useful in evaluating the approach routes of CAS in 12 patients. One patient had dissecting aneurysm of the thoracic aorta and another had aberrant right vertebral artery. In these two, the treatment strategy was changed from CAS to CEA. The treatment method was changed in 4 patients in total. CT angiography is useful for the detection of high-risk aortas for CAS and for the evaluation of safe approaches to the carotid artery.
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Optimization of patient dose and image quality with z-axis dose modulation for computed tomography (CT) head in acute head trauma and stroke. Emerg Radiol 2010; 18:103-7. [PMID: 20857165 DOI: 10.1007/s10140-010-0908-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2010] [Accepted: 09/06/2010] [Indexed: 10/19/2022]
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Rogalla P, Blobel J, Kandel S, Meyer H, Mews J, Kloeters C, Kashani H, Lembcke A, Paul N. Radiation dose optimisation in dynamic volume CT of the heart: tube current adaptation based on anterior-posterior chest diameter. Int J Cardiovasc Imaging 2010; 26:933-40. [PMID: 20422293 DOI: 10.1007/s10554-010-9630-3] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/12/2010] [Accepted: 04/05/2010] [Indexed: 11/26/2022]
Abstract
To compare tube current adaptation based on 3 body mass index (BMI) categories versus anterior-posterior chest diameter (APD) for radiation dose optimisation in patients undergoing dynamic volume cardiac CT. Two cardiac imaging centres participated in the study. 20 patients underwent a prospectively triggered 320-slice single beat cardiac CT using the X-ray tube current [mA] manually adjusted to the patient's BMI (group I). In 20 subsequent patients, the tube current was adapted according to the patient's APD (group II). All other parameters were kept constant. Image noise was defined as the standard deviation of attenuation values and measured using a ROI in the descending aorta. Variation in image noise was statistically compared between both patient groups. Average and standard deviation of pixel noise were 29.1 HU and 14.8 HU in group I and 28.0 HU and 4.2 HU in group II. Inter-individual variation of pixel noise was significantly lower in group II compared to group I (p < 0.0001). Tube current adaptation based on APD is superior to stepwise adaptation based on BMI for optimising radiation dose in dynamic volume cardiac CT and therefore limits unnecessary radiation dose while ensuring diagnostic image quality in patients with diverse body habitus.
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Affiliation(s)
- Patrik Rogalla
- Department of Medical Imaging, University Health Network, University of Toronto, Toronto, ON, Canada
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Das CJ, Makharia GK, Kumar R, Kumar R, Tiwari RP, Sharma R, Malhotra A. PET/CT colonography: a novel non-invasive technique for assessment of extent and activity of ulcerative colitis. Eur J Nucl Med Mol Imaging 2009; 37:714-21. [PMID: 20033154 DOI: 10.1007/s00259-009-1335-2] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2009] [Accepted: 11/10/2009] [Indexed: 01/22/2023]
Abstract
PURPOSE Extent of involvement and activity of ulcerative colitis (UC) is best evaluated by colonoscopy. Colonoscopy however carries risk during acute exacerbation. We investigated the utility of PET/CT colonography for assessment of extent and activity of UC. METHODS Within a 1-week window, 15 patients with mild to moderately active UC underwent colonoscopy and PET/CT colonography 60 min after injection of 10 mCi of (18)F-fluorodeoxyglucose (FDG). PET activity score based on the amount of FDG uptake and endoscopic mucosal activity in seven colonic segments of each patient was recorded. The mean maximum standardized uptake value (SUV(max)) of seven segments was compared with activity in liver. A PET activity grade of 0, 1, 2 or 3 was assigned to each region depending upon their SUV(max) ratio (colon segment to liver). RESULTS The extent of disease was left-sided colitis in five and pancolitis in ten. The mean Ulcerative Colitis Disease Activity Index (UCDAI) was 7.6. The number of segments involved as per colonoscopic evaluation and PET/CT colonography was 67 and 66, respectively. There was a good correlation for extent evaluation between the two modalities (kappa 55.3%, p = 0.02). One patient had grade 0 PET activity, nine had grade 2 and five had grade 3 PET activity. In six patients, there was one to one correlation between PET activity grades with that of endoscopic grade. One patient showed activity in the sacroiliac joint suggesting active sacroiliitis. CONCLUSION PET/CT colonography is a novel non-invasive technique for the assessment of extent and activity of the disease in patients with UC.
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Affiliation(s)
- Chandan J Das
- Department of Radiodiagnosis, All India Institute of Medical Sciences, New Delhi, India
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