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Chen J, Tu J, Huang S, Zhu Z, Tu Y. Is It Appropriate to Completely Eliminate Contact Shielding during CT Examination? A Discourse Based on Experimental Findings. HEALTH PHYSICS 2024; 126:46-55. [PMID: 37792391 DOI: 10.1097/hp.0000000000001742] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/05/2023]
Abstract
OBJECTIVE Through the integration of experimental data and literature, this study examines whether complete elimination of contact shielding during CT examination is warranted, with a particular focus on potential impacts to children's thyroid and pregnant women, as well as limitations associated with contact shielding. Methods: The thermoluminescent dosimeter (TLD) tablets were inserted into the phantom's five organs and tissues. Select fixed exposure, automatic exposure control (AEC), and use contact shielding combined into four experimental modes, with scanning of the phantom's four parts. Obtain the absorbed dose measurements within or outside the FOV. Statistical analysis was conducted using SPSS software. Results: (1) The AEC significantly reduces dose within and outside the FOV, with a dose reduction of 40%-60%. (2) The application of contact shielding outside the FOV significantly reduced the dose adjoin the FOV. (3) Both the use of AEC mode and contact shielding can effectively minimize the dose, with a reduction of 50-80%. (4) The shielding within the FOV may introduce image artifacts or interfere with AEC, the implementation of contact shielding outside FOV provides little reduction in radiation exposure risk through previous literature. (5) Contact shielding exhibits certain drawbacks in all aspects. Conclusion: The utilization of AEC mode in clinical CT should be widely adopted to minimize patient radiation exposure. In general, contact shielding both inside and outside the FOV should be avoided during exposure. However for children under 12 years old with thyroid gland examination, contact shielding could maximally reduce external radiation and may be appropriate. Pregnant women require careful evaluation when considering the use of contact shielding. Contact shielding should not be entirely abandoned.
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Affiliation(s)
- Jiwei Chen
- Department of Medical Engineering, Kunshan Hospital of Traditional Chinese Medicine, Kunshan, Jiangsu 215300, P.R. China
| | - Jianchun Tu
- Department of Radiology, Kunshan Hospital of Traditional Chinese Medicine, Kunshan, Jiangsu 215300, P.R. China
| | - Shengyan Huang
- Department of Nursing, Kunshan Hospital of Traditional Chinese Medicine, Kunshan, Jiangsu 215300, P.R. China
| | - Zhenhua Zhu
- Department of Medical Engineering, Kunshan Hospital of Traditional Chinese Medicine, Kunshan, Jiangsu 215300, P.R. China
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Di Rosso J, Krasser A, Tschauner S, Guss H, Sorantin E. Bismuth Shielding in Head Computed Tomography-Still Necessary? J Clin Med 2023; 13:25. [PMID: 38202032 PMCID: PMC10779489 DOI: 10.3390/jcm13010025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2023] [Revised: 12/11/2023] [Accepted: 12/14/2023] [Indexed: 01/12/2024] Open
Abstract
Introduction: Cranial CT scans are associated with radiation exposure to the eye lens, which is a particularly radiosensitive organ. Children are more vulnerable to radiation than adults. Therefore, it is essential to use the available dose reduction techniques to minimize radiation exposure. According to the European Consensus on patient contact shielding by the IRCP from 2021, shielding is not recommended in most body areas anymore. This study aims to evaluate whether bismuth shielding as well as its combination with other dose-saving technologies could still be useful. Methods: Cranial CT scans of a pediatric anthropomorphic phantom were performed on two up-to-date MDCT scanners. Eye lens dose measurements were performed using thermoluminescent dosimeters. Furthermore, the impact of BS and of the additional placement of standoff foam between the patient and BS on image quality was also assessed. Results: Bismuth shielding showed a significant lens dose reduction in both CT scanners (GE: 41.50 ± 4.04%, p < 0.001; Siemens: 29.75 ± 6.55%, p = 0.00). When combined with AEC, the dose was lowered even more (GE: 60.75 ± 3.30%, p < 0.001; Siemens: 41.25 ± 8.02%, p = 0.00). The highest eye dose reduction was achieved using BS + AEC + OBTCM (GE: 71.25 ± 2.98%, p < 0.001; Siemens: 58.75 ± 5.85%, p < 0.001). BS caused increased image noise in the orbital region, which could be mitigated by foam placement. Eye shielding had no effect on the image noise in the cranium. Conclusions: The use of BS in cranial CT can lead to a significant dose reduction, which can be further enhanced by its combination with other modern dose reduction methods. BS causes increase in image noise in the orbital region but not in the cranium. The additional use of standoff foam reduces image noise in the orbital region.
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Affiliation(s)
- Jana Di Rosso
- Division of Paediatric Radiology, Department of Radiology, Medical University of Graz, 8036 Graz, Austria (E.S.)
| | - Andreas Krasser
- Competence Centre for Medical Physics and Radiation Protection, University Hospital Graz, 8036 Graz, Austria
| | - Sebastian Tschauner
- Division of Paediatric Radiology, Department of Radiology, Medical University of Graz, 8036 Graz, Austria (E.S.)
| | - Helmuth Guss
- Competence Centre for Medical Physics and Radiation Protection, University Hospital Graz, 8036 Graz, Austria
| | - Erich Sorantin
- Division of Paediatric Radiology, Department of Radiology, Medical University of Graz, 8036 Graz, Austria (E.S.)
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Keshtkar M, Blouri B, Mahmoudabadi A, Alami A. EYE RADIATION DOSE SAVING IN HEAD CT EXAMINATIONS USING COPPER-BISMUTH RADIATION SHIELD. RADIATION PROTECTION DOSIMETRY 2023; 199:146-151. [PMID: 36484690 DOI: 10.1093/rpd/ncac249] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2022] [Revised: 10/22/2022] [Accepted: 11/08/2022] [Indexed: 06/17/2023]
Abstract
The aim of the present study is to fabricate a new shield with an optimal combination of copper and bismuth to protect the eyes in the head computed tomography (CT) examinations without compromising image quality. Radiation shields with different compositions were constructed. Computed Tomography Dose Index phantom was used to evaluate the effectiveness of shields in dose reduction and their impact on image quality quantitatively. The shield that caused the least noise in the phantom study was selected for human study. The 10%Bi-90%Cu shield had the least effect on increasing the image noise, and also no remarkable artifact was seen in the CT image of the phantom. The patient study showed that only in 25% of the study group the artifact was observed so that it did not distort the interpretation of the image. It can be concluded that the 10%Bi-90%Cu shield is flexible and durable and would be safely used in the clinic to reduce the eye radiation dose in head CT imaging without compromising image quality.
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Affiliation(s)
- Mohammad Keshtkar
- Medical Physics and Radiology Department, Faculty of Medicine, Infectious Diseases Research Center, Gonabad University of Medical Sciences, Sento road, Gonabad, Iran
| | - Basir Blouri
- Student of General Medicine, Faculty of Medicine, Gonabad University of Medical Sciences, Sento road, Gonabad, Iran
| | - Alireza Mahmoudabadi
- Medical Physics and Radiology Department, Faculty of Medicine, Infectious Diseases Research Center, Gonabad University of Medical Sciences, Sento road, Gonabad, Iran
| | - Ali Alami
- Department of Epidemiology and Biostatistics, School of Public Health; Social Determinants of Health Research Center, Gonabad University of Medical Sciences, Sento road, Gonabad, Iran
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Gillespie CD, Yates A, Murphy MC, Hughes M, Ewins K, NíAinle F, Bolster F, Rowan M, Foley S, MacMahon PJ. Breast Shielding Combined With an Optimized Computed Tomography Pulmonary Angiography Pregnancy Protocol: A Special Use-Case for Shielding? J Thorac Imaging 2023; 38:36-43. [PMID: 36162076 DOI: 10.1097/rti.0000000000000677] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
OBJECTIVES To determine the impact of breast shields on breast dose and image quality when combined with a low-dose computed tomography pulmonary angiography (CTPA) protocol for pregnancy. METHODS A low-dose CTPA protocol, with and without breast shields, was evaluated by anthropomorphic phantom and 20 prospectively recruited pregnant participants from January to October 2019. Thermoluminescent dosimeters measured surface and absorbed breast dose in the phantom and surface breast dose in participants. The Monte-Carlo method estimated the absorbed breast dose in participants. Image quality was assessed quantitatively by regions of interest analysis and subjectively by the Likert scale. Doses and image quality for CTPA alone were compared with CTPA with breast shields. RESULTS Mean surface and absorbed breast dose for CTPA alone were 1.3±0.4 and 2.8±1.5 mGy in participants, and 1.5±0.7 and 1.6±0.6 mGy in the phantom. Shielding reduced surface breast dose to 0.5±0.3 and 0.7±0.2 mGy in the phantom (66%) and study participants (48%), respectively. Absorbed breast dose reduced to 0.9±0.5 mGy (46%) in the phantom.Noise increased with breast shields at lower kV settings (80 to 100 kV) in the phantom; however, in study participants there was no significant difference between shield and no-shield groups for main pulmonary artery noise (no-shield: 34±9.8, shield: 36.3±7.2, P =0.56), SNR (no-shield: 11.2±3.7, shield: 10.8±2.6, P =0.74) or contrast-to-noise ratio (no-shield: 10.0±3.3, shield: 9.3±2.4, P =0.6). Median subjective image quality scores were comparable (no-shield: 4.0, interquartile range: 3.5 to 4.4, shield: 4.3, interquartile range: 4.0 to 4.5). CONCLUSION Combining low-dose CTPA with breast shields confers additional breast-dose savings without impacting image quality and yields breast doses approaching those of low-dose scintigraphy, suggesting breast shields play a role in protocol optimization for select groups.
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Affiliation(s)
| | | | | | | | - Karl Ewins
- Haematology, Mater Misericordiae University Hospital
| | | | - Ferdia Bolster
- Departments of Radiology
- School of Medicine, University College Dublin
| | - Michael Rowan
- Department of Medical Physics, St James Hospital, Dublin, Ireland
| | - Shane Foley
- Radiography & Diagnostic Imaging, School of Medicine, University College Dublin
| | - Peter J MacMahon
- Departments of Radiology
- School of Medicine, University College Dublin
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OUP accepted manuscript. Eur Heart J Cardiovasc Imaging 2022; 23:e279-e289. [DOI: 10.1093/ehjci/jeac048] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/07/2022] [Accepted: 03/02/2022] [Indexed: 11/14/2022] Open
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Ko CH, Lee SP, Hsieh YC, Lee YH, Yao MMS, Chan WP. Bismuth breast-shield use in chest computed tomography for efficient dose reduction and sufficient image quality. Medicine (Baltimore) 2021; 100:e26277. [PMID: 34160391 PMCID: PMC8238342 DOI: 10.1097/md.0000000000026277] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Accepted: 05/22/2021] [Indexed: 01/04/2023] Open
Abstract
BACKGROUND Radiosensitivity in the breasts increases the risk of carcinogenesis from exposure to the ionizing radiation of computed tomography (CT) administered in the course of medical attention. Bismuth shielding techniques have been used to reduce radiation, but image noise increased, degrading image quality. PURPOSE The aim of this study was to investigate how the use of iterative reconstruction (IR) combined with bismuth shielding influences image quality. MATERIALS AND METHODS Women aged at least 20 years with body mass indexes <28 were recruited and randomly assigned to 1 of 3 CT scanning protocols without shielding, with a bismuth breast shield before the scout view, or with a bismuth breast shield after the scout view. All obtained images were reconstructed using an IR algorithm. To evaluate radiation dose, 2 Gafchromic films were placed over the clothes, 1 near each nipple. RESULTS Average dose reduction was significant (27.99%, P < .05) when bismuth shielding was applied after the scout view. Using the contrast-to-noise ratio, the image quality was found to be superior when the IR algorithm was applied. Using quantitative evaluations by 2 radiologists applying a 4-point Likert scale, significant differences in image quality were not found among the 3 protocols. CONCLUSION Bismuth breast shields, particularly when used after acquiring scout images, are effective at reducing radiation dose without undermining the diagnostic value of the images when the IR technique is applied.
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Affiliation(s)
- Chih-Hsiang Ko
- Department of Radiology, Wan Fang Hospital, Taipei Medical University
- Department of Radiology, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan, Republic of China
| | - Shiou-Ping Lee
- Department of Radiology, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan, Republic of China
| | - Yi-Chien Hsieh
- Department of Radiology, Wan Fang Hospital, Taipei Medical University
- Department of Radiology, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan, Republic of China
| | - Yuan-Hao Lee
- Department of Radiology, Wan Fang Hospital, Taipei Medical University
| | - Melissa Min-Szu Yao
- Department of Radiology, Wan Fang Hospital, Taipei Medical University
- Department of Radiology, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan, Republic of China
| | - Wing P. Chan
- Department of Radiology, Wan Fang Hospital, Taipei Medical University
- Department of Radiology, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan, Republic of China
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Guidance for computed tomography (CT) imaging of the lungs for patients with cystic fibrosis (CF) in research studies. J Cyst Fibros 2020; 19:176-183. [DOI: 10.1016/j.jcf.2019.09.001] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2018] [Revised: 08/21/2019] [Accepted: 09/01/2019] [Indexed: 12/11/2022]
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El Merhi F, Bou-Fakhredin R, El Ashkar B, Ghieh D, Ghosn Y, Saade C. State of the art of coronary computed tomography angiography. Radiography (Lond) 2020; 26:174-182. [PMID: 32052781 DOI: 10.1016/j.radi.2019.10.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2019] [Revised: 09/21/2019] [Accepted: 10/02/2019] [Indexed: 01/07/2023]
Abstract
OBJECTIVES The aim of this paper is to evaluate contrast media (CM) bolus geometry and opacification patterns in the coronary arteries with particular focus on patient, scanner and safety considerations during coronary computed tomography angiography (CCTA). KEY FINDINGS The rapid evolution of computed tomography (CT) technology has seen this imaging modality challenge conventional coronary angiography in the evaluation of coronary artery disease. Increases in spatial and temporal resolutions have enabled CCTA to become the modality of choice when evaluating the coronary vascular tree as an alternative in the diagnostic algorithm for acute chest pain. However, these new technologic improvements in scanner technology have imposed new challenges for the optimisation of CM delivery and image acquisition strategies. CONCLUSION Understanding basic CM-imaging principles is essential for designing optimal injection protocols according to each specific clinical scenario, independently of scanner technology. IMPLICATIONS FOR PRACTICE With rapid advances in CT scanner technology including faster scan acquisitions, the risk of poor opacification of coronary vasculature increases significantly. Therefore, awareness of CM delivery protocols is paramount to consistently provide optimal image quality at a low radiation dose.
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Affiliation(s)
- F El Merhi
- Diagnostic Radiology Department, American University of Beirut Medical Center, P.O. Box: 11-0236 Riad El-Solh, Beirut, 1107 2020, Lebanon.
| | - R Bou-Fakhredin
- American University of Beirut, P.O. Box: 11-0236 Riad El-Solh, Beirut, 1107 2020, Lebanon.
| | - B El Ashkar
- Diagnostic Radiology Department, American University of Beirut Medical Center, P.O. Box: 11-0236 Riad El-Solh, Beirut, 1107 2020, Lebanon.
| | - D Ghieh
- Diagnostic Radiology Department, American University of Beirut Medical Center, P.O. Box: 11-0236 Riad El-Solh, Beirut, 1107 2020, Lebanon.
| | - Y Ghosn
- Diagnostic Radiology Department, American University of Beirut Medical Center, P.O. Box: 11-0236 Riad El-Solh, Beirut, 1107 2020, Lebanon.
| | - C Saade
- Diagnostic Radiology Department, American University of Beirut Medical Center, P.O. Box: 11-0236 Riad El-Solh, Beirut, 1107 2020, Lebanon.
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Sutanto H, Irdawati Y, Anam C, Fujibuchi T, Dougherty G, Hidayanto E, Arifin Z, Soedarsono JW, Bahrudin. An artifact-free thyroid shield in CT examination: a phantom study. Biomed Phys Eng Express 2020; 6:015029. [DOI: 10.1088/2057-1976/ab6ed1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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Kosaka H, Monzen H, Amano M, Tamura M, Hattori S, Kono Y, Nishimura Y. Radiation dose reduction to the eye lens in head CT using tungsten functional paper and organ-based tube current modulation. Eur J Radiol 2020; 124:108814. [PMID: 31945674 DOI: 10.1016/j.ejrad.2020.108814] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2019] [Revised: 11/18/2019] [Accepted: 12/28/2019] [Indexed: 10/25/2022]
Abstract
PURPOSE We investigated whether a tungsten functional paper (TFP) shield and/or organ-based tube current modulation (TCM) can reduce the dose to the eye lens. MATERIALS AND METHODS All scans were performed using our routine head examination protocol (spiral acquisition, 120 kVp, noise Index 3.5) with an anthropomorphic head phantom. The dose reduction rate was measured by the following methods with a scintillation fiber optic dosimeter: (a) without any dose reduction techniques (Original scan), (b) TFP shield, (c) TCM, and (d) TFP shield plus TCM. Image noise and CT number were obtained and compared between the three groups. In addition, image noise in method (d) was measured with varying distances between the TFP shield and eye lens. RESULTS The reduction rates using TFP shield, TCM, and TFP shield plus TCM compared with those for the Original scan were 17.8 %, 13.6 %, and 27.7 %, respectively. Image noise (mean ± standard deviation) in the anterior region for the Original scan, TFP shield, TCM, and TFP shield plus TCM were 4.1 ± 0.2, 4.6 ± 0.2, 4.4 ± 0.3, and 5.0 ± 0.2, while the CT numbers were 19.3 ± 0.8, 23.8 ± 0.8, 19.6 ± 0.8, and 24.1 ± 0.8, respectively. Increasing the distance between the TFP and the eye significantly decreased the CT number when using TFP shield plus TCM (p < .05). CONCLUSION TFP shield plus TCM reduced the dose to the eye lens in head CT while maintaining image quality with an air gap between the TFP and skin surface.
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Affiliation(s)
- Hiroyuki Kosaka
- Department of Medical Physics, Graduate School of Medical Sciences, Kindai University, 377-2 Ohno-higashi, Osaka-Sayama, Osaka, 589-8511, Japan.
| | - Hajime Monzen
- Department of Medical Physics, Graduate School of Medical Sciences, Kindai University, 377-2 Ohno-higashi, Osaka-Sayama, Osaka, 589-8511, Japan.
| | - Morikazu Amano
- Department of Radiology, Fujieda Municipal General Hospital, 4-1-11 Surugadai, Fujieda, Shizuoka, 426-8677, Japan.
| | - Mikoto Tamura
- Department of Medical Physics, Graduate School of Medical Sciences, Kindai University, 377-2 Ohno-higashi, Osaka-Sayama, Osaka, 589-8511, Japan.
| | - Shota Hattori
- Department of Medical Physics, Graduate School of Medical Sciences, Kindai University, 377-2 Ohno-higashi, Osaka-Sayama, Osaka, 589-8511, Japan.
| | - Yuki Kono
- Department of Central Radiology, Kindai University Hospital, 377-2 Ohno-higashi, Osaka-Sayama, Osaka, 589-8511, Japan.
| | - Yasumasa Nishimura
- Faculty of Medicine, Department of Radiation Oncology, Kindai University, 377-2, Ohno-Higashi, Osaka-Sayama, Osaka, 589-8511, Japan.
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Liao YL, Lai NK, Tyan YS, Tsai HY. Bismuth shield affecting CT image quality and radiation dose in adjacent and distant zones relative to shielding surface: A phantom study. Biomed J 2019; 42:343-351. [PMID: 31783995 PMCID: PMC6888723 DOI: 10.1016/j.bj.2019.04.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2017] [Revised: 03/08/2019] [Accepted: 04/12/2019] [Indexed: 02/05/2023] Open
Abstract
BACKGROUND To quantify image quality and radiation doses in regions adjacent to and distant from bismuth shields in computed tomography (CT). METHODS An American College of Radiology accreditation phantom with four solid rods embedded in a water-like background was scanned to verify CT number (CTN) accuracy when using bismuth shields. CTNs, image noise, and contrast-to-noise ratios (CNRs) were determined in the phantom at 80-140 kVp. Image quality was investigated on image portions in the zones adjacent (A zone) to and distant (D zone) from a bismuth shield. Surface radiation doses were measured using thermoluminescent dosimeters. Streak artefacts were graded on a 3-point-scale. RESULTS Changes in CTN caused by a bismuth shield resulted in changes in X-ray spectra. CTN changes were more apparent in the A zone than in the D zone, particularly for a low tube voltage. The degrees of CTN changes and image noise were proportional to the thickness of the bismuth shields. A 1-ply bismuth shield reduced surface radiation doses by 7.2%-15.5%. The overall CNRs were slightly degraded, and streak artefacts were acceptable. CONCLUSIONS Using a bismuth shield could result in significant CTN changes and perceivable artefacts, particularly for a superficial organ close to the shield, and is not recommended for quantification CT examinations or follow-up CT examinations.
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Affiliation(s)
- Ying-Lan Liao
- Health Physics Division, Institute of Nuclear Energy Research, Taoyuan, Taiwan
| | - Nan-Ku Lai
- Department of Medical Imaging, Chung Shan Medical University Hospital, Taichung, Taiwan; School of Medical Imaging and Radiological Sciences, Chung Shan Medical University, Taichung, Taiwan
| | - Yeu-Sheng Tyan
- Department of Medical Imaging, Chung Shan Medical University Hospital, Taichung, Taiwan; School of Medical Imaging and Radiological Sciences, Chung Shan Medical University, Taichung, Taiwan
| | - Hui-Yu Tsai
- Institute of Nuclear Engineering and Science, National Tsing Hua University, Hsinchu, Taiwan.
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Poon R, Badawy MK. Radiation dose and risk to the lens of the eye during CT examinations of the brain. J Med Imaging Radiat Oncol 2019; 63:786-794. [DOI: 10.1111/1754-9485.12950] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2019] [Revised: 08/11/2019] [Accepted: 08/19/2019] [Indexed: 10/26/2022]
Affiliation(s)
- Rebekah Poon
- Department of Medical Imaging and Radiation Sciences School of Primary and Allied Health Care Faculty of Medicine, Nursing and Health Sciences Monash University Clayton Victoria Australia
| | - Mohamed K Badawy
- Department of Medical Imaging and Radiation Sciences School of Primary and Allied Health Care Faculty of Medicine, Nursing and Health Sciences Monash University Clayton Victoria Australia
- Monash Imaging Monash Health Clayton Victoria Australia
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Hara T, Niwa S, Urikura A, Matsubara K, Hoshino T, Nishimaru E, Taniguchi T. Assessment of longitudinal beam property and contrast uniformity for 256- and 320-row area detector computed tomography scanners in the 160-mm nonhelical volume-acquisition mode. J Appl Clin Med Phys 2019; 20:164-170. [PMID: 31254457 PMCID: PMC6698757 DOI: 10.1002/acm2.12670] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2019] [Revised: 03/21/2019] [Accepted: 06/04/2019] [Indexed: 11/20/2022] Open
Abstract
Background Because the x‐ray property of patient longitudinal axis in area detector computed tomography (ADCT) depends on a heel effect, radiation dose and beam quality are not uniform along the long axis of the patient. Objective This study aimed to measure the longitudinal beam properties and contrast uniformity of ADCT scanners in the 160‐mm nonhelical volume‐acquisition (NVA) mode and provide useful datasets for the radiation dose reduction in ADCT examinations. Materials and Methods Two different types of ADCT scanners were used in this study. To assess the heel effect in 256‐ and 320‐row ADCT scanners, we measured dose profile, half‐value layer, and iodine contrast uniformity along longitudinal beam direction. Results The maximum effective energy difference within a 160‐mm x‐ray beam is approximately 4 keV. Maximum radiation dose on the anode side of the x‐ray tube showed approximately 40%–45% reduction compared with that on the isocenter position; the heel effect properties longitudinally differed throughout the x‐ray beam, and the decrease in the radiation dose in 256‐ and 320‐row ADCT scanners was observed on the patient table side and gantry side respectively. The CT numbers of iodinated solutions for 256‐row ADCT scanner were independent of the heel effect; nevertheless, the CT numbers of 320‐row ADCT scanner tended to increase on the patient table (cathode) side. Conclusion This study reveals that the radiation dose on the anode side of the x‐ray tube shows approximately 40%–45% reduction compared with that on the isocenter position, and the heel effect properties for 256‐ and 320‐row ADCT scanners longitudinally differ throughout the x‐ray beam. The x‐ray tube for individual ADCT scanners is mounted in an opposite direction along the long axis of the patient.
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Affiliation(s)
- Takanori Hara
- Department of Medical Technology, Nakatsugawa Municipal General Hospital, Nakatsugawa, Gifu, Japan
| | - Shinji Niwa
- Department of Medical Technology, Nakatsugawa Municipal General Hospital, Nakatsugawa, Gifu, Japan
| | - Atsushi Urikura
- Department of Diagnostic Radiology, Shizuoka Cancer Centre, Nagaizumi, Shizuoka, Japan
| | - Kosuke Matsubara
- Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, Kanazawa, Ishikawa, Japan
| | - Takashi Hoshino
- Department of Radiological Technology, Osaka College of High Technology, Osaka-shi, Osaka, Japan
| | - Eiji Nishimaru
- Department of Radiology, Hiroshima University Hospital, Minami-ku, Hiroshima, Japan
| | - Takuya Taniguchi
- Department of Radiology, Asahi University Hospital, Hashimoto-cho, Gifu, Japan
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The OPTICA study (Optimised Computed Tomography Pulmonary Angiography in Pregnancy Quality and Safety study): Rationale and design of a prospective trial assessing the quality and safety of an optimised CTPA protocol in pregnancy. Thromb Res 2019; 177:172-179. [DOI: 10.1016/j.thromres.2019.03.007] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2019] [Revised: 03/02/2019] [Accepted: 03/12/2019] [Indexed: 02/05/2023]
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Schaafs LA, Pfeil J, Köhlitz T, Hamm B, Niehues SM. LOW-DOSE COMPUTED TOMOGRAPHY OF THE PARANASAL SINUSES: PERFORMANCE OF TWO DIFFERENT ITERATIVE RECONSTRUCTION ALGORITHMS. RADIATION PROTECTION DOSIMETRY 2019; 183:386-392. [PMID: 30165539 DOI: 10.1093/rpd/ncy153] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2018] [Revised: 06/29/2018] [Accepted: 08/02/2018] [Indexed: 06/08/2023]
Abstract
To evaluate the performance of two iterative reconstruction algorithms in low-dose paranasal sinus computed tomography (CT). Sinus CT scans were reconstructed using Adaptive Iterative Dose Reduction 3D (AIDR 3D, n = 36 patients) or Sinogram Affirmed Iterative Reconstruction (SAFIRE, n = 32 patients). Reconstructed images were evaluated regarding subjective image quality, depiction of anatomic landmarks and noise (HU). Dose-length product (DLP), calculated effective dose (ED) and CT dose index (CTDIvol) were documented for each scan. Images were not significantly different in subjective image quality (p = 0.09) and conspicuity of anatomic landmarks (p = 0.28). Noise was significantly lower in images reconstructed with AIDR 3D (p = 0.012). DLP, ED and CTDIvol were significantly lower in the SAFIRE datasets (each p < 0.001). The results indicate that iterative reconstruction, independent of the manufacturer, enables for imaging the paranasal sinuses with an ED below 0.1 mSv while ensuring diagnostic image quality.
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Affiliation(s)
- Lars-Arne Schaafs
- Department of Radiology, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Campus Benjamin Franklin, Hindenburgdamm 30, Berlin, Germany
| | - Julian Pfeil
- Department of Radiology, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Campus Benjamin Franklin, Hindenburgdamm 30, Berlin, Germany
| | - Torsten Köhlitz
- Department of Radiology, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Campus Benjamin Franklin, Hindenburgdamm 30, Berlin, Germany
| | - Bernd Hamm
- Department of Radiology, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Campus Benjamin Franklin, Hindenburgdamm 30, Berlin, Germany
| | - Stefan Markus Niehues
- Department of Radiology, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Campus Benjamin Franklin, Hindenburgdamm 30, Berlin, Germany
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High-pitch, 120 kVp/30 mAs, low-dose dual-source chest CT with iterative reconstruction: Prospective evaluation of radiation dose reduction and image quality compared with those of standard-pitch low-dose chest CT in healthy adult volunteers. PLoS One 2019; 14:e0211097. [PMID: 30677082 PMCID: PMC6345490 DOI: 10.1371/journal.pone.0211097] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2017] [Accepted: 01/08/2019] [Indexed: 01/08/2023] Open
Abstract
PURPOSE Objective of this study was to evaluate the effectiveness of the iterative reconstruction of high-pitch dual-source chest CT (IR-HP-CT) scanned with low radiation exposure compared with low dose chest CT (LDCT). MATERIALS AND METHODS This study was approved by the institutional review board. Thirty healthy adult volunteers (mean age 44 years) were enrolled in this study. All volunteers underwent both IR-HP-CT and LDCT. IR-HP-CT was scanned with 120 kVp tube voltage, 30 mAs tube current and pitch 3.2 and reconstructed with sinogram affirmed iterative reconstruction. LDCT was scanned with 120 kVp tube voltage, 40 mAs tube current and pitch 0.8 and reconstructed with B50 filtered back projection. Image noise, and signal to noise ratio (SNR) of the infraspinatus muscle, subcutaneous fat and lung parenchyma were calculated. Cardiac motion artifact, overall image quality and artifacts was rated by two blinded readers using 4-point scale. The dose-length product (DLP) (mGy∙cm) were obtained from each CT dosimetry table. Scan length was calculated from the DLP results. The DLP parameter was a metric of radiation output, not of patient dose. Size-specific dose estimation (SSDE, mGy) was calculated using the sum of the anteroposterior and lateral dimensions and effective radiation dose (ED, mSv) were calculated using CT dosimetry index. RESULTS Approximately, mean 40% of SSDE (2.1 ± 0.2 mGy vs. 3.5 ± 0.3 mGy) and 34% of ED (1.0 ± 0.1 mSv vs. 1.5 ± 0.1 mSv) was reduced in IR-HP-CT compared to LDCT (P < 0.0001). Image noise was reduced in the IR-HP-CT (16.8 ± 2.8 vs. 19.8 ± 3.4, P = 0.0001). SNR of lung and aorta of IR-HP-CT showed better results compared with that of LDCT (22.2 ± 5.9 vs. 33.0 ± 7.8, 1.9 ± 0.4 vs 1.1 ± 0.3, P < 0.0001). The score of cardiac pulsation artifacts were significantly reduced on IR-HP-CT (3.8 ± 0.4, 95% confidence interval, 3.7‒4.0) compared with LDCT (1.6 ± 0.6, 95% confidence interval, 1.3‒1.8) (P < 0.0001). SNR of muscle and fat, beam hardening artifact and overall subjective image quality of the mediastinum, lung and chest wall were comparable on both scans (P ≥ 0.05). CONCLUSION IR-HP-CT with 120 kVp and 30 mAs tube setting in addition to an iterative reconstruction reduced cardiac motion artifact and radiation exposure while representing similar image quality compared with LDCT.
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Jang H, Hur J, Choi BW, Im DJ, Hong YJ, Kim YJ, Lee HJ. Effects of bismuth breast shielding on iodine quantification in dual-energy computed tomography: an experimental phantom study. Acta Radiol 2018; 59:1475-1481. [PMID: 29635925 DOI: 10.1177/0284185118768098] [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] [Indexed: 11/17/2022]
Abstract
BACKGROUND Although the bismuth breast shield can reduce radiation exposure to the breast during dual-energy computed tomography (DECT), it can potentially affect material quantification on DECT due to artifacts. PURPOSE To evaluate the effects of bismuth breast shielding on iodine quantification and radiation exposure in DECT. MATERIAL AND METHODS Small balloons were made with 0.2%, 0.6% and 1.0% blended iodinated contrast (370 mg/mL of iodine) with water. The balloons were located at both anterior and posterior lungs in an adult anthropomorphic chest phantom. DECT was performed with and without breast shielding. Afterwards, iodine concentration values were measured for each balloon on the iodine maps. Absorbed radiation doses in the breast were measured with the optically stimulated luminescence dosimeter. RESULTS After shielding, we obtained significantly decreased iodine quantification for all three concentrations with 0.78 ± 0.13 to 0.46 ± 0.13 mg/mL, 2.31 ± 0.17 to 1.68 ± 0.19 mg/mL, and 3.82 ± 0.10 to 2.84 ± 0.20 mg/mL at the anterior location, and 0.72 ± 0.11 to 0.48 ± 0.09 mg/mL, 2.24 ± 0.13 to 1.87 ± 0.21 mg/mL, and 3.75 ± 0.16 to 3.15 ± 0.14 mg/mL at the posterior location for the 0.2%, 0.6%, and 1.0% balloons, respectively ( P = 0.001 for all). After shielding, absorbed radiation doses to the breast significantly decreased by 14.8% (4.32 ± 0.33 to 3.68 ± 0.30 mGy; P = 0.005). CONCLUSION Although using the bismuth breast shield may decrease radiation exposure to the breast on DECT, it may also significantly affect iodine quantification.
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Affiliation(s)
- Hyunsik Jang
- Department of Radiology, Severance Hospital, Research Institute of Radiological Science, Yonsei University, College of Medicine, Seoul, Republic of Korea
| | - Jin Hur
- Department of Radiology, Severance Hospital, Research Institute of Radiological Science, Yonsei University, College of Medicine, Seoul, Republic of Korea
| | - Byoung Wook Choi
- Department of Radiology, Severance Hospital, Research Institute of Radiological Science, Yonsei University, College of Medicine, Seoul, Republic of Korea
| | - Dong Jin Im
- Department of Radiology, Severance Hospital, Research Institute of Radiological Science, Yonsei University, College of Medicine, Seoul, Republic of Korea
| | - Yoo Jin Hong
- Department of Radiology, Severance Hospital, Research Institute of Radiological Science, Yonsei University, College of Medicine, Seoul, Republic of Korea
| | - Young Jin Kim
- Department of Radiology, Severance Hospital, Research Institute of Radiological Science, Yonsei University, College of Medicine, Seoul, Republic of Korea
| | - Hye-Jeong Lee
- Department of Radiology, Severance Hospital, Research Institute of Radiological Science, Yonsei University, College of Medicine, Seoul, Republic of Korea
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Iterative Metallic Artifact Reduction for In-Plane Gonadal Shielding During Computed Tomographic Venography of Young Males. J Comput Assist Tomogr 2017; 42:269-276. [PMID: 28937486 DOI: 10.1097/rct.0000000000000670] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
OBJECTIVE The purpose of this study was to evaluate a gonadal shield (GS) and iterative metallic artifact reduction (IMAR) during computed tomography scans, regarding the image quality and radiation dose. METHODS A phantom was imaged with and without a GS. Prospectively enrolled, young male patients underwent lower extremity computed tomography venography (precontrast imaging without the GS and postcontrast imaging with the GS). Radiation dose was measured each time, and the GS-applied images were reconstructed by weighted filtered back projection and IMAR. RESULTS In the phantom study, image artifacts were significantly reduced by using IMAR (P = 0.031), whereas the GS reduced the radiation dose by 61.3%. In the clinical study (n = 29), IMAR mitigated artifacts from the GS, thus 96.6% of the IMAR image sets were clinically usable. Gonadal shielding reduced the radiation dose to the testes by 69.0%. CONCLUSIONS The GS in conjunction with IMAR significantly reduced the radiation dose to the testes while maintaining the image quality.
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Radiation dose-reduction strategies in thoracic CT. Clin Radiol 2017; 72:407-420. [DOI: 10.1016/j.crad.2016.11.021] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2016] [Revised: 10/31/2016] [Accepted: 11/14/2016] [Indexed: 01/08/2023]
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Inkoom S, Papadakis AE, Raissaki M, Perisinakis K, Schandorf C, Fletcher JJ, Damilakis J. PAEDIATRIC NECK MULTIDETECTOR COMPUTED TOMOGRAPHY: THE EFFECT OF BISMUTH SHIELDING ON THYROID DOSE AND IMAGE QUALITY. RADIATION PROTECTION DOSIMETRY 2017; 173:361-373. [PMID: 26891787 DOI: 10.1093/rpd/ncw007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2015] [Accepted: 01/01/2016] [Indexed: 06/05/2023]
Abstract
This study investigated the effect of bismuth shielding on thyroid dose and image quality in paediatric neck multidetector computed tomography (MDCT) performed with fixed tube current (FTC) and automatic exposure control (AEC). Four paediatric anthropomorphic phantoms representing the equivalent newborn, 1-, 5- and 10-y-old child were subjected to neck CT using a 16-slice MDCT system. Each scan was performed without and with single- and double-layered bismuth shield placed on the skin surface above the thyroid. Scans were repeated with cotton spacers of 1, 2 and 3 cm thick placed between the skin and shield, to study the effect of skin-to-shielding distance on image noise. Thyroid dose was measured with thermoluminescent dosemeters. The location of the thyroid within the phantom slices was determined by anthropometric data from patients' CT examinations whose body stature closely matched the phantoms. Effective dose (E) was estimated using the dose-length product (DLP) method. Image quality of resulted CT images was assessed through the image noise. Activation of AEC was found to decrease the thyroid dose by 46 % to the 10-y-old phantom subjected to neck CT. When FTC technique is used, single- and double-layered bismuth shielding was found to reduce the thyroid dose to the same phantom by 35 and 47 %, respectively. The corresponding reductions in AEC-activated scans were 60 and 66 %, respectively. Elevation of shields by 1-, 2- and 3-cm cotton spacers decreased the image noise by 69, 87 and 92 %, respectively, for single-layered FTC, without considerably affecting the thyroid dose. AEC was more effective in thyroid dose reduction than in-plane bismuth shields. Application of cotton spacers had no significant impact on thyroid dose, but significantly decreased the image noise.
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Affiliation(s)
- Stephen Inkoom
- Department of Medical Physics, Faculty of Medicine, University of Crete, P.O. Box 2208, 71003 Iraklion, Crete, Greece
| | - Antonios E Papadakis
- Department of Medical Physics, University Hospital of Heraklion, P. O. Box 1352, Heraklion 71110, Crete, Greece
| | - Maria Raissaki
- Department of Radiology, Faculty of Medicine, University of Crete, Iraklion 71003, Crete, Greece
| | - Kostas Perisinakis
- Department of Medical Physics, University Hospital of Heraklion, P. O. Box 1352, Heraklion 71110, Crete, Greece
| | - Cyril Schandorf
- School of Nuclear and Allied Sciences, University of Ghana, Atomic Campus, P. O. Box AE 1, Atomic, Accra, Ghana
| | - John J Fletcher
- Department of Applied Physics, Faculty of Applied Sciences, University for Development Studies, Navrongo Campus, Navrongo, Ghana
| | - John Damilakis
- Department of Medical Physics, University Hospital of Heraklion, P. O. Box 1352, Heraklion 71110, Crete, Greece
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New organ-based tube current modulation method to reduce the radiation dose during computed tomography of the head: evaluation of image quality and radiation dose to the eyes in the phantom study. Radiol Med 2017; 122:601-608. [DOI: 10.1007/s11547-017-0755-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2017] [Accepted: 03/15/2017] [Indexed: 10/19/2022]
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Cheezum MK, Redon CE, Burrell AS, Kaviratne AS, Bindeman J, Maeda D, Balmakhtar H, Pezel A, Wisniewski P, Delacruz P, Nguyen B, Bonner WM, Villines TC. Effects of Breast Shielding during Heart Imaging on DNA Double-Strand-Break Levels: A Prospective Randomized Controlled Trial. Radiology 2016; 281:62-71. [PMID: 27082782 PMCID: PMC5047130 DOI: 10.1148/radiol.2016152301] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Purpose To examine the effect of breast shielding on blood lymphocyte deoxyribonucleic acid (DNA) double-strand-break levels resulting from in vivo radiation and ex vivo radiation at breast-tissue level, and the effect of breast shielding on image quality. Materials and Methods The study was approved by institutional review and commpliant with HIPAA guidelines. Adult women who underwent 64-section coronary computed tomographic (CT) angiography and who provided informed consent were prospectively randomized to the use (n = 50) or absence (n = 51) of bismuth breast shields. Peripheral blood samples were obtained before and 30 minutes after in vivo radiation during CT angiography to compare DNA double-strand-break levels by γ-H2AX immunofluorescence in blood lymphocytes. To estimate DNA double-strand-break induction at breast-tissue level, a blood sample was taped to the sternum for ex vivo radiation with or without shielding. Data were analyzed by linear regression and independent sample t tests. Results Breast shielding had no effect on DNA double-strand-break levels from ex vivo radiation of blood samples under shields at breast-tissue level (unadjusted regression: β = .08; P = .43 versus no shielding), or in vivo radiation of circulating lymphocytes (β = -.07; P = .50). Predictors of increased DNA double-strand-break levels included total radiation dose, increasing tube potential, and tube current (P < .05). With current radiation exposures (median, 3.4 mSv), breast shielding yielded a 33% increase in image noise and 19% decrease in the rate of excellent quality ratings. Conclusion Among women who underwent coronary CT angiography, breast shielding had no effect on DNA double-strand-break levels in blood lymphocytes exposed to in vivo radiation, or ex vivo radiation at breast-tissue level. At present relatively low radiation exposures, breast shielding contributed to an increase in image noise and a decline in image quality. The findings support efforts to minimize radiation by primarily optimizing CT settings. (©) RSNA, 2016 Clinical trial registration no. NCT02617888 Online supplemental material is available for this article.
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Affiliation(s)
- Michael K. Cheezum
- From the Department of Medicine (Cardiology Service) (M.K.C., A.S.K., J.B., T.C.V.) and Department of Radiology (B.N.), Walter Reed National Military Medical Center, 8901 Wisconsin Ave, Bethesda, MD 20889; Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, Bethesda, Md (C.E.R., A.S.B., D.M., H.B., W.M.B.); Institute of Biomedical Sciences, The George Washington University, Washington, DC (A.S.B.); George Mason University, Fairfax, Va (H.B.); Uniformed Services University of Health Sciences, Bethesda, Md (A.P., P.W.); and Department of Medicine, San Antonio Military Medical Center, San Antonio, Tex (P.D.)
| | - Christophe E. Redon
- From the Department of Medicine (Cardiology Service) (M.K.C., A.S.K., J.B., T.C.V.) and Department of Radiology (B.N.), Walter Reed National Military Medical Center, 8901 Wisconsin Ave, Bethesda, MD 20889; Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, Bethesda, Md (C.E.R., A.S.B., D.M., H.B., W.M.B.); Institute of Biomedical Sciences, The George Washington University, Washington, DC (A.S.B.); George Mason University, Fairfax, Va (H.B.); Uniformed Services University of Health Sciences, Bethesda, Md (A.P., P.W.); and Department of Medicine, San Antonio Military Medical Center, San Antonio, Tex (P.D.)
| | - Allison S. Burrell
- From the Department of Medicine (Cardiology Service) (M.K.C., A.S.K., J.B., T.C.V.) and Department of Radiology (B.N.), Walter Reed National Military Medical Center, 8901 Wisconsin Ave, Bethesda, MD 20889; Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, Bethesda, Md (C.E.R., A.S.B., D.M., H.B., W.M.B.); Institute of Biomedical Sciences, The George Washington University, Washington, DC (A.S.B.); George Mason University, Fairfax, Va (H.B.); Uniformed Services University of Health Sciences, Bethesda, Md (A.P., P.W.); and Department of Medicine, San Antonio Military Medical Center, San Antonio, Tex (P.D.)
| | - Anthony S. Kaviratne
- From the Department of Medicine (Cardiology Service) (M.K.C., A.S.K., J.B., T.C.V.) and Department of Radiology (B.N.), Walter Reed National Military Medical Center, 8901 Wisconsin Ave, Bethesda, MD 20889; Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, Bethesda, Md (C.E.R., A.S.B., D.M., H.B., W.M.B.); Institute of Biomedical Sciences, The George Washington University, Washington, DC (A.S.B.); George Mason University, Fairfax, Va (H.B.); Uniformed Services University of Health Sciences, Bethesda, Md (A.P., P.W.); and Department of Medicine, San Antonio Military Medical Center, San Antonio, Tex (P.D.)
| | - Jody Bindeman
- From the Department of Medicine (Cardiology Service) (M.K.C., A.S.K., J.B., T.C.V.) and Department of Radiology (B.N.), Walter Reed National Military Medical Center, 8901 Wisconsin Ave, Bethesda, MD 20889; Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, Bethesda, Md (C.E.R., A.S.B., D.M., H.B., W.M.B.); Institute of Biomedical Sciences, The George Washington University, Washington, DC (A.S.B.); George Mason University, Fairfax, Va (H.B.); Uniformed Services University of Health Sciences, Bethesda, Md (A.P., P.W.); and Department of Medicine, San Antonio Military Medical Center, San Antonio, Tex (P.D.)
| | - Daisuke Maeda
- From the Department of Medicine (Cardiology Service) (M.K.C., A.S.K., J.B., T.C.V.) and Department of Radiology (B.N.), Walter Reed National Military Medical Center, 8901 Wisconsin Ave, Bethesda, MD 20889; Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, Bethesda, Md (C.E.R., A.S.B., D.M., H.B., W.M.B.); Institute of Biomedical Sciences, The George Washington University, Washington, DC (A.S.B.); George Mason University, Fairfax, Va (H.B.); Uniformed Services University of Health Sciences, Bethesda, Md (A.P., P.W.); and Department of Medicine, San Antonio Military Medical Center, San Antonio, Tex (P.D.)
| | - Houria Balmakhtar
- From the Department of Medicine (Cardiology Service) (M.K.C., A.S.K., J.B., T.C.V.) and Department of Radiology (B.N.), Walter Reed National Military Medical Center, 8901 Wisconsin Ave, Bethesda, MD 20889; Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, Bethesda, Md (C.E.R., A.S.B., D.M., H.B., W.M.B.); Institute of Biomedical Sciences, The George Washington University, Washington, DC (A.S.B.); George Mason University, Fairfax, Va (H.B.); Uniformed Services University of Health Sciences, Bethesda, Md (A.P., P.W.); and Department of Medicine, San Antonio Military Medical Center, San Antonio, Tex (P.D.)
| | - Ashly Pezel
- From the Department of Medicine (Cardiology Service) (M.K.C., A.S.K., J.B., T.C.V.) and Department of Radiology (B.N.), Walter Reed National Military Medical Center, 8901 Wisconsin Ave, Bethesda, MD 20889; Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, Bethesda, Md (C.E.R., A.S.B., D.M., H.B., W.M.B.); Institute of Biomedical Sciences, The George Washington University, Washington, DC (A.S.B.); George Mason University, Fairfax, Va (H.B.); Uniformed Services University of Health Sciences, Bethesda, Md (A.P., P.W.); and Department of Medicine, San Antonio Military Medical Center, San Antonio, Tex (P.D.)
| | - Piotr Wisniewski
- From the Department of Medicine (Cardiology Service) (M.K.C., A.S.K., J.B., T.C.V.) and Department of Radiology (B.N.), Walter Reed National Military Medical Center, 8901 Wisconsin Ave, Bethesda, MD 20889; Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, Bethesda, Md (C.E.R., A.S.B., D.M., H.B., W.M.B.); Institute of Biomedical Sciences, The George Washington University, Washington, DC (A.S.B.); George Mason University, Fairfax, Va (H.B.); Uniformed Services University of Health Sciences, Bethesda, Md (A.P., P.W.); and Department of Medicine, San Antonio Military Medical Center, San Antonio, Tex (P.D.)
| | - Panfilo Delacruz
- From the Department of Medicine (Cardiology Service) (M.K.C., A.S.K., J.B., T.C.V.) and Department of Radiology (B.N.), Walter Reed National Military Medical Center, 8901 Wisconsin Ave, Bethesda, MD 20889; Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, Bethesda, Md (C.E.R., A.S.B., D.M., H.B., W.M.B.); Institute of Biomedical Sciences, The George Washington University, Washington, DC (A.S.B.); George Mason University, Fairfax, Va (H.B.); Uniformed Services University of Health Sciences, Bethesda, Md (A.P., P.W.); and Department of Medicine, San Antonio Military Medical Center, San Antonio, Tex (P.D.)
| | - Binh Nguyen
- From the Department of Medicine (Cardiology Service) (M.K.C., A.S.K., J.B., T.C.V.) and Department of Radiology (B.N.), Walter Reed National Military Medical Center, 8901 Wisconsin Ave, Bethesda, MD 20889; Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, Bethesda, Md (C.E.R., A.S.B., D.M., H.B., W.M.B.); Institute of Biomedical Sciences, The George Washington University, Washington, DC (A.S.B.); George Mason University, Fairfax, Va (H.B.); Uniformed Services University of Health Sciences, Bethesda, Md (A.P., P.W.); and Department of Medicine, San Antonio Military Medical Center, San Antonio, Tex (P.D.)
| | - William M. Bonner
- From the Department of Medicine (Cardiology Service) (M.K.C., A.S.K., J.B., T.C.V.) and Department of Radiology (B.N.), Walter Reed National Military Medical Center, 8901 Wisconsin Ave, Bethesda, MD 20889; Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, Bethesda, Md (C.E.R., A.S.B., D.M., H.B., W.M.B.); Institute of Biomedical Sciences, The George Washington University, Washington, DC (A.S.B.); George Mason University, Fairfax, Va (H.B.); Uniformed Services University of Health Sciences, Bethesda, Md (A.P., P.W.); and Department of Medicine, San Antonio Military Medical Center, San Antonio, Tex (P.D.)
| | - Todd C. Villines
- From the Department of Medicine (Cardiology Service) (M.K.C., A.S.K., J.B., T.C.V.) and Department of Radiology (B.N.), Walter Reed National Military Medical Center, 8901 Wisconsin Ave, Bethesda, MD 20889; Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, Bethesda, Md (C.E.R., A.S.B., D.M., H.B., W.M.B.); Institute of Biomedical Sciences, The George Washington University, Washington, DC (A.S.B.); George Mason University, Fairfax, Va (H.B.); Uniformed Services University of Health Sciences, Bethesda, Md (A.P., P.W.); and Department of Medicine, San Antonio Military Medical Center, San Antonio, Tex (P.D.)
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Evaluation of a Net Dose-Reducing Organ-Based Tube Current Modulation Technique: Comparison With Standard Dose and Bismuth-Shielded Acquisitions. AJR Am J Roentgenol 2016; 206:1233-40. [DOI: 10.2214/ajr.15.15778] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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A Monte Carlo simulation for the estimation of patient dose in rest and stress cardiac computed tomography with a 320-detector row CT scanner. Phys Med 2015; 31:1029-1034. [DOI: 10.1016/j.ejmp.2015.08.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/03/2015] [Revised: 07/17/2015] [Accepted: 08/22/2015] [Indexed: 11/20/2022] Open
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Monte Carlo simulation of the dose distribution of ICRP adult reference computational phantoms for acquisitions with a 320 detector-row cone-beam CT scanner. Phys Med 2015; 31:452-62. [DOI: 10.1016/j.ejmp.2015.04.007] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/01/2014] [Revised: 03/05/2015] [Accepted: 04/12/2015] [Indexed: 01/21/2023] Open
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Breast Dose Reduction Options During Thoracic CT: Influence of Breast Thickness. AJR Am J Roentgenol 2015; 204:W421-8. [DOI: 10.2214/ajr.14.13255] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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Gaddikeri S, Andre JB, Benjert J, Hippe DS, Anzai Y. Impact of model-based iterative reconstruction on image quality of contrast-enhanced neck CT. AJNR Am J Neuroradiol 2015; 36:391-6. [PMID: 25300982 DOI: 10.3174/ajnr.a4123] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
BACKGROUND AND PURPOSE Improved image quality is clinically desired for contrast-enhanced CT of the neck. We compared 30% adaptive statistical iterative reconstruction and model-based iterative reconstruction algorithms for the assessment of image quality of contrast-enhanced CT of the neck. MATERIALS AND METHODS Neck contrast-enhanced CT data from 64 consecutive patients were reconstructed retrospectively by using 30% adaptive statistical iterative reconstruction and model-based iterative reconstruction. Objective image quality was assessed by comparing SNR, contrast-to-noise ratio, and background noise at levels 1 (mandible) and 2 (superior mediastinum). Two independent blinded readers subjectively graded the image quality on a scale of 1-5, (grade 5 = excellent image quality without artifacts and grade 1 = nondiagnostic image quality with significant artifacts). The percentage of agreement and disagreement between the 2 readers was assessed. RESULTS Compared with 30% adaptive statistical iterative reconstruction, model-based iterative reconstruction significantly improved the SNR and contrast-to-noise ratio at levels 1 and 2. Model-based iterative reconstruction also decreased background noise at level 1 (P = .016), though there was no difference at level 2 (P = .61). Model-based iterative reconstruction was scored higher than 30% adaptive statistical iterative reconstruction by both reviewers at the nasopharynx (P < .001) and oropharynx (P < .001) and for overall image quality (P < .001) and was scored lower at the vocal cords (P < .001) and sternoclavicular junction (P < .001), due to artifacts related to thyroid shielding that were specific for model-based iterative reconstruction. CONCLUSIONS Model-based iterative reconstruction offers improved subjective and objective image quality as evidenced by a higher SNR and contrast-to-noise ratio and lower background noise within the same dataset for contrast-enhanced neck CT. Model-based iterative reconstruction has the potential to reduce the radiation dose while maintaining the image quality, with a minor downside being prominent artifacts related to thyroid shield use on model-based iterative reconstruction.
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Affiliation(s)
- S Gaddikeri
- From the Department of Neuroradiology (S.G., J.B.A., Y.A.), University of Washington Medical Center, University of Washington, Seattle, Washington
| | - J B Andre
- From the Department of Neuroradiology (S.G., J.B.A., Y.A.), University of Washington Medical Center, University of Washington, Seattle, Washington
| | - J Benjert
- Department of Neuroradiology (J.B.), University of Washington and VA Puget Sound, Seattle, Washington
| | - D S Hippe
- Department of Radiology (D.S.H.), University of Washington, Seattle, Washington
| | - Y Anzai
- From the Department of Neuroradiology (S.G., J.B.A., Y.A.), University of Washington Medical Center, University of Washington, Seattle, Washington
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Vadvala H, Kim P, Mayrhofer T, Pianykh O, Kalra M, Hoffmann U, Ghoshhajra B. Coronary CTA using scout-based automated tube potential and current selection algorithm, with breast displacement results in lower radiation exposure in females compared to males. Cardiovasc Diagn Ther 2015; 4:470-9. [PMID: 25610804 DOI: 10.3978/j.issn.2223-3652.2014.12.07] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2014] [Accepted: 12/12/2014] [Indexed: 11/14/2022]
Abstract
PURPOSE To evaluate the effect of automatic tube potential selection and automatic exposure control combined with female breast displacement during coronary computed tomography angiography (CCTA) on radiation exposure in women versus men of the same body size. MATERIALS AND METHODS Consecutive clinical exams between January 2012 and July 2013 at an academic medical center were retrospectively analyzed. All examinations were performed using ECG-gating, automated tube potential, and tube current selection algorithm (APS-AEC) with breast displacement in females. Cohorts were stratified by sex and standard World Health Organization body mass index (BMI) ranges. CT dose index volume (CTDIvol), dose length product (DLP) median effective dose (ED), and size specific dose estimate (SSDE) were recorded. Univariable and multivariable regression analyses were performed to evaluate the effect of gender on radiation exposure per BMI. RESULTS A total of 726 exams were included, 343 (47%) were females; mean BMI was similar by gender (28.6±6.9 kg/m(2) females vs. 29.2±6.3 kg/m(2) males; P=0.168). Median ED was 2.3 mSv (1.4-5.2) for females and 3.6 (2.5-5.9) for males (P<0.001). Females were exposed to less radiation by a difference in median ED of -1.3 mSv, CTDIvol -4.1 mGy, and SSDE -6.8 mGy (all P<0.001). After adjusting for BMI, patient characteristics, and gating mode, females exposure was lower by a median ED of -0.7 mSv, CTDIvol -2.3 mGy, and SSDE -3.15 mGy, respectively (all P<0.01). CONCLUSIONS We observed a difference in radiation exposure to patients undergoing CCTA with the combined use of AEC-APS and breast displacement in female patients as compared to their BMI-matched male counterparts, with female patients receiving one third less exposure.
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Affiliation(s)
- Harshna Vadvala
- Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA
| | - Phillip Kim
- Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA
| | - Thomas Mayrhofer
- Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA
| | - Oleg Pianykh
- Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA
| | - Mannudeep Kalra
- Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA
| | - Udo Hoffmann
- Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA
| | - Brian Ghoshhajra
- Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA
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Brix G, Lechel U, Nekolla E, Griebel J, Becker C. Radiation protection issues in dynamic contrast-enhanced (perfusion) computed tomography. Eur J Radiol 2014; 84:2347-58. [PMID: 25480677 DOI: 10.1016/j.ejrad.2014.11.011] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2014] [Accepted: 11/11/2014] [Indexed: 11/25/2022]
Abstract
Dynamic contrast-enhanced (DCE) CT studies are increasingly used in both medical care and clinical trials to improve diagnosis and therapy management of the most common life-threatening diseases: stroke, coronary artery disease and cancer. It is thus the aim of this review to briefly summarize the current knowledge on deterministic and stochastic radiation effects relevant for patient protection, to present the essential concepts for determining radiation doses and risks associated with DCE-CT studies as well as representative results, and to discuss relevant aspects to be considered in the process of justification and optimization of these studies. For three default DCE-CT protocols implemented at a latest-generation CT system for cerebral, myocardial and cancer perfusion imaging, absorbed doses were measured by thermoluminescent dosimeters at an anthropomorphic body phantom and compared with thresholds for harmful (deterministic) tissue reactions. To characterize stochastic radiation risks of patients from these studies, life-time attributable cancer risks (LAR) were estimated using sex-, age-, and organ-specific risk models based on the hypothesis of a linear non-threshold dose-response relationship. For the brain, heart and pelvic cancer studies considered, local absorbed doses in the imaging field were about 100-190 mGy (total CTDI(vol), 200 mGy), 15-30 mGy (16 mGy) and 80-270 mGy (140 mGy), respectively. According to a recent publication of the International Commission on Radiological Protection (ICRP Publication 118, 2012), harmful tissue reactions of the cerebro- and cardiovascular systems as well as of the lenses of the eye become increasingly important at radiation doses of more than 0.5 Gy. The LARs estimated for the investigated cerebral and myocardial DCE-CT scenarios are less than 0.07% for males and 0.1% for females at an age of exposure of 40 years. For the considered tumor location and protocol, the corresponding LARs are more than 6 times as high. Stochastic radiation risks decrease substantially with age and are markedly higher for females than for males. To balance the diagnostic needs and patient protection, DCE-CT studies have to be strictly justified and carefully optimized in due consideration of the various aspects discussed in some detail in this review.
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Affiliation(s)
- Gunnar Brix
- Department of Medical and Occupational Radiation Protection, Federal Office for Radiation Protection, Ingolstädter Landstraße 1, D-85764 Oberschleissheim, Germany.
| | - Ursula Lechel
- Department of Medical and Occupational Radiation Protection, Federal Office for Radiation Protection, Ingolstädter Landstraße 1, D-85764 Oberschleissheim, Germany.
| | - Elke Nekolla
- Department of Medical and Occupational Radiation Protection, Federal Office for Radiation Protection, Ingolstädter Landstraße 1, D-85764 Oberschleissheim, Germany.
| | - Jürgen Griebel
- Department of Medical and Occupational Radiation Protection, Federal Office for Radiation Protection, Ingolstädter Landstraße 1, D-85764 Oberschleissheim, Germany.
| | - Christoph Becker
- Department of Clinical Radiology, Grosshadern Clinic, Hospital of the Ludwig-Maximilians University, Marchioninistraße 15, D-81377 Munich, Germany.
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Akhlaghi P, Miri-Hakimabad H, Rafat-Motavalli L. Effects of shielding the radiosensitive superficial organs of ORNL pediatric phantoms on dose reduction in computed tomography. J Med Phys 2014; 39:238-46. [PMID: 25525312 PMCID: PMC4258732 DOI: 10.4103/0971-6203.144490] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2014] [Revised: 08/28/2014] [Accepted: 08/28/2014] [Indexed: 11/04/2022] Open
Abstract
In computed tomography (CT), some superficial organs which have increased sensitivity to radiation, receive doses that are significant enough to be matter of concern. Therefore, in this study, the effects of using shields on the amount of dose reduction and image quality was investigated for pediatric imaging. Absorbed doses of breasts, eyes, thyroid and testes of a series of pediatric phantoms without and with different thickness of bismuth and lead were calculated by Monte Carlo simulation. Appropriate thicknesses of shields were chosen based on their weights, X-ray spectrum, and the amount of dose reduction. In addition, the effect of lead shield on image quality of a simple phantom was assessed quantitatively using region of interest (ROI) measurements. Considering the maximum reduction in absorbed doses and X-ray spectrum, using a lead shield with a maximum thickness of 0.4 mm would be appropriate for testes and thyroid and two other organs (which are exposed directly) should be protected with thinner shields. Moreover, the image quality assessment showed that lead was associated with significant increases in both noise and CT attenuation values, especially in the anterior of the phantom. Overall, the results suggested that shielding is a useful optimization tool in CT.
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Affiliation(s)
- Parisa Akhlaghi
- Department of Physics, Faculty of Sciences, Ferdowsi University of Mashhad, Mashhad, Iran
| | - Hashem Miri-Hakimabad
- Department of Physics, Faculty of Sciences, Ferdowsi University of Mashhad, Mashhad, Iran
| | - Laleh Rafat-Motavalli
- Department of Physics, Faculty of Sciences, Ferdowsi University of Mashhad, Mashhad, Iran
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Samei E. Pros and cons of organ shielding for CT imaging. Pediatr Radiol 2014; 44 Suppl 3:495-500. [PMID: 25304710 DOI: 10.1007/s00247-014-3084-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/10/2014] [Revised: 04/22/2014] [Accepted: 06/09/2014] [Indexed: 11/27/2022]
Abstract
With the increased importance of CT radiation dose to health care providers, patients and the general public, there is an increased responsibility to minimize patient dose effectively. Bismuth shields offer a simple strategy to reduce dose to certain anterior radiosensitive organs such as breasts and eyes. However, in order to reduce organ dose they must be used properly; improper use can lead to an actual increase in the patient dose. They also create a proportional increase in image noise in the section of the body adjacent to the shield and further reduce the quantitative precision of CT numbers. In addition, shielding can degrade the overall efficiency (by an order of approximately 10%) of the imaging process, reducing the theoretical image quality that can be expected from a certain level of patient dose. However, in spite of their significant disadvantages, there are certain clinical situations and practice considerations that provide qualified justification for their continued use.
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Affiliation(s)
- Ehsan Samei
- Carl E. Ravin Advanced Imaging Laboratories (RAI Labs), Duke Clinical Imaging Physics Group, Departments of Radiology, Medical Physics, Physics, Biomedical Engineering, and Electrical and Computer Engineering, Duke University, 2424 Erwin Road, Suite 302, Durham, NC, 27705, USA,
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Abstract
OBJECTIVE Organ-based tube current modulation has been shown to significantly reduce the radiation dose to the female breast in phantom studies. We sought to assess the proportions of female breast and glandular tissues that are within the range of organ-based tube current modulation in different age groups and whether these proportions could be optimized by clothing. The secondary objective of our study was to determine whether metal parts of brassieres cause artifacts that impair the diagnostic value. SUBJECTS AND METHODS Five hundred seventy-eight female patients undergoing chest CT were included in this study. Two hundred nine patients were prospectively examined wearing a brassiere (group A), and the control patients (group B; n = 369) were scanned according to our previous standard without wearing a brassiere during CT. The two groups were subdivided according to cup size (A-E). For CT data acquisition, an angle-dependent tube current modulation, which reduces the tube current for anterior tube position to minimize direct exposure to anteriorly located organs, was used. The proportion of breast tissue and glandular tissue located within and outside the region of tube current reduction was assessed. RESULTS The results showed that 60.4% of total breast tissue and 67.1% of glandular tissue was inside the region of tube current reduction in group B; the proportions were significantly improved, to an average of 91.3% and 96%, respectively, in group A. Diagnostically relevant artifacts were introduced in none of the patients. Patients' age correlated with this effect, with higher rates of improvement in the older patient group. Angle-dependent tube current modulation was most effective in patients with cup size A while wearing a brassiere. In this group, 97.5% of breast tissue and 98.1% of glandular tissue was inside the region of tube current reduction. Women with a cup size of E had the largest effect of wearing a brassiere, increasing the rate of breast tissue that was affected by angle-dependent tube current modulation from 30.0% to 83.3% and that of glandular tissue from 31.8% to 90.0%. CONCLUSION We show that wearing a brassiere increases the percentage of breast tissue within the region of reduced tube current and, therefore, improves the performance of angle-dependent tube current modulation technique.
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CT Radiation Dose: Current Controversies and Dose Reduction Strategies. AJR Am J Roentgenol 2013; 201:1283-90. [DOI: 10.2214/ajr.12.9720] [Citation(s) in RCA: 100] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
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Lai N, Chen T, Tyan Y, Tsai H. Off-centre effect on dose reduction to anterior surfaces with organ-based tube-current modulation. RADIAT MEAS 2013. [DOI: 10.1016/j.radmeas.2013.04.023] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Servaes S, Zhu X. The effects of bismuth breast shields in conjunction with automatic tube current modulation in CT imaging. Pediatr Radiol 2013; 43:1287-94. [PMID: 23700195 DOI: 10.1007/s00247-013-2687-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/05/2012] [Revised: 02/06/2013] [Accepted: 02/26/2013] [Indexed: 01/28/2023]
Abstract
BACKGROUND There are mechanisms within CT scanners and shielding that can be used to lower dose to patients. OBJECTIVE The objective of our study was to evaluate the dose changes and image quality with and without a breast shield for multidetector CT of the chest with angular tube current modulation. MATERIALS AND METHODS An anthropomorphic 5-year-old phantom was scanned with and without bismuth breast shielding and with and without angular tube current modulation. Image quality was assessed by measuring signal-to-noise ratio and contrast-to-noise ratio as well as measuring qualitatively. ANOVA single-factor p-value analysis of paired datasets was used for the statistical analysis. RESULTS The breast shielding and angular tube current modulation resulted in a dose reduction to 85% for the breast and 90% overall. Although no qualitative differences were noted with and without the breast shielding used with angular tube current modulation, there were statistically significant differences in the contrast-to-noise ratio and CT numbers. CONCLUSIONS When used with angular tube current modulation, breast shields influence the contrast-to-noise ratio and CT numbers, and therefore should not be used for chest CT. Greater dose reduction can be obtained by reducing the reference mAs (or reference noise index).
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Affiliation(s)
- Sabah Servaes
- Department of Radiology, The Children's Hospital of Philadelphia, 34th Street and Civic Center Boulevard, Philadelphia, PA, 19104, USA,
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Foley SJ, McEntee MF, Rainford LA. An evaluation of in-plane shields during thoracic CT. RADIATION PROTECTION DOSIMETRY 2013; 155:439-450. [PMID: 23460031 DOI: 10.1093/rpd/nct030] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The object of this study was to compare organ dose and image quality effects of using bismuth and barium vinyl in-plane shields with standard and low tube current thoracic CT protocols. A RANDO phantom was scanned using a 64-slice CT scanner and three different thoracic protocols. Thermoluminescent dosemeters were positioned in six locations to record surface and absorbed breast and lung doses. Image quality was assessed quantitatively using region of interest measurements. Scanning was repeated using bismuth and barium vinyl in-plane shields to cover the breasts and the results were compared with standard and reduced dose protocols. Dose reductions were most evident in the breast, skin and anterior lung when shielding was used, with mean reductions of 34, 33 and 10 % for bismuth and 23, 18 and 11 % for barium, respectively. Bismuth was associated with significant increases in both noise and CT attenuation values for all the three protocols, especially anteriorly and centrally. Barium shielding had a reduced impact on image quality. Reducing the overall tube current reduced doses in all the locations by 20-27 % with similar increases in noise as shielding, without impacting on attenuation values. Reducing the overall tube current best optimises dose with minimal image quality impact. In-plane shields increase noise and attenuation values, while reducing anterior organ doses primarily. Shielding remains a useful optimisation tool in CT and barium is an effective alternative to bismuth especially when image quality is of concern.
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Affiliation(s)
- S J Foley
- School of Medicine and Medical Science, University College Dublin, Dublin 4, Ireland.
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Affiliation(s)
- Jie Zhang
- Department of Radiology, College of Medicine, University of Kentucky, Lexington, Kentucky 40536, USA.
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Khong PL, Ringertz H, Donoghue V, Frush D, Rehani M, Appelgate K, Sanchez R. ICRP publication 121: radiological protection in paediatric diagnostic and interventional radiology. Ann ICRP 2013; 42:1-63. [PMID: 23218172 DOI: 10.1016/j.icrp.2012.10.001] [Citation(s) in RCA: 184] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Paediatric patients have a higher average risk of developing cancer compared with adults receiving the same dose. The longer life expectancy in children allows more time for any harmful effects of radiation to manifest, and developing organs and tissues are more sensitive to the effects of radiation. This publication aims to provide guiding principles of radiological protection for referring clinicians and clinical staff performing diagnostic imaging and interventional procedures for paediatric patients. It begins with a brief description of the basic concepts of radiological protection, followed by the general aspects of radiological protection, including principles of justification and optimisation. Guidelines and suggestions for radiological protection in specific modalities - radiography and fluoroscopy, interventional radiology, and computed tomography - are subsequently covered in depth. The report concludes with a summary and recommendations. The importance of rigorous justification of radiological procedures is emphasised for every procedure involving ionising radiation, and the use of imaging modalities that are non-ionising should always be considered. The basic aim of optimisation of radiological protection is to adjust imaging parameters and institute protective measures such that the required image is obtained with the lowest possible dose of radiation, and that net benefit is maximised to maintain sufficient quality for diagnostic interpretation. Special consideration should be given to the availability of dose reduction measures when purchasing new imaging equipment for paediatric use. One of the unique aspects of paediatric imaging is with regards to the wide range in patient size (and weight), therefore requiring special attention to optimisation and modification of equipment, technique, and imaging parameters. Examples of good radiographic and fluoroscopic technique include attention to patient positioning, field size and adequate collimation, use of protective shielding, optimisation of exposure factors, use of pulsed fluoroscopy, limiting fluoroscopy time, etc. Major paediatric interventional procedures should be performed by experienced paediatric interventional operators, and a second, specific level of training in radiological protection is desirable (in some countries, this is mandatory). For computed tomography, dose reduction should be optimised by the adjustment of scan parameters (such as mA, kVp, and pitch) according to patient weight or age, region scanned, and study indication (e.g. images with greater noise should be accepted if they are of sufficient diagnostic quality). Other strategies include restricting multiphase examination protocols, avoiding overlapping of scan regions, and only scanning the area in question. Up-to-date dose reduction technology such as tube current modulation, organ-based dose modulation, auto kV technology, and iterative reconstruction should be utilised when appropriate. It is anticipated that this publication will assist institutions in encouraging the standardisation of procedures, and that it may help increase awareness and ultimately improve practices for the benefit of patients.
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Comparison of coronary CT angiography image quality with and without breast shields. AJR Am J Roentgenol 2013; 200:529-36. [PMID: 23436841 DOI: 10.2214/ajr.11.8302] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
OBJECTIVE The purpose of this study is to compare the image quality of coronary CT angiography performed with and without breast shields. MATERIALS AND METHODS This study involved a retrospective cohort of 72 women with possible angina who underwent 64-MDCT retrospective ECG-gated coronary CT angiography at a single academic tertiary medical center. Images of 36 women scanned while wearing bismuth-coated latex breast shields and 36 control subjects scanned without shields, matched by heart rate and body mass index, were graded on a standardized Likert scale for image quality, stenosis, and plaque by two independent board-certified readers blinded to breast shields. RESULTS Seventy-two patients (mean [± SD] age, 53 ± 9 years) were included. The pre scan heart rate, body mass index, and Agatston score did not differ between groups. The median estimated radiation dose was 13.4 versus 16.1 mSv for those with and without breast shields (p = 0.003). For shielded versus unshielded scans, 86% versus 83% of coronary segments were rated excellent or above average (p = 0.4), median image quality was 2.0 for both groups, mean signal was 474 ± 75 and 452 ± 91 HU (p = 0.27), mean noise was 33.9 ± 8.5 and 29.8 ± 8.3 HU (p = 0.04), and median signal-to-noise ratio was 14.4 and 14.7 (p = 0.56), respectively. CONCLUSION Breast shields for women undergoing coronary CT angiography slightly increased noise but did not negatively affect signal, signal-to-noise ratio, quality, or interpretability. Breast shield use warrants further study.
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Optimised low-dose multidetector CT protocol for children with cranial deformity. Eur Radiol 2013; 23:2279-87. [DOI: 10.1007/s00330-013-2806-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2012] [Revised: 01/11/2013] [Accepted: 01/20/2013] [Indexed: 10/27/2022]
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Goldin D, Emerson S, Farah MC, Sokhandon F, Nandalur KR, Kumar S, Mezwa DG. Shielding artificially increases the attenuation of water: study of CT gradient attenuation induced by shielding (CT GAINS). Acad Radiol 2013; 20:231-7. [PMID: 22981602 DOI: 10.1016/j.acra.2012.07.016] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2012] [Revised: 06/27/2012] [Accepted: 07/31/2012] [Indexed: 01/31/2023]
Abstract
RATIONALE AND OBJECTIVES Quantitatively analyze the computed tomography (CT) attenuation effects caused by bismuth shields, which are used to reduce superficial organ dose. MATERIALS AND METHODS The solid water uniformity section of the American College of Radiology CT phantom was scanned with a modified chest CT protocol. Scans were performed with a bismuth breast shield in multiple configurations, emphasizing three clinically relevant orientations. Attenuation effects were measured as changes in mean Hounsfield unit (HU) values of equal midsagittal regions of interest (ROI). Multiple statistical techniques were used in regression analysis. RESULTS Bismuth shielding resulted in significant positive shifts of the expected Hounsfield unit values. The mean nonshielded CT attenuation was -0.16 ± 0.75 HU. Based on the clinically relevant ROI distance from the shield (~3-16 cm), the shielded values ranged from 43.8-4 HU, 45.8-10.1 HU, and 50.6-4.5 HU for shields 1, 2, and 3, respectively. All shield configurations displayed a statistically significant shift (P < .0001) at all distance ranges. The best fitting regression model was a quadratic function of distance versus logarithmic function of HU. A prediction table of the approximate shift in water HU values as a function of ROI distance from the shield was generated per shield type from their respective close-fitting regressions. CONCLUSIONS The data support the claim that bismuth shields increase the attenuation of water, which can cause inaccurate characterization of simple fluid, giving the appearance of complex fluid or even solid density. However, there is potential for anticipation of the attenuation effects to validate continued use of these shields for dose reduction.
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Affiliation(s)
- Dmitry Goldin
- Department of Radiology, Beaumont Health System, 3601 West 13 Mile Road, Royal Oak, MI 48073, USA.
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Nyman U, Björkdahl P, Olsson ML, Gunnarsson M, Goldman B. Low-dose radiation with 80-kVp computed tomography to diagnose pulmonary embolism: a feasibility study. Acta Radiol 2012; 53:1004-13. [PMID: 22940858 DOI: 10.1258/ar.2012.120327] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
BACKGROUND Mounting collective radiation doses from computed tomography (CT) implies an increased risk of radiation-induced cancer in exposed populations, especially in the young. PURPOSE To evaluate radiation dose and image quality at 80-kVp CT to diagnose acute pulmonary embolism (PE) compared with a previous study at 100 and 120 kVp with all other scanning parameters unchanged. MATERIAL AND METHODS A custom-made chest phantom with a 12 mg I/mL-syringe was scanned at 80/100/120 kVp to evaluate relative changes in computed tomographic dose index (CTDI(vol)), attenuation, image noise, and contrast-to-noise ratio (CNR). Fifty patients underwent 80 kVp 16-row detector CT at 100 "Quality reference" mAs. A total of 350 mg I/kg were injected to compensate for increased CNR at 80 kVp, while 300 mg I/kg had been used at 100/120 kVp. CTDI(vol), dose-length product (DLP), and estimated effective dose were evaluated including Monte Carlo simulations. Pulmonary artery attenuation and noise were measured and CNR calculated. Two radiologists evaluated subjective image quality using a four-grade scale. RESULTS Switching from 120 to 80 kVp in the phantom study decreased radiation dose by 67% while attenuation and noise increased 1.6 and 2.0 times, respectively, and CNR decreased by 16%. Switching from 120 to 80 kVp in the patient studies decreased estimated effective dose from 4.0 to 1.2 mSv (70% decrease) in median while pulmonary artery attenuation and noise roughly doubled from 332 to 653 HU and from 22 to 49 HU, respectively, resulting in similar CNR (13 vs. 12). At 80 kVp all examinations were regarded as adequate (8%) or excellent (92%). CONCLUSION Switching from 120 to 80 kVp CT without increased mAs but slightly increased iodine dose may be of special benefit to diagnose PE in younger individuals with preserved renal function where the primary aim is to minimize radiation dose and reaching levels below that of scintigraphy.
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Affiliation(s)
- Ulf Nyman
- Department of Radiology, University of Lund, Lasarettet Trelleborg, Trelleborg
| | | | - Marie-Louise Olsson
- Medical Radiation Physics, Department of Clinical Sciences, University of Lund, Skåne University Hospital, Malmö
| | - Mikael Gunnarsson
- Medical Radiation Physics, Department of Clinical Sciences, University of Lund, Skåne University Hospital, Malmö
| | - Bitte Goldman
- Department of Internal Medicine, Lasarettet Trelleborg, Trelleborg, Sweden
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de Broucker T, Pontana F, Santangelo T, Faivre JB, Tacelli N, Delannoy-Deken V, Duhamel A, Remy J, Rémy-Jardin M. Single- and dual-source chest CT protocols: Levels of radiation dose in routine clinical practice. Diagn Interv Imaging 2012; 93:852-8. [DOI: 10.1016/j.diii.2012.07.009] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Abstract
It is well known that paediatric patients are generally at greater risk for the development of cancer per unit of radiation dose compared with adults, due both to the longer life expectancy for any harmful effects of radiation to manifest, and the fact that developing organs and tissues are more sensitive to the effects of radiation. Multiple computed tomography (CT) examinations may cumulatively involve absorbed doses to organs and tissues that can sometimes approach or exceed the levels known from epidemiological studies to significantly increase the probability of cancer development. Radiation protection strategies include rigorous justification of CT examinations and the use of imaging techniques that are non-ionising, followed by optimisation of radiation dose exposure (according to the 'as low as reasonably achievable' principle). Special consideration should be given to the availability of dose reduction technology when acquiring CT scanners. Dose reduction should be optimised by adjustment of scan parameters (such as mAs, kVp, and pitch) according to patient weight or age, region scanned, and study indication (e.g. images with greater noise should be accepted if they are of sufficient diagnostic quality). Other strategies include restricting multiphase examination protocols, avoiding overlapping of scan regions, and only scanning the area in question. Newer technologies such as tube current modulation, organ-based dose modulation, and iterative reconstruction should be used when appropriate. Attention should also be paid to optimising study quality (e.g. by image post-processing to facilitate radiological diagnoses and interpretation). Finally, improving awareness through education and advocacy, and further research in paediatric radiological protection are important to help reduce patient dose.
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McCollough CH, Wang J, Gould RG, Orton CG. The use of bismuth breast shields for CT should be discouraged. Med Phys 2012; 39:2321-4. [DOI: 10.1118/1.3681014] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Einstein AJ, Elliston CD, Groves DW, Cheng B, Wolff SD, Pearson GDN, Robert Peters M, Johnson LL, Bokhari S, Johnson GW, Bhatia K, Pozniakoff T, Brenner DJ. Effect of bismuth breast shielding on radiation dose and image quality in coronary CT angiography. J Nucl Cardiol 2012; 19:100-8. [PMID: 22068687 PMCID: PMC3266996 DOI: 10.1007/s12350-011-9473-x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2011] [Accepted: 10/22/2011] [Indexed: 10/15/2022]
Abstract
BACKGROUND Coronary computed tomographic angiography (CCTA) is associated with high radiation dose to the female breasts. Bismuth breast shielding offers the potential to significantly reduce dose to the breasts and nearby organs, but the magnitude of this reduction and its impact on image quality and radiation dose have not been evaluated. METHODS Radiation doses from CCTA to critical organs were determined using metal-oxide-semiconductor field-effect transistors positioned in a customized anthropomorphic whole-body dosimetry verification phantom. Image noise and signal were measured in regions of interest (ROIs) including the coronary arteries. RESULTS With bismuth shielding, breast radiation dose was reduced 46%-57% depending on breast size and scanning technique, with more moderate dose reduction to the heart, lungs, and esophagus. However, shielding significantly decreased image signal (by 14.6 HU) and contrast (by 28.4 HU), modestly but significantly increased image noise in ROIs in locations of coronary arteries, and decreased contrast-to-noise ratio by 20.9%. CONCLUSIONS While bismuth breast shielding can significantly decrease radiation dose to critical organs, it is associated with an increase in image noise, decrease in contrast-to-noise, and changes tissue attenuation characteristics in the location of the coronary arteries.
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Affiliation(s)
- Andrew J Einstein
- Cardiology Division, Department of Medicine, Columbia University Medical Center/New York-Presbyterian Hospital, 622 West 168th Street PH 10-203A, New York, NY 10032, USA.
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Wang J, Duan X, Christner JA, Leng S, Grant KL, McCollough CH. Bismuth Shielding, Organ-based Tube Current Modulation, and Global Reduction of Tube Current for Dose Reduction to the Eye at Head CT. Radiology 2012; 262:191-8. [DOI: 10.1148/radiol.11110470] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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McCollough CH, Wang J, Berland LL. Bismuth Shields for CT Dose Reduction: Do They Help or Hurt? J Am Coll Radiol 2011; 8:878-9. [DOI: 10.1016/j.jacr.2011.09.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2011] [Accepted: 09/01/2011] [Indexed: 10/15/2022]
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Halliburton SS, Abbara S, Chen MY, Gentry R, Mahesh M, Raff GL, Shaw LJ, Hausleiter J. SCCT guidelines on radiation dose and dose-optimization strategies in cardiovascular CT. J Cardiovasc Comput Tomogr 2011; 5:198-224. [PMID: 21723512 DOI: 10.1016/j.jcct.2011.06.001] [Citation(s) in RCA: 360] [Impact Index Per Article: 27.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/04/2011] [Revised: 06/01/2011] [Accepted: 06/01/2011] [Indexed: 02/08/2023]
Abstract
Over the last few years, computed tomography (CT) has developed into a standard clinical test for a variety of cardiovascular conditions. The emergence of cardiovascular CT during a period of dramatic increase in radiation exposure to the population from medical procedures and heightened concern about the subsequent potential cancer risk has led to intense scrutiny of the radiation burden of this new technique. This has hastened the development and implementation of dose reduction tools and prompted closer monitoring of patient dose. In an effort to aid the cardiovascular CT community in incorporating patient-centered radiation dose optimization and monitoring strategies into standard practice, the Society of Cardiovascular Computed Tomography has produced a guideline document to review available data and provide recommendations regarding interpretation of radiation dose indices and predictors of risk, appropriate use of scanner acquisition modes and settings, development of algorithms for dose optimization, and establishment of procedures for dose monitoring.
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Affiliation(s)
- Sandra S Halliburton
- Imaging Institute, Heart and Vascular Institute, Cleveland Clinic, 9500 Euclid Avenue, J1-4, Cleveland, OH 44195, USA.
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