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Kul M, Kuru Öz D, Gürsoy Coruh A, Özalp Ateş F, Gülpınar B, Uzun Ç, Atasoy K. Biphasic split-bolus injection protocol for routine contrast-enhanced chest CT: comparison with conventional early-phase single bolus technique. Br J Radiol 2022; 95:20210775. [PMID: 35171718 PMCID: PMC10996411 DOI: 10.1259/bjr.20210775] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Revised: 02/03/2022] [Accepted: 02/08/2022] [Indexed: 11/05/2022] Open
Abstract
OBJECTIVES To present a routine contrast-enhanced chest CT protocol with a split-bolus injection technique achieving combined early- and delayed phase images with a single aquisition, and to compare this technique with a conventional early-phase single-bolus chest CT protocol we formerly used at our institution, in terms of attenuation of great thoracic vessels, pleura, included hepatic and portal venous enhancement, contrast-related artifacts, and image quality. METHODS A total of 202 patients, who underwent routine contrast-enhanced chest CT examination aquired with either conventional early-phase single-bolus technique (group A,n = 102) or biphasic split-bolus protocol (group B,n = 100), were retrospectively included. Attenuation measurements were made by two radiologists independently on mediastinal window settings using a circular ROI at the following sites: main pulmonary artery (PA) at its bifurcation level, thoracal aorta (TA) at the level of MPA bifurcation,portal vein (PV) at porta hepatis, left and right hepatic lobe, and if present, thickened pleura (>2 mm) at the level with the most intense enhancement. Respective normalized enhancement values were also calculated. Contrast-related artifacts were graded and qualitative evaluation of mediastinal lymph nodes was performed by both reviewers independently. Background noise was measured and contrast-to-noise ratios (CNRs) of the liver and TA were calculated. RESULTS While enhancement of thoracic vessels and normalised MPA enhancement did not differ significantly between both groups (p > 0.05), enhancement and normalised enhancement of pleura, liver parenchyma and PV was significantly greater in group B (p < 0.001). Perivenous artifacts limiting evaluation were less frequent in group B than in A and mediastinal lymph nodes were judged to be evaluated worse in group A than in group B with an excellent agreement between both observers. No significant difference was detected in CNRTA (p = 0.633), whereas CNR liver was higher in group B (p < 0.001). CONCLUSION Our split-bolus chest CT injection protocol enables simultaneous enhancement for both vascular structures and soft tissues, and thus, might raise diagnostic confidence without the need of multiple acquisitions. ADVANCES IN KNOWLEDGE We think that this CT protocol might also be a promising alternative in lung cancer staging, where combined contrast-enhanced CT of the chest and abdomen is indicated. We therefore suggest to further evaluate its diagnostic utility in this setting, in particular in comparison with a late delayed chest-upper abdominal CT imaging protocol.
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Affiliation(s)
- Melahat Kul
- Department of Radiology, School of Medicine, Ankara
University, Ankara,
Turkey
| | - Diğdem Kuru Öz
- Department of Radiology, School of Medicine, Ankara
University, Ankara,
Turkey
| | | | - Funda Özalp Ateş
- Department of Biostatistics, School of Medicine, Manisa Celal
Bayar University, Manisa,
Turkey
| | - Başak Gülpınar
- Department of Radiology, School of Medicine, Ankara
University, Ankara,
Turkey
| | - Çağlar Uzun
- Department of Radiology, School of Medicine, Ankara
University, Ankara,
Turkey
| | - K.Çetin Atasoy
- Department of Radiology, School of Medicine, Koç
University, İstanbul,
Turkey
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Wang Q, Fu Q, Pang C. A NEW METHOD FOR ESTIMATING INCREASE IN RADIATION DOSE ASSOCIATED WITH IODINATED CONTRAST USE. RADIATION PROTECTION DOSIMETRY 2022; 198:281-289. [PMID: 35368083 DOI: 10.1093/rpd/ncac026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2021] [Revised: 01/25/2022] [Accepted: 02/02/2022] [Indexed: 06/14/2023]
Abstract
This work investigates the impact of iodinated contrast medium (ICM) on radiation dose in computed tomography (CT) scans using linear models established through a phantom study. Thermoluminescence dosemeters (TLDs) were calibrated using semi-conductor X-ray dosemeters. An electron density phantom, with a vial containing TLDs and different concentrations of iodinated blood, were scanned at different tube voltages. Irradiated TLD outputs were measured and absorbed dose to iodinated blood calculated. CT numbers (tissue attenuation as measured by Hounsfield units) were plotted against absorbed doses to obtain linear models. Data from 49 real patient scans were used to validate the linear models. At each X-ray energy, CT numbers were linearly correlated with the absorbed doses, that is with the increase of blood iodine concentration, the CT number increased and the absorbed dose increased accordingly. ICM can cause an increase of organ dose; the average dose increases were 31.8 ± 8.9% for thyroid, 37.1 ± 9.2% for cardiac muscle, 77.7 ± 14.0% for cardiac chamber, 7.1 ± 2.3% for breast, 26.1 ± 7.3% for liver, 39.8 ± 11.8% for spleen, 96.3 ± 12.2% for renal cortex and 82.4 ± 11.6% for medulla nephrica. ICM used in enhanced CT scan resulted in increased organ doses. Our models for estimating organ dose based on CT number were established by experiment and verified in clinical use.
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Affiliation(s)
- Qiang Wang
- Department of Occupational Disease Prevention, Changzhou Center for Disease Control and Prevention, Changzhou, Jiangsu 213022, China
| | - Qiang Fu
- Department of Occupational Disease Prevention, Changzhou Center for Disease Control and Prevention, Changzhou, Jiangsu 213022, China
| | - Cong Pang
- The First People's Hospital of Changzhou, Changzhou, Jiangsu 213022, China
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Yoshida M, Nakaura T, Oda S, Kidoh M, Nagayama Y, Uetani H, Azuma M, Sakabe D, Hirai T, Funama Y. Effects of tube voltage and iodine contrast medium on radiation dose of whole-body CT. Acta Radiol 2022; 63:458-466. [PMID: 33709794 DOI: 10.1177/02841851211001539] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
BACKGROUND The low-tube-voltage scan generally needs a higher tube current than the conventional 120 kVp to maintain the image noise. In addition, the low-tube-voltage scan increases the photoelectric effect, which increases the radiation absorption in organs. PURPOSE To compare the organ radiation dose caused by iodine contrast medium between low tube voltage with low contrast medium and that of conventional 120-kVp protocol with standard contrast medium. MATERIAL AND METHODS After the propensity-matching analysis, 66 patients were enrolled including 33 patients with 120 kVp and 600 mgI/kg and 33 patients with 80 kVp and 300 mgI/kg (50% iodine reduction). The pre- and post-contrast phases were assessed in all patients. The Monte Carlo simulation tool was used to simulate the radiation dose. The computed tomography (CT) numbers for 10 organs and the organ doses were measured. The organ doses were normalized by the volume CT dose index, and the 120-kVp protocol was compared with the 80-kVp protocol. RESULTS On contrast-enhanced CT, there were no significant differences in the mean CT numbers of the organs between 80-kVp and 120-kVp protocols except for the pancreas, kidneys, and small intestine. The normalized organ doses at 80 kVp were significantly lower than those of 120 kVp in all organs (e.g. liver, 1.6 vs. 1.9; pancreas, 1.5 vs. 1.8; spleen, 1.7 vs. 2.0) on contrast-enhanced CT. CONCLUSION The low tube voltage with low-contrast-medium protocol significantly reduces organ doses at the same volume CT dose index setting compared with conventional 120-kVp protocol with standard contrast medium on contrast-enhanced CT.
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Affiliation(s)
| | | | - Seitaro Oda
- Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan
| | - Masafumi Kidoh
- Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan
| | | | - Hiroyuki Uetani
- Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan
| | - M Azuma
- Faculty of Medicine, University of Miyazaki, Miyazaki, Japan
| | - Daisuke Sakabe
- Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan
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Hoshika M, Nakaura T, Oda S, Kidoh M, Nagayama Y, Sakabe D, Hirai T, Funama Y. Comparison of the effects of varying tube voltage and iodinated concentration on increasing the iodinated radiation dose in computed tomography. Phys Med 2022; 95:57-63. [DOI: 10.1016/j.ejmp.2022.01.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/13/2021] [Revised: 12/09/2021] [Accepted: 01/20/2022] [Indexed: 11/16/2022] Open
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Holman R, Lorton O, Guillemin PC, Desgranges S, Contino-Pépin C, Salomir R. Perfluorocarbon Emulsion Contrast Agents: A Mini Review. Front Chem 2022; 9:810029. [PMID: 35083198 PMCID: PMC8785234 DOI: 10.3389/fchem.2021.810029] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2021] [Accepted: 12/09/2021] [Indexed: 12/31/2022] Open
Abstract
Perfluorocarbon emulsions offer a variety of applications in medical imaging. The substances can be useful for most radiological imaging modalities; including, magnetic resonance imaging, ultrasonography, computed tomography, and positron emission tomography. Recently, the substance has gained much interest for theranostics, with both imaging and therapeutic potential. As MRI sequences improve and more widespread access to 19F-MRI coils become available, perfluorocarbon emulsions have great potential for new commercial imaging agents, due to high fluorine content and previous regulatory approval as antihypoxants and blood substitutes. This mini review aims to discuss the chemistry and physics of these contrast agents, in addition to highlighting some of the past, recent, and potential applications.
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Affiliation(s)
- Ryan Holman
- Image Guided Interventions Laboratory (GR-949), Faculty of Medicine, University of Geneva, Geneva, Switzerland
- *Correspondence: Ryan Holman,
| | - Orane Lorton
- Image Guided Interventions Laboratory (GR-949), Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | - Pauline C. Guillemin
- Image Guided Interventions Laboratory (GR-949), Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | | | | | - Rares Salomir
- Image Guided Interventions Laboratory (GR-949), Faculty of Medicine, University of Geneva, Geneva, Switzerland
- Radiology Department, University Hospitals of Geneva, Geneva, Switzerland
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Dalah EZ, Obaideen A, Anam S, Khalid M, Nadishani T, Hashim S, Ghoshal SK. Cumulative lifetime attributed risks for patients subjected to contrast enhanced chest CT examinations. Radiat Phys Chem Oxf Engl 1993 2021. [DOI: 10.1016/j.radphyschem.2021.109710] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Van Cauteren T, Tanaka K, Belsack D, Van Gompel G, Kersemans V, Jochmans K, Droogmans S, de Mey J, Buls N. Potential increase in radiation-induced DNA double-strand breaks with higher doses of iodine contrast during coronary CT angiography. Med Phys 2021; 48:7526-7533. [PMID: 34564862 PMCID: PMC9293077 DOI: 10.1002/mp.15253] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2021] [Revised: 06/25/2021] [Accepted: 09/14/2021] [Indexed: 11/09/2022] Open
Abstract
PURPOSE To investigate the contrast media iodine dose dependency of radiation-induced DNA double-strand breaks (DSBs) during a coronary computed tomography angiography (CCTA) scan. METHODS This prospective patient study was approved by the ethical committee. Between November 2018 and July 2019, 50 patients (31 males and 19 females, mean age 64 years) were included in the study, 45 CCTA and five noncontrast-enhanced (NCE) cardiac computed tomography (CT) patients. A single-heartbeat scan protocol with a patient-tailored contrast media injection protocol was used, administering a patient-specific iodine dose. DNA double-strand breaks were quantified using a γH2AX foci assay on peripheral blood lymphocytes. The net amount of γH2AX/cell was normalized to the individual patient CT dose by the size-specific dose estimate (SSDE). Correlation between the administered and blood-iodine dose and the SSDE normalized amount of DNA DSBs was investigated using a Pearson correlation test. RESULTS CCTA patients were scanned with a mean CTDIvol of 10.6 ± 5.6 mGy, corresponding to a mean SSDE of 11.3 ± 5.3 mGy while the NCE cardiac CT patients were scanned with a mean CTDIvol of 6.00 ± 1.8 mGy, corresponding to a mean SSDE of 6.6 ± 2.7 mGy. The administered iodine dose ranged from 16.5 to 34.0 gI in the CCTA patients, resulting in a blood-iodine dose range from 5.1 to 15.0 gI in the exposed blood volume. A significant linear relationship (r = 0.79, p-value < 0.001) was observed between the blood iodine dose and SSDE normalized radiation-induced DNA DSBs. A similar significant linear relationship (r = 0.62, p-value < 0.001) was observed between the administered iodine dose and SSDE normalized radiation-induced DNA DSBs. CONCLUSIONS This study shows that contrast media iodine dose increases the level of radiation-induced DNA DSBs in peripheral blood lymphocytes in a linear dose-dependent manner with CCTA. Importantly, the level of DNA DSBs can be reduced by lowering the administered iodine dose.
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Affiliation(s)
- Toon Van Cauteren
- Department of RadiologyVrije Universiteit Brussel (VUB)Universitair Ziekenhuis Brussels (UZB)BrusselsBelgium
| | - Kaoru Tanaka
- Department of RadiologyVrije Universiteit Brussel (VUB)Universitair Ziekenhuis Brussels (UZB)BrusselsBelgium
| | - Dries Belsack
- Department of RadiologyVrije Universiteit Brussel (VUB)Universitair Ziekenhuis Brussels (UZB)BrusselsBelgium
| | - Gert Van Gompel
- Department of RadiologyVrije Universiteit Brussel (VUB)Universitair Ziekenhuis Brussels (UZB)BrusselsBelgium
| | - Veerle Kersemans
- Department of OncologyCRUK/MRC Institute for Radiation OncologyUniversity of OxfordOxfordUK
| | - Kristin Jochmans
- Department of HematologyVrije Universiteit Brussel (VUB)Universitair Ziekenhuis Brussels (UZB)BrusselsBelgium
| | - Steven Droogmans
- Department of CardiologyVrije Universiteit Brussel (VUB)Universitair Ziekenhuis Brussels (UZB)BrusselsBelgium
| | - Johan de Mey
- Department of RadiologyVrije Universiteit Brussel (VUB)Universitair Ziekenhuis Brussels (UZB)BrusselsBelgium
| | - Nico Buls
- Department of RadiologyVrije Universiteit Brussel (VUB)Universitair Ziekenhuis Brussels (UZB)BrusselsBelgium
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Strandberg L, Jonasson P, Larsson M. EVALUATION OF RADIATION DOSES USING CONE BEAM COMPUTED TOMOGRAPHY IN ENDOVASCULAR AORTIC REPAIR AND SCOLIOSIS PROCEDURES. RADIATION PROTECTION DOSIMETRY 2021; 195:306-313. [PMID: 33876250 DOI: 10.1093/rpd/ncab050] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Revised: 03/10/2021] [Accepted: 03/18/2021] [Indexed: 06/12/2023]
Abstract
The aim of this project was to evaluate the radiation dose to patients for cone beam computed tomography (CBCT) in endovascular aortic repair (EVAR) and scoliosis procedures and to compare radiation doses between CBCT and computed tomography (CT). An anthropomorphic phantom and Siemens and General Electric X-ray equipment were used. Default protocol settings were used for comparison of protocols and modalities. The ratio between the highest and lowest CBCT effective dose, for each equipment, had a maximum of 13 (Artis Pheno) for EVAR and 1.8 (Artis Zeego) for scoliosis. It is difficult to predict which modality gives the highest effective dose, e.g. for the CT protocol 'Aorta before EVAR' the ratio between effective doses varied from 0.12 to 1.8, between CBCT and CT. For CBCT EVAR, the effective dose and dose area product decreased using collimation or zoom.
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Affiliation(s)
- Louise Strandberg
- Section of Diagnostic Imaging and Functional Medicine, NU Hospital Group, SE-461 85 Trollhättan, Sweden
- Department of Radiation Physics, Institute of Clinical Sciences, The Sahlgrenska Academy at University of Gothenburg, SE-413 45 Gothenburg, Sweden
| | - Pernilla Jonasson
- Department of Medical Physics and Biomedical Engineering, Sahlgrenska University Hospital SE-413 45 Gothenburg, Sweden
| | - Maria Larsson
- Department of Radiation Physics, Institute of Clinical Sciences, The Sahlgrenska Academy at University of Gothenburg, SE-413 45 Gothenburg, Sweden
- Department of Medical Physics and Biomedical Engineering, Sahlgrenska University Hospital SE-413 45 Gothenburg, Sweden
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Ohira S, Koike Y, Akino Y, Kanayama N, Wada K, Ueda Y, Masaoka A, Washio H, Miyazaki M, Koizumi M, Ogawa K, Teshima T. Improvement of image quality for pancreatic cancer using deep learning-generated virtual monochromatic images: Comparison with single-energy computed tomography. Phys Med 2021; 85:8-14. [PMID: 33940528 DOI: 10.1016/j.ejmp.2021.03.035] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Revised: 02/25/2021] [Accepted: 03/30/2021] [Indexed: 01/15/2023] Open
Abstract
PURPOSE To construct a deep convolutional neural network that generates virtual monochromatic images (VMIs) from single-energy computed tomography (SECT) images for improved pancreatic cancer imaging quality. MATERIALS AND METHODS Fifty patients with pancreatic cancer underwent a dual-energy CT simulation and VMIs at 77 and 60 keV were reconstructed. A 2D deep densely connected convolutional neural network was modeled to learn the relationship between the VMIs at 77 (input) and 60 keV (ground-truth). Subsequently, VMIs were generated for 20 patients from SECT images using the trained deep learning model. RESULTS The contrast-to-noise ratio was significantly improved (p < 0.001) in the generated VMIs (4.1 ± 1.8) compared to the SECT images (2.8 ± 1.1). The mean overall image quality (4.1 ± 0.6) and tumor enhancement (3.6 ± 0.6) in the generated VMIs assessed on a five-point scale were significantly higher (p < 0.001) than that in the SECT images (3.2 ± 0.4 and 2.8 ± 0.4 for overall image quality and tumor enhancement, respectively). CONCLUSIONS The quality of the SECT image was significantly improved both objectively and subjectively using the proposed deep learning model for pancreatic tumors in radiotherapy.
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Affiliation(s)
- Shingo Ohira
- Department of Radiation Oncology, Osaka International Cancer Institute, Osaka, Japan; Department of Medical Physics and Engineering, Osaka University Graduate School of Medicine, Suita, Japan.
| | - Yuhei Koike
- Department of Radiology, Kansai Medical University, Osaka, Japan
| | - Yuichi Akino
- Division of Medical Physics, Oncology Center, Osaka University Hospital, Suita, Japan
| | - Naoyuki Kanayama
- Department of Radiation Oncology, Osaka International Cancer Institute, Osaka, Japan
| | - Kentaro Wada
- Department of Radiation Oncology, Osaka International Cancer Institute, Osaka, Japan
| | - Yoshihiro Ueda
- Department of Radiation Oncology, Osaka International Cancer Institute, Osaka, Japan
| | - Akira Masaoka
- Department of Radiation Oncology, Osaka International Cancer Institute, Osaka, Japan
| | - Hayate Washio
- Department of Radiation Oncology, Osaka International Cancer Institute, Osaka, Japan
| | - Masayoshi Miyazaki
- Department of Radiation Oncology, Osaka International Cancer Institute, Osaka, Japan
| | - Masahiko Koizumi
- Department of Medical Physics and Engineering, Osaka University Graduate School of Medicine, Suita, Japan
| | - Kazuhiko Ogawa
- Department of Radiation Oncology, Osaka University Graduate School of Medicine, Suita, Japan
| | - Teruki Teshima
- Department of Radiation Oncology, Osaka International Cancer Institute, Osaka, Japan
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Zawam Dalah E, Dhou S, Mudalige T, Amin F, Obaideen A. Challenges estimating patient organs doses undergoing enhanced chest CT examination: exploratory study. Biomed Phys Eng Express 2021; 7. [PMID: 33588398 DOI: 10.1088/2057-1976/abe68e] [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: 11/23/2020] [Accepted: 02/15/2021] [Indexed: 11/11/2022]
Abstract
Purpose: Estimate organs doses (ODs) of patients subjected to unenhanced (S1) and enhanced (S2) chest CT studies relying on image parameters such as Hounsfield Units (HUs).Materials and Methods: CT scans and images of a total of 16 patients who underwent two series of chest CT studies were obtained and retrospectively examined. OD increments of liver and pancreas for both series (S1 & S2) were estimated using two different independent methods, namely simulation approach using CT-EXPO and Amato's phantom-based fitting model (APFM). HUs were quantified for each organ by manually drawing fixed area-sized regions of interest (ROIs). The mean HUs were collected to obtain the ODs increments following APFM. Regression analysis was applied to find and assess the relationship between the HUs and the OD increments estimated using APFM and that using CT-EXPO. Spearman Coefficient and Wilcoxon Matched Pairedt-testwere conducted to show statistical correlation and difference between ODs increments using the two methods.Results:A strong significant difference was depicted between S1 and S2 scan series of liver and pancreas using CT-EXPO simulation. Mean HU values for S1 were lower than S2, resulting in statistically significant (p < 0.0001) HU changes. CT-EXPO simulation yielded significantly higher difference in ODs compared to the APFM for liver (p = 0.0455) and pancreas (p = 0.0031). Regression analysis revealed a strong relationship between HU of S1 and S2 and ODs increments using APFM in both organs (R2 = 0.99), dissimilar to CT-EXPO (R2 = 0.39 in liver andR2 = 0.05 in pancreas).Conclusions: Although CT-EXPO allows for estimating ODs accounting for major acquisition scan parameters, it is not a reliable tool to evaluate the impact of contrast enhancement on ODs. On the other hand, the APFM accounts for contrast enhancement accumulation yet only provides relative OD increments, an information of limited clinical use.
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Affiliation(s)
- Entesar Zawam Dalah
- Department of Clinical Support Services and Nursing Sector, Dubai Health Authority, Dubai, UAE.,Department of Medical Diagnostic Imaging, University of Sharjah, Sharjah, UAE
| | - Salam Dhou
- Department of Computer Science and Engineering, American University of Sharjah, Sharjah, UAE
| | - Thilini Mudalige
- Department of Medical Diagnostic Imaging, University of Sharjah, Sharjah, UAE
| | - Fatima Amin
- Department of Medical Diagnostic Imaging, University of Sharjah, Sharjah, UAE
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Sakabe D, Nakaura T, Oda S, Kidoh M, Utsunomiya D, Masahiro Hatemura RT, Funama Y. Decreasing the radiation dose for contrast-enhanced abdominal spectral CT with a half contrast dose: a matched-pair comparison with a 120 kVp protocol. BJR Open 2020; 2:20200006. [PMID: 33367197 PMCID: PMC7749088 DOI: 10.1259/bjro.20200006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2020] [Accepted: 09/18/2020] [Indexed: 12/15/2022] Open
Abstract
Objectives To compare the estimated radiation dose of 50% reduced iodine contrast medium (halfCM) for virtual monochromatic images (VMIs) with that of standard CM (stdCM) with a 120 kVp imaging protocol for contrast-enhanced CT (CECT). Methods We enrolled 30 adults with renal dysfunction who underwent abdominal CT with halfCM for spectral CT. As controls, 30 matched patients without renal dysfunction using stdCM were also enrolled. CT images were reconstructed with the VMIs at 55 keV with halfCM and 120 kVp images with stdCM and halfCM. The Monte-Carlo simulation tool was used to simulate the radiation dose. The organ doses were normalized to CTDIvol for the liver, pancreas, spleen, and kidneys and measured between halfCM and stdCM protocols. Results For the arterial phase, the mean organ doses normalized to CTDIvol for stdCM and halfCM were 1.22 and 1.29 for the liver, 1.50 and 1.35 for the spleen, 1.75 and 1.51 for the pancreas, and 1.89 and 1.53 for the kidneys. As compared with non-enhanced CT, the average increase in the organ dose was significantly lower for halfCM (13.8% ± 14.3 and 26.7% ± 16.7) than for stdCM (31.0% ± 14.3 and 38.5% ± 14.8) during the hepatic arterial and portal venous phases (p < 0.01). Conclusion As compared with stdCM with the 120 kVp imaging protocol, a 50% reduction in CM with VMIs with the 55 keV protocol allowed for a substantial reduction of the average organ dose of iodine CM while maintaining the iodine CT number for CECT. Advances in knowledge This study provides that the halfCM protocol for abdominal CT with a dual-layer-dual-energy CT can significantly reduce the increase in the average organ dose for non-enhanced CT as compared with the standard CM protocol.
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Affiliation(s)
| | - Takeshi Nakaura
- Department of Diagnostic Radiology, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan
| | - Seitaro Oda
- Department of Diagnostic Radiology, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan
| | - Masafumi Kidoh
- Department of Diagnostic Radiology, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan
| | - Daisuke Utsunomiya
- Diagnostic Radiology, Yokohama City University Graduate School of Medicine, Yokohama, Japan
| | | | - Yoshinori Funama
- Department of Medical Physics, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan
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Harbron RW, Abdelhalim M, Ainsbury EA, Eakins JS, Alam A, Lee C, Modarai B. Patient radiation dose from x-ray guided endovascular aneurysm repair: a Monte Carlo approach using voxel phantoms and detailed exposure information. JOURNAL OF RADIOLOGICAL PROTECTION : OFFICIAL JOURNAL OF THE SOCIETY FOR RADIOLOGICAL PROTECTION 2020; 40:704-726. [PMID: 32428884 DOI: 10.1088/1361-6498/ab944e] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Endovascular aneurysm repair (EVAR) is a well-established minimally invasive technique that relies on x-ray guidance to introduce a stent through the femoral artery and manipulate it into place. The aim of this study was to estimate patient organ and effective doses from EVAR procedures using anatomically realistic computational phantoms and detailed exposure information from radiation dose structured reports (RDSR). Methods: Lookup tables of conversion factors relating kerma area product (PKA) to organ doses for 49 different beam angles were produced using Monte Carlo simulations (MCNPX2.7) with International Commission on Radiological Protection (ICRP) adult male and female voxel phantoms for EVAR procedures of varying complexity (infra-renal, fenestrated/branched and thoracic EVAR). Beam angle specific correction factors were calculated to adjust doses according to x-ray energy. A MATLAB function was written to find the appropriate conversion factor in the lookup table for each exposure described in the RDSR, perform energy corrections and multiply by the respective exposure PKA. Using this approach, organ doses were estimated for 183 EVAR procedures in which RDSRs were available. A number of simplified dose estimation methodologies were also investigated for situations in which RDSR data are not available. Results: Mean estimated bone marrow doses were 57 (range: 2-247), 86 (2-328) and 54 (8-250) mGy for infra-renal, fenestrated/branched and thoracic EVAR, respectively. Respective effective doses were 27 (1-208), 54 (1-180) and 37 (5-167) mSv. Dose estimates using non-individualised, average conversion factors, along with those produced using the alternative Monte Carlo code PCXMC, yielded reasonably similar results overall, though variation for individual procedures could exceed 100% for some organs. In conclusion, radiation doses from x-ray guided endovascular aneurysm repairs are potentially high, though this must be placed in the context of the life sparing nature and high success rate for this procedure.
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Affiliation(s)
- Richard W Harbron
- Population Health Sciences Institute, Newcastle University, Royal Victoria Infirmary, Queen Victoria Road, Newcastle-upon-Tyne NE1 4LP, United Kingdom. NIHR Health Protection Research Unit in Chemical and Radiation Threats and Hazards, Newcastle University, Newcastle-upon-Tyne United Kingdom
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Karami H, Miri-Hakimabad H, Hoseinian-Azghadi E. The effect of contrast material on radiation dose during computed tomography pulmonary angiography. Z Med Phys 2020; 30:211-221. [PMID: 32540162 DOI: 10.1016/j.zemedi.2020.03.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2019] [Revised: 03/26/2020] [Accepted: 03/30/2020] [Indexed: 11/20/2022]
Abstract
This study evaluated the impact of contrast material (CM) on radiation dose for adults undergoing computed tomography pulmonary angiography (CTPA). A previously developed physiologically based pharmacokinetic (PBPK) model and phantoms representing the average (reference) adult male and female individual were used to evaluate the iodine concentration in tissues as a function of time elapsed since the initiation of iodinated contrast medium administration. In order to estimate the radiation dose more accurately, a detailed model of pulmonary vessels was added to the phantoms. Then, the material composition of phantoms was modified to include the iodine concentration in different organs and tissues at different acquisition times after CM injection. The calculations were performed using Monte Carlo N-Particle extended code (MCNPX) version 2.6.0. The radiation dose estimates during CTPA were provided as a function of scan acquisition time after injection considering the distribution of iodinated CM within ICRP reference phantoms. It was shown that the estimated radiation dose to the lungs could be 31-40% (27-34%) larger when considering the effect of iodinated contrast administration with injection rate of 5 (3)mL/s. Moreover, the effective dose for contrast-enhanced CT (CECT) would be utmost 10-13% larger than that for non-enhanced CT (NECT). The radiation doses to the other organs in-/outside the scanned region would be decreased if the scan performed on time. In case of late scanning, absorbed dose decreases slightly for lungs (∼15-20%) whereas becomes (∼10% or more) higher than its NECT value for some organs such as heart muscle, kidneys, and spleen. To sum up, the late scanning (Δt>5s after the end of injection) is not recommended because of higher dose delivered to other organs than the lungs (particularly heart muscle).
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Affiliation(s)
- Haleh Karami
- Physics Department, Faculty of Science, Ferdowsi University of Mashhad, Mashhad, Iran
| | - Hashem Miri-Hakimabad
- Physics Department, Faculty of Science, Ferdowsi University of Mashhad, Mashhad, Iran.
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Karout L, El Asmar K, Naffaa L, Abi-Ghanem AS, El-Merhi F, Salman R, Saade C. Balancing act between quantitative and qualitative image quality between nonionic iodinated dimer and monomer at various vessel sizes during computed tomography: a phantom study. Biomed Phys Eng Express 2020; 6:035001. [PMID: 33438646 DOI: 10.1088/2057-1976/ab78dc] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
PURPOSE Investigate the impact of nonionic dimer and monomer on iodine quantification in different vessel sizes when employing a vascular specific phantom and varying iodinated contrast media (ICM) concentrations during computed tomography (CT). MATERIALS AND METHODS We created a vascular specific phantom (30 cm) to simulate human blood vessel diameters (25 cylinders of different diameters: 10 × 9mm, 10 × 12mm and 5 × 21mm). The phantom was filled with two ICM separately: Group: Iohexol(monomer)350 mg ml-1 and B: Iodixanol(Dimer)320 mg ml-1. Cylinders of same size were filled with increasing ICM concentration(10%-100%) while large cylinders were filled in quartiles(25%-100%). Phantom was scanned with different tube potential (80-140kVp), current (50-400mAs), reconstruction method [filtered back projection (FBP), hybrid-based iterative reconstruction (HBIR) and model-based iterative reconstruction (MBIR)] for each ICM. Chi-square was employed to compare mean opacification, contrast/noise ratio (CNR) and noise. Qualitative analysis was assessed by Visual grading characteristic (VGC) and Cohens-kappa analyses. RESULTS At 80 and140kVp significant difference in opacification between Group A (2054 ± 1040HU and 1696 ± 1027HU) and B (2169 ± 1105HU and 1568 ± 1034HU) was demonstrated (p < 0.001). However, at 100 and 120kVp no difference was noted (p > 0.05). When comparing image noise, it was higher in Group A compared to B (p < 0.05). CNR was higher in Group B (119.99 ± 126.10HU) than A (107.09 ± 102.56HU) (p < 0.0001). VGC: Group A outperformed B in image opacification in all vessel sizes and ICM concentrations except at medium vessels with concentration group 2(0.4-0.6 mg ml-1). Cohens'-kappa: agreement in opacification between each ICM group and iodine concentration 1(0-0.3 mg ml-1): κ = 0.253 and 0.014 respectively, concentration 2(0.4-0.6 mg ml-1):κ = -0.017 and -0.005 respectively and concentration 3(0.7-1 mg ml-1):κ = 0.031 and 0.115 respectively. CONCLUSION Nonionic dimer (Iodixanol) surpasses monomer (Iohexol) in quantitative image quality assessment by having lower image noise and higher CNR during CT.
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Affiliation(s)
- Lina Karout
- Diagnostic Radiology Department, American University of Beirut Medical Center, Beirut, American University of Beirut Medical Center, Beirut, Lebanon. P O Box: 11-0236 Riad El-Solh, Beirut, 1107 2020, Lebanon
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15
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Ren Z, Zhang X, Hu Z, Li D, Liu Z, Wei D, Jia Y, Yu N, Yu Y, Lei Y, Chen X, Guo C, Ren Z, He T. Reducing Radiation Dose and Improving Image Quality in CT Portal Venography Using 80 kV and Adaptive Statistical Iterative Reconstruction-V in Slender Patients. Acad Radiol 2020; 27:233-243. [PMID: 31031186 DOI: 10.1016/j.acra.2019.02.022] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2019] [Revised: 02/26/2019] [Accepted: 02/27/2019] [Indexed: 01/23/2023]
Abstract
OBJECTIVE To explore the feasibility of reducing radiation dose and improving image quality in CT portal venography (CTPV) using 80 kV and adaptive statistical iterative reconstruction-V(ASIR-V) in slender patients in comparison with conventional protocol using 120 kV and ASIR. METHODS Sixty slender patients for enhanced abdominal CT scanning were randomly divided into group A and group B. Group A used the conventional 120 kV tube voltage, 600 mgI/kg contrast dose and reconstructed with the recommended 40% ASIR. Group B used 80 kV tube voltage, 350 mgI/kg contrast dose and reconstructed with ASIR-V from 40% to 100% with 10% interval. The CT values and standard deviation (SD) values of the main portal vein, left branch, and right branch of portal vein, liver, and erector spinae at the same level were measured to calculate the signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR). The image quality was subjectively scored by two experienced radiologists blindly using a 5-point criterion. The contrast dose, volumetric CT dose index, and dose length product were recorded in both groups and the effective dose was calculated. RESULTS There was no significant difference in general data between the two groups (p > 0.05), the effective dose and contrast dose in group B were reduced by 63.3% (p < 0.001) and 39.7% (p < 0.001), respectively compared with group A. With the percentage of ASIR-V increased in group B, the CT values showed no significant difference, while the SD values gradually decreased and SNR values and CNR values increased accordingly. Compared with group A, group B demonstrated similar CT values (p > 0.05), while the SD values with 80% ASIR-V to 100% ASIR-V were significantly lower than those of 40% ASIR (p < 0.001), and the SNR values and CNR values with 70% ASIR-V to 100% ASIR-V were significantly higher than those of 40% ASIR (p < 0.001). The subjective image quality scores by the two radiologists had excellent consistency (kappa value>0.75, p < 0.001), and the final subjective image quality scores and the subjective scores in each of the 5 scoring categories with 60% ASIR-V to 100% ASIR-V were all significantly higher than those of 40% ASIR, and 80% ASIR-V obtained the highest subjective score among different reconstructions. CONCLUSION In CTPV, the application of 80 kV and ASIR-V reconstruction in slender patients can significantly reduce radiation dose (by 63.3%) and contrast agent dose (by 39.7%). Compared with the recommended 40% ASIR using 120 kV, ASIR-V with 80% to 100% percentages can further improve image quality and with 80% ASIR-V being the best reconstruction algorithm. ADVANCES IN KNOWLEDGE CTPV with 80 kV and ASIR-V algorithm in slender patients can significantly reduce radiation dose and contrast agent dose as well as improve image quality, compared with the conventional 120 kV protocol using 40% ASIR.
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Shirasaka T, Nagao M, Yamasaki Y, Kojima T, Kondo M, Hamasaki H, Kamitani T, Kato T, Asayama Y. Low Radiation Dose and High Image Quality of 320-Row Coronary Computed Tomography Angiography Using a Small Dose of Contrast Medium and Refined Scan Timing Prediction. J Comput Assist Tomogr 2020; 44:7-12. [PMID: 31939875 DOI: 10.1097/rct.0000000000000951] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
OBJECTIVE The aim of the study was to investigate the feasibility of coronary computed tomography (CT) angiography with a low kilovoltage peak scan and a refined scan timing prediction using a small contrast medium (CM) dose. METHODS In protocol A, 120-kVp scanning and a standard CM dose were used. The scan timing was fixed. In protocol B, 80 kVp and a 60% CM dose were used. The scan timing was determined according to the interval from the CM arrival to the peak time in the ascending aorta. We measured the CT number and recorded the radiation dose. RESULTS Higher CT numbers were observed in the left circumflex (proximal, P = 0.0235; middle, P = 0.0007; distal, P < 0.0001) in protocol B compared with protocol A. The radiation dose in protocol B was significantly lower than in protocol A (2.2 ± 0.9 vs 4.3 ± 1.7 mSv). CONCLUSIONS Low-contrast, low-radiation dose, high-image quality coronary CT angiography can be performed with low kilovoltage peak scanning and a refined scan timing prediction.
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Affiliation(s)
- Takashi Shirasaka
- From the Division of Radiology, Department of Medical Technology, Kyushu University Hospital, Fukuoka, Fukuoka Prefecture
| | - Michinobu Nagao
- Department of Diagnostic Imaging & Nuclear Medicine, Tokyo Women's Medical University, Shinjuku-ku, Tokyo
| | | | - Tsukasa Kojima
- From the Division of Radiology, Department of Medical Technology, Kyushu University Hospital, Fukuoka, Fukuoka Prefecture
| | - Masatoshi Kondo
- From the Division of Radiology, Department of Medical Technology, Kyushu University Hospital, Fukuoka, Fukuoka Prefecture
| | - Hiroshi Hamasaki
- From the Division of Radiology, Department of Medical Technology, Kyushu University Hospital, Fukuoka, Fukuoka Prefecture
| | | | - Toyoyuki Kato
- From the Division of Radiology, Department of Medical Technology, Kyushu University Hospital, Fukuoka, Fukuoka Prefecture
| | - Yoshiki Asayama
- Advanced Imaging and Interventional Radiology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Fukuoka Prefecture, Japan
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Tan SK, Ng KH, Yeong CH, Raja Aman RRA, Mohamed Sani F, Abdul Aziz YF, Sun Z. Personalized administration of contrast medium with high delivery rate in low tube voltage coronary computed tomography angiography. Quant Imaging Med Surg 2019; 9:552-564. [PMID: 31143647 DOI: 10.21037/qims.2019.03.13] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Background High delivery rate is an important factor in optimizing contrast medium administration in coronary computed tomography angiography (CCTA). A personalized contrast volume calculation algorithm incorporating high iodine delivery rate (IDR) can reduce total iodine dose (TID) and produce optimal vessel contrast enhancement (VCE) in low tube voltage CCTA. In this study, we developed and validated an algorithm for calculating the volume of contrast medium delivered at a high rate for patients undergoing retrospectively ECG-gated CCTA with low tube voltage protocol. Methods The algorithm for an IDR of 2.22 gI·s-1 was developed based on the relationship between VCE and contrast volume in 141 patients; test bolus parameters and characteristics in 75 patients; and, tube voltage in a phantom study. The algorithm was retrospectively tested in 45 patients who underwent retrospectively ECG-gated CCTA with a 100 kVp protocol. Image quality, TID and radiation dose exposure were compared with those produced using the 120 kVp and routine contrast protocols. Results Age, sex, body surface area (BSA) and peak contrast enhancement (PCE) were significant predictors for VCE (P<0.05). A strong linear correlation was observed between VCE and contrast volume (r=0.97, P<0.05). The 100-to-120 kVp contrast enhancement conversion factor (Ec) was calculated at 0.81. Optimal VCE (250 to 450 HU) and diagnostic image quality were obtained with significant reductions in TID (32.1%) and radiation dose (38.5%) when using 100 kVp and personalized contrast volume calculation algorithm compared with 120 kVp and routine contrast protocols (P<0.05). Conclusions The proposed algorithm could significantly reduce TID and radiation exposure while maintaining optimal VCE and image quality in CCTA with 100 kVp protocol.
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Affiliation(s)
- Sock Keow Tan
- Department of Biomedical Imaging, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia.,University of Malaya Research Imaging Centre (UMRIC), Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia
| | - Kwan Hoong Ng
- Department of Biomedical Imaging, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia.,University of Malaya Research Imaging Centre (UMRIC), Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia
| | - Chai Hong Yeong
- School of Medicine, Faculty of Health and Medical Sciences, Taylor's University, Subang Jaya, Malaysia
| | - Raja Rizal Azman Raja Aman
- Department of Biomedical Imaging, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia.,University of Malaya Research Imaging Centre (UMRIC), Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia
| | - Fadhli Mohamed Sani
- Department of Biomedical Imaging, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia.,University of Malaya Research Imaging Centre (UMRIC), Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia
| | - Yang Faridah Abdul Aziz
- Department of Biomedical Imaging, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia.,University of Malaya Research Imaging Centre (UMRIC), Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia
| | - Zhonghua Sun
- Discipline of Medical Radiation Sciences, Curtin University, Perth, Australia
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Nikkilä A, Raitanen J, Lohi O, Auvinen A. Radiation exposure from computerized tomography and risk of childhood leukemia: Finnish register-based case-control study of childhood leukemia (FRECCLE). Haematologica 2018; 103:1873-1880. [PMID: 29976736 PMCID: PMC6278981 DOI: 10.3324/haematol.2018.187716] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2018] [Accepted: 06/26/2018] [Indexed: 12/31/2022] Open
Abstract
The only well-established risk factors for childhood leukemia are high-dose ionizing radiation and Down syndrome. Computerized tomography is a common source of low-dose radiation. In this study, we examined the magnitude of the risk of childhood leukemia after pediatric computed tomography examinations. We evaluated the association of computed tomography scans with risk of childhood leukemia in a nationwide register-based case-control study. Cases (n=1,093) were identified from the population-based Finnish Cancer Registry and three controls, matched by gender and age, were randomly selected for each case from the Population Registry. Information was also obtained on birth weight, maternal smoking, parental socioeconomic status and background gamma radiation. Data on computed tomography scans were collected from the ten largest hospitals in Finland, covering approximately 87% of all pediatric computed tomography scans. Red bone marrow doses were estimated with NCICT dose calculation software. The data were analyzed using exact conditional logistic regression analysis. A total of 15 cases (1.4%) and ten controls (0.3%) had undergone one or more computed tomography scans, excluding a 2-year latency period. For one or more computed tomography scans, we observed an odds ratio of 2.82 (95% confidence interval: 1.05 – 7.56). Cumulative red bone marrow dose from computed tomography scans showed an excess odds ratio of 0.13 (95% confidence interval: 0.02 – 0.26) per mGy. Our results are consistent with the notion that even low doses of ionizing radiation observably increase the risk of childhood leukemia. However, the observed risk estimates are somewhat higher than those in earlier studies, probably due to random error, although unknown predisposing factors cannot be ruled out.
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Affiliation(s)
- Atte Nikkilä
- Faculty of Medicine and Biosciences, University of Tampere
| | - Jani Raitanen
- Faculty of Social Sciences, University of Tampere.,UKK Institute for Health Promotion Research, Tampere
| | - Olli Lohi
- Faculty of Medicine and Biosciences, University of Tampere.,Tampere Center for Child Health Research, University of Tampere and Tampere University Hospital
| | - Anssi Auvinen
- Faculty of Social Sciences, University of Tampere.,UKK Institute for Health Promotion Research, Tampere.,STUK - Radiation and Nuclear Safety Authority, Helsinki, Finland
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What is the underestimation of radiation dose to the pediatric thyroid gland from contrast enhanced CT, if contrast medium uptake is not taken into account? Phys Med 2018; 49:95-98. [DOI: 10.1016/j.ejmp.2018.05.009] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/20/2018] [Revised: 05/07/2018] [Accepted: 05/08/2018] [Indexed: 11/17/2022] Open
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Harbron RW, Ainsbury EA, Bouffler SD, Tanner RJ, Pearce MS, Eakins JS. The impact of iodinated contrast media on intravascular and extravascular absorbed doses in X-ray imaging: A microdosimetric analysis. Phys Med 2018; 46:140-147. [PMID: 29519400 DOI: 10.1016/j.ejmp.2018.02.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/29/2017] [Revised: 12/22/2017] [Accepted: 02/01/2018] [Indexed: 12/27/2022] Open
Abstract
Studies suggest iodinated contrast media (ICM) may increase organ dose and blood cell DNA damage for a given X-ray exposure. The impact of ICM on dose/damage to extravascular cells and cancer risks is unclear. METHODS We used Monte Carlo modelling to investigate the microscopic distribution of absorbed dose outside the lumen of arteries, capillaries and interstitial fluids containing blood and various concentrations of iodine. Models were irradiated with four X-ray spectra representing clinical procedures. RESULTS For the artery model, The average dose enhancement factors (DEF) to blood were 1.70, 2.38, 7.38, and 12.34 for mass concentrations of iodine in blood (ρiI) of 5, 10, 50 and 100 mg/ml, respectively, compared to 0 mg/ml. Average DEFs were reduced to 1.26, 1.51, 3.48 and 5.56, respectively, in the first micrometre of the vessel wall, falling to 1.01, 1.02, 1.06 and 1.09 at 40-50 μm from the lumen edge. For the capillary models, DEF for extravascular tissues was on average 48% lower than DEF for the whole model, including capillaries. A similar situation was observed for the interstitial model, with DEF to the cell nucleus being 35% lower than DEF for the whole model. CONCLUSIONS While ICM may modify the absorbed doses from diagnostic X-ray examinations, the effect is smaller than suggested by assays of circulating blood cells or blood dose enhancement. Conversely, the potentially large increase in dose to the endothelium of blood vessels means that macroscopic organ doses may underestimate the risk of radiation induced cardiovascular disease for ICM-enhanced exposures.
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Affiliation(s)
- Richard W Harbron
- Institute of Health and Society, Newcastle University, Royal Victoria Infirmary, Queen Victoria Road, Newcastle-upon-Tyne NE1 4LP, UK; NIHR Health Protection Research Unit in Chemical and Radiation Threats and Hazards, Newcastle University, UK.
| | - Elizabeth A Ainsbury
- Public Health England, Centre for Radiation, Chemical and Environmental Hazards, Chilton, Didcot OX11 0RQ, UK
| | - Simon D Bouffler
- Public Health England, Centre for Radiation, Chemical and Environmental Hazards, Chilton, Didcot OX11 0RQ, UK
| | - Rick J Tanner
- Public Health England, Centre for Radiation, Chemical and Environmental Hazards, Chilton, Didcot OX11 0RQ, UK
| | - Mark S Pearce
- Institute of Health and Society, Newcastle University, Royal Victoria Infirmary, Queen Victoria Road, Newcastle-upon-Tyne NE1 4LP, UK; NIHR Health Protection Research Unit in Chemical and Radiation Threats and Hazards, Newcastle University, UK
| | - Jonathan S Eakins
- Public Health England, Centre for Radiation, Chemical and Environmental Hazards, Chilton, Didcot OX11 0RQ, UK
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Abstract
BACKGROUND Radiation exposure is a well-known risk factor for thyroid cancer. However, the specific effects of diagnostic radiation exposure on thyroid cancer risk are controversial. The purpose of this study was to perform a systematic review and meta-analysis to assess the effects of diagnostic radiation exposure on thyroid cancer risk. METHODS The PubMed and EMBASE databases were searched to identify eligible studies. Summary odds ratio (OR) estimates and confidence intervals (CIs) were used to compute the risk of thyroid cancer using fixed- and random-effects models. Subgroup and sensitivity analyses were performed to evaluate the potential heterogeneity. RESULTS Nine studies from 12 publications were included in the meta-analysis. Overall exposure to diagnostic radiation exposure was associated with a significantly increased thyroid cancer risk (OR = 1.52 [CI 1.13-2.04]). The subgroup and sensitivity analyses revealed similar results. By type of exposure, exposure to computed tomography scans (OR = 1.46 [CI 1.27-1.68]) or dental x-rays (OR = 1.69 [CI 1.17-2.44]) were associated with an increased thyroid cancer risk. Head and neck (OR = 1.31 [CI 1.02-1.69]) and chest (OR = 1.71 [CI 1.09-2.69]) exposure to diagnostic radiation was associated with an increased thyroid cancer risk. CONCLUSIONS The results of this meta-analysis indicate that diagnostic radiation exposure is associated with an increased thyroid cancer risk. Therefore, to the extent that it will not compromise the information being sought, radiation exposure to the thyroid should be minimized during diagnostic examinations.
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Affiliation(s)
- Mi Ah Han
- 1 Department of Preventive Medicine, College of Medicine, Chosun University , Korea
| | - Jin Hwa Kim
- 2 Department of Internal Medicine, College of Medicine, Chosun University , Korea
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22
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Harbron R, Ainsbury EA, Bouffler SD, Tanner RJ, Eakins JS, Pearce MS. Enhanced radiation dose and DNA damage associated with iodinated contrast media in diagnostic X-ray imaging. Br J Radiol 2017; 90:20170028. [PMID: 28830201 DOI: 10.1259/bjr.20170028] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
A review was undertaken of studies reporting increased DNA damage in circulating blood cells and increased organ doses, for X-ray exposures enhanced by iodinated contrast media (ICM), compared to unenhanced imaging. This effect may be due to ICM molecules acting as a source of secondary radiation (Auger/photoelectrons, fluorescence X-rays) following absorption of primary X-ray photons. It is unclear if the reported increase in DNA damage to blood cells necessarily implies an increased risk of developing cancer. Upon ICM-enhancement, the attenuation properties of blood differ substantially from surrounding tissues. Increased energy deposition is likely to occur within very close proximity to ICM molecules (within a few tens of micrometres). Consequently, in many situations, damage and dose enhancement may be restricted to the blood and vessel wall only. Increased cancer risks may be possible, in cases where ICM molecules are given sufficient time to reach the capillary network and interstitial fluid at the time of exposure. In all situations, the extrapolation of blood cell damage to other tissues requires caution where contrast media are involved. Future research is needed to determine the impact of ICM on dose to cells outside the blood itself and vessel walls, and to determine the concentration of ICM in blood vessels and interstitial fluid at the time of exposure.
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Affiliation(s)
- Richard Harbron
- 1 Institute of Health and Society, Newcastle University, Newcastle upon Tyne, UK.,2 Health Protection Research Unit for Chemical & Radiation Threats & Hazards, Newcastle University, Newcastle upon Tyne, UK
| | - Elizabeth A Ainsbury
- 3 Centre for Radiation, Chemical and Environmental Hazards, Public Health England, Chilton, UK
| | - Simon D Bouffler
- 3 Centre for Radiation, Chemical and Environmental Hazards, Public Health England, Chilton, UK
| | - Rick J Tanner
- 3 Centre for Radiation, Chemical and Environmental Hazards, Public Health England, Chilton, UK
| | - Jonathan S Eakins
- 3 Centre for Radiation, Chemical and Environmental Hazards, Public Health England, Chilton, UK
| | - Mark S Pearce
- 1 Institute of Health and Society, Newcastle University, Newcastle upon Tyne, UK.,2 Health Protection Research Unit for Chemical & Radiation Threats & Hazards, Newcastle University, Newcastle upon Tyne, UK
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Perisinakis K, Tzedakis A, Spanakis K, Papadakis AE, Hatzidakis A, Damilakis J. The effect of iodine uptake on radiation dose absorbed by patient tissues in contrast enhanced CT imaging: Implications for CT dosimetry. Eur Radiol 2017; 28:151-158. [DOI: 10.1007/s00330-017-4970-1] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2017] [Revised: 06/01/2017] [Accepted: 06/28/2017] [Indexed: 11/25/2022]
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Streitmatter SW, Stewart RD, Jenkins PA, Jevremovic T. DNA double strand break (DSB) induction and cell survival in iodine-enhanced computed tomography (CT). Phys Med Biol 2017; 62:6164-6184. [PMID: 28703119 DOI: 10.1088/1361-6560/aa772d] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
A multi-scale Monte Carlo model is proposed to assess the dosimetric and biological impact of iodine-based contrast agents commonly used in computed tomography. As presented, the model integrates the general purpose MCNP6 code system for larger-scale radiation transport and dose assessment with the Monte Carlo damage simulation to determine the sub-cellular characteristics and spatial distribution of initial DNA damage. The repair-misrepair-fixation model is then used to relate DNA double strand break (DSB) induction to reproductive cell death. Comparisons of measured and modeled changes in reproductive cell survival for ultrasoft characteristic k-shell x-rays (0.25-4.55 keV) up to orthovoltage (200-500 kVp) x-rays indicate that the relative biological effectiveness (RBE) for DSB induction is within a few percent of the RBE for cell survival. Because of the very short range of secondary electrons produced by low energy x-ray interactions with contrast agents, the concentration and subcellular distribution of iodine within and near cellular targets have a significant impact on the estimated absorbed dose and number of DSB produced in the cell nucleus. For some plausible models of the cell-level distribution of contrast agent, the model predicts an increase in RBE-weighted dose (RWD) for the endpoint of DSB induction of 1.22-1.40 for a 5-10 mg ml-1 iodine concentration in blood compared to an RWD increase of 1.07 ± 0.19 from a recent clinical trial. The modeled RWD of 2.58 ± 0.03 is also in good agreement with the measured RWD of 2.3 ± 0.5 for an iodine concentration of 50 mg ml-1 relative to no iodine. The good agreement between modeled and measured DSB and cell survival estimates provides some confidence that the presented model can be used to accurately assess biological dose for other concentrations of the same or different contrast agents.
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Affiliation(s)
- Seth W Streitmatter
- Nuclear Engineering Program, The University of Utah, 50 S. Central Campus Drive, 1206 MEB, Salt Lake City, UT 84112, United States of America. Department of Radiology and Imaging Sciences, University of Utah Health, 30 North 1900 East #1A71, Salt Lake City, UT 84132, United States of America
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Sahbaee P, Abadi E, Segars WP, Marin D, Nelson RC, Samei E. The Effect of Contrast Material on Radiation Dose at CT: Part II. A Systematic Evaluation across 58 Patient Models. Radiology 2017; 283:749-757. [PMID: 28287916 DOI: 10.1148/radiol.2017152852] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Purpose To estimate the radiation dose as a result of contrast medium administration in a typical abdominal computed tomographic (CT) examination across a library of contrast material-enhanced computational patient models. Materials and Methods In part II of this study, first, the technique described in part I of this study was applied to enhance the extended cardiac-torso models with patient-specific iodine-time profiles reflecting the administration of contrast material. Second, the patient models were deployed to assess the patient-specific organ dose as a function of time in a typical abdominal CT examination using Monte Carlo simulation. In this hypothesis-generating study, organ dose refers to the total energy deposited in the unit mass of the tissue inclusive of iodine. Third, a study was performed as a strategy to anticipate the biologically relevant dose (absorbed dose to tissue) in highly perfused organs such as the liver and kidney. The time-varying organ-dose increment values relative to those for unenhanced CT examinations were reported. Results The results from the patient models subjected to the injection protocol indicated up to a total 53%, 30%, 35%, 54%, 27%, 18%, 17%, and 24% increase in radiation dose delivered to the heart, spleen, liver, kidneys, stomach, colon, small intestine, and pancreas, respectively. The biologically relevant dose increase with respect to the dose at an unenhanced CT examination was in the range of 0%-18% increase for the liver and 27% for the kidney across 58 patient models. Conclusion The administration of contrast medium increases the total radiation dose. However, radiation dose, while relevant to be included in estimating the risk associated with contrast-enhanced CT, may still not fully characterize the total biologic effects. Therefore, given the fact that many CT diagnostic decisions would be impossible without the use of iodine, this study suggests the need to consider the effect of iodinated contrast material on the organ doses to patients undergoing CT studies when designing CT protocols. © RSNA, 2017 Online supplemental material is available for this article.
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Affiliation(s)
- Pooyan Sahbaee
- From the Carl E. Ravin Advanced Imaging Laboratories, Department of Radiology, Duke University Medical Center, 2424 Erwin Rd, Suite 302, Durham, NC 27705 (P.S., E.A., W.P.S., D.M., R.C.N., E.S.); and Department of Physics, North Carolina State University, Raleigh, NC (P.S.)
| | - Ehsan Abadi
- From the Carl E. Ravin Advanced Imaging Laboratories, Department of Radiology, Duke University Medical Center, 2424 Erwin Rd, Suite 302, Durham, NC 27705 (P.S., E.A., W.P.S., D.M., R.C.N., E.S.); and Department of Physics, North Carolina State University, Raleigh, NC (P.S.)
| | - W Paul Segars
- From the Carl E. Ravin Advanced Imaging Laboratories, Department of Radiology, Duke University Medical Center, 2424 Erwin Rd, Suite 302, Durham, NC 27705 (P.S., E.A., W.P.S., D.M., R.C.N., E.S.); and Department of Physics, North Carolina State University, Raleigh, NC (P.S.)
| | - Daniele Marin
- From the Carl E. Ravin Advanced Imaging Laboratories, Department of Radiology, Duke University Medical Center, 2424 Erwin Rd, Suite 302, Durham, NC 27705 (P.S., E.A., W.P.S., D.M., R.C.N., E.S.); and Department of Physics, North Carolina State University, Raleigh, NC (P.S.)
| | - Rendon C Nelson
- From the Carl E. Ravin Advanced Imaging Laboratories, Department of Radiology, Duke University Medical Center, 2424 Erwin Rd, Suite 302, Durham, NC 27705 (P.S., E.A., W.P.S., D.M., R.C.N., E.S.); and Department of Physics, North Carolina State University, Raleigh, NC (P.S.)
| | - Ehsan Samei
- From the Carl E. Ravin Advanced Imaging Laboratories, Department of Radiology, Duke University Medical Center, 2424 Erwin Rd, Suite 302, Durham, NC 27705 (P.S., E.A., W.P.S., D.M., R.C.N., E.S.); and Department of Physics, North Carolina State University, Raleigh, NC (P.S.)
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Sahbaee P, Segars WP, Marin D, Nelson RC, Samei E. The Effect of Contrast Material on Radiation Dose at CT: Part I. Incorporation of Contrast Material Dynamics in Anthropomorphic Phantoms. Radiology 2017; 283:739-748. [PMID: 28092496 DOI: 10.1148/radiol.2016152851] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Purpose To develop a method to incorporate the propagation of contrast material into computational anthropomorphic phantoms for estimation of organ dose at computed tomography (CT). Materials and Methods A patient-specific physiologically based pharmacokinetic (PBPK) model of the human cardiovascular system was incorporated into 58 extended cardiac-torso (XCAT) patient phantoms. The PBPK model comprised compartmental models of vessels and organs unique to each XCAT model. For typical injection protocols, the dynamics of the contrast material in the body were described according to a series of patient-specific iodine mass-balance differential equations, the solutions to which provided the contrast material concentration time curves for each compartment. Each organ was assigned to a corresponding time-varying iodinated contrast agent to create the contrast material-enhanced five-dimensional XCAT models, in which the fifth dimension represents the dynamics of contrast material. To validate the accuracy of the models, simulated aortic and hepatic contrast-enhancement results throughout the models were compared with previously published clinical data by using the percentage of discrepancy in the mean, time to 90% peak, peak value, and slope of enhancement in a paired t test at the 95% significance level. Results The PBPK model allowed effective prediction of the time-varying concentration curves of various contrast material administrations in each organ for different patient models. The contrast-enhancement results were in agreement with results of previously published clinical data, with mean percentage, time to 90% peak, peak value, and slope of less than 10% (P > .74), 4%, 7%, and 14% for uniphasic and 12% (P > .56), 4%, 12%, and 14% for biphasic injection protocols, respectively. The exception was hepatic enhancement results calculated for a uniphasic injection protocol for which the discrepancy was less than 25%. Conclusion A technique to model the propagation of contrast material in XCAT human models was developed. The models with added contrast material propagation can be applied to simulate contrast-enhanced CT examinations. © RSNA, 2017 Online supplemental material is available for this article.
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Affiliation(s)
- Pooyan Sahbaee
- From the Carl E. Ravin Advanced Imaging Laboratories (P.S., W.P.S., E.S.) and Departments of Radiology (P.S., D.M., R.C.N., E.S.), Medical Physics Graduate Program (W.P.S., E.S.), and Biomedical Engineering, Electrical and Computer Engineering, and Physics (E.S.), Duke University Medical Center, 2424 Erwin Rd, Suite 302, Durham, NC 27705; and Department of Physics, NC State University, Raleigh, NC (P.S.)
| | - W Paul Segars
- From the Carl E. Ravin Advanced Imaging Laboratories (P.S., W.P.S., E.S.) and Departments of Radiology (P.S., D.M., R.C.N., E.S.), Medical Physics Graduate Program (W.P.S., E.S.), and Biomedical Engineering, Electrical and Computer Engineering, and Physics (E.S.), Duke University Medical Center, 2424 Erwin Rd, Suite 302, Durham, NC 27705; and Department of Physics, NC State University, Raleigh, NC (P.S.)
| | - Daniele Marin
- From the Carl E. Ravin Advanced Imaging Laboratories (P.S., W.P.S., E.S.) and Departments of Radiology (P.S., D.M., R.C.N., E.S.), Medical Physics Graduate Program (W.P.S., E.S.), and Biomedical Engineering, Electrical and Computer Engineering, and Physics (E.S.), Duke University Medical Center, 2424 Erwin Rd, Suite 302, Durham, NC 27705; and Department of Physics, NC State University, Raleigh, NC (P.S.)
| | - Rendon C Nelson
- From the Carl E. Ravin Advanced Imaging Laboratories (P.S., W.P.S., E.S.) and Departments of Radiology (P.S., D.M., R.C.N., E.S.), Medical Physics Graduate Program (W.P.S., E.S.), and Biomedical Engineering, Electrical and Computer Engineering, and Physics (E.S.), Duke University Medical Center, 2424 Erwin Rd, Suite 302, Durham, NC 27705; and Department of Physics, NC State University, Raleigh, NC (P.S.)
| | - Ehsan Samei
- From the Carl E. Ravin Advanced Imaging Laboratories (P.S., W.P.S., E.S.) and Departments of Radiology (P.S., D.M., R.C.N., E.S.), Medical Physics Graduate Program (W.P.S., E.S.), and Biomedical Engineering, Electrical and Computer Engineering, and Physics (E.S.), Duke University Medical Center, 2424 Erwin Rd, Suite 302, Durham, NC 27705; and Department of Physics, NC State University, Raleigh, NC (P.S.)
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Detection of Renal Stones on Portal Venous Phase CT: Comparison of Thin Axial and Coronal Maximum-Intensity-Projection Images. AJR Am J Roentgenol 2016; 207:1200-1204. [DOI: 10.2214/ajr.16.16099] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Harbron R. What do recent epidemiological studies tell us about the risk of cancer from radiation doses typical of diagnostic radiography? Radiography (Lond) 2016. [DOI: 10.1016/j.radi.2016.08.007] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Navin P, Murray AM, Nandikumar K, Waldron R, Tuohy B, Casey M. Shaped-bolus protocol reduces contrast medium volume in abdominal CT while maintaining image quality. Clin Radiol 2016; 72:265.e1-265.e5. [PMID: 27884388 DOI: 10.1016/j.crad.2016.10.011] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2016] [Revised: 09/10/2016] [Accepted: 10/18/2016] [Indexed: 01/29/2023]
Abstract
AIM To prospectively assess whether bolus shaping to exponentially decrease the contrast medium injection rate leads to alteration in image validity or renal function. MATERIALS AND METHODS In this prospective study, patients alternatively received 100 ml contrast medium versus 75 ml via bolus shaping. Image quality was assessed via measurement of attenuation values in the aorta, liver, and spleen and also blinded subjective assessment of image sharpness, low contrast detectability, image noise, and overall quality. Renal function was assessed by change in creatinine levels up to 72 hours post-contrast medium administration. RESULTS Of 190 abdominal computed tomography (CT) studies performed in the 3-month period, 98 received the 75 ml dose. There was no significant difference in renal function or objective image quality with a significant improvement in image sharpness in the 100 ml group. CONCLUSIONS By using bolus-shaping software, it is possible to maintain objective image quality while reducing the contrast medium load to the patient. This has significant implications regarding clinical practice in decreasing cost and risks associated with iodinated contrast media.
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Affiliation(s)
- P Navin
- Department of Radiology, Mayo General Hospital, Castlebar, County Mayo, Ireland.
| | - A M Murray
- Department of Radiology, Mayo General Hospital, Castlebar, County Mayo, Ireland
| | - K Nandikumar
- Department of Radiology, Mayo General Hospital, Castlebar, County Mayo, Ireland
| | - R Waldron
- Department of General Surgery, Mayo General Hospital, Castlebar, County Mayo, Ireland
| | - B Tuohy
- Department of Physics, Saolta University Healthcare Group, Galway, Ireland
| | - M Casey
- Department of Radiology, Mayo General Hospital, Castlebar, County Mayo, Ireland
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Camera L, Liccardo I, Romano F, Liuzzi R, Rispo A, Imbriaco M, Testa A, Luglio G, De Fronzo S, Castiglione F, Bucci L, Brunetti A. Diagnostic efficacy of single-pass abdominal multidetector-row CT: prospective evaluation of a low dose protocol. Br J Radiol 2016; 90:20160612. [PMID: 27826994 DOI: 10.1259/bjr.20160612] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
OBJECTIVE To evaluate the diagnostic efficacy of single-pass contrast-enhanced multidetector CT (CE-MDCT) performed with a low-radiation high-contrast (LR-HC) dose protocol in selected patients with non-traumatic acute bowel disease. METHODS 65 (32 males, 33 females; aged 20-67 years) consecutive patients with non-traumatic acute bowel disease underwent single-pass CE-MDCT performed 70-100 s after i.v. bolus injection of a non-ionic iodinated contrast medium (CM) (370 mgI ml-1). In 46 (70%) patients with a clinical and/or ultrasonographic suspicion of inflammatory bowel disease, up to 1.2-1.4 l of a 7% polyethylene-glycol solution was orally administered 45-60 mins prior to the CT examination. Patients were then divided into two groups according to age: Group A (20-44 years; n = 34) and Group B (45-70 years; n = 31). Noise index (NI) and CM dose were selected as follows: Group A (NI = 15; 2.5 ml kg-1) and Group B (NI = 12.5; 2 ml kg-1). All patients of Group A underwent thyroid functional tests at 4-6 weeks. Final diagnoses were obtained by open (n = 12) or laparoscopic surgery (n = 4), endoscopy w/without biopsy (n = 24) and clinical (n = 19) and/or instrumental (ultrasonography) (n = 6) follow-up at 11 ± 4 months (range 6-18 mo.). Statistical analysis was performed by χ2 and Student's t-test for categorical and continuous variables, respectively. RESULTS Sensitivity and specificity were 91.3 vs 95.4% (p = 0.905) and 90.9 vs 88.8% (p = 0.998) with an overall diagnostic accuracy of 91.1 vs 93.5% (p = 0.756), whereas the radiation (in millisievert) and CM dose (in millilitre) were 7.5 ± 2.8 mSv and 155 ± 30 ml for Group A and 14.1 ± 5.3 mSv and 130 ± 24 ml for Group B (p < 0.001), respectively. No patients of Group A showed laboratory signs of thyrotoxicosis at follow-up. CONCLUSION The LR-HC has proved to be a safe and a dose-effective protocol in the evaluation of selected young patients with non-traumatic acute bowel disease. Advances in knowledge: (1) As reaching the highest diagnostic benefit to risk ratio (AHARA) appears to be the current principle of MDCT imaging, an increased amount of iodinated CM (0.7-0.9 gI ml-1) can be safely administered to young patients (<40 years) with normal thyroid and renal function to compensate for the lower image quality resulting from low-dose CT protocols performed with the standard filter back-projection algorithm. Such an approach will result in a significant reduction of the radiation dose, which could be otherwise achieved only using iterative reconstruction algorithms combined with either low tube voltage and/or low tube current protocols. (2) An optimal scan delay (Tdelay) for a venous phase caudocranial acquisition can be calculated by the following formula: Tdelay = CI + 25 - TSD, where CI is the duration of the contrast injection, 25 is the average of the sum of abdominal aortic and peak hepatic arrival times and TSD is the scan duration. With such an approach, the radiation exposure resulting from bolus tracking, albeit performed with low-dose scans, can be spared in patients with normal transit times.
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Affiliation(s)
- Luigi Camera
- 1 Section of Diagnostic Imaging, Department of Advanced Biomedical Sciences, University "Federico II", Naples, Italy.,2 National Research Council (CNR), Institute of Biostructures and Bioimaging, Naples, Italy
| | - Immacolata Liccardo
- 1 Section of Diagnostic Imaging, Department of Advanced Biomedical Sciences, University "Federico II", Naples, Italy
| | - Federica Romano
- 1 Section of Diagnostic Imaging, Department of Advanced Biomedical Sciences, University "Federico II", Naples, Italy
| | - Raffaele Liuzzi
- 2 National Research Council (CNR), Institute of Biostructures and Bioimaging, Naples, Italy
| | - Antonio Rispo
- 3 Section of Gastroenterology, Department of Clinical Medicine and Surgery, University "Federico ll", Naples, Italy
| | - Massimo Imbriaco
- 1 Section of Diagnostic Imaging, Department of Advanced Biomedical Sciences, University "Federico II", Naples, Italy
| | - Anna Testa
- 3 Section of Gastroenterology, Department of Clinical Medicine and Surgery, University "Federico ll", Naples, Italy
| | - Gaetano Luglio
- 4 Section of Colo-rectal Surgery, Department of Clinical Medicine and Surgery, University "Federico ll", Naples, Italy
| | - Simona De Fronzo
- 1 Section of Diagnostic Imaging, Department of Advanced Biomedical Sciences, University "Federico II", Naples, Italy
| | - Fabiana Castiglione
- 3 Section of Gastroenterology, Department of Clinical Medicine and Surgery, University "Federico ll", Naples, Italy
| | - Luigi Bucci
- 4 Section of Colo-rectal Surgery, Department of Clinical Medicine and Surgery, University "Federico ll", Naples, Italy
| | - Arturo Brunetti
- 1 Section of Diagnostic Imaging, Department of Advanced Biomedical Sciences, University "Federico II", Naples, Italy
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Exponentially Decelerated Contrast Media Injection Rate Combined With a Novel Patient-Specific Contrast Formula Reduces Contrast Volume Administration and Radiation Dose During Computed Tomography Pulmonary Angiography. J Comput Assist Tomogr 2016; 40:370-4. [DOI: 10.1097/rct.0000000000000371] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Amato E, Asero G, Leotta S, Auditore L, Salamone I, Mannino G, Privitera S, Gueli A. Influence of the X-ray beam quality on the dose increment in CT with iodinated contrast medium. JOURNAL OF X-RAY SCIENCE AND TECHNOLOGY 2016; 24:267-278. [PMID: 27002906 DOI: 10.3233/xst-160551] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
BACKGROUND In computed tomography (CT), the image contrast is given by the difference in X-ray attenuation in the various tissues of the patient and contrast media are used to enhance image contrast in anatomic regions characterized by similar attenuation coefficients. OBJECTIVE Aim of the present work is to enlarge the range of applicability of the method previously introduced for organ dosimetry in contrast-enhanced CT, by studying the effects of X-ray beam quality on the parameters of the model. Furthermore, an experimental method for the evaluation of the attenuation properties of iodinated solutions is proposed. METHODS Monte Carlo simulations of anthropomorphic phantoms were carried out to determine a bi-parametrical (a and b) analytical relationship between iodine concentration and dose increase in organs of interest as a function of the tube kilo-voltage peak potential (kVp) and filtration. Experimental measurements of increments in Hounsfield Units (HU) were conducted in several CT scanners, at all the kVp available, in order to determine the parameter γ which relates the HU increment with the iodine mass fraction. A cylindrical phantom that can be filled with iodine solutions provided with an axial housing for a pencil ionization chamber was designed and assembled in order to measure the attenuation properties of iodine solutions under irradiation of a CT scanner and to obtain a further validation of Monte Carlo simulations. RESULTS The simulation-derived parameters of the model, a and b, are only slightly dependent upon the tube kilo-voltage peak potential and filtration, while such scanner-dependent features influence mainly the experimentally-derived γ parameter. Relative dose variations registered by the ionization chamber inside the iodine-filled cylindrical phantom decrease when the X-ray mean energy increases, and reaches about 50% for 10 mg/ml of iodine. CONCLUSIONS The dosimetric method for contrast-enhanced CT can be applied to all CT scanners by adopting average simulative parameters and by carrying out a simple measurement with a series of iodine contrast solutions. The novel experimental methodology introduced can provide a direct measurement of iodine attenuation properties.
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Affiliation(s)
- Ernesto Amato
- Department of Biomedical Sciences and of Morphologic and Functional Imaging, Section of Radiological Sciences, University of Messina, Messina, Italy
| | - Grazia Asero
- PH3DRA (Physics for Dating Diagnostic Dosimetry Research and Applications) Laboratories, Department of Physics and Astronomy, University of Catania, Catania, Italy
| | - Salvatore Leotta
- Department of Physics and Earth Sciences, University of Messina, Messina, Italy
| | - Lucrezia Auditore
- Department of Physics and Earth Sciences, University of Messina, Messina, Italy
| | - Ignazio Salamone
- Department of Biomedical Sciences and of Morphologic and Functional Imaging, Section of Radiological Sciences, University of Messina, Messina, Italy
- University Hospital "Policlinico Gaetano Martino", Messina, Italy
| | - Giovanni Mannino
- University Hospital "Policlinico - Vittorio Emanuele", Catania, Italy
| | - Salvatore Privitera
- PH3DRA (Physics for Dating Diagnostic Dosimetry Research and Applications) Laboratories, Department of Physics and Astronomy, University of Catania, Catania, Italy
| | - Anna Gueli
- PH3DRA (Physics for Dating Diagnostic Dosimetry Research and Applications) Laboratories, Department of Physics and Astronomy, University of Catania, Catania, Italy
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Berrington de Gonzalez A, Kleinerman RA. CT Scanning: Is the Contrast Material Enhancing the Radiation Dose and Cancer Risk as Well as the Image? Radiology 2015; 275:627-9. [PMID: 25997129 DOI: 10.1148/radiol.2015150605] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Amy Berrington de Gonzalez
- From the Radiation Epidemiology Branch, Division of Cancer Epidemiology and Genetics (DCEG), National Cancer Institute, 6120 Executive Blvd, Bethesda, MD 20892
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Renal stones on portal venous phase contrast-enhanced CT: does intravenous contrast interfere with detection? ACTA ACUST UNITED AC 2015; 39:526-32. [PMID: 24504541 DOI: 10.1007/s00261-014-0082-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
PURPOSE To determine the sensitivity of portal venous phase contrast-enhanced CT for the detection of renal stones. METHODS This retrospective study included 97 CT examinations of the abdomen without and with intravenous contrast, including 85 (87.6%) examinations with at least one renal stone on the "gold standard" noncontrast images, as scored by a single radiologist. Three other radiologists each independently reviewed only the contrast-enhanced images from all 97 examinations and recorded all renal stones. Reviewer sensitivity for stones was categorized by stone diameter. Reviewer sensitivity and specificity for stone disease were also calculated on a per-kidney basis. RESULTS The 97 cases included a total of 238 stones ≥1 mm, with a mean (±SD) of 1.2 ± 1.9 stones per kidney and a stone diameter of 3.5 ± 3.0 mm. Pooling data for the three reviewers, sensitivity for all stones was 81%; sensitivity for stones ≥2, ≥3, ≥4, and ≥5 mm was 88%, 95%, 99%, and 98%, respectively. Sensitivity for stone disease on a per-kidney basis was 94% when considering all stones; when considering only stones ≥2, ≥3, and ≥4 mm, sensitivity was 96%, 99%, and 100%, respectively. Specificity for stone disease on a per-kidney basis was 98% overall, 99% when considering only stones ≥2 mm, and 100% when considering only stones ≥3 mm. CONCLUSION Contrast-enhanced CT is highly sensitive for the detection of renal stones ≥3 mm in diameter and less sensitive for smaller stones. In cases where the clinical diagnosis is uncertain and performance of a CT examination is being contemplated, intravenous contrast utilization would allow assessment for stone disease while also optimizing evaluation for other conditions.
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He W, Huda W, Mah E, Yao H. Does administering iodine in radiological procedures increase patient doses? Med Phys 2014; 41:113901. [PMID: 25370675 DOI: 10.1118/1.4898594] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE The authors investigated the changes in the pattern of energy deposition in tissue equivalent phantoms following the introduction of iodinated contrast media. METHODS The phantom consisted of a small "contrast sphere," filled with water or iodinated contrast, located at the center of a 28 cm diameter water sphere. Monte Carlo simulations were performed using mcnp5 codes, validated by simulating irradiations with analytical solutions. Monoenergetic x-rays ranging from 35 to 150 keV were used to simulate exposures to spheres containing contrast agent with iodine concentrations ranging from 1 to 100 mg/ml. Relative values of energy imparted to the contrast sphere, as well as to the whole phantom, were calculated. Changes in patterns of energy deposition around the contrast sphere were also investigated. RESULTS Small contrast spheres can increase local absorbed dose by a factor of 13, but the corresponding increase in total energy absorbed was negligible (<1%). The highest localized dose increases were found to occur at incident photon energies of about 60 keV. For a concentration of about 10 mg/ml, typical of clinical practice, localized absorbed doses were generally increased by about a factor of two. At this concentration of 10 mg/ml, the maximum increase in total energy deposition in the phantom was only 6%. These simulations demonstrated that increases in contrast sphere doses were offset by corresponding dose reductions at distal and posterior locations. CONCLUSIONS Adding iodine can result in values of localized absorbed dose increasing by more than an order of magnitude, but the total energy deposition is generally very modest (i.e., <10%). Their data show that adding iodine primarily changes the pattern of energy deposition in the irradiated region, rather than increasing patient doses per se.
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Affiliation(s)
- Wenjun He
- Clemson-MUSC Bioengineering Program, Department of Bioengineering, Clemson University, Charleston, South Carolina 29425
| | - Walter Huda
- Department of Radiology and Radiological Science, Medical University of South Carolina (MUSC), Charleston, South Carolina 29425
| | - Eugene Mah
- Department of Radiology and Radiological Science, Medical University of South Carolina (MUSC), Charleston, South Carolina 29425
| | - Hai Yao
- Clemson-MUSC Bioengineering Program, Department of Bioengineering, Clemson University, Charleston, South Carolina 29425
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Amato E, Italiano A. An analytical model for calculating internal dose conversion coefficients for non-human biota. RADIATION AND ENVIRONMENTAL BIOPHYSICS 2014; 53:455-459. [PMID: 24668284 DOI: 10.1007/s00411-014-0526-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2013] [Accepted: 02/17/2014] [Indexed: 06/03/2023]
Abstract
To assess the radiation burden of non-human living organisms, dose coefficients are available in the literature, precalculated by assuming an ellipsoidal shape of each organism. A previously developed analytical method was applied for the determination of absorbed fractions inside ellipsoidal volumes from alpha, beta, and gamma radiations to the calculation of dose conversion coefficients (DCCs) for 15 reference organisms, animals and plants, either terrestrial, amphibian, or aquatic, and six radionuclides ((14)C, (90)Sr, (60)Co, (137)Cs, (238)U, and (241)Am). The results were compared with the reference values reported in Publication 108 of the International Commission on Radiological Protection, in which a different calculation approach for DCCs was employed. The results demonstrate that the present analytical method, originally intended for applications in internal dosimetry of nuclear medicine therapy, gives consistent results for all the beta-, beta-gamma-, and alpha-emitting radionuclides tested in a wide range of organism masses, between 8 mg and 1.3 kg. The applicability of the method proposed can take advantage from its ease of implementation in an ordinary electronic spreadsheet, allowing to calculate, for virtually all possible radionuclide emission spectra, the DCCs for ellipsoidal models of non-human living organisms in the environment.
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Affiliation(s)
- Ernesto Amato
- Section of Radiological Sciences, Department Biomedical Sciences and of Morphologic and Functional Imaging, University of Messina, Messina, Italy
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Seidenbusch M, Harder D, Regulla D. Systematic survey of the dose enhancement in tissue-equivalent materials facing medium- and high-Z backscatterers exposed to X-rays with energies from 5 to 250 keV. RADIATION AND ENVIRONMENTAL BIOPHYSICS 2014; 53:437-453. [PMID: 24633421 DOI: 10.1007/s00411-014-0524-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2013] [Accepted: 02/08/2014] [Indexed: 06/03/2023]
Abstract
The present study has been inspired by the results of earlier dose measurements in tissue-equivalent materials adjacent to thin foils of aluminum, copper, tin, gold, and lead. Large dose enhancements have been observed in low-Z materials near the interface when this ensemble was irradiated with X-rays of qualities known from diagnostic radiology. The excess doses have been attributed to photo-, Compton, and Auger electrons released from the metal surfaces. Correspondingly, high enhancements of biological effects have been observed in single cell layers arranged close to gold surfaces. The objective of the present work is to systematically survey, by calculation, the values of the dose enhancement in low-Z media facing backscattering materials with a variety of atomic numbers and over a large range of photon energies. Further parameters to be varied are the distance of the point of interest from the interface and the kind of the low-Z material. The voluminous calculations have been performed using the PHOTCOEF algorithm, a proven set of interpolation functions fitted to long-established Monte Carlo results, for primary photon energies between 5 and 250 keV and for atomic numbers varying over the periodic system up to Z = 100. The calculated results correlate well with our previous experimental results. It is shown that the values of the dose enhancement (a) vary strongly in dependence upon Z and photon energy; (b) have maxima in the energy region from 40 to 60 keV, determined by the K and L edges of the backscattering materials; and (c) are valued up to about 130 for "International Commission on Radiological Protection (ICRP) soft tissue" (soft tissue composition recommended by the ICRP) as the adjacent low-Z material. Maximum dose enhancement associated with the L edge occurs for materials with atomic numbers between 50 and 60, e.g., barium (Z = 56) and iodine (Z = 53). Such materials typically serve as contrast media in medical X-ray diagnostics. The gradual reduction in the dose enhancement with increasing distance from the material interface, owed to the limited ranges of the emitted secondary electrons, has been documented in detail. The discussion is devoted to practical radiological aspects of the dose enhancement phenomenon. Cytogenetic effects in cell layers closely proximate to surfaces of medium-Z materials might vary over two orders of magnitude, because the dose enhancement is accompanied by the earlier observed about twofold increase in the low-dose RBEM at a tissue-to-gold interface.
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Affiliation(s)
- M Seidenbusch
- Paediatric Radiology, Institute for Clinical Radiology, Dr. von Hauner's Children's Hospital, Ludwig-Maximilians-University of Munich, Lindwurmstr. 4, 80337, Munich, Germany,
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Amato E, Italiano A, Baldari S. Absorbed fractions for alpha particles in ellipsoidal volumes. Phys Med Biol 2013; 58:5449-59. [PMID: 23877354 DOI: 10.1088/0031-9155/58/16/5449] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Internal dosimetry of alpha particles is gaining attention due to the increasing applications in cancer treatment and also for the assessment of environmental contamination from radionuclides. We developed a Monte Carlo simulation in GEANT4 in order to calculate the absorbed fractions for monoenergetic alpha particles in the energy interval between 0.1 and 10 MeV, uniformly distributed in ellipsoids made of soft tissue. For each volume, we simulated a spherical shape, three oblate and three prolate ellipsoids, and one scalene shape. For each energy and for every geometrical configuration, an analytical relationship between the absorbed fraction and a 'generalized radius' was found; and the dependence of the fit parameters on the alpha energy is discussed and fitted by parametric functions. With the proposed formulation, the absorbed fraction for alpha particles in the energy range explored can be calculated for volumes and for ellipsoidal shapes of practical interest. This method can be applied to the evaluation of absorbed fraction from alpha-emitting radionuclides. The contribution to the deposited energy coming from electron and photon emissions can be accounted for exploiting the specific formulations previously introduced. As an example of application, the dosimetry of (213)Bi and its decay chain in ellipsoids is reported.
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Affiliation(s)
- Ernesto Amato
- Section of Radiological Sciences, Department Biomedical Sciences and of Morphologic and Functional Imaging, University of Messina, Italy.
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