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Papadakis AE, Giannakaki V, Stratakis J, Myronakis M, Zaidi H, Damilakis J. Digital phantom versus patient-specific radiation dosimetry in adult routine thorax CT examinations. J Appl Clin Med Phys 2024; 25:e14389. [PMID: 38778565 PMCID: PMC11244670 DOI: 10.1002/acm2.14389] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2023] [Revised: 04/09/2024] [Accepted: 04/23/2024] [Indexed: 05/25/2024] Open
Abstract
PURPOSE The aim of this study was to compare the organ doses assessed through a digital phantom-based and a patient specific-based dosimetric tool in adult routine thorax computed tomography (CT) examinations with reference to physical dose measurements performed in anthropomorphic phantoms. METHODS Two Monte Carlo based dose calculation tools were used to assess organ doses in routine adult thorax CT examinations. These were a digital phantom-based dosimetry tool (NCICT, National Cancer Institute, USA) and a patient-specific individualized dosimetry tool (ImpactMC, CT Imaging GmbH, Germany). Digital phantoms and patients were classified in four groups according to their water equivalent diameter (Dw). Normalized to volume computed tomography dose index (CTDIvol), organ dose was assessed for lungs, esophagus, heart, breast, active bone marrow, and skin. Organ doses were compared to measurements performed using thermoluminescent detectors (TLDs) in two physical anthropomorphic phantoms that simulate the average adult individual as a male (Alderson Research Labs, USA) and as a female (ATOM Phantoms, USA). RESULTS The average percent difference of NCICT to TLD and ImpactMC to TLD dose measurements across all organs in both sexes was 13% and 6%, respectively. The average ± 1 standard deviation in dose values across all organs with NCICT, ImpactMC, and TLDs was ± 0.06 (mGy/mGy), ± 0.19 (mGy/mGy), and ± 0.13 (mGy/mGy), respectively. Organ doses decreased with increasing Dw in both NCICT and ImpactMC. CONCLUSION Organ doses estimated with ImpactMC were in closer agreement to TLDs compared to NCICT. This may be attributed to the inherent property of ImpactMC methodology to generate phantoms that resemble the realistic anatomy of the examined patient as opposed to NCICT methodology that incorporates an anatomical discrepancy between phantoms and patients.
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Affiliation(s)
- Antonios E. Papadakis
- University Hospital of HeraklionMedical Physics DepartmentStavrakia, HeraklionCreteGreece
| | - Vassiliki Giannakaki
- University Hospital of HeraklionMedical Physics DepartmentStavrakia, HeraklionCreteGreece
| | - John Stratakis
- University Hospital of HeraklionMedical Physics DepartmentStavrakia, HeraklionCreteGreece
| | - Marios Myronakis
- University Hospital of HeraklionMedical Physics DepartmentStavrakia, HeraklionCreteGreece
| | - Habib Zaidi
- Division of Nuclear Medicine and Molecular ImagingGeneva University HospitalGenevaSwitzerland
- Department of Nuclear Medicine and Molecular ImagingUniversity of GroningenUniversity Medical Center GroningenGroningenNetherlands
- Department of Nuclear MedicineUniversity of Southern DenmarkOdenseDenmark
- University Research and Innovation CenterObuda UniversityBudapestHungary
| | - John Damilakis
- University of Crete, Medical SchoolMedical Physics DepartmentStavrakia, HeraklionCreteGreece
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Rehani MM, Xu XG. Dose, dose, dose, but where is the patient dose? RADIATION PROTECTION DOSIMETRY 2024; 200:945-955. [PMID: 38847407 DOI: 10.1093/rpd/ncae137] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2023] [Revised: 05/14/2024] [Accepted: 05/17/2024] [Indexed: 06/25/2024]
Abstract
The article reviews the historical developments in radiation dose metrices in medical imaging. It identifies the good, the bad, and the ugly aspects of current-day metrices. The actions on shifting focus from International Commission on Radiological Protection (ICRP) Reference-Man-based population-average phantoms to patient-specific computational phantoms have been proposed and discussed. Technological developments in recent years involving AI-based automatic organ segmentation and 'near real-time' Monte Carlo dose calculations suggest the feasibility and advantage of obtaining patient-specific organ doses. It appears that the time for ICRP and other international organizations to embrace 'patient-specific' dose quantity representing risk may have finally come. While the existing dose metrices meet specific demands, emphasis needs to be also placed on making radiation units understandable to the medical community.
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Affiliation(s)
- Madan M Rehani
- Massachusetts General Hospital, Radiology Department, Boston, MA, 02114, United States
| | - Xie George Xu
- University of Science and Technology of China (USTC), College of Nuclear Science & Technology, Hefei, Anhui Province, 230026, China
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Martin CJ, Barnard M, de Vocht F. Evaluation of risks of cardiovascular disease from radiation exposure linked to computed tomography scans in the UK. JOURNAL OF RADIOLOGICAL PROTECTION : OFFICIAL JOURNAL OF THE SOCIETY FOR RADIOLOGICAL PROTECTION 2024; 44:011513. [PMID: 38422514 DOI: 10.1088/1361-6498/ad2ebd] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/09/2023] [Accepted: 02/29/2024] [Indexed: 03/02/2024]
Abstract
Epidemiological studies of patient populations have shown that high doses of radiation increase risks of cardiovascular disease (CVD). Results from a recent meta-analysis of 93 epidemiological studies covering a wide range of doses provided evidence of a causal association between radiation exposure and CVD, and indicated excess relative risk per Gy for maximum dose below 500 mGy or delivered at low dose rates. These doses cover the range of organ doses expected from multiple diagnostic computed tomography (CT) scans. Dose-effect factors for the excess absolute risk of mortality from CVD following radiation exposure were derived from the meta-analysis. The present study uses these factors to estimate excess risks of mortality for various types of CVD, including cerebrovascular disease (CeVD), from CT scans of the body and head, assuming that the meta-analytic factors were accurate and represented a causal relationship. Estimates are based on cumulative doses to the heart and brain from CT scans performed on 105 574 patients on 12 CT scanners over a period of 5½ years. The results suggest that the excess number of deaths from CeVD could be 7 or 26 per 100 000 patients depending whether threshold brain doses of 200 mGy or 50 mGy, respectively are assumed. These results could have implications for head CT scans. However, the results rely on the validity of risk factors derived in the meta-analysis informing this assessment and which include significant uncertainties. Further incidence studies should provide better information on risk factors and dose thresholds, particularly for CeVD following head CT scans.
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Affiliation(s)
- Colin J Martin
- Department of Clinical Physics and Bioengineering, University of Glasgow, Glasgow, United Kingdom
| | - Michael Barnard
- Department of Radiation Physics and Protection, Oxford University Hospitals NHS Foundation Trust, Oxford, United Kingdom
| | - Frank de Vocht
- Population Health Sciences, Bristol Medical School, University of Bristol, Bristol, United Kingdom
- NIHR Applied Research Collaboration West (ARC West), Bristol, United Kingdom
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Fong G, Herts B, Primak A, Segars P, Li X. Effect of tin spectral filtration on organ and effective dose in CT colonography and CT lung cancer screening. Med Phys 2024; 51:103-112. [PMID: 37962008 DOI: 10.1002/mp.16836] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2023] [Revised: 10/07/2023] [Accepted: 10/29/2023] [Indexed: 11/15/2023] Open
Abstract
BACKGROUND Studies of tin spectral filtration have demonstrated potential in reducing radiation dose while maintaining image quality for unenhanced computed tomography (CT) scans. The extent of dose reduction, however, was commonly measured using the change in the scanner's reported CTDIvol . This method does not account for how tin filtration affects patient organ and effective dose. PURPOSE To investigate the effect of tin filtration on patient organ and effective dose for CT Lung Cancer Screening (LCS) and CT Colonography (CTC). METHODS A previously-developed Monte Carlo program was adapted to model a 96-row CT scanner (Somatom Force, Siemens Healthineers) with tin filtration capabilities at 100 kV (100Sn) and 150 kV (150Sn). The program was then validated using experimental CTDIvol measurements at all available kV (70-150 kV) and tin-filtered kV options (100Sn and 150Sn). After validation, the program simulated LCS scans of the chest and CTC scan of the abdomen-pelvis for a population of 53 computational patient models from the extended cardiac-torso family. Each scan was performed using three different spectra: 120 kV, 100Sn, and 150Sn. CTDIvol -normalized organ doses and DLP-normalized effective doses, commonly referred to as dose conversion factors, were compared between the different spectra. RESULTS For all LCS and CTC scans, CTDIvol -normalized organ doses and DLP-normalized effective doses increased with increasing beam hardness (120 kV, 100Sn, 150 Sn). For LCS, relative for 120 kV, conversion factors for 100Sn produced a median increase in effective dose of 9%, with organ dose increases of 8% to lung, 5% to breast, 15% to thyroid, and 3% to skin. Conversion factors for 150Sn produced a median increase in effective dose of 20%, with organ dose increases of 16%, 18%, 26%, and 12% to these same organs, respectively. For CTC, relative for 120 kV, conversion factors for 100Sn produced a median increase in effective dose of 12%, with organ dose increases of 9% to colon, 10% to liver, 11% to stomach, and 4% to skin. Conversion factors for 150Sn produced a median increase in effective dose of 21%, with organ dose increases of 16%, 17%, 19%, and 10% to these same organs, respectively. CONCLUSIONS Results show that dose conversion factors are greater when using tin filtration and should be considered when evaluating tin's potential for dose reduction.
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Affiliation(s)
- Grant Fong
- Cleveland Clinic, Imaging Institute, Cleveland, Ohio, USA
| | - Brian Herts
- Cleveland Clinic, Imaging Institute, Cleveland, Ohio, USA
| | - Andrew Primak
- Siemens Medical Solutions USA Inc., Malvern, Pennsylvania, USA
| | - Paul Segars
- Duke University, Durham, North Carolina, USA
| | - Xiang Li
- Cleveland Clinic, Imaging Institute, Cleveland, Ohio, USA
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Alsaihati N, Ria F, Solomon J, Ding A, Frush D, Samei E. Making CT Dose Monitoring Meaningful: Augmenting Dose with Imaging Quality. Tomography 2023; 9:798-809. [PMID: 37104136 PMCID: PMC10145563 DOI: 10.3390/tomography9020065] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2023] [Revised: 03/31/2023] [Accepted: 04/04/2023] [Indexed: 04/28/2023] Open
Abstract
Due to the concerns about radiation dose associated with medical imaging, radiation dose monitoring systems (RDMSs) are now utilized by many radiology providers to collect, process, analyze, and manage radiation dose-related information. Currently, most commercially available RDMSs focus only on radiation dose information and do not track any metrics related to image quality. However, to enable comprehensive patient-based imaging optimization, it is equally important to monitor image quality as well. This article describes how RDMS design can be extended beyond radiation dose to simultaneously monitor image quality. A newly designed interface was evaluated by different groups of radiology professionals (radiologists, technologists, and physicists) on a Likert scale. The results show that the new design is effective in assessing both image quality and safety in clinical practices, with an overall average score of 7.8 out of 10.0 and scores ranging from 5.5 to 10.0. Radiologists rated the interface highest at 8.4 out of 10.0, followed by technologists at 7.6 out of 10.0, and medical physicists at 7.5 out of 10.0. This work demonstrates how the assessment of the radiation dose can be performed in conjunction with the image quality using customizable user interfaces based on the clinical needs associated with different radiology professions.
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Affiliation(s)
- Njood Alsaihati
- Carl E. Ravin Advanced Imaging Laboratories, Department of Radiology, Duke University Medical Center, Durham, NC 27710, USA
- Clinical Imaging Physics Group, Department of Radiology, Duke University Medical Center, Durham, NC 27710, USA
| | - Francesco Ria
- Carl E. Ravin Advanced Imaging Laboratories, Department of Radiology, Duke University Medical Center, Durham, NC 27710, USA
- Clinical Imaging Physics Group, Department of Radiology, Duke University Medical Center, Durham, NC 27710, USA
- Center for Virtual Imaging Trials, Department of Radiology, Duke University Medical Center, Durham, NC 27710, USA
| | - Justin Solomon
- Carl E. Ravin Advanced Imaging Laboratories, Department of Radiology, Duke University Medical Center, Durham, NC 27710, USA
- Clinical Imaging Physics Group, Department of Radiology, Duke University Medical Center, Durham, NC 27710, USA
- Center for Virtual Imaging Trials, Department of Radiology, Duke University Medical Center, Durham, NC 27710, USA
| | - Aiping Ding
- Carl E. Ravin Advanced Imaging Laboratories, Department of Radiology, Duke University Medical Center, Durham, NC 27710, USA
- Clinical Imaging Physics Group, Department of Radiology, Duke University Medical Center, Durham, NC 27710, USA
| | - Donald Frush
- Carl E. Ravin Advanced Imaging Laboratories, Department of Radiology, Duke University Medical Center, Durham, NC 27710, USA
- Center for Virtual Imaging Trials, Department of Radiology, Duke University Medical Center, Durham, NC 27710, USA
| | - Ehsan Samei
- Carl E. Ravin Advanced Imaging Laboratories, Department of Radiology, Duke University Medical Center, Durham, NC 27710, USA
- Clinical Imaging Physics Group, Department of Radiology, Duke University Medical Center, Durham, NC 27710, USA
- Center for Virtual Imaging Trials, Department of Radiology, Duke University Medical Center, Durham, NC 27710, USA
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Tabari A, Li X, Yang K, Liu B, Gee MS, Westra SJ. Patient-level dose monitoring in computed tomography: tracking cumulative dose from multiple multi-sequence exams with tube current modulation in children. Pediatr Radiol 2021; 51:2498-2506. [PMID: 34532817 DOI: 10.1007/s00247-021-05160-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/20/2021] [Revised: 06/08/2021] [Accepted: 07/23/2021] [Indexed: 11/26/2022]
Abstract
BACKGROUND In children exposed to multiple computed tomography (CT) exams, performed with varying z-axis coverage and often with tube current modulation, it is inaccurate to add volume CT dose index (CTDIvol) and size-specific dose estimate (SSDE) to obtain cumulative dose values. OBJECTIVE To introduce the patient-size-specific z-axis dose profile and its dose line integral (DLI) as new dose metrics, and to use them to compare cumulative dose calculations against conventional measures. MATERIALS AND METHODS In all children with 2 or more abdominal-pelvic CT scans performed from 2013 through 2019, we retrospectively recorded all series kV, z-axis tube current profile, CTDIvol, dose-length product (DLP) and calculated SSDE. We constructed dose profiles as a function of z-axis location for each series. One author identified the z-axis location of the superior mesenteric artery origin on each series obtained to align the dose profiles for construction of each patient's cumulative profile. We performed pair-wise comparisons between the peak dose of the cumulative patient dose profile and ΣSSDE, and between ΣDLI and ΣDLP. RESULTS We recorded dose data in 143 series obtained in 48 children, ages 0-2 years (n=15) and 8-16 years (n=33): ΣSSDE 12.7±6.7 and peak dose 15.1±8.1 mGy, ΣDLP 278±194 and ΣDLI 550±292 mGy·cm. Peak dose exceeded ΣSSDE by 20.6% (interquartile range [IQR]: 9.9-26.4%, P<0.001), and ΣDLI exceeded ΣDLP by 114% (IQR: 86.5-147.0%, P<0.001). CONCLUSION Our methodology represents a novel approach for evaluating radiation exposure in recurring pediatric abdominal CT examinations, both at the individual and population levels. Under a wide range of patient variables and acquisition conditions, graphic depiction of the cumulative z-axis dose profile across and beyond scan ranges, including the peak dose of the profile, provides a better tool for cumulative dose documentation than simple summations of SSDE. ΣDLI is advantageous in characterizing overall energy absorption over ΣDLP, which significantly underestimated this in all children.
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Affiliation(s)
- Azadeh Tabari
- Department of Radiology, Massachusetts General Hospital, 34 Fruit St., Boston, MA, 02114, USA
| | - Xinhua Li
- Department of Radiology, Massachusetts General Hospital, 34 Fruit St., Boston, MA, 02114, USA
| | - Kai Yang
- Department of Radiology, Massachusetts General Hospital, 34 Fruit St., Boston, MA, 02114, USA
| | - Bob Liu
- Department of Radiology, Massachusetts General Hospital, 34 Fruit St., Boston, MA, 02114, USA
| | - Michael S Gee
- Department of Radiology, Massachusetts General Hospital, 34 Fruit St., Boston, MA, 02114, USA
| | - Sjirk J Westra
- Department of Radiology, Massachusetts General Hospital, 34 Fruit St., Boston, MA, 02114, USA.
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Martin CJ, Barnard M. Potential risks of cardiovascular and cerebrovascular disease and cancer due to cumulative doses received from diagnostic CT scans? JOURNAL OF RADIOLOGICAL PROTECTION : OFFICIAL JOURNAL OF THE SOCIETY FOR RADIOLOGICAL PROTECTION 2021; 41:1243-1257. [PMID: 34525460 DOI: 10.1088/1361-6498/ac270f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/25/2021] [Accepted: 09/15/2021] [Indexed: 06/13/2023]
Abstract
Potential risks from radiation exposure on the development of cardiovascular and cerebrovascular disease are indicated by epidemiological studies. Medical exposures give the largest dose to the population from artificial sources, with cumulative doses from multiple CT scans being significant. Data on doses from scans performed on 12 CT scanners in three hospitals over a period of 5½ years, derived using RadimetricsTMsoftware, have been reviewed for 105 757 patients. Data have been downloaded for heart, brain, thyroid, and effective doses, and cumulative doses analysed using ExcelTMspreadsheets. 2.4% of patients having body CT scans received cumulative doses to the heart over 100 mSv, 9% of whom were under 50 years. 9.6% of patients having head CT scans received cumulative doses to the brain over 100 mSv with 0.08% over 500 mSv from whom 41% were under 50 years, but only 1.3% of patients scanned had thyroid/carotid artery doses over 100 mSv. An approximate evaluation of potential risks from exposures of the heart above 100 mSv and brain over 500 mSv for patients under 60 years would suggest that at most only one patient would demonstrate any excess risk from vascular disease resulting from the exposures. 0.67% of patients scanned received effective doses over 100 mSv, in line with results from European studies, with 8.4% being under 50 years. The application of age and sex specific risk coefficients relating to excess cancer incidence suggests that two or three patients with effective doses over 100 mSv and five patients with effective doses between 50 and 100 mSv, from those examined, might develop cancer as a result of exposure. However, this will be an overestimate, since it does not take patients' health into account. Exposure management software can aid in evaluating cumulative doses and identifying individual patients receiving substantial doses from repetitive imaging.
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Affiliation(s)
- Colin J Martin
- Department of Clinical Physics and Bioengineering, University of Glasgow, Glasgow, United Kingdom
| | - Michael Barnard
- Department of Radiation Physics and Protection, Oxford University Hospitals NHS Foundation Trust, Oxford, United Kingdom
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Omidi R, Zare MH, Zamani H, Dalvand S, Masjedi H, Razavi-Ratki SK, Rahbar S. Patterns and trends of population radiation exposure and projected the risk of exposure-induced death from gamma camera examinations in Yazd Province. J Med Imaging Radiat Sci 2021; 52:595-605. [PMID: 34782277 DOI: 10.1016/j.jmir.2021.08.020] [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: 04/08/2021] [Revised: 08/02/2021] [Accepted: 08/31/2021] [Indexed: 11/26/2022]
Abstract
INTRODUCTION The use of nuclear medicine examinations as imaging modalities has recently increased. This study aimed to assess the radiation dose delivered to patients from common diagnostic nuclear medicine examinations and estimate the risk of exposure-induced death (REID). In addition, the frequency of nuclear medicine procedures were evaluated from 2015-2018. MATERIALS AND METHODS The data were collected from adult patients who had undergone cardiac, skeletal, renal, lacrimal, and thyroid imaging. For each patient, the effective dose was calculated using dose conversion factors, and REID was estimated using PCXMC. The frequency of examinations between 2015 and 2018 was obtained from the hospital information system (HIS). RESULTS The highest estimated effective dose was attributed to the scans of myocardial stress (8.09 ± 1.28 mSv), myocardial rest (5.59 ± 1.27 mSv), and thyroid imaging (3.93 ± 0.55 mSv). In addition, cardiac stress examination had the highest REID values for solid cancers (212.5 ± 67.5) and bone scans had the highest REID values for leukemia (11.5 ± 2.5). A large increase in the number of myocardial perfusion scans was a significant contributor to an increase in collective effective dose from 23.37 man-Sv in 2015 to 49.47 man-Sv in 2018, a compound annual growth rate (CAGR) of 26%. CONCLUSION Although the annual frequency and per capita effective dose of nuclear medicine procedures in Yazd Province increased continuously, they were comparably lower than those reported for other countries. Despite this, the cancer risks of nuclear medicine scans at the individual level are negligible (around 0.01% excess fatal cancer risk), yet the increasing tendency for these examinations could be of concern.
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Affiliation(s)
- Reza Omidi
- Medical Physics Department, Student at Shahid Sadoughi University of Medical Sciences, Yazd, Iran
| | - Mohammad Hosein Zare
- Medical Physics Department, Shahid Sadoughi University of Medical Sciences, Yazd, Iran
| | - Hamed Zamani
- Medical Physics Department, Student at Shahid Sadoughi University of Medical Sciences, Yazd, Iran
| | - Saman Dalvand
- Medical Physics Department, Student at Tarbiat Modares University, Tehran, Iran.
| | - Hamidreza Masjedi
- Medical Physics Department, Student at Shahid Sadoughi University of Medical Sciences, Yazd, Iran
| | - Seid Kazem Razavi-Ratki
- Clinical Research Development Center of Shahid Sadoughi Hospital, Shahid Sadoughi University of Medical Sciences, Shohadaye Gomnam Blvd, Yazd, Yazd Province, Yazd, Iran.
| | - Shiva Rahbar
- Medical Physics Department, Student at Shahid Sadoughi University of Medical Sciences, Yazd, Iran
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Moghadam N, Lecomte R, Mercure S, Rehani MM, Nassiri MA. Simplified size adjusted dose reference levels for adult CT examinations: A regional study. Eur J Radiol 2021; 142:109861. [PMID: 34280596 DOI: 10.1016/j.ejrad.2021.109861] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Revised: 06/30/2021] [Accepted: 07/06/2021] [Indexed: 12/19/2022]
Abstract
PURPOSE To investigate retrospective classification of adult patients into small, average, and large based on effective diameter (EDia) from localizer image of computed tomography (CT) scans and to develop regional diagnostic reference levels (DRLs) and achievable doses (AD). METHOD The patients falling within the mean ± standard deviation (SD) of EDia were classified as average; those below this range as small and above as large. The CTDIvol,dose-length-product (DLP) and size-specific dose estimates (SSDE) of all adult patients undergoing CT examinations in 8 CT facilities for 11 months (Dec. 2019 - Oct. 2020) were evaluated. The 75th and 50th percentile values were compared with national and international values. RESULTS Of the total of 69,434 CT examinations, nearly 80% fell within average size. The 75th percentile values of CTDIvol and DLP for small patients for abdomen-pelvic exams were nearly half of average sized patients. Similarly, the 75th percentile values for large patients were nearly double. Similar findings were not found for chest exams. Analysis of image quality and dose factors such as noise, mean axial length, slice thickness, mean number of sequences, use of iterative reconstruction and tube current modulation (TCM) resulted in identification of opportunities for improvement and optimization of different CT facilities. CONCLUSIONS DRLs for adult patients were found to vary widely with patient size and thus establishing DRLs only for standard sized patient is not adequate. Simplified and intuitive methods for size classification was shown to provide meaningful information for optimization for patients outside the standard size adult.
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Affiliation(s)
- Narjes Moghadam
- Centre de recherche du Centre hospitalier universitaire de Sherbrooke (CRCHUS), Sherbrooke, Québec, Canada; Centre intégré universitaire de santé et de services sociaux de l'Estrie - Centre hospitalier universitaire de Sherbrooke (CIUSSS de l'Estrie - CHUS), Sherbrooke, Québec, Canada.
| | - Roger Lecomte
- Centre de recherche du Centre hospitalier universitaire de Sherbrooke (CRCHUS), Sherbrooke, Québec, Canada; Department of Nuclear Medicine and Radiobiology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Canada
| | - Stéphane Mercure
- Centre intégré universitaire de santé et de services sociaux de l'Estrie - Centre hospitalier universitaire de Sherbrooke (CIUSSS de l'Estrie - CHUS), Sherbrooke, Québec, Canada
| | - Madan M Rehani
- Radiology Department, Massachusetts General Hospital, Boston, MA, USA
| | - Moulay Ali Nassiri
- Centre de recherche du Centre hospitalier universitaire de Sherbrooke (CRCHUS), Sherbrooke, Québec, Canada; Centre intégré universitaire de santé et de services sociaux de l'Estrie - Centre hospitalier universitaire de Sherbrooke (CIUSSS de l'Estrie - CHUS), Sherbrooke, Québec, Canada; Department of Nuclear Medicine and Radiobiology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Canada
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Harrison JD, Balonov M, Bochud F, Martin C, Menzel HG, Ortiz-Lopez P, Smith-Bindman R, Simmonds JR, Wakeford R. ICRP Publication 147: Use of Dose Quantities in Radiological Protection. Ann ICRP 2021; 50:9-82. [PMID: 33653178 DOI: 10.1177/0146645320911864] [Citation(s) in RCA: 58] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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Sundell VM, Kortesniemi M, Siiskonen T, Kosunen A, Rosendahl S, Büermann L. PATIENT-SPECIFIC DOSE ESTIMATES IN DYNAMIC COMPUTED TOMOGRAPHY MYOCARDIAL PERFUSION EXAMINATION. RADIATION PROTECTION DOSIMETRY 2021; 193:24-36. [PMID: 33693932 PMCID: PMC8227483 DOI: 10.1093/rpd/ncab016] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Revised: 12/09/2020] [Accepted: 01/26/2021] [Indexed: 05/07/2023]
Abstract
The study aimed to implement realistic source models of a computed tomography (CT) scanner and Monte Carlo simulations to actual patient data and to calculate patient-specific organ and effective dose estimates for patients undergoing dynamic CT myocardial perfusion examinations. Source models including bowtie filter, tube output and x-ray spectra were determined for a dual-source Siemens Somatom Definition Flash scanner. Twenty CT angiography patient datasets were merged with a scaled International Commission on Radiological Protection (ICRP) 110 voxel phantom. Dose simulations were conducted with ImpactMC software. Effective dose estimates varied from 5.0 to 14.6 mSv for the 80 kV spectrum and from 8.9 to 24.7 mSv for the 100 kV spectrum. Significant differences in organ doses and effective doses between patients emphasise the need to use actual patient data merged with matched anthropomorphic anatomy in the dose simulations to achieve a reasonable level of accuracy in the dose estimation procedure.
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Affiliation(s)
- V-M Sundell
- HUS Medical Imaging Center, Helsinki University Central Hospital, Helsinki, Uusimaa, Finland
- Department of Physics, University of Helsinki, P.O. Box 64, 00014 University of Helsinki, Finland
| | - M Kortesniemi
- HUS Medical Imaging Center, Helsinki University Central Hospital, Helsinki, Uusimaa, Finland
| | - T Siiskonen
- STUK-Radiation and Nuclear Safety Authority, Laippatie 4, Helsinki 00880, Finland
| | - A Kosunen
- STUK-Radiation and Nuclear Safety Authority, Laippatie 4, Helsinki 00880, Finland
| | - S Rosendahl
- Department 6.2 Dosimetry for radiation therapy and diagnostic radiology, Physikalisch-Technische Bundesanstalt, Bundesallee 100, Braunschweig 38116, Germany
| | - L Büermann
- Department 6.2 Dosimetry for radiation therapy and diagnostic radiology, Physikalisch-Technische Bundesanstalt, Bundesallee 100, Braunschweig 38116, Germany
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Ria F, Fu W, Chalian H, Abadi E, Segars PW, Fricks R, Khoshpouri P, Samei E. A comparison of COVID-19 and imaging radiation risk in clinical patient populations. JOURNAL OF RADIOLOGICAL PROTECTION : OFFICIAL JOURNAL OF THE SOCIETY FOR RADIOLOGICAL PROTECTION 2020; 40:10.1088/1361-6498/abbf3b. [PMID: 33027775 PMCID: PMC9757494 DOI: 10.1088/1361-6498/abbf3b] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Accepted: 10/07/2020] [Indexed: 06/11/2023]
Abstract
The outbreak of coronavirus SARS-COV2 affected more than 180 countries necessitating fast and accurate diagnostic tools. Reverse transcriptase polymerase chain reaction (RT-PCR) has been identified as a gold standard test with Chest CT and Chest Radiography showing promising results as well. However, radiological solutions have not been used extensively for the diagnosis of COVID-19 disease, partly due to radiation risk. This study aimed to provide quantitative comparison of imaging radiation risk versus COVID risk. The analysis was performed in terms of mortality rate per age group. COVID-19 mortality was extracted from epidemiological data across 299, 004 patients published by ISS-Integrated surveillance of COVID-19 in Italy. For radiological risk, the study considered 659 Chest CT performed in adult patients. Organ doses were estimated using a Monte Carlo method and then used to calculate Risk Index that was converted into an upper bound for related mortality rate following NCI-SEER data. COVID-19 mortality showed a rapid rise for ages >30 years old (min: 0.30%; max: 30.20%), whereas only four deaths were reported in the analysed patient cohort for ages <20 years old. The rates decreased for radiation risk across age groups. The median mortality rate across all ages for Chest-CT and Chest-Radiography were 0.007% (min: 0.005%; max: 0.011%) and 0.0003% (min: 0.0002%; max: 0.0004%), respectively. COVID-19, Chest Radiography, and Chest CT mortality rates showed different magnitudes and trends across age groups. In higher ages, the risk of COVID-19 far outweighs that of radiological exams. Based on risk comparison alone, Chest Radiography and CT for COVID-19 care is justified for patients older than 20 and 30 years old, respectively. Notwithstanding other aspects of diagnosis, the present results capture a component of risk consideration associated with the use of imaging for COVID. Once integrated with other diagnostic factors, they may help inform better management of the pandemic.
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Affiliation(s)
- Francesco Ria
- Carl E. Ravin Advanced Imaging Labs and Clinical Imaging Physics Group, Duke University Health System, 2424 Erwin Road, Suite 302, Durham, NC 27710, United States of America
| | - Wanyi Fu
- Carl E. Ravin Advanced Imaging Labs, Duke University Health System, 2424 Erwin Road, Suite 302, Durham, NC 27710, United States of America
| | - Hamid Chalian
- Radiology Department, Duke University Health System, 2301 Erwin Road, Durham, NC 27710, United States of America
| | - Ehsan Abadi
- Carl E. Ravin Advanced Imaging Labs, Duke University Health System, 2424 Erwin Road, Suite 302, Durham, NC 27710, United States of America
| | - Paul W Segars
- Carl E. Ravin Advanced Imaging Labs, Duke University Health System, 2424 Erwin Road, Suite 302, Durham, NC 27710, United States of America
| | - Rafael Fricks
- Carl E. Ravin Advanced Imaging Labs, Duke University Health System, 2424 Erwin Road, Suite 302, Durham, NC 27710, United States of America
- Department of Veterans Affairs, 508 Fulton St, Durham, NC 27705, United States of America
| | - Pegah Khoshpouri
- Radiology Department, Duke University Health System, 2301 Erwin Road, Durham, NC 27710, United States of America
| | - Ehsan Samei
- Carl E. Ravin Advanced Imaging Labs, Clinical Imaging Physics Group, Medical Physics Graduate Program, Departments of Radiology, Physics, Biomedical Engineering, and Electrical and Computer Engineering, Duke University, 2424 Erwin Road, Suite 302, Durham, NC 27710, United States of America
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13
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Abadi E, Segars WP, Tsui BMW, Kinahan PE, Bottenus N, Frangi AF, Maidment A, Lo J, Samei E. Virtual clinical trials in medical imaging: a review. J Med Imaging (Bellingham) 2020; 7:042805. [PMID: 32313817 PMCID: PMC7148435 DOI: 10.1117/1.jmi.7.4.042805] [Citation(s) in RCA: 68] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2019] [Accepted: 03/23/2020] [Indexed: 12/13/2022] Open
Abstract
The accelerating complexity and variety of medical imaging devices and methods have outpaced the ability to evaluate and optimize their design and clinical use. This is a significant and increasing challenge for both scientific investigations and clinical applications. Evaluations would ideally be done using clinical imaging trials. These experiments, however, are often not practical due to ethical limitations, expense, time requirements, or lack of ground truth. Virtual clinical trials (VCTs) (also known as in silico imaging trials or virtual imaging trials) offer an alternative means to efficiently evaluate medical imaging technologies virtually. They do so by simulating the patients, imaging systems, and interpreters. The field of VCTs has been constantly advanced over the past decades in multiple areas. We summarize the major developments and current status of the field of VCTs in medical imaging. We review the core components of a VCT: computational phantoms, simulators of different imaging modalities, and interpretation models. We also highlight some of the applications of VCTs across various imaging modalities.
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Affiliation(s)
- Ehsan Abadi
- Duke University, Department of Radiology, Durham, North Carolina, United States
| | - William P. Segars
- Duke University, Department of Radiology, Durham, North Carolina, United States
| | - Benjamin M. W. Tsui
- Johns Hopkins University, Department of Radiology, Baltimore, Maryland, United States
| | - Paul E. Kinahan
- University of Washington, Department of Radiology, Seattle, Washington, United States
| | - Nick Bottenus
- Duke University, Department of Biomedical Engineering, Durham, North Carolina, United States
- University of Colorado Boulder, Department of Mechanical Engineering, Boulder, Colorado, United States
| | - Alejandro F. Frangi
- University of Leeds, School of Computing, Leeds, United Kingdom
- University of Leeds, School of Medicine, Leeds, United Kingdom
| | - Andrew Maidment
- University of Pennsylvania, Department of Radiology, Philadelphia, Pennsylvania, United States
| | - Joseph Lo
- Duke University, Department of Radiology, Durham, North Carolina, United States
| | - Ehsan Samei
- Duke University, Department of Radiology, Durham, North Carolina, United States
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14
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Kotb MA, Elmahdy HN, Seif El Dein HM, Mostafa FZ, Refaey MA, Rjoob KWY, Draz IH, Basanti CWS. The Machine Learned Stethoscope Provides Accurate Operator Independent Diagnosis of Chest Disease. MEDICAL DEVICES-EVIDENCE AND RESEARCH 2020; 13:13-22. [PMID: 32158281 PMCID: PMC6986244 DOI: 10.2147/mder.s221029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Accepted: 12/03/2019] [Indexed: 11/23/2022] Open
Abstract
Introduction Contemporary stethoscope has limitations in diagnosis of chest conditions, necessitating further imaging modalities. Methods We created 2 diagnostic computer aided non-invasive machine-learning models to recognize chest sounds. Model A was interpreter independent based on hidden markov model and mel frequency cepstral coefficient (MFCC). Model B was based on MFCC, hidden markov model, and chest sound wave image interpreter dependent analysis (phonopulmonography (PPG)). Results We studied 464 records of actual chest sounds belonging to 116 children diagnosed by clinicians and confirmed by other imaging diagnostic modalities. Model A had 96.7% overall correct classification rate (CCR), 100% sensitivity and 100% specificity in discrimination between normal and abnormal sounds. CCR was 100% for normal vesicular sounds, crepitations 89.1%, wheezes 97.6%, and bronchial breathing 100%. Model B's CCR was 100% for normal vesicular sounds, crepitations 97.3%, wheezes 97.6%, and bronchial breathing 100%. The overall CCR was 98.7%, sensitivity and specificity were 100%. Conclusion Both models demonstrated very high precision in the diagnosis of chest conditions and in differentiating normal from abnormal chest sounds irrespective of operator expertise. Incorporation of computer-aided models in stethoscopes promises prompt, precise, accurate, cost-effective, non-invasive, operator independent, objective diagnosis of chest conditions and reduces number of unnecessary imaging studies.
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Affiliation(s)
- Magd Ahmed Kotb
- Department of Pediatrics, Faculty of Medicine, Cairo University, Cairo, Egypt
| | - Hesham Nabih Elmahdy
- Information Technology Department, Vice-Dean of Faculty of Computers and Information, Cairo University, Giza, Egypt
| | | | | | - Mohammed Ahmed Refaey
- Information Technology Department, Vice-Dean of Faculty of Computers and Information, Cairo University, Giza, Egypt
| | - Khaled Waleed Younis Rjoob
- Information Technology Department, Vice-Dean of Faculty of Computers and Information, Cairo University, Giza, Egypt
| | - Iman H Draz
- Department of Pediatrics, Faculty of Medicine, Cairo University, Cairo, Egypt
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15
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Zhang D, Liu X, Duan X, Bankier AA, Rong J, Palmer MR. Estimating patient water equivalent diameter from CT localizer images - A longitudinal and multi-institutional study of the stability of calibration parameters. Med Phys 2020; 47:2139-2149. [PMID: 32086943 DOI: 10.1002/mp.14102] [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: 10/01/2019] [Revised: 02/07/2020] [Accepted: 02/12/2020] [Indexed: 11/06/2022] Open
Abstract
PURPOSE Water equivalent diameter (WED) is a robust patient-size descriptor. Localizer-based WED estimation is less sensitive to truncation errors resulting from limited field of view, and produces WED estimates at different locations within one localizer radiograph, prior to the initiation of axial scans. This method is considered difficult to implement by the clinical community due to the necessary calibration between localizer pixel values (LPV) and attenuation, and the unknown stability of calibration results across scanners and over time. We investigated the stability of calibration results across 25 computed tomography (CT) scanners from three medical centers, and their stability over 3 ∼ 29 months for 14 of those scanners. METHODS Localizer and axial images of ACR and body computed tomography dose index phantoms were acquired, using routine clinical techniques (120 kV and lateral localizers) on each of the 25 CT scanners: 8 GE scanners (CT750HD, VCT, and Revolution), 8 Siemens scanners (Definition AS, Force, Flash, and Edge), 5 Canon scanners (Aquilion-One, Aquilion-Prime80, and Aquilion-64), and 4 Philips scanners (iCT 256, iQon, and Ingenuity). By associating axial images with the corresponding localizer lines, the relationship between the scaled water equivalent area (WEA) and averaged LPV were established through regression analysis. RESULTS Linear relationships between the scaled WEA and the averaged LPV were observed in all 25 CT scanners ( R 2 > 0.999 ). Calibration parameters were similar for CT scanners from the same vendor: the coefficients of variation (COV) were ≤ 1% in all four vendor groups for the calibration slope, and < 7% for the intercept. By analyzing the deviation of WED resulted from errors in the calibration slope or intercept alone, we derived the tolerance ranges for the slope or intercept for a given WED error level. The variation of slope and intercept from different CT scanners of the same vendor introduced <±2.5% error in the estimated WED for subjects of 20 and 30-cm WED. The calibration parameters remained stable over time, with the maximum deviations all within the boundary values that introduce ±2.5% error in the estimated WED for subjects of 20 and 30-cm WED. CONCLUSIONS The stability in calibration results among CT scanners of the same vendor and over time demonstrated the feasibility of implementing WED estimation for routine clinical use.
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Affiliation(s)
- Da Zhang
- Department of Radiology, Beth Israel Deaconess Medical Center, Boston, MA, 02215, USA.,Harvard Medical School, Boston, MA, 02215, USA
| | - Xinming Liu
- Department of Imaging Physics, MD Anderson Cancer Center, Houston, TX, 77230, USA
| | - Xinhui Duan
- Department of Radiology, UT Southwest Medical Center, Dallas, TX, 75390, USA
| | - Alexander A Bankier
- Department of Radiology, University of Massachusetts Medical School, Worcester, MA, 01655, USA
| | - John Rong
- Department of Imaging Physics, MD Anderson Cancer Center, Houston, TX, 77230, USA
| | - Matthew R Palmer
- Department of Radiology, Beth Israel Deaconess Medical Center, Boston, MA, 02215, USA.,Harvard Medical School, Boston, MA, 02215, USA
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16
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Medson K, Vargas-Paris R, Nordgren-Rogberg A, Sigbergsdottir A, Nyrén S, Lindholm P. Primary diagnosis of pulmonary embolism with unenhanced MRI for patients not eligible for CTPA: Clinical outcome. Eur J Radiol Open 2019; 6:315-319. [PMID: 31692624 PMCID: PMC6804887 DOI: 10.1016/j.ejro.2019.08.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2019] [Revised: 08/15/2019] [Accepted: 08/16/2019] [Indexed: 12/12/2022] Open
Abstract
Purpose To follow up the clinical outcome of patients with suspected pulmonary embolism (PE), in those only imaged using unenhanced, free-breathing magnetic resonance imaging (MRI). Methods and materials Fifty-seven patients aged 29-99 years (mean 70, SD 18) that could not undergo Computed Tomography Pulmonary Angiography (CTPA) were offered alternative imaging diagnostics in parallel with ongoing methodological studies validating MRI vs CTPA. Contraindications included renal failure (n = 44), severe iodine contrast allergy (n = 10), pregnancy (n = 2) and radioactive iodine therapy (n = 1). The unenhanced MRI protocol was based on free-breathing, steady-state free precession with no cardiac or respiratory gating. Retrospective review of the electronic medical record (EMR) was made of 0-12 months post-imaging and was collected during 2012-2018. Results All 57 MRIs were of diagnostic quality and 12 pulmonary embolisms were diagnosed. Of the 57 patients, 44 were already on, or had started anticoagulation therapy due to clinical suspicion of PE. Four of the patients were put on anticoagulation after the positive MRI and 13 were taken off anticoagulation after a negative MRI report. Other diagnoses reported (considering dyspnea) were pleural effusion (n = 24), consolidation (n = 12) and pericardial effusion (n = 2). One patient had a deep vein thrombosis (DVT) within three months of our negative MRI result and then had a stroke within one year. Another patient suffered a stroke within three months of being diagnosed (by MRI) with PE and given anticoagulation as treatment. Conclusions Our method supported or altered clinical decision-making and treatment in this cohort. A diagnostic tool for PE without intravenous contrast agent or radiation is of great benefit for certain patients.
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Affiliation(s)
- Koshiar Medson
- Department of Physiology and Pharmacology, Karolinska Institutet, SE-171 77 Stockholm, Sweden.,Thoracic radiology, Imaging and Physiology, Karolinska University Hospital, SE-171 76 Stockholm, Sweden
| | - Roberto Vargas-Paris
- Department of Physiology and Pharmacology, Karolinska Institutet, SE-171 77 Stockholm, Sweden.,Abdominal Radiology, Imaging and Physiology, Karolinska University Hospital, SE-171 76 Stockholm, Sweden
| | - Anna Nordgren-Rogberg
- Department of Physiology and Pharmacology, Karolinska Institutet, SE-171 77 Stockholm, Sweden.,Thoracic radiology, Imaging and Physiology, Karolinska University Hospital, SE-171 76 Stockholm, Sweden
| | | | - Sven Nyrén
- Thoracic radiology, Imaging and Physiology, Karolinska University Hospital, SE-171 76 Stockholm, Sweden.,Department of Molecular Medicine and Surgery, Karolinska Institutet, Karolinska University Hospital, Solna (L1:00), SE-171 76 Stockholm, Sweden
| | - Peter Lindholm
- Department of Physiology and Pharmacology, Karolinska Institutet, SE-171 77 Stockholm, Sweden.,Thoracic radiology, Imaging and Physiology, Karolinska University Hospital, SE-171 76 Stockholm, Sweden
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17
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Papadimitroulas P, Balomenos A, Kopsinis Y, Loudos G, Alexakos C, Karnabatidis D, Kagadis GC, Kostou T, Chatzipapas K, Visvikis D, Mountris KA, Jaouen V, Katsanos K, Diamantopoulos A, Apostolopoulos D. A Review on Personalized Pediatric Dosimetry Applications Using Advanced Computational Tools. IEEE TRANSACTIONS ON RADIATION AND PLASMA MEDICAL SCIENCES 2019. [DOI: 10.1109/trpms.2018.2876562] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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18
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Tabari A, Patino M, Westra SJ, Shailam R, Sagar P, Sahani DV, Nimkin K, Gee MS. Initial clinical experience with high-pitch dual-source CT as a rapid technique for thoraco-abdominal evaluation in awake infants and young children. Clin Radiol 2019; 74:977.e9-977.e15. [PMID: 31561835 DOI: 10.1016/j.crad.2019.08.021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2019] [Accepted: 08/23/2019] [Indexed: 10/26/2022]
Abstract
AIM To evaluate dual-source high-pitch computed tomography (HPCT) imaging of the chest and abdomen as a rapid scanning technique to obtain diagnostic-quality imaging evaluation of infants and young children without sedation. MATERIALS AND METHODS Fifty-three paediatric patients (age 24.1±2 months) who underwent chest or abdomen HPCT (≥1.5) and standard pitch CT (SPCT, <1.5) on a dual-source 128-row multidetector CT system were included in the study. Image quality assessment was performed by two paediatric radiologists for diagnostic confidence, image artefacts, and image noise. Objective image noise was measured. RESULTS Most of the CT examinations were performed in children who were >1 year old (n=15 and n=20) followed by ≤1 year old (n=8 and n=10) in SPCT and HPCT, respectively. The mean radiation dose (SSDE) from HPCT was 1.96±1 mGy compared to 2.2±1 mGy for SPCT (p=0.3). No major artefacts were reported and overall image quality of all HPCT examinations was acceptable diagnostically. In addition, objective image noise values were not significantly different between HPCT compared with SPCT (11±3 versus 11±5, p=0.7). CONCLUSION Ultra-fast, HPCT can be performed without the need for sedation as a potential alternative to anaesthetised magnetic resonance imaging in infants and young children.
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Affiliation(s)
- A Tabari
- Division of Pediatric Imaging, Department of Radiology, Massachusetts General Hospital, Boston, MA, USA; Department of Radiology, Harvard Medical School, Boston, MA, USA.
| | - M Patino
- Department of Radiology, Harvard Medical School, Boston, MA, USA; Division of Abdominal Imaging, Department of Radiology, Massachusetts General Hospital, Boston, MA, USA
| | - S J Westra
- Division of Pediatric Imaging, Department of Radiology, Massachusetts General Hospital, Boston, MA, USA; Department of Radiology, Harvard Medical School, Boston, MA, USA
| | - R Shailam
- Division of Pediatric Imaging, Department of Radiology, Massachusetts General Hospital, Boston, MA, USA; Department of Radiology, Harvard Medical School, Boston, MA, USA
| | - P Sagar
- Division of Pediatric Imaging, Department of Radiology, Massachusetts General Hospital, Boston, MA, USA; Department of Radiology, Harvard Medical School, Boston, MA, USA
| | - D V Sahani
- Department of Radiology, Harvard Medical School, Boston, MA, USA; Division of Abdominal Imaging, Department of Radiology, Massachusetts General Hospital, Boston, MA, USA
| | - K Nimkin
- Division of Pediatric Imaging, Department of Radiology, Massachusetts General Hospital, Boston, MA, USA; Department of Radiology, Harvard Medical School, Boston, MA, USA
| | - M S Gee
- Division of Pediatric Imaging, Department of Radiology, Massachusetts General Hospital, Boston, MA, USA; Department of Radiology, Harvard Medical School, Boston, MA, USA
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19
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Kostou T, Papadimitroulas P, Papaconstadopoulos P, Devic S, Seuntjens J, Kagadis GC. Size-specific dose estimations for pediatric chest, abdomen/pelvis and head CT scans with the use of GATE. Phys Med 2019; 65:181-190. [PMID: 31494372 DOI: 10.1016/j.ejmp.2019.08.020] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/16/2019] [Revised: 07/24/2019] [Accepted: 08/29/2019] [Indexed: 01/17/2023] Open
Abstract
PURPOSE The purpose of this study is to create an organ dose database for pediatric individuals undergoing chest, abdomen/pelvis, and head computed tomography (CT) examinations, and to report the differences in absorbed organ doses, when anatomical differences exist for pediatric patients. METHODS The GATE Monte Carlo (MC) toolkit was used to model the GE BrightSpeed Elite CT model. The simulated scanner model was validated with the standard Computed Tomography Dose Index (CTDI) head phantom. Twelve computational models (2.1-14 years old) were used. First, contributions to effective dose and absorbed doses per CTDIvol and per 100 mAs were estimated for all organs. Then, doses per CTDIvol were correlated with patient model weight for the organs inside the scan range for chest and abdomen/pelvis protocols. Finally, effective doses per dose-length product (DLP) were estimated and compared with the conventional conversion k-factors. RESULTS The system was validated against experimental CTDIw measurements. The doses per CTDIvol and per 100 mAs for selected organs were estimated. The magnitude of the dependency between the dose and the anatomical characteristics was calculated with the coefficient of determination at 0.5-0.7 for the internal scan organs for chest and abdomen/pelvis protocols. Finally, effective doses per DLP were compared with already published data, showing discrepancies between 13 and 29% and were correlated strongly with the total weight (R2 > 0.8) for the chest and abdomen protocols. CONCLUSIONS Big differences in absorbed doses are reported even for patients of similar age or same gender, when anatomical differences exist on internal organs of the body.
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Affiliation(s)
- Theodora Kostou
- University of Patras, Department of Medical Physics, Patras, Greece
| | | | | | - Slobodan Devic
- McGill University, Department of Medical Physics, Montreal, Canada
| | - Jan Seuntjens
- McGill University, Department of Medical Physics, Montreal, Canada
| | - George C Kagadis
- University of Patras, Department of Medical Physics, Patras, Greece.
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20
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Magnetic resonance angiography imaging of pulmonary embolism using agents with blood pool properties as an alternative to computed tomography to avoid radiation exposure. Eur J Radiol 2019; 113:165-173. [PMID: 30927943 DOI: 10.1016/j.ejrad.2019.02.007] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2018] [Revised: 01/30/2019] [Accepted: 02/07/2019] [Indexed: 11/22/2022]
Abstract
PURPOSE To evaluate the feasibility and accuracy of a combined magnetic resonance angiography (MRA) - magnetic resonance venography (MRV) protocol using contrast agents with blood pool properties, gadofosveset trisodium and gadobenate dimeglumine, in the evaluation of pulmonary embolus (PE) and deep venous thrombosis (DVT) as compared to the standard clinical reference imaging modalities; computed tomography pulmonary angiography (CTPA) and color-coded Duplex ultrasound (DUS). MATERIALS AND METHODS This prospective clinical study recruited patients presenting to the emergency department with clinical suspicion for PE and scheduled for a clinically indicated CTPA. We performed both MRA of the chest for the evaluation of PE as well as MRV of the pelvis and thighs to evaluate for DVT using a single contrast injection. MRA-MRV data was compared to the clinical reference standard CTPA and DUS, respectively. RESULTS A total of 40 patients were recruited. The results on a per-patient basis comparing MRA to CTPA for pulmonary embolus yielded 100% sensitivity and 97% specificity. There was a small subset of patients that underwent clinical DUS to evaluate for DVT, which demonstrated a sensitivity and specificity of 100% for MRV. CONCLUSIONS This single-center, preliminary study using contrast agents with blood pool properties to perform a relatively rapid combined MRA-MRV exam to image for PE and above knee DVT shows potential as an alternative imaging choice to CTPA. Further large-scale, multicentre studies are warranted.
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Abstract
Medical imaging often involves radiation and thus radiation protection. Radiation protection in medicine is only one component of the broader calling of health care professionals: fostering human health. As such, radiation risk needs to be put into the context of the larger mandate of improved outcomes in health care. Medical physicists, according to the new vision of Medical Physics 3.0, make a significant contribution to this mandate as they engage proactively and meaningfully in patient care. Facing the new realities of value-based, personalized, and evidence-based practice, Medical Physics 3.0 is an initiative to make physics inform every patient's care by fostering new skills and expanding horizons for the medical physics profession. It provides a framework by which medical physicists can maintain and improve their integral roles in, and contributions to, health care, its innovation, and its precision. One way that Medical Physics 3.0 will manifest itself in medical imaging practice is by engaging physicists to ensure the precise and optimized use of radiation. Optimization takes place through knowing the defining attributes of the technology in use, the specifics of the patient's situation, and the goals of the imaging and/or intervention. The safety as well as the quality of the procedure is ascertained quantitatively and optimized prospectively, ensuring a proper balance between quality and safety to offer maximum potential benefit to the patient. The results of procedures across the health care operation are then retrospectively analyzed to ensure that each procedure has, in actuality, delivered the targeted quality and safety objectives. Characterizing quality and safety in quantitative terms, objectively optimizing them in the practice of personalized care, and analyzing the results from clinical operations all require the unique combination of precision and innovation that physicists bring to the development and practice of medicine.
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Affiliation(s)
- Ehsan Samei
- Duke Clinical Imaging Physics Group, Medical Physics Graduate Program, Carl E. Ravin Advanced Imaging Laboratories (RAI Labs), Departments of Radiology, Physics, Biomedical Engineering, Electrical and Computer Engineering, Duke University Medical Center, 2424 Erwin Road, Suite 302, Durham, NC 27710
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22
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Zhou DD, Sun P, Jia Z, Zhu W, Shi G, Kong B, Wang H, Zhang H. Multisection computed tomography: Results from a Chinese survey on radiation dose metrics. J Chin Med Assoc 2019; 82:155-160. [PMID: 30839508 DOI: 10.1097/jcma.0000000000000019] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
BACKGROUND As multisection spiral computed tomography (MSCT) have been extensively used, it is important to consider the amounts of doses the patients are exposed during a computed tomography (CT) examination. The aim of the current study was to summarize MSCT doses in Chinese patients to establish the diagnostic reference levels (DRLs). METHODS Radiation dose metrics were retrospectively collected from 164,073 CT examinations via the Radimetrics Enterprise Platform. Radiation dose metrics (volume CT dose index [CTDIvol], dose-length product [DLP], effective dose [ED], and organ dose) and size-specific dose estimate (SSDE) were calculated for adults and children based on anatomic area and scanner type. RESULTS The median CTDIvol and DLP values were highest in the head at 51.7 mGy (interquartile range [IQR], 33.2-51.7 mGy) and 906.5 mGy·cm (IQR, 582.4-1068.2 mGy·cm) and lowest in the chest at 7.9 mGy (IQR, 7.9-10.3 mGy) and 284.8 mGy·cm (IQR, 249.0-412.6 mGy·cm), respectively. The median SSDE values of chest and pelvis were 12.1 mGy (IQR, 10.8-14.1 mGy) and 36.3 mGy (IQR, 34.0-38.9 mGy), respectively. EDs for children were similar to adults except for an increased 1.5-, 0.77-, and 1.7-fold in the chest, neck, and pelvis, respectively (p < 0.001). Furthermore, radiation doses tended to increase with increasing slice number and decrease when exposure reduction techniques were used. CONCLUSION Our findings provide a basis for the evaluation of CT radiation doses and evidence for establishment of DRLs in China.
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Affiliation(s)
- Dan-Dan Zhou
- Department of Radiology, The First Hospital of Jilin University, Changchun, China
| | - Pengfei Sun
- Department of Radiology, The First Hospital of Jilin University, Changchun, China
| | - Zhifang Jia
- Department of Clinical Epidemiology, The First Hospital of Jilin University, Changchun, China
| | - Wanan Zhu
- Department of Radiology, The First Hospital of Jilin University, Changchun, China
| | - Guang Shi
- Department of Radiology, The First Hospital of Jilin University, Changchun, China
| | - Boyu Kong
- Department of Radiology, The First Hospital of Jilin University, Changchun, China
| | - Haifeng Wang
- Department of Neurosurgery, The First Hospital of Jilin University, Changchun, China
| | - Huimao Zhang
- Department of Radiology, The First Hospital of Jilin University, Changchun, China
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23
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Samei E, Järvinen H, Kortesniemi M, Simantirakis G, Goh C, Wallace A, Vano E, Bejan A, Rehani M, Vassileva J. Medical imaging dose optimisation from ground up: expert opinion of an international summit. JOURNAL OF RADIOLOGICAL PROTECTION : OFFICIAL JOURNAL OF THE SOCIETY FOR RADIOLOGICAL PROTECTION 2018; 38:967-989. [PMID: 29769433 DOI: 10.1088/1361-6498/aac575] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
As in any medical intervention, there is either a known or an anticipated benefit to the patient from undergoing a medical imaging procedure. This benefit is generally significant, as demonstrated by the manner in which medical imaging has transformed clinical medicine. At the same time, when it comes to imaging that deploys ionising radiation, there is a potential associated risk from radiation. Radiation risk has been recognised as a key liability in the practice of medical imaging, creating a motivation for radiation dose optimisation. The level of radiation dose and risk in imaging varies but is generally low. Thus, from the epidemiological perspective, this makes the estimation of the precise level of associated risk highly uncertain. However, in spite of the low magnitude and high uncertainty of this risk, its possibility cannot easily be refuted. Therefore, given the moral obligation of healthcare providers, 'first, do no harm,' there is an ethical obligation to mitigate this risk. Precisely how to achieve this goal scientifically and practically within a coherent system has been an open question. To address this need, in 2016, the International Atomic Energy Agency (IAEA) organised a summit to clarify the role of Diagnostic Reference Levels to optimise imaging dose, summarised into an initial report (Järvinen et al 2017 Journal of Medical Imaging 4 031214). Through a consensus building exercise, the summit further concluded that the imaging optimisation goal goes beyond dose alone, and should include image quality as a means to include both the benefit and the safety of the exam. The present, second report details the deliberation of the summit on imaging optimisation.
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Affiliation(s)
- Ehsan Samei
- Department of Radiology, Duke University, Durham, North Carolina, United States of America
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Radiation dose in non-dental cone beam CT applications: a systematic review. LA RADIOLOGIA MEDICA 2018; 123:765-777. [DOI: 10.1007/s11547-018-0910-7] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2018] [Accepted: 05/24/2018] [Indexed: 10/14/2022]
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Franck C, Smeets P, Lapeire L, Achten E, Bacher K. Estimating the Patient-specific Dose to the Thyroid and Breasts and Overall Risk in Chest CT When Using Organ-based Tube Current Modulation. Radiology 2018; 288:164-169. [PMID: 29584596 DOI: 10.1148/radiol.2018170757] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Purpose To assess the potential dose reduction to the thyroid and breasts in chest computed tomography (CT) with organ-based tube current modulation (OBTCM). Materials and Methods In this retrospective study (from January 2015 to December 2016), the location of the breasts with respect to the reduced tube current zone was determined. With Monte Carlo simulations, patient-specific dose distributions of chest CT scans were calculated for 50 female patients (mean age, 53.7 years ± 17.5; range, 20-80 years). The potential dose reduction with OBTCM was assessed. In addition, simulations of clinical OBTCM scans were made for 17 of the 50 female patients (mean age, 43.8 years ± 17.1; range, 20-69 years). Posterior organs in the field of view were analyzed and lifetime attributable risk (LAR) of cancer incidence and mortality was estimated. Image quality between standard CT and OBTCM scans was compared. Results No women had all breast tissue within the reduced tube current zone. Dose reductions of 18% in the thyroid and 9% in the breasts were observed, whereas the doses in lung, liver, and kidney were 17%, 11%, and 26% higher. Overall, the LAR for cancer incidence was not significantly different between conventional and OBTCM scanning (P = .06). Image quality improved with OBTCM (P < .002). Conclusion The potential benefit of OBTCM to the female breast in chest CT is overestimated because of a limited reduced tube current zone; despite a 9% dose reduction to the female breast, posterior organs will absorb up to 26% more radiation, resulting in no reduction in radiation-induced malignancies. © RSNA, 2018.
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Affiliation(s)
- Caro Franck
- From the Department of Medical Physics, Ghent University, Profetuinstraat 86, 9000 Ghent, Belgium (C.F., K.B.); and Departments of Radiology (P.S., E.A.) and Medical Oncology (L.L.), Ghent University Hospital, Ghent, Belgium
| | - Peter Smeets
- From the Department of Medical Physics, Ghent University, Profetuinstraat 86, 9000 Ghent, Belgium (C.F., K.B.); and Departments of Radiology (P.S., E.A.) and Medical Oncology (L.L.), Ghent University Hospital, Ghent, Belgium
| | - Lore Lapeire
- From the Department of Medical Physics, Ghent University, Profetuinstraat 86, 9000 Ghent, Belgium (C.F., K.B.); and Departments of Radiology (P.S., E.A.) and Medical Oncology (L.L.), Ghent University Hospital, Ghent, Belgium
| | - Eric Achten
- From the Department of Medical Physics, Ghent University, Profetuinstraat 86, 9000 Ghent, Belgium (C.F., K.B.); and Departments of Radiology (P.S., E.A.) and Medical Oncology (L.L.), Ghent University Hospital, Ghent, Belgium
| | - Klaus Bacher
- From the Department of Medical Physics, Ghent University, Profetuinstraat 86, 9000 Ghent, Belgium (C.F., K.B.); and Departments of Radiology (P.S., E.A.) and Medical Oncology (L.L.), Ghent University Hospital, Ghent, Belgium
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Kasraie N, Jordan D, Keup C, Westra S. Optimizing Communication With Parents on Benefits and Radiation Risks in Pediatric Imaging. J Am Coll Radiol 2018; 15:809-817. [PMID: 29555251 DOI: 10.1016/j.jacr.2018.01.032] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2017] [Revised: 01/19/2018] [Accepted: 01/23/2018] [Indexed: 01/20/2023]
Abstract
Effective radiation risk communication is a core competency for radiology care providers and can prevent and resolve potential conflicts while helping achieve effective public health safeguards. The authors present a synopsis of the challenges to holding such dialogue and review published methods for strengthening and maintaining this discourse. Twelve strategies are discussed in this article that can help alleviate concerns about the iatrogenic risk associated with medical imaging using radiation exposure.
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Affiliation(s)
- Nima Kasraie
- Children's Mercy Hospital, Kansas City, Missouri.
| | - David Jordan
- University Hospitals Cleveland Medical Center, Cleveland, Ohio
| | | | - Sjirk Westra
- MassGeneral Hospital for Children, Boston, Massachusetts
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Segars WP, Tsui BMW, Jing Cai, Fang-Fang Yin, Fung GSK, Samei E. Application of the 4-D XCAT Phantoms in Biomedical Imaging and Beyond. IEEE TRANSACTIONS ON MEDICAL IMAGING 2018; 37:680-692. [PMID: 28809677 PMCID: PMC5809240 DOI: 10.1109/tmi.2017.2738448] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
The four-dimensional (4-D) eXtended CArdiac-Torso (XCAT) series of phantoms was developed to provide accurate computerized models of the human anatomy and physiology. The XCAT series encompasses a vast population of phantoms of varying ages from newborn to adult, each including parameterized models for the cardiac and respiratory motions. With great flexibility in the XCAT's design, any number of body sizes, different anatomies, cardiac or respiratory motions or patterns, patient positions and orientations, and spatial resolutions can be simulated. As such, the XCAT phantoms are gaining a wide use in biomedical imaging research. There they can provide a virtual patient base from which to quantitatively evaluate and improve imaging instrumentation, data acquisition, techniques, and image reconstruction and processing methods which can lead to improved image quality and more accurate clinical diagnoses. The phantoms have also found great use in radiation dosimetry, radiation therapy, medical device design, and even the security and defense industry. This review paper highlights some specific areas in which the XCAT phantoms have found use within biomedical imaging and other fields. From these examples, we illustrate the increasingly important role that computerized phantoms and computer simulation are playing in the research community.
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Hassan AI, Skalej M, Schlattl H, Hoeschen C. Determination and verification of the x-ray spectrum of a CT scanner. J Med Imaging (Bellingham) 2018; 5:013506. [PMID: 29430476 DOI: 10.1117/1.jmi.5.1.013506] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2017] [Accepted: 01/10/2018] [Indexed: 11/14/2022] Open
Abstract
The accuracy of Monte Carlo (MC) simulations in estimating the computed tomography radiation dose is highly dependent on the proprietary x-ray source information. To address this, this study develops a method to precisely estimate the x-ray spectrum and bowtie (BT) filter thickness of the x-ray source based on physical measurements and calculations. The static x-ray source of the CT localizer radiograph was assessed to measure the total filtration at the isocenter for the x-ray spectrum characterization and the BT profile (air-kerma values as a function of fan angle). With these values, the utilized BT filter in the localizer radiograph was assessed by integrating the measured air kerma in a full 360-deg cycle. The consistency observed between the integrated BT filter profiles and the directly measured profiles pointed to the similarity in the utilized BT filter in terms of thickness and material between the static and rotating x-ray geometries. Subsequently, the measured air kerma was used to calculate the BT filter thickness and was verified using MC simulations by comparing the calculated and measured air-kerma values, where a very good agreement was observed. This would allow a more accurate computed tomography simulation and facilitate the estimation of the dose delivered to the patients.
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Affiliation(s)
- Ahmad Ibrahim Hassan
- Otto von Guericke Universität Magdeburg, Universitätsklinikum Magdeburg A.ö.R., Institut für Neuroradiologie, Magdeburg, Deutschland, Germany.,Otto von Guericke Universität, Institut für Medizintechnik, Fakultät für Elektrotechnik und Informationstechnik Universitätsplatz, Magdeburg, Deutschland, Germany
| | - Martin Skalej
- Otto von Guericke Universität Magdeburg, Universitätsklinikum Magdeburg A.ö.R., Institut für Neuroradiologie, Magdeburg, Deutschland, Germany
| | - Helmut Schlattl
- Institute of Radiation Protection, Helmholtz Zentrum München-German Research Center for Environmental Health, Neuherberg, Deutschland, Germany
| | - Christoph Hoeschen
- Otto von Guericke Universität, Institut für Medizintechnik, Fakultät für Elektrotechnik und Informationstechnik Universitätsplatz, Magdeburg, Deutschland, Germany
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Samei E, Tian X, Paul Segars W, Frush DP. Radiation risk index for pediatric CT: a patient-derived metric. Pediatr Radiol 2017; 47:1737-1744. [PMID: 28856394 DOI: 10.1007/s00247-017-3973-z] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/02/2016] [Revised: 05/25/2017] [Accepted: 08/18/2017] [Indexed: 10/19/2022]
Abstract
BACKGROUND There is a benefit in characterizing radiation-induced cancer risk in pediatric chest and abdominopelvic CT: a singular metric that represents the whole-body radiation burden while also accounting for age, gender and organ sensitivity. OBJECTIVE To compute an index of radiation risk for pediatric chest and abdominopelvic CT. MATERIALS AND METHODS Using a protocol approved by our institutional review board, 42 pediatric patients (age: 0-16 years, weight: 2-80 kg) were modeled into virtual whole-body anatomical models. Organ doses were estimated for clinical chest and abdominopelvic CT examinations of the patients using validated Monte Carlo simulations of two major scanner models. Using age-, size- and gender-specific organ risk coefficients, the values were converted to normalized effective dose (by dose length product) (denoted as the k factor) and a normalized risk index (denoted as the q factor). An analysis was performed to determine how these factors are correlated with patient age and size for both males and females to provide a strategy to better characterize individualized risk. RESULTS The k factor was found to be exponentially correlated with the average patient diameter. For both genders, the q factor also exhibited an exponential relationship with both the average patient diameter and with patient age. For both factors, the differences between the scanner models were less than 8%. CONCLUSION The study defines a whole-body radiation risk index for chest and abdominopelvic CT imaging, that incorporates individual estimated organ dose values, organ radiation sensitivity, patient size, exposure age and patient gender. This indexing metrology enables the assessment and potential improvement of chest and abdominopelvic CT performance through surveillance of practice dose profiles across patients and may afford improved informed communication.
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Affiliation(s)
- Ehsan Samei
- Department of Radiology, Carl E. Ravin Advanced Imaging Laboratories, Duke University Medical Center, Durham, NC, USA.,Department of Biomedical Engineering, Electrical and Computer Engineering, Duke University Medical Center, Durham, NC, USA.,Medical Physics Graduate Program, Duke University Medical Center, Durham, NC, USA
| | - Xiaoyu Tian
- Department of Radiology, Carl E. Ravin Advanced Imaging Laboratories, Duke University Medical Center, Durham, NC, USA
| | - W Paul Segars
- Department of Radiology, Carl E. Ravin Advanced Imaging Laboratories, Duke University Medical Center, Durham, NC, USA.,Medical Physics Graduate Program, Duke University Medical Center, Durham, NC, USA
| | - Donald P Frush
- Medical Physics Graduate Program, Duke University Medical Center, Durham, NC, USA. .,Division of Pediatric Radiology, Department of Radiology, Duke University Medical Center, 1905 McGovern-Davison Children's Health Center, Durham, NC, 27710, USA.
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Andersson M, Eckerman K, Mattsson S. Lifetime attributable risk as an alternative to effective dose to describe the risk of cancer for patients in diagnostic and therapeutic nuclear medicine. Phys Med Biol 2017; 62:9177-9188. [PMID: 29064376 DOI: 10.1088/1361-6560/aa959c] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The aim of this study is to implement lifetime attributable risk (LAR) predictions of cancer for patients of various age and gender, undergoing diagnostic investigations or treatments in nuclear medicine and to compare the outcome with a population risk estimate using effective dose and the International Commission on Radiological Protection risk coefficients. The radiation induced risk of cancer occurrence (incidence) or death from four nuclear medicine procedures are estimated for both male and female between 0 and 120 years. Estimations of cancer risk are performed using recommended administered activities for two diagnostic (18F-FDG and 99mTc-phosphonate complex) and two therapeutic (131I-iodide and 223Ra-dichloride) radiopharmaceuticals to illustrate the use of cancer risk estimations in nuclear medicine. For 18F-FDG, the cancer incidence for a male of 5, 25, 50 and 75 years at exposure is 0.0021, 0.0010, 0.0008 and 0.0003, respectively. For 99mTc phosphonates complex the corresponding values are 0.000 59, 0.000 34, 0.000 27 and 0.000 13, respectively. For an 131I-iodide treatment with 3.7 GBq and 1% uptake 24 h after administration, the cancer incidence for a male of 25, 50 and 75 years at exposure is 0.041, 0.029 and 0.012, respectively. For 223Ra-dichloride with an administration of 21.9 MBq the cancer incidence for a male of 25, 50 and 75 years is 0.31, 0.21 and 0.09, respectively. The LAR estimations are more suitable in health care situations involving individual patients or specific groups of patients than the health detriment based on effective dose, which represents a population average. The detriment consideration in effective dose adjusts the cancer incidence for suffering of non-lethal cancers while LAR predicts morbidity (incidence) or mortality (cancer). The advantages of these LARs are that they are gender and age specific, allowing risk estimations for specific patients or subgroups thus better representing individuals in health care than effective dose.
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Affiliation(s)
- Martin Andersson
- Department of Translational Medicine, Medical Radiation Physics, Lund University, Malmö, Sweden
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Organ doses and lifetime attributable risk evaluations for scoliosis examinations of adolescent patients with the EOS imaging system. Radiol Med 2017; 123:305-313. [PMID: 29164365 DOI: 10.1007/s11547-017-0828-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2017] [Accepted: 10/27/2017] [Indexed: 10/18/2022]
Abstract
PURPOSE The goal of this work is to evaluate organ doses and lifetime attributable risk of cancer incidence and mortality in scoliosis examinations of adolescent patients performed with EOS imaging system, in order to optimize patient dose and protocols. METHODS An anthropomorphic phantom of a normal patient, with thermoluminescent dosimeters in correspondence with the main organs at risk, was imaged with both EOS and computed radiography (CR). For each modality, effective dose was calculated from the measured organ doses. Lifetime attributable risk was computed accordingly to the Committee on the Biological Effects of Ionizing Radiation (BEIR VII) and Public Health England (HPA) publications. RESULTS Except for testes and eyes, which were excluded from the scan in CR protocol, for all the other organs the doses delivered with CR examination were higher than these delivered by EOS system. The effective dose in EOS examination (0.43 ± 0.04 mSv) is about two times less than the dose in computed radiography with anti-scatter grid examination (0.87 ± 0.09 mSv), and, consequently, also the cancer probability is lower (5.4 vs 9.7 number of any cancers induction cases per 100,000 person examined, for a 20-year-old male patient). CONCLUSIONS The EOS system is efficient in limiting patient dose. The shielding of testes and the exclusion of eyes from the scan could allow to further reduce the dose.
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Dzierma Y, Minko P, Ziegenhain F, Bell K, Buecker A, Rübe C, Jagoda P. Abdominal imaging dose in radiology and radiotherapy - Phantom point dose measurements, effective dose and secondary cancer risk. Phys Med 2017; 43:49-56. [PMID: 29195562 DOI: 10.1016/j.ejmp.2017.10.019] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/15/2017] [Revised: 10/20/2017] [Accepted: 10/21/2017] [Indexed: 11/28/2022] Open
Abstract
PURPOSE To compare abdominal imaging dose from 3D imaging in radiology (standard/low-dose/dual-energy CT) and radiotherapy (planning CT, kV cone-beam CT (CBCT)). METHODS Dose was measured by thermoluminescent dosimeters (TLD's) placed at 86 positions in an anthropomorphic phantom. Point, organ and effective dose were assessed, and secondary cancer risk from imaging was estimated. RESULTS Overall dose and mean organ dose comparisons yield significantly lower dose for the optimized radiology protocols (dual-source and care kV), with an average dose of 0.34±0.01 mGy and 0.54±0.01 mGy (average ± standard deviation), respectively. Standard abdominal CT and planning CT involve considerably higher dose (13.58 ± 0.18 mGy and 18.78±0.27 mGy, respectively). The CBCT dose show a dose fall-off near the field edges. On average, dose is reduced as compared with the planning or standard CT (3.79 ± 0.21 mGy for 220° rotation and 7.76 ± 0.37 mGy for 360°), unless the high-quality setting is chosen (20.30 ± 0.96 mGy). The mean organ doses show a similar behavior, which translates to the estimated secondary cancer risk. The modelled risk is in the range between 0.4 cases per million patient years (PY) for the radiological scans dual-energy and care kV, and 300 cases per million PY for the high-quality CBCT setting. CONCLUSIONS Modern radiotherapy imaging techniques (while much lower in dose than radiotherapy), involve considerably more dose to the patient than modern radiology techniques. Given the frequency of radiotherapy imaging, a further reduction in radiotherapy imaging dose appears to be both desirable and technically feasible.
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Affiliation(s)
- Yvonne Dzierma
- Department of Radiotherapy and Radiation Oncology, Saarland University Medical Center, Kirrberger Str. Geb. 6.5, D-66421 Homburg/Saar, Germany.
| | - Peter Minko
- Department of Diagnostic and Interventional Radiology, Saarland University Medical Center, Kirrberger Str. Geb. 50.1, D-66421 Homburg/Saar, Germany
| | - Franziska Ziegenhain
- Department of Radiotherapy and Radiation Oncology, Saarland University Medical Center, Kirrberger Str. Geb. 6.5, D-66421 Homburg/Saar, Germany
| | - Katharina Bell
- Department of Radiotherapy and Radiation Oncology, Saarland University Medical Center, Kirrberger Str. Geb. 6.5, D-66421 Homburg/Saar, Germany
| | - Arno Buecker
- Department of Diagnostic and Interventional Radiology, Saarland University Medical Center, Kirrberger Str. Geb. 50.1, D-66421 Homburg/Saar, Germany
| | - Christian Rübe
- Department of Radiotherapy and Radiation Oncology, Saarland University Medical Center, Kirrberger Str. Geb. 6.5, D-66421 Homburg/Saar, Germany
| | - Philippe Jagoda
- Department of Diagnostic and Interventional Radiology, Saarland University Medical Center, Kirrberger Str. Geb. 50.1, D-66421 Homburg/Saar, Germany
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Samei E, Li X, Frush DP. Size-based quality-informed framework for quantitative optimization of pediatric CT. J Med Imaging (Bellingham) 2017; 4:031209. [PMID: 28840168 DOI: 10.1117/1.jmi.4.3.031209] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2017] [Accepted: 07/06/2017] [Indexed: 11/14/2022] Open
Abstract
The purpose of this study was to formulate a systematic, evidence-based method to relate quantitative diagnostic performance to radiation dose, enabling a multidimensional system to optimize computed tomography imaging across pediatric populations. Based on two prior foundational studies, radiation dose was assessed in terms of organ doses, effective dose ([Formula: see text]), and risk index for 30 patients within nine color-coded pediatric age-size groups as a function of imaging parameters. The cases, supplemented with added noise and simulated lesions, were assessed in terms of nodule detection accuracy in an observer receiving operating characteristic study. The resulting continuous accuracy-dose relationships were used to optimize individual scan parameters. Before optimization, the nine protocols had a similar [Formula: see text] of [Formula: see text] with accuracy decreasing from 0.89 for the youngest patients to 0.67 for the oldest. After optimization, a consistent target accuracy of 0.83 was established for all patient categories with [Formula: see text] ranging from 1 to 10 mSv. Alternatively, isogradient operating points targeted a consistent ratio of accuracy-per-unit-dose across the patient categories. The developed model can be used to optimize individual scan parameters and provide for consistent diagnostic performance across the broad range of body sizes in children.
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Affiliation(s)
- Ehsan Samei
- Duke University Medical Center, Departments of Radiology, Physics, Biomedical Engineering, and Electrical and Computer Engineering, Carl E. Ravin Advanced Imaging Laboratories, Medical Physics Graduate Program, Durham, North Carolina, United States
| | - Xiang Li
- Cleveland Clinic, Imaging Institute, Section of Medical Physics, Cleveland, Ohio, United States
| | - Donald P Frush
- Duke University Medical Center, Division of Pediatric Radiology, Department of Radiology, Medical Physics Graduate Program, Durham, North Carolina, United States
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Tschauner S, Marterer R, Nagy E, Apfaltrer G, Riccabona M, Singer G, Stücklschweiger G, Guss H, Sorantin E. Surface radiation dose comparison of a dedicated extremity cone beam computed tomography (CBCT) device and a multidetector computed tomography (MDCT) machine in pediatric ankle and wrist phantoms. PLoS One 2017; 12:e0178747. [PMID: 28570626 PMCID: PMC5453596 DOI: 10.1371/journal.pone.0178747] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2016] [Accepted: 05/18/2017] [Indexed: 11/24/2022] Open
Abstract
Objectives To evaluate and compare surface doses of a cone beam computed tomography (CBCT) and a multidetector computed tomography (MDCT) device in pediatric ankle and wrist phantoms. Methods Thermoluminescent dosimeters (TLD) were used to measure and compare surface doses between CBCT and MDCT in a left ankle and a right wrist pediatric phantom. In both modalities adapted pediatric dose protocols were utilized to achieve realistic imaging conditions. All measurements were repeated three times to prove test-retest reliability. Additionally, objective and subjective image quality parameters were assessed. Results Average surface doses were 3.8 ±2.1 mGy for the ankle, and 2.2 ±1.3 mGy for the wrist in CBCT. The corresponding surface doses in optimized MDCT were 4.5 ±1.3 mGy for the ankle, and 3.4 ±0.7 mGy for the wrist. Overall, mean surface dose was significantly lower in CBCT (3.0 ±1.9 mGy vs. 3.9 ±1.2 mGy, p<0.001). Subjectively rated general image quality was not significantly different between the study protocols (p = 0.421), whereas objectively measured image quality parameters were in favor of CBCT (p<0.001). Conclusions Adapted extremity CBCT imaging protocols have the potential to fall below optimized pediatric ankle and wrist MDCT doses at comparable image qualities. These possible dose savings warrant further development and research in pediatric extremity CBCT applications.
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Affiliation(s)
- Sebastian Tschauner
- Division of Pediatric Radiology, Department of Radiology, Medical University of Graz, Graz, Austria
- * E-mail:
| | - Robert Marterer
- Division of Pediatric Radiology, Department of Radiology, Medical University of Graz, Graz, Austria
| | - Eszter Nagy
- Division of Pediatric Radiology, Department of Radiology, Medical University of Graz, Graz, Austria
| | - Georg Apfaltrer
- Division of Pediatric Radiology, Department of Radiology, Medical University of Graz, Graz, Austria
| | - Michael Riccabona
- Division of Pediatric Radiology, Department of Radiology, Medical University of Graz, Graz, Austria
| | - Georg Singer
- Division of General Pediatric and Adolescence Surgery, Medical University of Graz, Graz, Austria
| | - Georg Stücklschweiger
- Competence Centre for Medical Physics and Radiation Protection, University Hospital Graz, Graz, Austria
| | - Helmuth Guss
- Competence Centre for Medical Physics and Radiation Protection, University Hospital Graz, Graz, Austria
| | - Erich Sorantin
- Division of Pediatric Radiology, Department of Radiology, Medical University of Graz, Graz, Austria
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Variability in Radiation Dose From Repeat Identical CT Examinations: Longitudinal Analysis of 2851 Patients Undergoing 12,635 Thoracoabdominal CT Scans in an Academic Health System. AJR Am J Roentgenol 2017; 208:1285-1296. [DOI: 10.2214/ajr.16.17070] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Carver DE, Kost SD, Fraser ND, Segars WP, Pickens DR, Price RR, Stabin MG. Realistic phantoms to characterize dosimetry in pediatric CT. Pediatr Radiol 2017; 47:691-700. [PMID: 28283725 PMCID: PMC5420344 DOI: 10.1007/s00247-017-3805-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/09/2016] [Revised: 12/07/2016] [Accepted: 02/10/2017] [Indexed: 10/24/2022]
Abstract
BACKGROUND The estimation of organ doses and effective doses for children receiving CT examinations is of high interest. Newer, more realistic anthropomorphic body models can provide information on individual organ doses and improved estimates of effective dose. MATERIALS AND METHODS Previously developed body models representing 50th-percentile individuals at reference ages (newborn, 1, 5, 10 and 15 years) were modified to represent 10th, 25th, 75th and 90th height percentiles for both genders and an expanded range of ages (3, 8 and 13 years). We calculated doses for 80 pediatric reference phantoms from simulated chest-abdomen-pelvis exams on a model of a Philips Brilliance 64 CT scanner. Individual organ and effective doses were normalized to dose-length product (DLP) and fit as a function of body diameter. RESULTS We calculated organ and effective doses for 80 reference phantoms and plotted them against body diameter. The data were well fit with an exponential function. We found DLP-normalized organ dose to correlate strongly with body diameter (R2>0.95 for most organs). Similarly, we found a very strong correlation with body diameter for DLP-normalized effective dose (R2>0.99). Our results were compared to other studies and we found average agreement of approximately 10%. CONCLUSION We provide organ and effective doses for a total of 80 reference phantoms representing normal-stature children ranging in age and body size. This information will be valuable in replacing the types of vendor-reported doses available. These data will also permit the recording and tracking of individual patient doses. Moreover, this comprehensive dose database will facilitate patient matching and the ability to predict patient-individualized dose prior to examination.
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Affiliation(s)
- Diana E Carver
- Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, 1161 21st Avenue South, Nashville, TN, 37232, USA.
| | - Susan D Kost
- Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, 1161 21st Avenue South, Nashville, TN, 37232, USA
| | - Nicholas D Fraser
- Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, 1161 21st Avenue South, Nashville, TN, 37232, USA
| | - W Paul Segars
- Carl E. Ravin Advanced Imaging Laboratories, Duke University, Hock Plaza Suite 302, 2424 Erwin Road, Durham, NC, 27705, USA
| | - David R Pickens
- Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, 1161 21st Avenue South, Nashville, TN, 37232, USA
| | - Ronald R Price
- Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, 1161 21st Avenue South, Nashville, TN, 37232, USA
| | - Michael G Stabin
- Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, 1161 21st Avenue South, Nashville, TN, 37232, USA
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Liang B, Gao Y, Chen Z, Xu XG. Evaluation of Effective Dose from CT Scans for Overweight and Obese Adult Patients Using the VirtualDose Software. RADIATION PROTECTION DOSIMETRY 2017; 174:216-225. [PMID: 27242344 PMCID: PMC7462054 DOI: 10.1093/rpd/ncw119] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2015] [Revised: 03/23/2016] [Accepted: 04/20/2016] [Indexed: 06/01/2023]
Abstract
This paper evaluates effective dose (ED) of overweight and obese patients who undergo body computed tomography (CT) examinations. ED calculations were based on tissue weight factors in the International Commission on Radiological Protection Publication 103 (ICRP 103). ED per unit dose length product (DLP) are reported as a function of the tube voltage, body mass index (BMI) of patient. The VirtualDose software was used to calculate ED for male and female obese phantoms representing normal weight, overweight, obese 1, obese 2 and obese 3 patients. Five anatomic regions (chest, abdomen, pelvis, abdomen/pelvis and chest/abdomen/pelvis) were investigated for each phantom. The conversion factors were computed from the DLP, and then compared with data previously reported by other groups. It was observed that tube voltage and BMI are the major factors that influence conversion factors of obese patients, and that ED computed using ICRP 103 tissue weight factors were 24% higher for a CT chest examination and 21% lower for a CT pelvis examination than the ED using ICRP 60 factors. For body CT scans, increasing the tube voltage from 80 to 140 kVp would increase the conversion factors by as much as 19-54% depending on the patient's BMI. Conversion factor of female patients was ~7% higher than the factors of male patients. DLP and conversion factors were used to estimate ED, where conversion factors depended on tube voltage, sex, BMI and tissue weight factors. With increasing number of obese individuals, using size-dependence conversion factors will improve accuracy, in estimating patient radiation dose.
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Affiliation(s)
- Baohui Liang
- School of Nuclear Science and Technology, University of Science and Technology of China, Hefei, Anhui Province, P.R. China
- Department of Medical Imaging, BengBu Medical College, Bengbu, Anhui Province, P.R. China
| | - Yiming Gao
- Nuclear Engineering Program, Rensselaer Polytechnic Institute, Troy, NY 12180, USA
| | - Zhi Chen
- School of Nuclear Science and Technology, University of Science and Technology of China, Hefei, Anhui Province, P.R. China
| | - X. George Xu
- School of Nuclear Science and Technology, University of Science and Technology of China, Hefei, Anhui Province, P.R. China
- Nuclear Engineering Program, Rensselaer Polytechnic Institute, Troy, NY 12180, USA
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Muryn JS, Morgan AG, Liptak CL, Dong FF, Segars WP, Primak AN, Li X. Analysis of uncertainties in Monte Carlo simulated organ and effective dose in chest CT: scanner- and scan-related factors. Phys Med Biol 2017; 62:3175-3203. [DOI: 10.1088/1361-6560/aa60d7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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39
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Yang K, Li X, George Xu X, Liu B. Direct and fast measurement of CT beam filter profiles with simultaneous geometrical calibration. Med Phys 2017; 44:57-70. [PMID: 28102951 DOI: 10.1002/mp.12024] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2016] [Revised: 11/03/2016] [Accepted: 11/12/2016] [Indexed: 01/28/2023] Open
Abstract
PURPOSE To accurately measure the beam filter profiles from a variety of CT scanner models and to provide reference data for Monte Carlo simulations of CT scanners. METHODS This study proposed a new method to measure CT beam filter profiles using a linear-array x-ray detector (X-Scan 0.8f3-512; Detection Technology Inc., Espoo, Finland) under gantry rotation mode. A robust geometrical calibration approach was developed to determine key geometrical parameters by considering the x-ray focal spot location relative to the linear-array detector and the gantry's angular increment at each acquisition point. CT beam intensity profiles were synthesized from continuously measured data during a 10° gantry rotation range with calibrated detector response and system geometry information. Relative transmission profiles of nineteen sets of beam filters were then derived for nine different CT scanner models from three different manufacturers. Equivalent aluminum thickness profiles of these beam filters were determined by analytical calculation using the Spektr Matlab software package to match the measured transmission profiles. Three experiments were performed to validate the accuracy of the geometrical calibration, detector response modeling, and the derived equivalent aluminum thickness profiles. RESULTS The beam intensity profiles measured from gantry rotation mode showed very good agreement with those measured with gantry stationary mode, with a maximal difference of 3%. The equivalent aluminum thickness determined by this proposed method agreed well with what was measured by an ion chamber, with a mean difference of 0.4%. The determined HVL profiles matched well with data from a previous study (max difference of 4.7%). CONCLUSIONS An accurate and robust method to directly measure profiles from a broad list of beam filters and CT scanner models was developed, implemented, and validated. Useful reference data was provided for future research on CT system modeling.
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Affiliation(s)
- Kai Yang
- Division of Diagnostic Imaging Physics, Department of Radiology, Massachusetts General Hospital, 55 Fruit Street, Boston, MA 02114, USA
| | - Xinhua Li
- Division of Diagnostic Imaging Physics, Department of Radiology, Massachusetts General Hospital, 55 Fruit Street, Boston, MA 02114, USA
| | - X George Xu
- Nuclear Engineering Program, Rensselaer Polytechnic Institute, Troy, New York, 12180, USA
| | - Bob Liu
- Division of Diagnostic Imaging Physics, Department of Radiology, Massachusetts General Hospital, 55 Fruit Street, Boston, MA 02114, USA
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40
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Fu W, Tian X, Sturgeon GM, Agasthya G, Segars WP, Goodsitt MM, Kazerooni EA, Samei E. CT breast dose reduction with the use of breast positioning and organ-based tube current modulation. Med Phys 2017; 44:665-678. [DOI: 10.1002/mp.12076] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2016] [Revised: 10/31/2016] [Accepted: 12/14/2016] [Indexed: 12/11/2022] Open
Affiliation(s)
- Wanyi Fu
- Carl E. Ravin Advanced Imaging Laboratories; Department of Radiology; Department of Electrical and Computer Engineering; Duke University; Durham North Carolina 27705 USA
| | - Xiaoyu Tian
- Carl E. Ravin Advanced Imaging Laboratories; Department of Radiology; Department of Biomedical Engineering; Duke University; Durham North Carolina 27705 USA
| | - Gregory M. Sturgeon
- Carl E. Ravin Advanced Imaging Laboratories; Department of Radiology; Duke University; Durham North Carolina 27705 USA
| | - Greeshma Agasthya
- Carl E. Ravin Advanced Imaging Laboratories; Department of Radiology; Duke University; Durham North Carolina 27705 USA
| | - William Paul Segars
- Carl E. Ravin Advanced Imaging Laboratories; Department of Radiology; Department of Biomedical Engineering; Duke University; Durham North Carolina 27705 USA
| | | | - Ella A. Kazerooni
- Department of Radiology; University of Michigan; Ann Arbor Michigan 48109 USA
| | - Ehsan Samei
- Carl E. Ravin Advanced Imaging Laboratories; Department of Radiology; Medical Physics Graduate Program; Departments of Physics, Biomedical Engineering, and Electrical and Computer Engineering; Duke University; Durham North Carolina 27705 USA
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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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The impact of patient table on size-specific dose estimate (SSDE). AUSTRALASIAN PHYSICAL & ENGINEERING SCIENCES IN MEDICINE 2016; 40:153-158. [DOI: 10.1007/s13246-016-0497-z] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2016] [Accepted: 10/29/2016] [Indexed: 10/20/2022]
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Nassiri MA, Rouleau M, Després P. CT dose reduction: approaches, strategies and results from a province-wide program in Quebec. JOURNAL OF RADIOLOGICAL PROTECTION : OFFICIAL JOURNAL OF THE SOCIETY FOR RADIOLOGICAL PROTECTION 2016; 36:346-362. [PMID: 27270762 DOI: 10.1088/0952-4746/36/2/346] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Many studies have shown a statistically significant increase of life-time risk of radiation-induced cancer from CT examinations. In this context, in Canada, the Quebec's provincial clinical center of expertise in radiation safety (CECR) has led a province-wide tour of 180 CT installations in order to: (i) evaluate the technical and functional performance of CT scanners, (ii) evaluate and improve radiation safety practices and (iii) initiate, with local teams, a CT dose optimization process. The CT tour consisted of a two day visit of CT installations by a CECR multidisciplinary team of medical physicists, engineers and medical imaging technologists (MITs) carried out in close collaboration with local teams composed of MITs, radiologists, physicists, engineers and managers. The CECR has evaluated 112 CT scanners since 2011. Optimization of CT protocols was performed in all centers visited. The average dose reduction obtained from optimization was [Formula: see text], [Formula: see text] and [Formula: see text] for adult head, thorax and abdomen-pelvis, respectively. The main recommendations often made by the CECR experts were: (1) the implementation of low-dose protocols for the follow-up of pulmonary nodules and for renal calculi, (2) the compliance to the prescribed scan range as defined by local guidelines, (3) the correct positioning of patients and (4) the use of bismuth shielding to reduce the dose to radiosensitive organs. The CECR approach to optimize CT doses to patients is based on the active participation of local stakeholders and takes into account the performance of CT scanners. The clinical requirements as expressed by radiologists remain at the core of the optimization process.
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Affiliation(s)
- Moulay Ali Nassiri
- Centre d'expertise clinique en radioprotection (CECR), Sherbrooke (Québec), Canada. Centre intégré universitaire de santé et de services sociaux de l'Estrie-Centre hospitalier universitaire de Sherbrooke (Québec), Canada
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Martin CJ, Abuhaimed A, Sankaralingam M, Metwaly M, Gentle DJ. Organ doses can be estimated from the computed tomography (CT) dose index for cone-beam CT on radiotherapy equipment. JOURNAL OF RADIOLOGICAL PROTECTION : OFFICIAL JOURNAL OF THE SOCIETY FOR RADIOLOGICAL PROTECTION 2016; 36:215-229. [PMID: 26975735 DOI: 10.1088/0952-4746/36/2/215] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Cone beam computed tomography (CBCT) systems are fitted to radiotherapy linear accelerators and used for patient positioning prior to treatment by image guided radiotherapy (IGRT). Radiotherapists' and radiographers' knowledge of doses to organs from CBCT imaging is limited. The weighted CT dose index for a reference beam of width 20 mm (CTDIw,ref) is displayed on Varian CBCT imaging equipment known as an On-Board Imager (OBI) linked to the Truebeam linear accelerator. This has the potential to provide an indication of organ doses. This knowledge would be helpful for guidance of radiotherapy clinicians preparing treatments. Monte Carlo simulations of imaging protocols for head, thorax and pelvic scans have been performed using EGSnrc/BEAMnrc, EGSnrc/DOSXYZnrc, and ICRP reference computational male and female phantoms to derive the mean absorbed doses to organs and tissues, which have been compared with values for the CTDIw,ref displayed on the CBCT scanner console. Substantial variations in dose were observed between male and female phantoms. Nevertheless, the CTDIw,ref gave doses within ±21% for the stomach and liver in thorax scans and 2 × CTDIw,ref can be used as a measure of doses to breast, lung and oesophagus. The CTDIw,ref could provide indications of doses to the brain for head scans, and the colon for pelvic scans. It is proposed that knowledge of the link between CTDIw for CBCT should be promoted and included in the training of radiotherapy staff.
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Affiliation(s)
- Colin J Martin
- Department of Clinical Physics, University of Glasgow, Glasgow, UK
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45
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Tian X, Segars WP, Dixon RL, Samei E. Convolution-based estimation of organ dose in tube current modulated CT. Phys Med Biol 2016; 61:3935-54. [PMID: 27119974 PMCID: PMC5070791 DOI: 10.1088/0031-9155/61/10/3935] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Estimating organ dose for clinical patients requires accurate modeling of the patient anatomy and the dose field of the CT exam. The modeling of patient anatomy can be achieved using a library of representative computational phantoms (Samei et al 2014 Pediatr. Radiol. 44 460-7). The modeling of the dose field can be challenging for CT exams performed with a tube current modulation (TCM) technique. The purpose of this work was to effectively model the dose field for TCM exams using a convolution-based method. A framework was further proposed for prospective and retrospective organ dose estimation in clinical practice. The study included 60 adult patients (age range: 18-70 years, weight range: 60-180 kg). Patient-specific computational phantoms were generated based on patient CT image datasets. A previously validated Monte Carlo simulation program was used to model a clinical CT scanner (SOMATOM Definition Flash, Siemens Healthcare, Forchheim, Germany). A practical strategy was developed to achieve real-time organ dose estimation for a given clinical patient. CTDIvol-normalized organ dose coefficients ([Formula: see text]) under constant tube current were estimated and modeled as a function of patient size. Each clinical patient in the library was optimally matched to another computational phantom to obtain a representation of organ location/distribution. The patient organ distribution was convolved with a dose distribution profile to generate [Formula: see text] values that quantified the regional dose field for each organ. The organ dose was estimated by multiplying [Formula: see text] with the organ dose coefficients ([Formula: see text]). To validate the accuracy of this dose estimation technique, the organ dose of the original clinical patient was estimated using Monte Carlo program with TCM profiles explicitly modeled. The discrepancy between the estimated organ dose and dose simulated using TCM Monte Carlo program was quantified. We further compared the convolution-based organ dose estimation method with two other strategies with different approaches of quantifying the irradiation field. The proposed convolution-based estimation method showed good accuracy with the organ dose simulated using the TCM Monte Carlo simulation. The average percentage error (normalized by CTDIvol) was generally within 10% across all organs and modulation profiles, except for organs located in the pelvic and shoulder regions. This study developed an improved method that accurately quantifies the irradiation field under TCM scans. The results suggested that organ dose could be estimated in real-time both prospectively (with the localizer information only) and retrospectively (with acquired CT data).
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Affiliation(s)
- Xiaoyu Tian
- Department of Biomedical Engineering, Duke University, Durham, NC 27705, USA
- Carl E Ravin Advanced Imaging Laboratories, Duke University, Durham, NC 27705, USA
| | - W Paul Segars
- Carl E Ravin Advanced Imaging Laboratories, Duke University, Durham, NC 27705, USA
- Department of Radiology, Duke University, Durham, NC 27705, USA
- Medical Physics Graduate Program, Duke University, Durham, NC 27705, USA
| | - Robert L Dixon
- Department of Radiology, Wake Forest University School of Medicine, Winston-Salem, NC 27103, USA
| | - Ehsan Samei
- Department of Biomedical Engineering, Duke University, Durham, NC 27705, USA
- Carl E Ravin Advanced Imaging Laboratories, Duke University, Durham, NC 27705, USA
- Department of Radiology, Duke University, Durham, NC 27705, USA
- Medical Physics Graduate Program, Duke University, Durham, NC 27705, USA
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46
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Papadakis AE, Perisinakis K, Damilakis J. Development of a method to estimate organ doses for pediatric CT examinations. Med Phys 2016; 43:2108. [DOI: 10.1118/1.4944867] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
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Thompson JD, Chakraborty DP, Szczepura K, Tootell AK, Vamvakas I, Manning DJ, Hogg P. Effect of reconstruction methods and x-ray tube current-time product on nodule detection in an anthropomorphic thorax phantom: A crossed-modality JAFROC observer study. Med Phys 2016; 43:1265-74. [PMID: 26936711 PMCID: PMC4752545 DOI: 10.1118/1.4941017] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Purpose: To evaluate nodule detection in an anthropomorphic chest phantom in computed tomography (CT) images reconstructed with adaptive iterative dose reduction 3D (AIDR3D) and filtered back projection (FBP) over a range of tube current–time product (mAs). Methods: Two phantoms were used in this study: (i) an anthropomorphic chest phantom was loaded with spherical simulated nodules of 5, 8, 10, and 12 mm in diameter and +100, −630, and −800 Hounsfield units electron density; this would generate CT images for the observer study; (ii) a whole-body dosimetry verification phantom was used to ultimately estimate effective dose and risk according to the model of the BEIR VII committee. Both phantoms were scanned over a mAs range (10, 20, 30, and 40), while all other acquisition parameters remained constant. Images were reconstructed with both AIDR3D and FBP. For the observer study, 34 normal cases (no nodules) and 34 abnormal cases (containing 1–3 nodules, mean 1.35 ± 0.54) were chosen. Eleven observers evaluated images from all mAs and reconstruction methods under the free-response paradigm. A crossed-modality jackknife alternative free-response operating characteristic (JAFROC) analysis method was developed for data analysis, averaging data over the two factors influencing nodule detection in this study: mAs and image reconstruction (AIDR3D or FBP). A Bonferroni correction was applied and the threshold for declaring significance was set at 0.025 to maintain the overall probability of Type I error at α = 0.05. Contrast-to-noise (CNR) was also measured for all nodules and evaluated by a linear least squares analysis. Results: For random-reader fixed-case crossed-modality JAFROC analysis, there was no significant difference in nodule detection between AIDR3D and FBP when data were averaged over mAs [F(1, 10) = 0.08, p = 0.789]. However, when data were averaged over reconstruction methods, a significant difference was seen between multiple pairs of mAs settings [F(3, 30) = 15.96, p < 0.001]. Measurements of effective dose and effective risk showed the expected linear dependence on mAs. Nodule CNR was statistically higher for simulated nodules on images reconstructed with AIDR3D (p < 0.001). Conclusions: No significant difference in nodule detection performance was demonstrated between images reconstructed with FBP and AIDR3D. mAs was found to influence nodule detection, though further work is required for dose optimization.
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Affiliation(s)
- J D Thompson
- Directorate of Radiography, University of Salford, Frederick Road Campus, Salford, Greater Manchester M6 6PU, United Kingdom and Department of Radiology, Furness General Hospital, University Hospitals of Morecambe Bay NHS Foundation Trust, Dalton Lane, Barrow-in-Furness LA14 4LF, United Kingdom
| | - D P Chakraborty
- Department of Radiology, University of Pittsburgh, FARP Building, Room 212, 3362 Fifth Avenue, Pittsburgh, Pennsylvania 15213
| | - K Szczepura
- Directorate of Radiography, University of Salford, Frederick Road Campus, Salford, Greater Manchester M6 6PU, United Kingdom
| | - A K Tootell
- Directorate of Radiography, University of Salford, Frederick Road Campus, Salford, Greater Manchester M6 6PU, United Kingdom
| | - I Vamvakas
- Department of Radiology, Christie Hospitals NHS Foundation Trust, 550 Wilmslow Road, Manchester M20 4BX, United Kingdom
| | - D J Manning
- Faculty of Health and Medicine, Lancaster Medical School, Furness College, Lancaster University, Lancaster LA1 4YG, United Kingdom
| | - P Hogg
- Directorate of Radiography, University of Salford, Frederick Road Campus, Salford, Greater Manchester M6 6PU, United Kingdom and Department of Radiography, Karolinksa Institute, Solnavägen 1, Solna 171 77, Sweden
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48
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Tian X, Yin Z, De Man B, Samei E. Estimation of Radiation Dose in CT Based on Projection Data. J Digit Imaging 2016; 29:615-21. [PMID: 26893140 DOI: 10.1007/s10278-016-9869-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Managing and optimizing radiation dose has become a core problem for the CT community. As a fundamental step for dose optimization, accurate and computationally efficient dose estimates are crucial. The purpose of this study was to devise a computationally efficient projection-based dose metric. The absorbed energy and object mass were individually modeled using the projection data. The absorbed energy was estimated using the difference between intensity of the primary photon and the exit photon. The mass was estimated using the volume under the attenuation profile. The feasibility of the approach was evaluated across phantoms with a broad size range, various kVp settings, and two bowtie filters, using a simulation tool, the Computer Assisted Tomography SIMulator (CATSIM) software. The accuracy of projection-based dose estimation was validated against Monte Carlo (MC) simulations. The relationship between projection-based dose metric and MC dose estimate was evaluated using regression models. The projection-based dose metric showed a strong correlation with Monte Carlo dose estimates (R (2) > 0.94). The prediction errors for the projection-based dose metric were all below 15 %. This study demonstrated the feasibility of computationally efficient dose estimation requiring only the projection data.
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Affiliation(s)
- Xiaoyu Tian
- Department of Biomedical Engineering, Carl E. Ravin Advanced Imaging Laboratories, Department of Radiology, Duke University Medical Center, 2424 Erwin Road, Suite 302, Durham, NC, 27705, USA
| | - Zhye Yin
- CT Systems and Applications Laboratory, GE Global Research, Niskayuna, NY, 12309, USA
| | - Bruno De Man
- CT Systems and Applications Laboratory, GE Global Research, Niskayuna, NY, 12309, USA
| | - Ehsan Samei
- Department of Biomedical Engineering, Carl E. Ravin Advanced Imaging Laboratories, Department of Radiology, Duke University Medical Center, 2424 Erwin Road, Suite 302, Durham, NC, 27705, USA. .,Medical Physics Graduate Program, Departments of Radiology, Electrical and Computer Engineering, and Physics, Duke University Medical Center, Durham, NC, 27705, USA.
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49
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Tian X, Li X, Segars WP, Frush DP, Samei E. Prospective estimation of organ dose in CT under tube current modulation. Med Phys 2015; 42:1575-85. [PMID: 25832048 DOI: 10.1118/1.4907955] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
PURPOSE Computed tomography (CT) has been widely used worldwide as a tool for medical diagnosis and imaging. However, despite its significant clinical benefits, CT radiation dose at the population level has become a subject of public attention and concern. In this light, optimizing radiation dose has become a core responsibility for the CT community. As a fundamental step to manage and optimize dose, it may be beneficial to have accurate and prospective knowledge about the radiation dose for an individual patient. In this study, the authors developed a framework to prospectively estimate organ dose for chest and abdominopelvic CT exams under tube current modulation (TCM). METHODS The organ dose is mainly dependent on two key factors: patient anatomy and irradiation field. A prediction process was developed to accurately model both factors. To model the anatomical diversity and complexity in the patient population, the authors used a previously developed library of computational phantoms with broad distributions of sizes, ages, and genders. A selected clinical patient, represented by a computational phantom in the study, was optimally matched with another computational phantom in the library to obtain a representation of the patient's anatomy. To model the irradiation field, a previously validated Monte Carlo program was used to model CT scanner systems. The tube current profiles were modeled using a ray-tracing program as previously reported that theoretically emulated the variability of modulation profiles from major CT machine manufacturers Li et al., [Phys. Med. Biol. 59, 4525-4548 (2014)]. The prediction of organ dose was achieved using the following process: (1) CTDIvol-normalized-organ dose coefficients (horgan) for fixed tube current were first estimated as the prediction basis for the computational phantoms; (2) each computation phantom, regarded as a clinical patient, was optimally matched with one computational phantom in the library; (3) to account for the effect of the TCM scheme, a weighted organ-specific CTDIvol [denoted as CTDIvol organ,weighted] was computed for each organ based on the TCM profile and the anatomy of the "matched" phantom; (4) the organ dose was predicted by multiplying the weighted organ-specific CTDIvol with the organ dose coefficients (horgan). To quantify the prediction accuracy, each predicted organ dose was compared with the corresponding organ dose simulated from the Monte Carlo program with the TCM profile explicitly modeled. RESULTS The predicted organ dose showed good agreements with the simulated organ dose across all organs and modulation profiles. The average percentage error in organ dose estimation was generally within 20% across all organs and modulation profiles, except for organs located in the pelvic and shoulder regions. For an average CTDIvol of a CT exam of 10 mGy, the average error at full modulation strength (α = 1) across all organs was 0.91 mGy for chest exams, and 0.82 mGy for abdominopelvic exams. CONCLUSIONS This study developed a quantitative model to predict organ dose for clinical chest and abdominopelvic scans. Such information may aid in the design of optimized CT protocols in relation to a targeted level of image quality.
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Affiliation(s)
- Xiaoyu Tian
- Department of Biomedical Engineering, Carl E. Ravin Advanced Imaging Laboratories, Department of Radiology, Duke University, Durham, North Carolina 27705
| | - Xiang Li
- Department of Physics, Cleveland State University, Cleveland, Ohio 44115
| | - W Paul Segars
- Carl E. Ravin Advanced Imaging Laboratories, Department of Radiology, Medical Physics Graduate Program, Duke University Medical Center, Durham, North Carolina 27705
| | - Donald P Frush
- Division of Pediatric Radiology, Department of Radiology, Medical Physics Graduate Program, Duke University Medical Center, Durham, North Carolina 27710
| | - Ehsan Samei
- Carl E. Ravin Advanced Imaging Laboratories, Department of Radiology, Medical Physics Graduate Program, Departments of Physics and Biomedical Engineering, Duke University Medical Center, Durham, North Carolina 27705
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Franck C, Vandevoorde C, Goethals I, Smeets P, Achten E, Verstraete K, Thierens H, Bacher K. The role of Size-Specific Dose Estimate (SSDE) in patient-specific organ dose and cancer risk estimation in paediatric chest and abdominopelvic CT examinations. Eur Radiol 2015; 26:2646-55. [PMID: 26670320 DOI: 10.1007/s00330-015-4091-7] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2015] [Revised: 10/21/2015] [Accepted: 10/27/2015] [Indexed: 12/11/2022]
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