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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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Deevband MR, Mohammadi H, Salimi Y, Mostaar A, Deravi N, Fathi M, Vakili K, Yaghoobpoor S, Ghorbani M, Divband A, Tavakoli M. Introducing fitting models for estimating age-specific dose and effective dose in paediatric patients undergoing head, chest and abdomen-pelvis imaging protocols: a patient study. J Med Radiat Sci 2024; 71:251-260. [PMID: 38454637 PMCID: PMC11177019 DOI: 10.1002/jmrs.772] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2023] [Accepted: 02/03/2024] [Indexed: 03/09/2024] Open
Abstract
INTRODUCTION Concerns regarding the adverse consequences of radiation have increased due to the expanded application of computed tomography (CT) in medical practice. Certain studies have indicated that the radiation dosage depends on the anatomical region, the imaging technique employed and patient-specific variables. The aim of this study is to present fitting models for the estimation of age-specific dose estimates (ASDE), in the same direction of size-specific dose estimates, and effective doses based on patient age, gender and the type of CT examination used in paediatric head, chest and abdomen-pelvis imaging. METHODS A total of 583 paediatric patients were included in the study. Radiometric data were gathered from DICOM files. The patients were categorised into five distinct groups (under 15 years of age), and the effective dose, organ dose and ASDE were computed for the CT examinations involving the head, chest and abdomen-pelvis. Finally, the best fitting models were presented for estimation of ASDE and effective doses based on patient age, gender and the type of examination. RESULTS The ASDE in head, chest, and abdomen-pelvis CT examinations increases with increasing age. As age increases, the effective dose in head and abdomen-pelvis CT scans decreased. However, for chest scans, the effective dose initially showed a decreasing trend until the first year of life; after that, it increases in correlation with age. CONCLUSIONS Based on the presented fitting model for the ASDE, these CT scan quantities depend on factors such as patient age and the type of CT examination. For the effective dose, the gender was also included in the fitting model. By utilising the information about the scan type, region and age, it becomes feasible to estimate the ASDE and effective dose using the models provided in this study.
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Affiliation(s)
- Mohammad Reza Deevband
- Department of Medical Physics and Biomedical Engineering, Faculty of MedicineShahid Beheshti University of Medical Sciences and Health ServicesTehranIran
| | - Habib Mohammadi
- Department of Medical Physics and Biomedical Engineering, Faculty of MedicineShahid Beheshti University of Medical Sciences and Health ServicesTehranIran
| | - Yazdan Salimi
- Department of Medical Physics and Biomedical Engineering, Faculty of MedicineShahid Beheshti University of Medical Sciences and Health ServicesTehranIran
| | - Ahmad Mostaar
- Department of Medical Physics and Biomedical Engineering, Faculty of MedicineShahid Beheshti University of Medical Sciences and Health ServicesTehranIran
| | - Niloofar Deravi
- Faculty of MedicineShahid Beheshti University of Medical SciencesTehranIran
| | - Mobina Fathi
- Faculty of MedicineShahid Beheshti University of Medical SciencesTehranIran
| | - Kimia Vakili
- Faculty of MedicineShahid Beheshti University of Medical SciencesTehranIran
| | - Shirin Yaghoobpoor
- Faculty of MedicineShahid Beheshti University of Medical SciencesTehranIran
| | - Mehdi Ghorbani
- Department of Medical Physics and Biomedical Engineering, Faculty of MedicineShahid Beheshti University of Medical Sciences and Health ServicesTehranIran
| | - Abolhasan Divband
- Department of Pediatrics, Faculty of MedicineCollege/Hormozgan University of Medical ScienceBandar AbbasIran
| | - Meysam Tavakoli
- Department of Radiation Oncology, Winship Cancer InstituteEmory UniversityAtlantaGeorgiaUSA
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Osman ND, Abdulkadir MK, Shuaib IL, Nasirudin RA. Evaluation of a new predictive equation for automated calculation of size-specific dose estimate (SSDE) in CT imaging. Radiography (Lond) 2024; 30:237-244. [PMID: 38035439 DOI: 10.1016/j.radi.2023.11.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Revised: 11/04/2023] [Accepted: 11/13/2023] [Indexed: 12/02/2023]
Abstract
INTRODUCTION The adoption of size-specific dose estimate (SSDE) in clinical practice is still limited owing to the tedious and complex manual measurement of individual patient size for the clinical calculation of SSDE. Thus, the automation of SSDE is imperative. This study aims to evaluate a predictive equation for the automated calculation of SSDE. METHODS A user-friendly software was developed to accurately predict the individual size-specific dose estimation of paediatric patients undergoing computed tomography (CT) scans of the head, thorax, and abdomen. The software includes a calculation equation developed based on a novel SSDE prediction equation that used a population's pre-determined percentage difference between volume-weighted computed tomography dose index (CTDIvol) and SSDE with age. American Association of Physicists in Medicine (AAPM RPT 204) method (manual) and segmentation-based SSDE calculators (indoseCT and XXautocalc) were used to assess the proposed software predictions comparatively. RESULTS The results of this study show that the automated equation-based calculation of SSDE and the manual and segmentation-based calculation of SSDE are in good agreement for patients. The differences between the automated equation-based calculation of SSDE and the manual and segmentation-based calculation are less than 3%. CONCLUSION This study validated an accurate SSDE calculator that allows users to enter key input values and calculate SSDE. IMPLICATION FOR PRACTICE The automated equation-based SSDE software (PESSD) seems a promising tool for estimating individualised CT doses during CT scans.
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Affiliation(s)
- N D Osman
- Advanced Medical and Dental Institute, Universiti Sains Malaysia, Kepala Batas, 13200, Penang, Malaysia
| | - M K Abdulkadir
- Advanced Medical and Dental Institute, Universiti Sains Malaysia, Kepala Batas, 13200, Penang, Malaysia; Department of Radiography, Faculty of Basic Clinical Sciences, University of Ilorin, 240213 Ilorin, Nigeria.
| | - I L Shuaib
- Advanced Medical and Dental Institute, Universiti Sains Malaysia, Kepala Batas, 13200, Penang, Malaysia
| | - R A Nasirudin
- Department of Radiography, Faculty of Basic Clinical Sciences, University of Ilorin, 240213 Ilorin, Nigeria
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Aboyewa OB, Laternser C, Popescu A, Murphy N, Shah D, Monge MC, Rigsby CK, Golestanirad L, Webster G, Kim D. Cumulative radiation dose from medical imaging in paediatric congenital heart disease patients with epicardial cardiac implantable electronic devices. EUROPEAN HEART JOURNAL. IMAGING METHODS AND PRACTICE 2024; 2:qyae060. [PMID: 39045197 PMCID: PMC11251694 DOI: 10.1093/ehjimp/qyae060] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/06/2024] [Accepted: 05/23/2024] [Indexed: 07/25/2024]
Abstract
Aims To determine whether paediatric congenital heart disease (CHD) patients with epicardial cardiac implantable electronic devices (CIEDs) receive high cumulative effective doses (CEDs) of ionizing radiation from medical imaging tests. Methods and results We compared 28 paediatric CHD patients with epicardial CIEDs (cases) against 40 patients with no CIED matched by age at operation, sex, surgical era, and CHD diagnosis (controls). We performed a retrospective review of radiation exposure from medical imaging exams between 2006 and 2022. Radiation dose from computed tomography (CT) and X-ray radiography was calculated using the National Cancer Institute Radiation Dosimetry Tool. We performed univariate analysis to compare the CED between the two groups. In the case subgroup, we convened experts' review to adjudicate the prevalence of CT exams that should have been performed with magnetic resonance imaging (MRI) in the absence of a CIED. Children (median age 2.5 years at implant) with CIEDs received significantly higher median CED compared with matched controls (6.90 vs. 1.72 mSv, P = 0.0018). In cases, expert adjudication showed that 80% of the CT exams would have been performed with MRI in the absence of a CIED. This resulted, on average, a five-fold increase in the effective dose (ED) from post-lead implant CTs. Conclusion Paediatric CHD patients with CIED received four times higher CED than matched controls. Improved access to medical imaging tests without ionizing radiation, such as MRI, could potentially reduce the ED in CIED patients by up to five times.
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Affiliation(s)
- Oluyemi B Aboyewa
- Department of Biomedical Engineering, Northwestern University, 2145 Sheridan Road, E310, Evanston, IL 60208, USA
- Department of Radiology, Feinberg School of Medicine, Northwestern University, 737 N. Michigan Avenue Suite 1600, Chicago, IL 60611, USA
| | - Christina Laternser
- Division of Cardiology, Department of Pediatrics, Ann & Robert H. Lurie Children’s Hospital, 225 E Chicago Avenue, Chicago, IL 60611, USA
| | - Andrada Popescu
- Department of Medical Imaging, Ann & Robert H. Lurie Children’s Hospital, 225 E Chicago Avenue, Chicago, IL 60611, USA
| | - Nicole Murphy
- Department of Medical Imaging, Ann & Robert H. Lurie Children’s Hospital, 225 E Chicago Avenue, Chicago, IL 60611, USA
| | - Dhaivat Shah
- Division of Cardiology, Department of Pediatrics, Ann & Robert H. Lurie Children’s Hospital, 225 E Chicago Avenue, Chicago, IL 60611, USA
| | - Michael C Monge
- Division of Cardiovascular Surgery, Department of Surgery, Ann & Robert H. Lurie Children’s Hospital, 225 E Chicago Avenue, Chicago, IL 60611, USA
| | - Cynthia K Rigsby
- Department of Medical Imaging, Ann & Robert H. Lurie Children’s Hospital, 225 E Chicago Avenue, Chicago, IL 60611, USA
| | - Laleh Golestanirad
- Department of Biomedical Engineering, Northwestern University, 2145 Sheridan Road, E310, Evanston, IL 60208, USA
- Department of Radiology, Feinberg School of Medicine, Northwestern University, 737 N. Michigan Avenue Suite 1600, Chicago, IL 60611, USA
| | - Gregory Webster
- Division of Cardiology, Department of Pediatrics, Ann & Robert H. Lurie Children’s Hospital, 225 E Chicago Avenue, Chicago, IL 60611, USA
| | - Daniel Kim
- Department of Biomedical Engineering, Northwestern University, 2145 Sheridan Road, E310, Evanston, IL 60208, USA
- Department of Radiology, Feinberg School of Medicine, Northwestern University, 737 N. Michigan Avenue Suite 1600, Chicago, IL 60611, USA
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刘 颖, 孟 婷, 章 浩, 路 鹤. [Model construction and software design of computed tomography radiation system based on visualization]. SHENG WU YI XUE GONG CHENG XUE ZA ZHI = JOURNAL OF BIOMEDICAL ENGINEERING = SHENGWU YIXUE GONGCHENGXUE ZAZHI 2023; 40:989-995. [PMID: 37879929 PMCID: PMC10600423 DOI: 10.7507/1001-5515.202201053] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 01/26/2022] [Revised: 02/16/2023] [Indexed: 10/27/2023]
Abstract
The Monte Carlo N-Particle (MCNP) is often used to calculate the radiation dose during computed tomography (CT) scans. However, the physical calculation process of the model is complicated, the input file structure of the program is complex, and the three-dimensional (3D) display of the geometric model is not supported, so that the researchers cannot establish an accurate CT radiation system model, which affects the accuracy of the dose calculation results. Aiming at these two problems, this study designed a software that visualized CT modeling and automatically generated input files. In terms of model calculation, the theoretical basis was based on the integration of CT modeling improvement schemes of major researchers. For 3D model visualization, LabVIEW was used as the new development platform, constructive solid geometry (CSG) was used as the algorithm principle, and the introduction of editing of MCNP input files was used to visualize CT geometry modeling. Compared with a CT model established by a recent study, the root mean square error between the results simulated by this visual CT modeling software and the actual measurement was smaller. In conclusion, the proposed CT visualization modeling software can not only help researchers to obtain an accurate CT radiation system model, but also provide a new research idea for the geometric modeling visualization method of MCNP.
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Affiliation(s)
- 颖 刘
- 上海理工大学 健康科学与工程学院(上海 200093)School of Health Science and Engineering, University of Shanghai for Science and Technology, Shanghai 200093, P. R. China
| | - 婷 孟
- 上海理工大学 健康科学与工程学院(上海 200093)School of Health Science and Engineering, University of Shanghai for Science and Technology, Shanghai 200093, P. R. China
| | - 浩伟 章
- 上海理工大学 健康科学与工程学院(上海 200093)School of Health Science and Engineering, University of Shanghai for Science and Technology, Shanghai 200093, P. R. China
| | - 鹤晴 路
- 上海理工大学 健康科学与工程学院(上海 200093)School of Health Science and Engineering, University of Shanghai for Science and Technology, Shanghai 200093, P. R. China
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Shah MA, Ahmad M, Khalid S, Qaseem SMD, Siddiqui S, Talib S, Rather SA, Firdous A. Multivariate Analysis of Effective Dose and Size-Specific Dose Estimates for Thorax and Abdominal Computed Tomography. J Med Phys 2023; 48:210-218. [PMID: 37576100 PMCID: PMC10419744 DOI: 10.4103/jmp.jmp_102_22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2022] [Revised: 05/10/2023] [Accepted: 05/10/2023] [Indexed: 08/15/2023] Open
Abstract
The study aimed to compute the effective dose (E) and size-specific dose estimate (SSDE) of routine adult patients undergoing thorax and abdominal computed tomography (CT) imaging and to present their multivariate analysis. All adult thorax and abdominal CT examinations conducted from March 2022 to June 2022 were prospectively included in this study. The Water Equivalent Diameter (Dw) and SSDE of all the examinations were computed from CT dose index volume (CTDIvol) and Dose length product (DLP) displayed on the dose report in the CT console. The multivariate statistical analysis was performed to investigate the correlation of SSDE and E on CTDIvol, Dw area of the region of interest (ROI) (AreaROI), body mass index (BMI), conversion factor (fsize) and hounsfield (HUmean) number in the ROI at 95% level of significance (P < 0.05). The linear regression analysis was performed to investigate the dependence of SSDE and E on other parameters for both abdominal and thorax patients. A total number of 135 (Abdomen = 61 and Thorax = 74) measurements were performed. The mean value of effective dose for abdomen and thorax patients was found to be 7.17 ± 3.94 and 4.89 ± 2.16 mSv, respectively. The SSDE was observed to be 13.24 ± 3.61 and 13.04 ± 3.61 mGy for thorax and abdomen respectively. The multivariate analysis suggests that SSDE for abdominal CT is found significantly dependent on CTDIvol, Dw and fsize with P < 0.05 and E is found to be significantly dependent on DLP, AreaROI, Dw and fsize at 95% level of confidence for abdominal CT imaging. SSDE for thorax CT was found significantly dependent on BMI, CTDIvol, HUmean, Dw and fsize at 95% level of confidence. Furthermore, E was observed dependent on DLP at P < 0.05. The linear regression analysis also shows that E is strongly correlated with DLP (r = 1.0) for both thorax and abdominal CT, further the SSDE was observed strongly correlated with CTDIvol with r = 0.79 and r = 0.86 for abdomen and thorax CT respectively. A strong correlation was observed between BMI and for Dw abdominal CT imaging (r = 0.68). The mean value of SSDE for thorax is slightly greater than abdomen. The average value of effective dose for abdomen and thorax measurements was found to be 7.17 ± 3.94 and 4.89 ± 2.16 mSv and , correspondingly. SSDE for both abdomen and thorax CT is significantly dependent on CTDIvol, Dw and fsize at 95% level of confidence. The strong correlation was also observed E on DLP and SSDE on CTDIvol for both Abdomen and Thorax CT. The strong dependence of Dw on BMI (r = 0.68) is due to the excessive fat concentration around the stomach and abdomen.
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Affiliation(s)
- Mudasir Ashraf Shah
- Department of Radiodiagnosis, Faculty of Medicine, Jawaharlal Nehru Medical College, Aligarh Muslim University, Aligarh, Uttar Pradesh, India
| | - Mehtab Ahmad
- Department of Radiodiagnosis, Faculty of Medicine, Jawaharlal Nehru Medical College, Aligarh Muslim University, Aligarh, Uttar Pradesh, India
| | - Saifullah Khalid
- Department of Radiodiagnosis, Faculty of Medicine, Jawaharlal Nehru Medical College, Aligarh Muslim University, Aligarh, Uttar Pradesh, India
| | - Syed M. Danish Qaseem
- Department of Radiodiagnosis, Faculty of Medicine, Jawaharlal Nehru Medical College, Aligarh Muslim University, Aligarh, Uttar Pradesh, India
| | - Shaista Siddiqui
- Department of Radiodiagnosis, Faculty of Medicine, Jawaharlal Nehru Medical College, Aligarh Muslim University, Aligarh, Uttar Pradesh, India
| | - Sayema Talib
- Department of Radiodiagnosis, Faculty of Medicine, Jawaharlal Nehru Medical College, Aligarh Muslim University, Aligarh, Uttar Pradesh, India
| | - Sajad Ahmed Rather
- Department of Radiological Physics and Bio-Engineering, Sher-i-Kashmir Institute of Medical Sciences, Srinagar, India
| | - Arfat Firdous
- Department of Physics, Government Degree College, Sumbal, Jammu and Kashmir, India
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Qu S, Liu H, Xie T, Giger ML, Quan G, Zaidi H. Patient-specific fetal radiation dosimetry for pregnant patients undergoing abdominal and pelvic CT imaging. Med Phys 2023. [PMID: 36799714 DOI: 10.1002/mp.16304] [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: 08/03/2022] [Revised: 01/18/2023] [Accepted: 01/31/2023] [Indexed: 02/18/2023] Open
Abstract
BACKGROUND Accurate estimation of fetal radiation dose is crucial for risk-benefit analysis of radiological imaging, while the radiation dosimetry studies based on individual pregnant patient are highly desired. PURPOSE To use Monte Carlo calculations for estimation of fetal radiation dose from abdominal and pelvic computed tomography (CT) examinations for a population of patients with a range of variations in patients' anatomy, abdominal circumference, gestational age (GA), fetal depth (FD), and fetal development. METHODS Forty-four patient-specific pregnant female models were constructed based on CT imaging data of pregnant patients, with gestational ages ranging from 8 to 35 weeks. The simulation of abdominal and pelvic helical CT examinations was performed on three validated commercial scanner systems to calculate organ-level fetal radiation dose. RESULTS The absorbed radiation dose to the fetus ranged between 0.97 and 2.24 mGy, with an average of 1.63 ± 0.33 mGy. The CTDIvol -normalized fetal dose ranged between 0.56 and 1.30, with an average of 0.94 ± 0.25. The normalized fetal organ dose showed significant correlations with gestational age, maternal abdominal circumference (MAC), and fetal depth. The use of ATCM technique increased the fetal radiation dose in some patients. CONCLUSION A technique enabling the calculation of organ-level radiation dose to the fetus was developed from models of actual anatomy representing a range of gestational age, maternal size, and fetal position. The developed maternal and fetal models provide a basis for reliable and accurate radiation dose estimation to fetal organs.
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Affiliation(s)
- Shuiyin Qu
- Institute of Radiation Medicine, Fudan University, Shanghai, China.,Department of Engineering Physics, Tsinghua University, Beijing, China
| | - Haikuan Liu
- Institute of Radiation Medicine, Fudan University, Shanghai, China
| | - Tianwu Xie
- Institute of Radiation Medicine, Fudan University, Shanghai, China.,Division of Nuclear Medicine and Molecular Imaging, Geneva University Hospital, Geneva, Switzerland
| | - Maryellen L Giger
- University of Chicago, Department of Radiology, Committee on Medical Physics, Chicago, Illinois, USA
| | - Guotao Quan
- Shanghai United Imaging Intelligence Co., Ltd., Shanghai, China
| | - Habib Zaidi
- Division of Nuclear Medicine and Molecular Imaging, Geneva University Hospital, Geneva, Switzerland.,Geneva Neuroscience Center, Geneva University, Geneva, Switzerland.,Department of Nuclear Medicine and Molecular Imaging, University of Groningen, University Medical Center Groningen, Groningen, Netherlands.,Department of Nuclear Medicine, University of Southern Denmark, Odense, Denmark
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Jansen JT, Shrimpton PC, Edyvean S. Development of a generalized method to allow the estimation of doses to the ICRP reference adults from CT, on the basis of normalized organ and CTDI dose data determined by Monte Carlo calculation for a range of contemporary scanners. Phys Med Biol 2023; 68. [PMID: 36634363 DOI: 10.1088/1361-6560/acb2a8] [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: 07/21/2022] [Accepted: 01/12/2023] [Indexed: 01/14/2023]
Abstract
Objective. Development of a method to provide organ and effective dose coefficients to reference adults for any CT scanner based on values ofCTDImeasured both in air and in standard CT dosimetry phantoms.Approach. Results from previous Monte Carlo simulations for a range of contemporary CT scanners have been analyzed to provide linear models relating values of organ dose (normalized toCTDIfree-in-air), for each slab of 3 reference phantoms (ICRP Male/Female, and AH hermaphrodite), to similarly normalized values ofCTDIin standard CT dosimetry phantoms. Three methods have been investigated to apply the models to values ofCTDIfor a 'new' scanner not previously simulated: a Generic approach using averaged normalized organ dose profiles for whole body exposure of the phantoms; and two processes for matching the scanner, on the basis of normalized organ doses or effective dose (nE103,phan), to one of the 102 sets of dose coefficients previously calculated for 12 contemporary CT scanner models, from 4 manufacturers, operating under a range of conditions.Main results. The merit of each method has been quantitatively assessed when applied to both the present contemporary scanners with each test data set being excluded in turn during the matching process, and also to 3 previously-simulated older scanners. Whereas all three methods appear viable, with all doses being within 1% and 10% for the contemporary and old scanners respectively, matching tonE103,phanis overall the approach preferred in practice, yielding an uncertainty of around 6% in estimated values ofnE103,phan. The present methodology also provides superior performance when compared against some other common normalization factors forE103,phan.Significance. The CT dose model and the data sets will be incorporated into a new CT dosimetry tool that will be made available from UKHSA in support of facilitating improvements in patient protection.
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Affiliation(s)
- Jan Tm Jansen
- Radiation, Chemical and Environmental Hazards, United Kingdom Health Security Agency, Chilton, Didcot, Oxfordshire, OX11 0RQ, United Kingdom
| | - Paul C Shrimpton
- Radiation, Chemical and Environmental Hazards, United Kingdom Health Security Agency, Chilton, Didcot, Oxfordshire, OX11 0RQ, United Kingdom
| | - Sue Edyvean
- Radiation, Chemical and Environmental Hazards, United Kingdom Health Security Agency, Chilton, Didcot, Oxfordshire, OX11 0RQ, United Kingdom
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Ye Z, Qi M, Zhao Y, Wei W, Xu XG. ESTIMATION OF FETAL AND PEDIATRIC DOSES FROM CHEST CT EXAMINATIONS USING VIRTUALDOSE SOFTWARE. RADIATION PROTECTION DOSIMETRY 2023; 199:52-60. [PMID: 36373995 DOI: 10.1093/rpd/ncac225] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2021] [Revised: 09/28/2022] [Accepted: 10/15/2022] [Indexed: 06/16/2023]
Abstract
Pregnant women and children sometimes had to undergo chest computed tomography (CT) scans during the Corona Virus Disease 2019 (COVID-19) pandemic. This study estimated the fetal and pediatric doses from chest CT scans. Organ doses and effective doses were calculated using the VirtualDose-CT software. Two groups of computational human phantoms, pregnant females and pediatric patients were used in this study. The results of doses normalized to volumetric CT Dose Index (CTDIvol) can be used universally for other dosimetry studies. Based on our calculations and international survey data of CTDIvol, fetal absorbed doses from COVID-19-related chest CT were found to be 0.04-0.36, 0.05-0.44 and 0.07-0.61 mGy for 3, 6 and 9 months of pregnancy, respectively. When the scan range is extended to the abdominal region, fetal doses increase by almost 4-fold. Effective doses for COVID-19-related chest CT were 1.62-13.77, 1.58-13.46, 1.57-13.33 and 1.29-10.98 mSv for the newborn, 1-, 5- and 10-y-old children, respectively. In addition, the effects of specific axial scan ranges exceeding the thorax region were evaluated. Although doses from chest CT scans are small, such data allow radiologists and patients to be informed of the dose levels and ways to avoid unnecessary radiation.
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Affiliation(s)
- Zirui Ye
- School of Nuclear Science and Technology, University of Science and Technology of China, Hefei 230026, China
- Institute of Nuclear Medical Physics, University of Science and Technology of China, Hefei 230026, China
| | - Miao Qi
- School of Nuclear Science and Technology, University of Science and Technology of China, Hefei 230026, China
- Institute of Nuclear Medical Physics, University of Science and Technology of China, Hefei 230026, China
| | - Yingming Zhao
- Department of Radiology, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei 230001, China
| | - Wei Wei
- Department of Radiology, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei 230001, China
| | - X George Xu
- School of Nuclear Science and Technology, University of Science and Technology of China, Hefei 230026, China
- Institute of Nuclear Medical Physics, University of Science and Technology of China, Hefei 230026, China
- Department of Radiation Oncology, The First Affiliated Hospital of USTC, University of Science and Technology of China, Hefei 230001, China
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Evaluation of radiation dose accuracy calculated using IndoseCT software with direct measurement on polyester-resin phantoms. Radiat Phys Chem Oxf Engl 1993 2022. [DOI: 10.1016/j.radphyschem.2022.110473] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Li X, Marschall TA, Yang K, Liu B. Advancing size-specific dose estimates in CT examinations: Dose estimates at longitudinal positions of scans. Med Phys 2021; 49:1303-1311. [PMID: 34894408 DOI: 10.1002/mp.15402] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2021] [Revised: 10/29/2021] [Accepted: 11/22/2021] [Indexed: 11/08/2022] Open
Abstract
PURPOSE American Association of Physicists in Medicine (AAPM) (Report 204) introduced the size-specific dose estimate (SSDE) for the average dose to the center of a fixed-mA scan. International standards establish a method that CT manufacturers and radiation dose index monitoring software may use to calculate SSDE(z) at longitudinal positions of scans with fixed mA or tube current modulation, and its scan range average SSDE ( z ) ¯ . We sought to test how accurate SSDE(z) is in tracking the average dose to the transverse slab of an axial image slice (Dslice ), evaluated with Monte Carlo calculation, in the chest and abdominopelvic examinations. METHODS We retrospectively identified 65 consecutive adult patients undergoing whole-body CT for transcatheter aortic valve implantation planning. Examination parameters (kV, mA, CTDIvol ) were extracted from the DICOM headers. Patient water equivalent diameter DW (z) was calculated at each image slice, excluding the patient table. A previously validated Monte Carlo simulation (Geant4) program was used to evaluate Dslice from the chest and abdominopelvic examinations. Alternatively, SSDE(z) was calculated at each slice. The results of the two methods were compared with descriptive statistical outcomes (R, version 4.0.2). RESULTS In chest and abdominopelvic CT examinations, Dslice largely changed with anatomic location and uniformly fell off toward scan range edges. Scan range averages SSDE ( z ) ¯ and D slice ¯ were consistent within 2.5%-3.1% (median) and 6.3%-10.4% (maximum) in two examinations. On individual image slices, SSDE(z) could be lower or higher than Dslice , with deviation ranging from -18.3% to 85% in two edges (2 × 5 cm) of scan range and from -35.2% to 18.7% in the remaining central region of the scan. CONCLUSION This study provides critical inputs for quality assurance programs. SSDE ( z ) ¯ is useful to track the average dose of all image slices, but further development may be useful for tracking patient dose at the level of individual image slices, especially near a scan range edge.
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Affiliation(s)
- Xinhua Li
- Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Theodore A Marschall
- Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Kai Yang
- Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Bob Liu
- Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, 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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Fujii K, Nomura K, Muramatsu Y, Ota H. PATIENT-SPECIFIC ORGAN DOSE EVALUATION BASED ON MONTE CARLO SIMULATION AND DOSE METRICS IN PAEDIATRIC CHEST-ABDOMEN-PELVIS CT EXAMINATIONS. RADIATION PROTECTION DOSIMETRY 2021; 197:46-53. [PMID: 34726759 DOI: 10.1093/rpd/ncab157] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2021] [Revised: 10/04/2021] [Accepted: 10/07/2021] [Indexed: 06/13/2023]
Abstract
This study aimed to determine organ doses based on Monte Carlo (MC) simulations for individual paediatric patients undergoing chest-abdomen-pelvis computed tomography (CT) examinations and to evaluate correlations of organ doses with dose metrics. MC simulations were performed by inputting detailed descriptions of a CT scanner, scanning parameters and CT images of 51 paediatric patients aged from 0 to 10 years into the simulation software. Organ doses for six radiosensitive organs were determined from dose distribution images obtained as the simulation results. The correlations of organ doses with dose metrics such as volume CT dose index, size-specific dose estimates (SSDEs), and organ-specific SSDEs were evaluated from the corresponding coefficients of determination. Organ doses for ages of 0-1 and 1-5 years were 22%-32% lower than those for ages of 5-10 years. Organ doses exhibited higher linear correlations with SSDEs and organ-specific SSDEs, and can be easily estimated using the linear regression.
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Affiliation(s)
- Keisuke Fujii
- Nagoya University Graduate School of Medicine, Department of Integrated Health Sciences, 1-1-20 Daiko-Minami, Higashi-ku, Nagoya, Aichi 461-8673, Japan
- National Cancer Center Hospital East, Department of Radiological Technology, 6-5-1 Kashiwanoha, Kashiwa, Chiba 277-8577, Japan
| | - Keiichi Nomura
- National Cancer Center Hospital East, Department of Radiological Technology, 6-5-1 Kashiwanoha, Kashiwa, Chiba 277-8577, Japan
| | - Yoshihisa Muramatsu
- National Cancer Center Hospital East, Department of Radiological Technology, 6-5-1 Kashiwanoha, Kashiwa, Chiba 277-8577, Japan
| | - Hiroyuki Ota
- National Cancer Center Hospital East, Department of Radiological Technology, 6-5-1 Kashiwanoha, Kashiwa, Chiba 277-8577, Japan
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Salimi Y, Shiri I, Akhavanallaf A, Mansouri Z, Saberi Manesh A, Sanaat A, Pakbin M, Askari D, Sandoughdaran S, Sharifipour E, Arabi H, Zaidi H. Deep learning-based fully automated Z-axis coverage range definition from scout scans to eliminate overscanning in chest CT imaging. Insights Imaging 2021; 12:162. [PMID: 34743251 PMCID: PMC8572075 DOI: 10.1186/s13244-021-01105-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2021] [Accepted: 10/09/2021] [Indexed: 01/07/2023] Open
Abstract
BACKGROUND Despite the prevalence of chest CT in the clinic, concerns about unoptimized protocols delivering high radiation doses to patients still remain. This study aimed to assess the additional radiation dose associated with overscanning in chest CT and to develop an automated deep learning-assisted scan range selection technique to reduce radiation dose to patients. RESULTS A significant overscanning range (31 ± 24) mm was observed in clinical setting for over 95% of the cases. The average Dice coefficient for lung segmentation was 0.96 and 0.97 for anterior-posterior (AP) and lateral projections, respectively. By considering the exact lung coverage as the ground truth, and AP and lateral projections as input, The DL-based approach resulted in errors of 0.08 ± 1.46 and - 1.5 ± 4.1 mm in superior and inferior directions, respectively. In contrast, the error on external scout views was - 0.7 ± 4.08 and 0.01 ± 14.97 mm for superior and inferior directions, respectively.The ED reduction achieved by automated scan range selection was 21% in the test group. The evaluation of a large multi-centric chest CT dataset revealed unnecessary ED of more than 2 mSv per scan and 67% increase in the thyroid absorbed dose. CONCLUSION The proposed DL-based solution outperformed previous automatic methods with acceptable accuracy, even in complicated and challenging cases. The generizability of the model was demonstrated by fine-tuning the model on AP scout views and achieving acceptable results. The method can reduce the unoptimized dose to patients by exclunding unnecessary organs from field of view.
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Affiliation(s)
- Yazdan Salimi
- Division of Nuclear Medicine and Molecular Imaging, Geneva University Hospital, 1211, Geneva, Switzerland
| | - Isaac Shiri
- Division of Nuclear Medicine and Molecular Imaging, Geneva University Hospital, 1211, Geneva, Switzerland
| | - Azadeh Akhavanallaf
- Division of Nuclear Medicine and Molecular Imaging, Geneva University Hospital, 1211, Geneva, Switzerland
| | - Zahra Mansouri
- Department of Biomedical Engineering and Medical Physics, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Abdollah Saberi Manesh
- Division of Nuclear Medicine and Molecular Imaging, Geneva University Hospital, 1211, Geneva, Switzerland
| | - Amirhossein Sanaat
- Division of Nuclear Medicine and Molecular Imaging, Geneva University Hospital, 1211, Geneva, Switzerland
| | - Masoumeh Pakbin
- Imaging Department, Qom University of Medical Sciences, Qom, Iran
| | - Dariush Askari
- Department of Radiology Technology, Shahid Beheshti University of Medical, Tehran, Iran
| | - Saleh Sandoughdaran
- Men's Health and Reproductive Health Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Ehsan Sharifipour
- Neuroscience Research Center, Qom University of Medical Sciences, Qom, Iran
| | - Hossein Arabi
- Division of Nuclear Medicine and Molecular Imaging, Geneva University Hospital, 1211, Geneva, Switzerland
| | - Habib Zaidi
- Division of Nuclear Medicine and Molecular Imaging, Geneva University Hospital, 1211, Geneva, Switzerland.
- Geneva University Neurocenter, Geneva University, Geneva, Switzerland.
- Department of Nuclear Medicine and Molecular Imaging, University of Groningen, University Medical Center Groningen, Groningen, Netherlands.
- Department of Nuclear Medicine, University of Southern Denmark, Odense, Denmark.
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15
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Martin CJ, Abuhaimed A, Lee C. Dose quantities for measurement and comparison of doses to individual patients in computed tomography (CT). JOURNAL OF RADIOLOGICAL PROTECTION : OFFICIAL JOURNAL OF THE SOCIETY FOR RADIOLOGICAL PROTECTION 2021; 41:792-808. [PMID: 33690180 DOI: 10.1088/1361-6498/abecf5] [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: 02/04/2021] [Accepted: 03/09/2021] [Indexed: 06/12/2023]
Abstract
The dose quantities displayed routinely on CT scanners, the volume averaged CT dose index (CTDIvol) and dose length product, provide measures of doses calculated for standard phantoms. The American Association of Medical Physics has published conversion factors for the adjustment of CTDIvolto take account of variations in patient size, the results being termed size-specific dose estimate (SSDE). However, CTDIvoland SSDE, while useful in comparing and optimising doses from a set procedure, do not provide risk-related information that takes account of the organs and tissues irradiated and associated cancer risks. A derivative of effective dose that takes account of differences in body and organ sizes and masses, referred to here as size-specific effective dose (SED), can provide such information. Data on organ doses from NCICT software that is based on Monte Carlo simulations of CT scans for 193 adult phantoms have been used to compute values of SED for CT examinations of the trunk and results compared with corresponding values of SSDE. Relationships within ±8% were observed between SED and SSDE for scans extending over similar regions for phantoms with a wide range of sizes. Coefficients have been derived from fits of the data to estimate SED values from SSDEs for different regions of the body for scans of standard lengths based on patient height. A method developed to take account of differences in scan length gave SED results within ±5% of values calculated using the NCI phantom library. This approach could potentially be used to estimate SED from SSDE values, allowing their display at the time a CT scan is performed.
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Affiliation(s)
- Colin J Martin
- Department of Clinical Physics and Bioengineering, University of Glasgow, Gartnavel Royal Hospital, Glasgow G12 0XH, United Kingdom
| | - Abdullah Abuhaimed
- King Abdulaziz City for Science and Technology (KACST), Riyadh, Saudi Arabia
| | - Choonsik Lee
- Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Rockville, MD, United States of America
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16
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Estimating Specific Patient Organ Dose for Chest CT Examinations with Monte Carlo Method. APPLIED SCIENCES-BASEL 2021. [DOI: 10.3390/app11198961] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Purpose: The purpose of this study was to preliminarily estimate patient-specific organ doses in chest CT examinations for Chinese adults, and to investigate the effect of patient size on organ doses. Methods: By considering the body-size and body-build effects on the organ doses and taking the mid-chest water equivalent diameter (WED) as a body-size indicator, the chest scan images of 18 Chinese adults were acquired on a multi-detector CT to generate the regional voxel models. For each patient, the lungs, heart, and breasts (glandular breast tissues for both breasts) were segmented, and other organs were semi-automated segmented based on their HU values. The CT scanner and patient models simulated by MCNPX 2.4.0 software (Los Alamos National LaboratoryLos Alamos, USA) were used to calculate lung, breast, and heart doses. CTDIvol values were used to normalize simulated organ doses, and the exponential estimation model between the normalized organ dose and WED was investigated. Results: Among the 18 patients in this study, the simulated doses of lung, heart, and breast were 18.15 ± 2.69 mGy, 18.68 ± 2.87 mGy, and 16.11 ± 3.08 mGy, respectively. Larger patients received higher organ doses than smaller ones due to the higher tube current used. The ratios of lung, heart, and breast doses to the CTDIvol were 1.48 ± 0.22, 1.54 ± 0.20, and 1.41 ± 0.13, respectively. The normalized organ doses of all the three organs decreased with the increase in WED, and the normalized doses decreased more obviously in the lung and the heart than that in the breasts. Conclusions: The output of CT scanner under ATCM is positively related to the attenuation of patients, larger-size patients receive higher organ doses. The organ dose normalized by CTDIvol was negatively correlated with patient size. The organ doses could be estimated by using the indicated CTDIvol combined with the estimated WED.
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17
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Ma R, Qiu R, Wu Z, Ren L, Hu A, Li WB, Li J. Development of Chinese mesh-type pediatric reference phantom series and application in dose assessment of Chinese undergoing computed tomography scanning. Phys Med Biol 2021; 66. [PMID: 34407526 DOI: 10.1088/1361-6560/ac1ef1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2020] [Accepted: 08/18/2021] [Indexed: 11/12/2022]
Abstract
Pediatric patients are in a growing stage with more dividing cells than adults. Therefore, they are more sensitive to the radiation dose when undergoing computed tomography (CT) scanning. It is necessary and essential to assess the organ absorbed dose and effective dose to children. Monte Carlo simulation with computational phantoms is one of the most used methods for dose calculation in medical imaging and radiotherapy. Because of the vast change of the pediatric body with age increasing, many research groups developed series pediatric phantoms for various ages. However, most of the existing pediatric reference phantoms were developed based on Caucasian populations, which is not conformable to Chinese pediatric patients. The use of different phantoms can contribute to a difference in the dose calculation. To assess the CT dose of Chinese pediatric patients more accurately, we developed the Chinese pediatric reference phantoms series, including the 3-month (CRC3m), 1-year-old (CRC01), 5-year-old (CRC05), 10-year-old (CRC10), 15-year-old male (CRCM15), and a 15-year-old female (CRCF15) phantoms. Furthermore, we applied them to dose assessment of patients undergoing CT scanning. The GE LightSpeed 16 CT scanner was simulated and the paper presents the detailed process of phantoms development and the establishment of the CT dose database (with x-ray tube voltages of 120, 100 and 80 kVp, with collimators of 20, 10, and 5 mm width, with filters for head and body), compares for the 1-year-old results with other results based on different phantoms and analyzes the CT dose calculation results. It was found that the difference in phantoms' characteristics, organ masses and positions had a significant impact on the CT dose calculation outcomes. For the 1-year-old phantom, the dose results of organs fully covered by the x-ray beam were within 10% difference from the results of other studies. For organs partially covered and not covered by the scan range, the maximum differences came up to 84% (stomach dose, chest examinations) and 463% (gonads dose, chest examinations) respectively. The findings are helpful for the dose optimization of Chinese pediatric patients undergoing CT scanning. The developed phantoms could be applied in dose estimation of other medical modalities.
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Affiliation(s)
- Ruiyao Ma
- Department of Engineering Physics, Tsinghua University, Beijing, People's Republic of China.,Institute of Radiation Medicine, Helmholtz Zentrum München-German Research Center for Environmental Health (GmbH), Neuherberg, Germany.,Key Laboratory of Particle & Radiation Imaging, Tsinghua University, Ministry of Education, Beijing, People's Republic of China
| | - Rui Qiu
- Department of Engineering Physics, Tsinghua University, Beijing, People's Republic of China.,Key Laboratory of Particle & Radiation Imaging, Tsinghua University, Ministry of Education, Beijing, People's Republic of China
| | - Zhen Wu
- Joint Institute of Tsinghua University & Nuctech Company Limited Beijing, People's Republic of China
| | - Li Ren
- Department of Engineering Physics, Tsinghua University, Beijing, People's Republic of China.,Key Laboratory of Particle & Radiation Imaging, Tsinghua University, Ministry of Education, Beijing, People's Republic of China
| | - Ankang Hu
- Department of Engineering Physics, Tsinghua University, Beijing, People's Republic of China.,Key Laboratory of Particle & Radiation Imaging, Tsinghua University, Ministry of Education, Beijing, People's Republic of China
| | - Wei Bo Li
- Institute of Radiation Medicine, Helmholtz Zentrum München-German Research Center for Environmental Health (GmbH), Neuherberg, Germany
| | - Junli Li
- Department of Engineering Physics, Tsinghua University, Beijing, People's Republic of China.,Key Laboratory of Particle & Radiation Imaging, Tsinghua University, Ministry of Education, Beijing, People's Republic of China
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18
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Won T, Lee AK, Choi HD, Lee C. Radiation dose from computed tomography scans for Korean pediatric and adult patients. JOURNAL OF RADIATION PROTECTION AND RESEARCH 2021; 46:98-105. [PMID: 38894707 PMCID: PMC11185358 DOI: 10.14407/jrpr.2021.00010] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/06/2021] [Accepted: 03/03/2021] [Indexed: 06/21/2024]
Abstract
Background In recent events of the Coronavirus Disease 2019 (COVID-19) pandemic, CT scans are being globally used as a complement to the reverse-transcription polymerase chain reaction (RT-PCR) tests. It will be important to be aware of major organ dose levels, which are more relevant quantity to derive potential long-term adverse effect, for Korean pediatric and adult patients undergoing CT for COVID-19. Materials and Methods We calculated organ dose conversion coefficients for Korean pediatric and adult CT patients directly from Korean pediatric and adult computational phantoms combined with Monte Carlo radiation transport techniques. We then estimated major organ doses delivered to the Korean child and adult patients undergoing CT for COVID-19 combining the dose conversion coefficients and the international survey data. We also compared our Korean dose conversion coefficients with those from Caucasian reference pediatric and adult phantoms. Results and discussion Based on the dose conversion coefficients we established in this study and the international survey data of COVID-19-related CT scans, we found that Korean 7-year-old child and adult males may receive about 4 - 32 mGy and 3 - 21 mGy of lung dose, respectively. We learned that the lung dose conversion coefficient for the Korean child phantom was up to 1.5-fold greater than that for the Korean adult phantom. We also found no substantial difference in dose conversion coefficients between Korean and Caucasian phantoms. Conclusion We estimated radiation dose delivered to the Korean child and adult phantoms undergoing COVID-19-related CT examinations. The dose conversion coefficients derived for different CT scan types can be also used universally for other dosimetry studies concerning Korean CT scans. We also confirmed that the Caucasian-based CT organ dose calculation tools may be used for the Korean population with reasonable accuracy.
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Affiliation(s)
- Tristan Won
- Winston Churchill High School, Potomac, MD 20854
| | - Ae-Kyoung Lee
- Electronics and Telecommunications Research Institute, Daejeon, South Korea
| | - Hyung-do Choi
- Electronics and Telecommunications Research Institute, Daejeon, South Korea
| | - Choonsik Lee
- Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Rockville, MD 20850
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Kiapour M, Ebrahimnejad Gorji K, Mehraeen R, Ghaemian N, Niksirat Sustani F, Abedi-Firouzjah R, Shabestani Monfared A. Can Common Lead Apron in Testes Region Cause Radiation Dose Reduction during Chest CT Scan? A Patient Study. J Biomed Phys Eng 2021; 11:497-504. [PMID: 34458197 PMCID: PMC8385221 DOI: 10.31661/jbpe.v0i0.2104-1307] [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: 04/14/2021] [Accepted: 05/31/2021] [Indexed: 06/13/2023]
Abstract
BACKGROUND Computed tomography (CT) is a routine procedure for diagnosing using ionization radiation which has hazardous effects especially on sensitive organs. OBJECTIVE The aim of this study was to quantify the dose reduction effect of lead apron shielding on the testicular region during routine chest CT scans. MATERIAL AND METHODS In this measurement study, the routine chest CT examinations were performed for 30 male patients with common lead aprons folded and positioned in testis regions. The patient's mean body mass index (BMI) was 26.2 ± 4.6 kg/m2. To calculate the doses at testis region, three thermoluminescent dosimeters (TLD-100) were attached at the top surface of the apron as an indicator of the doses without shielding, and three TLDs under the apron for doses with shielding. The TLD readouts were compared using SPSS software (Wilcoxon test) version 16. RESULTS The radiation dose in the testicular regions was reduced from 0.46 ± 0.04 to 0.20 ± 0.04 mGy in the presence of lead apron shielding (p < 0.001), the reduction was equal to 56%. Furthermore, the heritable risk probability was obtained at 2.0 ×10-5 % and 4.6 ×10-5 % for the patients using the lead apron shield versus without shield, respectively. CONCLUSION Applying common lead aprons as shielding in the testis regions of male patients undergoing chest CT scans can reduce the radiation doses significantly. Therefore, this shield can be recommended for routine chest CT examinations.
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Affiliation(s)
- Mohammad Kiapour
- MSc, Student Research Committee, Babol University of Medical Sciences, Babol, Iran
| | - Kourosh Ebrahimnejad Gorji
- PhD, Department of Medical Physics Radiobiology and Radiation Protection, School of Medicine, Babol University of Medical Sciences, Babol, Iran
| | - Rahele Mehraeen
- MD, Department of Pediatric Radiology, Babol University of Medical Sciences, Babol, Iran
| | - Naser Ghaemian
- MD, Department of Radiology and Radiotherapy, School of Medicine, Babol University of Medical Sciences, Babol, Iran
| | - Fatemeh Niksirat Sustani
- MSc, Department of Medical Physics Radiobiology and Radiation Protection, School of Medicine, Babol University of Medical Sciences, Babol, Iran
| | - Razzagh Abedi-Firouzjah
- MSc, Department of Medical Physics Radiobiology and Radiation Protection, School of Medicine, Babol University of Medical Sciences, Babol, Iran
| | - Ali Shabestani Monfared
- PhD, Cancer Research Center, Health Research Institute, Babol University of Medical Sciences, Babol, Iran
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20
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Fetal dose evaluation for body CT examinations of pregnant patients during all stages of pregnancy. Eur J Radiol 2021; 141:109780. [PMID: 34049058 DOI: 10.1016/j.ejrad.2021.109780] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2020] [Revised: 04/23/2021] [Accepted: 05/13/2021] [Indexed: 11/23/2022]
Abstract
PURPOSE CTDIvol-to-fetal-dose coefficients from Monte Carlo simulations are useful for fetal dose evaluations, but the available data is limited to the fetus being completely inside the abdominopelvic scan range. Whereas in a chest examination, the fetus is completely outside the scan range. In an abdominal examination, the fetus after 16 gestational weeks is partly in the scan region, and an earlier fetus is completely outside of it. This work proposes a practical approach to evaluate fetal dose for pregnant patients undergoing body CT examinations, without using Monte Carlo simulation. METHODS The proposed method was based on the z-axis dose profile computed for a CT examination, considering CTDIvol, scan range, mA, and maternal WED (water equivalent diameter) at the fetus centroid. Fetal average dose was calculated over the fetus z-axis coverage. For validation, we considered a reference dataset of 24 pregnant patients, each underwent two abdominopelvic examinations (fixed mA, tube current modulation). WED was 30.1 ± 3.3 (25.3-35.6) cm [mean(range)]. Gestational age was <5 weeks for one patient, and 20.3 ± 9.1 (5-35.9) weeks for the others. Fetal depth (from the anterior skin surface to the most anterior part of fetus) was 6.1 ± 2.1 (2.5-10.9) cm. We further considered three whole-body models of a pregnant patient (gestational age, 3, 6, 9 months; weight, 62-73 kg) undergoing chest, abdominal, and abdominopelvic examinations (fixed mA). For the patients and models, profile-based fetal dose calculations were compared with the results of Monte Carlo simulations. Statistical software (R, version 3.5.1) was used to determine the mean and 95th percentile. RESULTS The fetal dose difference between profile-based evaluations and Monte Carlo simulations was (5.9 ± 3.8)% for 24 fixed-mA examinations, (5.8 ± 4.6)% for 24 tube current modulated examinations, and (8.8 ± 5.9)% for the whole-body models in three scan ranges. CONCLUSIONS Profile-based fetal dose calculations can be performed for patients in body CT, considering maternal size, fetus size and location, and whether fetus is completely inside, partly inside, or outside scan ranges.
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21
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Layman RR, Hardy AJ, Kim HJ, Chou EN, Bostani M, Cagnon C, Cody D, McNitt‐Gray M. A comparison of breast and lung doses from chest CT scans using organ-based tube current modulation (OBTCM) vs. Automatic tube current modulation (ATCM). J Appl Clin Med Phys 2021; 22:97-109. [PMID: 33939253 PMCID: PMC8130227 DOI: 10.1002/acm2.13198] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Revised: 01/12/2021] [Accepted: 01/20/2021] [Indexed: 12/11/2022] Open
Abstract
PURPOSE The purpose of this work was to estimate and compare breast and lung doses of chest CT scans using organ-based tube current modulation (OBTCM) to those from conventional, attenuation-based automatic tube current modulation (ATCM) across a range of patient sizes. METHODS Thirty-four patients (17 females, 17 males) who underwent clinically indicated CT chest/abdomen/pelvis (CAP) examinations employing OBTCM were collected from two multi-detector row CT scanners. Patient size metric was assessed as water equivalent diameter (Dw ) taken at the center of the scan volume. Breast and lung tissues were segmented from patient image data to create voxelized models for use in a Monte Carlo transport code. The OBTCM schemes for the chest portion were extracted from the raw projection data. ATCM schemes were estimated using a recently developed method. Breast and lung doses for each TCM scenario were estimated for each patient model. CTDIvol -normalized breast (nDbreast ) and lung (nDlung ) doses were subsequently calculated. The differences between OBTCM and ATCM normalized organ dose estimates were tested using linear regression models that included CT scanner and Dw as covariates. RESULTS Mean dose reduction from OBTCM in nDbreast was significant after adjusting for the scanner models and patient size (P = 0.047). When pooled with females and male patient, mean dose reduction from OBTCM in nDlung was observed to be trending after adjusting for the scanner model and patient size (P = 0.085). CONCLUSIONS One specific manufacturer's OBTCM was analyzed. OBTCM was observed to significantly decrease normalized breast relative to a modeled version of that same manufacturer's ATCM scheme. However, significant dose savings were not observed in lung dose over all. Results from this study support the use of OBTCM chest protocols for females only.
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Affiliation(s)
- Rick R. Layman
- Department of Imaging PhysicsThe University of Texas MD Anderson Cancer CenterHoustonTXUSA
| | - Anthony J. Hardy
- Materials Engineering Division/Non‐destructive Evaluation GroupLivermore National LaboratoryLivermoreCA94550USA
| | - Hyun J. Kim
- Department of Radiological SciencesDavid Geffen School of MedicineUniversity of California, Los AngelesLos AngelesCAUSA
| | - Ei Ne Chou
- Fielding School of Public HealthUniversity of California Los AngelesLos AngelesCAUSA
| | - Maryam Bostani
- Department of Radiological SciencesDavid Geffen School of MedicineUniversity of California, Los AngelesLos AngelesCAUSA
- Physics and Biology in Medicine Graduate ProgramDavid Geffen School of MedicineUniversity of California Los AngelesLos AngelesCA90024USA
| | - Chris Cagnon
- Department of Radiological SciencesDavid Geffen School of MedicineUniversity of California, Los AngelesLos AngelesCAUSA
- Physics and Biology in Medicine Graduate ProgramDavid Geffen School of MedicineUniversity of California Los AngelesLos AngelesCA90024USA
| | - Dianna Cody
- Department of Imaging PhysicsThe University of Texas MD Anderson Cancer CenterHoustonTXUSA
| | - Michael McNitt‐Gray
- Department of Radiological SciencesDavid Geffen School of MedicineUniversity of California, Los AngelesLos AngelesCAUSA
- Physics and Biology in Medicine Graduate ProgramDavid Geffen School of MedicineUniversity of California Los AngelesLos AngelesCA90024USA
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22
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Assessment of organ doses for CT patients based on x-ray attenuation using water equivalent diameter. Radiat Phys Chem Oxf Engl 1993 2021. [DOI: 10.1016/j.radphyschem.2020.109332] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
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23
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Fu W, Ria F, Segars WP, Choudhury KR, Wilson JM, Kapadia AJ, Samei E. Patient-Informed Organ Dose Estimation in Clinical CT: Implementation and Effective Dose Assessment in 1048 Clinical Patients. AJR Am J Roentgenol 2021; 216:824-834. [PMID: 33474986 PMCID: PMC8018383 DOI: 10.2214/ajr.19.22482] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
OBJECTIVE. The purpose of this study is to comprehensively implement a patient-informed organ dose monitoring framework for clinical CT and compare the effective dose (ED) according to the patient-informed organ dose with ED according to the dose-length product (DLP) in 1048 patients. MATERIALS AND METHODS. Organ doses for a given examination are computed by matching the topogram to a computational phantom from a library of anthropomorphic phantoms and scaling the fixed tube current dose coefficients by the examination volume CT dose index (CTDIvol) and the tube-current modulation using a previously validated convolution-based technique. In this study, the library was expanded to 58 adult, 56 pediatric, five pregnant, and 12 International Commission on Radiological Protection (ICRP) reference models, and the technique was extended to include multiple protocols, a bias correction, and uncertainty estimates. The method was implemented in a clinical monitoring system to estimate organ dose and organ dose-based ED for 647 abdomen-pelvis and 401 chest examinations, which were compared with DLP-based ED using a t test. RESULTS. For the majority of the organs, the maximum errors in organ dose estimation were 18% and 8%, averaged across all protocols, without and with bias correction, respectively. For the patient examinations, DLP-based ED was significantly different from organ dose-based ED by as much as 190.9% and 234.7% for chest and abdomen-pelvis scans, respectively (mean, 9.0% and 24.3%). The differences were statistically significant (p < .001) and exhibited overestimation for larger-sized patients and underestimation for smaller-sized patients. CONCLUSION. A patient-informed organ dose estimation framework was comprehensively implemented applicable to clinical imaging of adult, pediatric, and pregnant patients. Compared with organ dose-based ED, DLP-based ED may overestimate effective dose for larger-sized patients and underestimate it for smaller-sized patients.
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Affiliation(s)
- Wanyi Fu
- Department of Radiology, Duke University, 2424 Erwin Rd, Ste 302, Durham, NC 27705
- Department of Electrical and Computer Engineering, Duke University, Durham, NC
- Carl E. Ravin Advanced Imaging Laboratories, Duke University, Durham, NC
| | - Francesco Ria
- Carl E. Ravin Advanced Imaging Laboratories, Duke University, Durham, NC
- Clinical Imaging Physics Group, Duke University Health System, Durham, NC
| | - William Paul Segars
- Department of Radiology, Duke University, 2424 Erwin Rd, Ste 302, Durham, NC 27705
- Carl E. Ravin Advanced Imaging Laboratories, Duke University, Durham, NC
- Medical Physics Graduate Program, Duke University, Durham, NC
- Department of Biomedical Engineering, Duke University, Durham, NC
| | | | - Joshua M Wilson
- Clinical Imaging Physics Group, Duke University Health System, Durham, NC
- Medical Physics Graduate Program, Duke University, Durham, NC
| | - Anuj J Kapadia
- Department of Radiology, Duke University, 2424 Erwin Rd, Ste 302, Durham, NC 27705
- Carl E. Ravin Advanced Imaging Laboratories, Duke University, Durham, NC
- Medical Physics Graduate Program, Duke University, Durham, NC
- Department of Physics, Duke University, Durham, NC
| | - Ehsan Samei
- Department of Radiology, Duke University, 2424 Erwin Rd, Ste 302, Durham, NC 27705
- Department of Electrical and Computer Engineering, Duke University, Durham, NC
- Carl E. Ravin Advanced Imaging Laboratories, Duke University, Durham, NC
- Clinical Imaging Physics Group, Duke University Health System, Durham, NC
- Medical Physics Graduate Program, Duke University, Durham, NC
- Department of Biomedical Engineering, Duke University, Durham, NC
- Department of Physics, Duke University, Durham, NC
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Fujii K, Nomura K, Muramatsu Y, Goto T, Obara S, Ota H, Tsukagoshi S. Correlation analysis of organ doses determined by Monte Carlo simulation with dose metrics for patients undergoing chest-abdomen-pelvis CT examinations. Phys Med 2020; 77:1-9. [DOI: 10.1016/j.ejmp.2020.07.016] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/30/2020] [Revised: 07/04/2020] [Accepted: 07/12/2020] [Indexed: 01/09/2023] Open
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Fehrmann ML, Schegerer A, Werncke T, Schlattl H. COMPARISON OF EXPERIMENTAL AND NUMERICAL METHODS OF PATIENT DOSE ESTIMATIONS IN CT USING ANTHROPOMORPHIC MODELS. RADIATION PROTECTION DOSIMETRY 2020; 190:71-83. [PMID: 32744624 DOI: 10.1093/raddos/ncaa070] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/20/2020] [Revised: 02/20/2020] [Accepted: 04/05/2020] [Indexed: 06/11/2023]
Abstract
The common methods for patient dose estimations in computed tomography (CT) are thermoluminescence dosemeter (TLD) measurements or the usage of software packages based on Monte Carlo simulations like CT-Expo or the newer CTVoxDos, which uses the ICRP Reference Adult Male (ICRP 110). Organ (OD) and effective doses of a CT protocol of the upper abdomen are compared. Compared to CTVoxDos, ODs inferred by TLD measurement using an anthropomorphic phantom differ by $\mathbf{(19\pm 16)\,\%}$ inside the primary radiation field, $\mathbf{(14\pm 2)\,\%}$ for partially primary irradiated organs and $\mathbf{(34\pm 38)\,\%}$ in the scattered radiation field. ODs estimated by CT-Expo show a mean deviation of $\mathbf{(16\pm 9)\,\%}$ (primary irradiated) and $\mathbf{(28\pm 31)\,\%}$ (scatter irradiated) from ODs estimated by CTVoxDos.
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Affiliation(s)
- M L Fehrmann
- Institute of Radiation Medicine, Helmholtz Zentrum München-German Research Center for Environmental Health, 85764 Neuherberg, Germany
- Lehrstuhl für Experimentelle Physik IV, Technische Universität Dortmund, 44227 Dortmund, Germany
| | - A Schegerer
- Medizinischer und beruflicher Strahlenschutz, Bundesamt für Strahlenschutz, 85764 Neuherberg, Germany
- Hirslanden AG, 8152 Glattpark, Switzerland
| | - T Werncke
- Institut für Diagnostische und Interventionelle Radiologie, Medizinische Hochschule Hannover, 30625 Hannover, Germany
| | - H Schlattl
- Institute of Radiation Medicine, Helmholtz Zentrum München-German Research Center for Environmental Health, 85764 Neuherberg, Germany
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26
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Lee C, Liu J, Griffin K, Folio L, Summers RM. Adult patient-specific CT organ dose estimations using automated segmentations and Monte Carlo simulations. Biomed Phys Eng Express 2020; 6:045016. [PMID: 33444276 DOI: 10.1088/2057-1976/ab98e6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
We aimed to determine feasibility in calculating patient-specific organ doses for abdominal computed tomography (CT) exams using an automated segmentation technique dedicated to abdominal organs combined with Monte Carlo simulation of a clinical CT scanner. We conducted the automated segmentation of five major abdominal organs (left and right kidneys, pancreas, spleen, and liver) for ten adult patients and calculated organ-specific doses for each patient. We observed significant variability (Coefficient of Variation up to 32%) in organ mass across the ten patients, which was up to two-fold greater or smaller than the reference organ mass for the ICRP reference adult male and female. Comparison of patient-specific organ dose per CTDIvol with those from the ICRP reference phantoms confirmed that reference phantom-based dose reporting programs cannot capture inter-patient dose variability, and dosimetric errors can go up to nearly 40%. We demonstrated an automated method for patient-specific organ dose calculations, which took about 45 min per patient. When the automatic segmentation method is extended to more organs and faster Monte Carlo calculation technique is employed, our method should be useful for patient-specific dose monitoring at the organ level and for epidemiological investigations of health risks in CT patients.
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Affiliation(s)
- Choonsik Lee
- Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Rockville, MD 20850, United States of America
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27
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Abuhaimed A, Martin CJ. A Monte Carlo investigation of dose length product of cone beam computed tomography scans. JOURNAL OF RADIOLOGICAL PROTECTION : OFFICIAL JOURNAL OF THE SOCIETY FOR RADIOLOGICAL PROTECTION 2020; 40:393-409. [PMID: 31986511 DOI: 10.1088/1361-6498/ab703c] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The dose length product (DLP) provides a measurement related to energy imparted from a computed tomography (CT) scan. The DLP is based on the volume-averaged CT dose index (CTDI vol), which is designed for fan beams. The aims of this study were to investigate the use of DLP for scans with wide beams used in cone beam CT (DLP CBCT) in radiotherapy that would be analogous to the DLP of fan beam scans (DLP CT), and to compare the efficiencies of DLP CT and DLP CBCT in reporting the total energy imparted in patients. A validated Monte Carlo model of a kV imaging system integrated into a Varian TrueBeam linac was employed. The DLP CT was assessed by multiplying the CTDI vol for a 20 mm fan beam by scan length, and the DLP CBCT determined through multiplying the CTDI vol, estimated for wide beams using a correction factor based on free-in-air measurements, by the beam width. Two scan protocols for head and body were investigated for tube potentials between 80 and 140 kV and a range of scan lengths/widths. Efficiency values were estimated by normalising the DLP CT and DLP CBCT with respect to the corresponding dose profile integrals (DPIs), which were evaluated within 900 mm long phantoms. The results show that the DLP CBCT values were within 1% of those for DLP CT of similar length performed on the same system, and the efficiencies decrease with tube potential. However, whereas DLP values for fan beams are approximately proportional to scan length, those for wide beams decrease by ∼2% between beam widths of 20 and 320 mm. As a result, while the DLP CT efficiency is similar over all scan lengths, that for DLP CBCT increases slightly with beam width. The DLP CT and DLP CBCT underestimated the total energy imparted by comparable amounts with efficiencies within the range of 80-81% and 80-83% for the head scans, and 71-76% and 70-77% for the body scans, respectively. The results indicate that the DLP CBCT can be considered as an analogous dose index to the DLP CT. It could, therefore, be used for quantification of doses from imaging in radiotherapy and provide a valuable tool to aid optimisation.
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Affiliation(s)
- Abdullah Abuhaimed
- King Abdulaziz City for Science and Technology (KACST), Riyadh, Saudi Arabia
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Estimation of size-specific dose estimates (SSDE) for paediatric and adults patients based on a single slice. Phys Med 2020; 74:30-39. [PMID: 32403067 DOI: 10.1016/j.ejmp.2020.05.001] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/17/2020] [Revised: 03/15/2020] [Accepted: 05/01/2020] [Indexed: 02/04/2023] Open
Abstract
Volume averaged CT dose index (CTDIvol) is an important dose index utilized for CT dosimetry. Measurements of CTDIvol are performed in reference cylindrical phantoms of specified diameters. A size-specific dose estimate (SSDE) has been recommended for assessment of doses delivered to individual patients. Evaluation of the SSDE requires the size of the scanned region of the patient to be estimated in terms of water-equivalent diameter (Dw) to allow calculation of a dose value appropriate for the patient. Estimation of Dw, however, may be challenging and time consuming as it requires assessment of Dw for each slice within the scanned region. A study has been carried out to investigate the suitability of using Dw,mid for a single slice at the middle of the scanned region to estimate a value of Dw,mean to apply to all slices. 351 phantoms (158 paediatric and 193 adult) developed from reconstructed CT images of patients were employed. Six scan regions were studied: chest, abdomen, pelvis, chest and abdomen, abdomen and pelvis, and the whole trunk. Results show that the use of Dw,mid can lead to over or underestimation of Dw,mean by up to 13% for paediatric and adult patients. SSDE values based on Dw,mid and Dw,mean were assessed for each phantom, and a linear regression analysis was performed. Use of the analysis could provide a simple and practical approach to assessing SSDE for a given scan based on Dw,mid with the root-mean-square errors estimated to be in the range of 1.2%-4.0% for paediatric and 1.2%-5.9% for adults.
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29
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De Mattia C, Campanaro F, Rottoli F, Colombo PE, Pola A, Vanzulli A, Torresin A. Patient organ and effective dose estimation in CT: comparison of four software applications. Eur Radiol Exp 2020; 4:14. [PMID: 32060664 PMCID: PMC7021892 DOI: 10.1186/s41747-019-0130-5] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2019] [Accepted: 11/05/2019] [Indexed: 01/13/2023] Open
Abstract
Background Radiation dose in computed tomography (CT) has become a topic of high interest due to the increasing numbers of CT examinations performed worldwide. Hence, dose tracking and organ dose calculation software are increasingly used. We evaluated the organ dose variability associated with the use of different software applications or calculation methods. Methods We tested four commercial software applications on CT protocols actually in use in our hospital: CT-Expo, NCICT, NCICTX, and Virtual Dose. We compared dose coefficients, estimated organ doses and effective doses obtained by the four software applications by varying exposure parameters. Our results were also compared with estimates reported by the software authors. Results All four software applications showed dependence on tube voltage and volume CT dose index, while only CT-Expo was also dependent on other exposure parameters, in particular scanner model and pitch caused a variability till 50%. We found a disagreement between our results and those reported by the software authors (up to 600%), mainly due to a different extent of examined body regions. The relative range of the comparison of the four software applications was within 35% for most organs inside the scan region, but increased over the 100% for organs partially irradiated and outside the scan region. For effective doses, this variability was less evident (ranging from 9 to 36%). Conclusions The two main sources of organ dose variability were the software application used and the scan region set. Dose estimate must be related to the process used for its calculation.
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Affiliation(s)
- Cristina De Mattia
- Department of Medical Physics, ASST Grande Ospedale Metropolitano Niguarda, Piazza Ospedale Maggiore, 3, 20162, Milan, Italy
| | - Federica Campanaro
- Department of Medical Physics, ASST Grande Ospedale Metropolitano Niguarda, Piazza Ospedale Maggiore, 3, 20162, Milan, Italy
| | - Federica Rottoli
- Department of Medical Physics, ASST Grande Ospedale Metropolitano Niguarda, Piazza Ospedale Maggiore, 3, 20162, Milan, Italy
| | - Paola Enrica Colombo
- Department of Medical Physics, ASST Grande Ospedale Metropolitano Niguarda, Piazza Ospedale Maggiore, 3, 20162, Milan, Italy
| | - Andrea Pola
- Department of Energy, Politecnico di Milano, via La Masa, 34, 20156, Milan, Italy
| | - Angelo Vanzulli
- Department of Radiology, ASST Grande Ospedale Metropolitano Niguarda, Piazza Ospedale Maggiore, 3, 20162, Milan, Italy.
| | - Alberto Torresin
- Department of Medical Physics, ASST Grande Ospedale Metropolitano Niguarda, Piazza Ospedale Maggiore, 3, 20162, Milan, Italy
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Akhavanallaf A, Xie T, Zaidi H. Assessment of uncertainties associated with Monte Carlo-based personalized dosimetry in clinical CT examinations. Phys Med Biol 2020; 65:045008. [PMID: 31935713 DOI: 10.1088/1361-6560/ab6b45] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The clinical value of x-ray computed tomography (CT) has skyrocketed in the last decade while at the same time being the main source of medical exposure to the population. Concerns regarding the potential health hazards associated with the use of ionizing radiation were raised and an appropriate estimation of absorbed dose to patients is highly desired. In this work, we aim to validate our developed Monte Carlo CT simulator using in-phantom dose measurements and further assess the impact of personalized scan-related parameters on dosimetric calculations. We developed a Monte Carlo-based CT simulator for personalized organ level dose calculations, in which the CT source model, patient-specific computational model and personalized scanning protocol were integrated. The CT simulator was benchmarked using an ionization chamber and standard CT Dose Index phantom while the dosimetry methodology was validated through experimental measurements using thermoluminescent dosimeters (TLDs) embedded within an anthropomorphic phantom. Patient-specific scan protocols extracted from CT raw data and DICOM image metadata, respectively, were fed as input into the CT simulator to calculate individualized dose profiles. Thereby, the dosimetric uncertainties associated with using different protocol-related parameters were investigated. The absolute absorbed dose difference between measurements and simulations using the ionization chamber was less than 3%. In the case of the anthropomorphic phantom, the absolute absorbed dose difference between simulations and TLD measurements ranged from -8.3% to 22%, with a mean absolute difference of 14% while the uncertainties of protocol-related input parameters introduced an extra absolute error of 15% to the simulated results compared with TLD measurements. The developed methodology can be employed for accurate estimation of organ level dose from clinical CT examinations. The validated methodology can be further developed to produce an accurate MC simulation model with a reduced computational burden.
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Affiliation(s)
- Azadeh Akhavanallaf
- Division of Nuclear Medicine and Molecular Imaging, Geneva University Hospital, CH-1211 Geneva 4, Switzerland
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31
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Davoudi M, Khoramian D, Abedi-Firouzjah R, Ataei G. STRATEGY OF COMPUTED TOMOGRAPHY IMAGE OPTIMISATION IN CERVICAL VERTEBRAE AND NECK SOFT TISSUE IN EMERGENCY PATIENTS. RADIATION PROTECTION DOSIMETRY 2019; 187:98-102. [PMID: 31135908 DOI: 10.1093/rpd/ncz145] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Revised: 04/27/2019] [Accepted: 05/03/2019] [Indexed: 06/09/2023]
Abstract
INTRODUCTION With regards to the use of ionisation radiation in the computed tomography (CT), optimal parameters should be used to reduce the risk of incidence of secondary cancers in patients who are constantly exposed to X-rays. The aim of this study was to optimise the parameters used in CT scan of cervical vertebrae and neck soft tissue with minimal loss of image quality in emergency patients. MATERIALS AND METHODS In this study, the patients were divided into two groups. The first group consisted of patients scanned with default parameters and the second group scanned with optimised parameters. All the study has been implemented in emergency settings. The cases included cervical vertebrae and soft tissue protocols. Common CT dose descriptors including weighted computed tomography dose index (CTDIw), volumetric CTDI (CTDIvol), dose length product (DLP), effective dose (ED) and image noise were measured for each group. The ImpactDose program was used to estimate the organs doses. Statistical analysis was performed using Kruskal-Wallis test using SPSS software. RESULTS There was no significant quality reduction in the optimised images. Decreasing in radiation dose parameters for the soft tissue was: kVp=16.7%, mAs=64.3% and pitch=24.1%, and for the cervical vertebrae was: kVp=16.7%, mAs=54.2% and pitch=48.3%. Consequently, decreasing these parameters reduced CTDIw=81.0%, CTDIvol=90.0% and DLP = 90.2% in the cervical vertebral protocol, as well as CTDIw=75.5%, CTDIvol=81.3% and DLP = 81.4% in the soft tissue protocol. CONCLUSION Regarding the results, the optimised parameters in the mentioned organ scan reduce the radiation dose in the target area and the organs surrounding. Therefore, these protocols can be used for reducing the risk of cancer.
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Affiliation(s)
- Mohammad Davoudi
- MSc of Medical Radiation Engineering, Department of Medical Imaging Center, Babol University of Medical Sciences Babol, Iran
| | - Daryoush Khoramian
- The Advocate Center for Clinical Research, Ayatollah Yasrebi Hospital, Kashan, Iran
| | - Razzagh Abedi-Firouzjah
- Department of Medical Physics Radiobiology and Radiation Protection, Babol University of Medical Sciences, Babol, Iran
| | - Gholamreza Ataei
- Department of Radiology Technology, Faculty of Paramedical Sciences, Babol University of Medical Science, Babol, Iran
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Sharma S, Kapadia A, Fu W, Abadi E, Segars WP, Samei E. A real-time Monte Carlo tool for individualized dose estimations in clinical CT. Phys Med Biol 2019; 64:215020. [PMID: 31539892 DOI: 10.1088/1361-6560/ab467f] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The increasing awareness of the adverse effects associated with radiation exposure in computed tomography (CT) has necessesitated the quantification of dose delivered to patients for better risk assessment in the clinic. The current methods for dose quantification used in the clinic are approximations, lacking realistic models for the irradiation conditions utilized in the scan and the anatomy of the patient being imaged, which limits their relevance for a particular patient. The established gold-standard technique for individualized dose quantification uses Monte Carlo (MC) simulations to obtain patient-specific estimates of organ dose in anatomically realistic computational phantoms to provide patient-specific estimates of organ dose. Although accurate, MC simulations are computationally expensive, which limits their utility for time-constrained applications in the clinic. To overcome these shortcomings, a real-time GPU-based MC tool based on FDA's MC-GPU framework was developed for patient and scanner-specific dosimetry in the clinic. The tool was validated against (1) AAPM's TG-195 reference datasets and (2) physical measurements of dose acquired using TLD chips in adult and pediatric anthropomorphic phantoms. To demonstrate its utility towards providing individualized dose estimates, it was integrated with an automatic segmentation method for generating patient-specific models, which were then used to estimate patient- and scanner-specific organ doses for a select population of 50 adult patients using a clinically relevant CT protocol. The organ dose estimates were compared to corresponding dose estimates from a previously validated MC method based on Penelope. The dose estimates from our MC tool agreed within 5% for all organs (except thyroid) tabulated by TG-195 and within 10% for all TLD locations in the adult and pediactric phantoms, across all validation cases. Compared against Penelope, the organ dose estimates agreed within 3% on average for all organs in the patient population study. The average run duration for each patient was estimated at 23.79 s, representing a significant speedup (~700×) over existing non-parallelized MC methods. The accuracy of dose estimates combined with a significant improvement in execution times suggests a feasible solution utilizing the proposed MC tool for real-time individualized dosimetry in the clinic.
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Affiliation(s)
- Shobhit Sharma
- Department of Physics, Duke University, Durham, NC 27705, United States of America. Carl E Ravin Advanced Imaging Laboratories, Duke University, Durham, NC 27705, United States of America. Author to whom any correspondence should be addressed
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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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Choudhary N, Rana BS, Shukla A, Oinam AS, Singh NP, Kumar S. PATIENTS DOSE ESTIMATION IN CT EXAMINATIONS USING SIZE SPECIFIC DOSE ESTIMATES. RADIATION PROTECTION DOSIMETRY 2019; 184:256-262. [PMID: 30496523 DOI: 10.1093/rpd/ncy207] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2018] [Revised: 10/30/2018] [Accepted: 11/06/2018] [Indexed: 06/09/2023]
Abstract
The present work reports data of radiation exposure to the patients during head, chest, pelvis and abdomen CT examinations performed on a third-generation 16-slice CT machine. Radiation exposure was estimated using size specific dose estimates (SSDE) method, which takes into account patient's physical dimensions in phantom measured computed tomography dose index (CTDI) value. The reported median CT dose volume index CTDIvol values in head, chest, pelvis and abdomen examinations were 26.76, 16.27, 29.81 and 14.74 mGy, respectively. The median doses evaluated using SSDE methodology for the above mentioned procedure were 54.1, 23.1, 42.8 and 20.1 mGy, respectively. Our results showed variation in dose values estimated using CTDI and SSDE methods in all examinations. The evaluated SSDE values were also compared to the values derived from data reported by the American Association of Physicist in Medicine (AAPM). SSDE values in present measurements are 4-8% lower than AAPM values. The present results show that CTDI parameters recorded on CT console should not be used to specify patient dose during CT procedures.
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Affiliation(s)
- Neha Choudhary
- Department of Radiotherapy, Shanti Mukand Hospita, New Delhi, India
| | | | - Arvind Shukla
- Department of Radiotherapy, R. N. T Medical College, Udaipur, India
| | | | | | - Sanjeev Kumar
- Department of Physics, G. G. D. S. D. College, Chandigarh, India
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Ebrahimi-Khankook A, Akhlaghi P, Vejdani-Noghreiyan A. Studying the lung dose uncertainty during chest CT scans using phantoms with statistical lung volumes and shapes. JOURNAL OF RADIOLOGICAL PROTECTION : OFFICIAL JOURNAL OF THE SOCIETY FOR RADIOLOGICAL PROTECTION 2019; 39:443-454. [PMID: 30673649 DOI: 10.1088/1361-6498/ab0116] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
In recent years, there has been increasing interest in constructing a series of deformable phantoms which follow the statistical distributions of some anatomical variations, known as 'statistical phantoms'. The main purpose of this study was to develop statistical phantoms by considering the variations in lung volume and shape, in order to evaluate the lung dose uncertainty for individuals undergoing chest computed tomography. Calculations were performed for 100 statistical lung volume phantoms and 70 statistical lung shape phantoms at tube voltages of 80 and 120 kVp, with the use of Monte Carlo MCNP code. The obtained results indicate that dose fluctuations for low tube voltage (80 kVp) are higher than those at 120 kVp. Moreover, it shows that the impact of statistical variations in lung volume on dose discrepancy (5% to 7%) is higher than the impact of statistical lung shape variations (around 2%).
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36
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Hardy AJ, Angel E, Bostani M, Cagnon C, McNitt-Gray M. Estimating fetal dose from tube current-modulated (TCM) and fixed tube current (FTC) abdominal/pelvis CT examinations. Med Phys 2019; 46:2729-2743. [PMID: 30893477 DOI: 10.1002/mp.13499] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2018] [Revised: 03/12/2019] [Accepted: 03/13/2019] [Indexed: 11/05/2022] Open
Abstract
PURPOSE The purpose of this work was to estimate scanner-independent CTDIvol -to-fetal-dose coefficients for tube current-modulated (TCM) and fixed tube current (FTC) computed tomography (CT) examinations of pregnant patients of various gestational ages undergoing abdominal/pelvic CT examinations. METHODS For 24 pregnant patients of gestational age from <5 to 36 weeks who underwent clinically indicated CT examinations, voxelized models of maternal and fetal (or embryo) anatomy were created from abdominal/pelvic image data. Absolute fetal dose (Dfetus ) was estimated using Monte Carlo (MC) simulations of helical scans covering the abdomen and pelvis for TCM and FTC scans. Estimated TCM schemes were generated for each patient model using a validated method that accounts for patient attenuation and scanner output limits for one scanner model and were incorporated into MC simulations. FTC scans were also simulated for each patient model with multidetector row CT scanners from four manufacturers. Normalized fetal dose estimates, nDfetus , was obtained by dividing Dfetus from the MC simulations by CTDIvol . Patient size was described using water equivalent diameter (Dw ) measured at the three-dimensional geometric centroid of the fetus. Fetal depth (DEf ) was measured from the anterior skin surface to the anterior part of the fetus. nDfetus and Dw were correlated using an exponential model to develop equations for fetal dose conversion coefficients for TCM and FTC abdominal/pelvic CT examinations. Additionally, bivariate linear regression was performed to analyze the correlation of nDfetus with Dw and fetal depth (DEf ). For one scanner model, nDfetus from TCM was compared to FTC and the size-specific dose estimate (SSDE) conversion coefficients (f-factors) from American Association of Physicists in Medicine (AAPM) Report 204. nDfetus from FTC simulations was averaged across all scanners for each patient ( n D fetus ¯ ) . n D fetus ¯ was then compared with SSDE f-factors and correlated with Dw using an exponential model and with Dw and DEf using a bivariate linear model. RESULTS For TCM, the coefficient of determination (R2 ) of nDfetus and Dw was observed to be 0.73 using an exponential model. Using the bivariate linear model with Dw and DEf , an R2 of 0.78 was observed. For the TCM technology modeled, TCM yielded nDfetus values that were on average 6% and 17% higher relative to FTC and SSDE f-factors, respectively. For FTC, the R2 of n D fetus ¯ with respect to Dw was observed to be 0.64 using an exponential model. Using the bivariate linear model, an R2 of 0.75 was observed for n D fetus ¯ with respect to Dw and DEf . A mean difference of 0.4% was observed between n D fetus ¯ and SSDE f-factors. CONCLUSION Good correlations were observed for nDfetus from TCM and FTC scans using either an exponential model with Dw or a bivariate linear model with both Dw and DEf . These results indicate that fetal dose from abdomen/pelvis CT examinations of pregnant patients of various gestational ages may be reasonably estimated with models that include (a) scanner-reported CTDIvol and (b) Dw as a patient size metric, in addition to (c) DEf if available. These results also suggest that SSDE f-factors may provide a reasonable (within ±25%) estimate of nDfetus for TCM and FTC abdomen/pelvis CT exams.
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Affiliation(s)
- Anthony J Hardy
- Department of Radiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, 90024, USA.,Physics and Biology in Medicine Graduate Program, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, 90024, USA
| | - Erin Angel
- Canon Medical Systems USA, Inc., Tustin, CA, 92780, USA
| | - Maryam Bostani
- Department of Radiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, 90024, USA.,Physics and Biology in Medicine Graduate Program, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, 90024, USA
| | - Chris Cagnon
- Department of Radiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, 90024, USA.,Physics and Biology in Medicine Graduate Program, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, 90024, USA
| | - Michael McNitt-Gray
- Department of Radiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, 90024, USA.,Physics and Biology in Medicine Graduate Program, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, 90024, USA
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Giansante L, Martins JC, Nersissian DY, Kiers KC, Kay FU, Sawamura MVY, Lee C, Gebrim EMMS, Costa PR. Organ doses evaluation for chest computed tomography procedures with TL dosimeters: Comparison with Monte Carlo simulations. J Appl Clin Med Phys 2018; 20:308-320. [PMID: 30508315 PMCID: PMC6333138 DOI: 10.1002/acm2.12505] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2018] [Revised: 09/22/2018] [Accepted: 10/25/2018] [Indexed: 12/05/2022] Open
Abstract
Purpose To evaluate organ doses in routine and low‐dose chest computed tomography (CT) protocols using an experimental methodology. To compare experimental results with results obtained by the National Cancer Institute dosimetry system for CT (NCICT) organ dose calculator. To address the differences on organ dose measurements using tube current modulation (TCM) and fixed tube current protocols. Methods An experimental approach to evaluate organ doses in pediatric and adult anthropomorphic phantoms using thermoluminescent dosimeters (TLDs) was employed in this study. Several analyses were performed in order to establish the best way to achieve the main results in this investigation. The protocols used in this study were selected after an analysis of patient data collected from the Institute of Radiology of the School of Medicine of the University of São Paulo (InRad). The image quality was evaluated by a radiologist from this institution. Six chest adult protocols and four chest pediatric protocols were evaluated. Lung doses were evaluated for the adult phantom and lung and thyroid doses were evaluated for the pediatric phantom. The irradiations were performed using both a GE and a Philips CT scanner. Finally, organ doses measured with dosimeters were compared with Monte Carlo simulations performed with NCICT. Results After analyzing the data collected from all CT examinations performed during a period of 3 yr, the authors identified that adult and pediatric chest CT are among the most applied protocol in patients in that clinical institution, demonstrating the relevance on evaluating organ doses due to these examinations. With regards to the scan parameters adopted, the authors identified that using 80 kV instead of 120 kV for a pediatric chest routine CT, with TCM in both situations, can lead up to a 28.7% decrease on the absorbed dose. Moreover, in comparison to the standard adult protocol, which is performed with fixed mAs, TCM, and ultra low‐dose protocols resulted in dose reductions of up to 35.0% and 90.0%, respectively. Finally, the percent differences found between experimental and Monte Carlo simulated organ doses were within a 20% interval. Conclusions The results obtained in this study measured the impact on the absorbed dose in routine chest CT by changing several scan parameters while the image quality could be potentially preserved.
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Affiliation(s)
- Louise Giansante
- Group of Radiation Dosimetry and Medical Physics, Institute of Physics, University of São Paulo (IFUSP), São Paulo, SP, Brazil
| | - Juliana C Martins
- Group of Radiation Dosimetry and Medical Physics, Institute of Physics, University of São Paulo (IFUSP), São Paulo, SP, Brazil.,Ludwig-Maximilians-Universität München (LMU), Munich, Germany
| | - Denise Y Nersissian
- Group of Radiation Dosimetry and Medical Physics, Institute of Physics, University of São Paulo (IFUSP), São Paulo, SP, Brazil
| | - Karen C Kiers
- Group of Radiation Dosimetry and Medical Physics, Institute of Physics, University of São Paulo (IFUSP), São Paulo, SP, Brazil.,Vrije Universiteit Amsterdam (VU), Amsterdam, The Netherlands
| | - Fernando U Kay
- Institute of Radiology, School of Medicine, University of São Paulo (InRad), São Paulo, SP, Brazil
| | - Marcio V Y Sawamura
- Institute of Radiology, School of Medicine, University of São Paulo (InRad), São Paulo, SP, Brazil
| | - Choonsik Lee
- Division of Cancer Epidemiology & Genetics, National Cancer Institute, National Institutes of Health (NIH), Bethesda, MD, USA
| | - Eloisa M M S Gebrim
- Institute of Radiology, School of Medicine, University of São Paulo (InRad), São Paulo, SP, Brazil
| | - Paulo R Costa
- Group of Radiation Dosimetry and Medical Physics, Institute of Physics, University of São Paulo (IFUSP), São Paulo, SP, Brazil
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Burton CS, Malkus A, Ranallo F, Szczykutowicz TP. Technical Note: Model-based magnification/minification correction of patient size surrogates extracted from CT localizers. Med Phys 2018; 46:165-172. [DOI: 10.1002/mp.13251] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2018] [Revised: 08/22/2018] [Accepted: 09/11/2018] [Indexed: 01/07/2023] Open
Affiliation(s)
- Christiane Sarah Burton
- Department of Radiology; University of Wisconsin-Madison; 1111 Highland Avenue Madison WI 53705 USA
| | - Annie Malkus
- Department of Medical Physics; University of Wisconsin-Madison; 1111 Highland Avenue, Rm 1005 Madison WI 53705 USA
| | - Frank Ranallo
- Departments of Medical Physics and Radiology; University of Wisconsin-Madison; 1111 Highland Avenue Madison WI 53705 USA
| | - Timothy P. Szczykutowicz
- Departments of Radiology, Medical Physics, and Biomedical Engineering; University of Wisconsin-Madison; 1111 Highland Avenue Madison WI 53705 USA
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Abuhaimed A, Martin CJ. A Monte Carlo study of impact of scan position for cone beam CT on doses to organs and effective dose. Radiat Phys Chem Oxf Engl 1993 2018. [DOI: 10.1016/j.radphyschem.2018.05.014] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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40
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Hardy AJ, Bostani M, McMillan K, Zankl M, McCollough C, Cagnon C, McNitt-Gray M. Estimating lung, breast, and effective dose from low-dose lung cancer screening CT exams with tube current modulation across a range of patient sizes. Med Phys 2018; 45:4667-4682. [PMID: 30118143 DOI: 10.1002/mp.13131] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2018] [Revised: 06/26/2018] [Accepted: 07/12/2018] [Indexed: 12/12/2022] Open
Abstract
PURPOSE The purpose of this study was to estimate the radiation dose to the lung and breast as well as the effective dose from tube current modulated (TCM) lung cancer screening (LCS) scans across a range of patient sizes. METHODS Monte Carlo (MC) methods were used to calculate lung, breast, and effective doses from a low-dose LCS protocol for a 64-slice CT that used TCM. Scanning parameters were from the protocols published by AAPM's Alliance for Quality CT. To determine lung, breast, and effective doses from lung cancer screening, eight GSF/ICRP voxelized phantom models with all radiosensitive organs identified were used to estimate lung, breast, and effective doses. Additionally, to extend the limited size range provided by the GSF/ICRP phantom models, 30 voxelized patient models of thoracic anatomy were generated from LCS patient data. For these patient models, lung and breast were semi-automatically segmented. TCM schemes for each of the GSF/ICRP phantom models were generated using a validated method wherein tissue attenuation and scanner limitations were used to determine the TCM output as a function of table position and source angle. TCM schemes for voxelized patient models were extracted from the raw projection data. The water equivalent diameter, Dw, was used as the patient size descriptor. Dw was estimated for the GSF/ICRP models. For the thoracic patient models, Dw was extracted from the DICOM header of the CT localizer radiograph. MC simulations were performed using the TCM scheme for each model. Absolute organ doses were tallied and effective doses were calculated using ICRP 103 tissue weighting factors for the GSF/ICRP models. Metrics of scanner radiation output were determined based on each model's TCM scheme, including CTDIvol , dose length product (DLP), and CTDIvol, Low Att , a previously described regional metric of scanner output covering most of the lungs and breast. All lung and breast doses values were normalized by scan-specific CTDIvol and CTDIvol, Low Att . Effective doses were normalized by scan-specific CTDIvol and DLP. Absolute and normalized doses were reported as a function of Dw. RESULTS Lung doses normalized by CTDIvol, Low Att were modeled as an exponential relationship with respect to Dw with coefficients of determination (R2 ) of 0.80. Breast dose normalized by CTDIvol, Low Att was modeled with an exponential relationship to Dw with an R2 of 0.23. For all eight GSF/ICRP phantom models, the effective dose using TCM protocols was below 1.6 mSv. Effective doses showed some size dependence but when normalized by DLP demonstrated a constant behavior. CONCLUSION Lung, breast, and effective doses from LCS CT exams with TCM were estimated with respect to patient size. Normalized lung dose can be reasonably estimated with a measure of a patient size such as Dw and regional metric of CTDIvol covering the thorax such as CTDIvol, Low Att , while normalized breast dose can also be estimated with a regional metric of CTDIvol but with a larger degree of variability than observed for lung. Effective dose normalized by DLP can be estimated with a constant multiplier.
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Affiliation(s)
- Anthony J Hardy
- Department of Radiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, 90024, USA.,Physics and Biology in Medicine Graduate Program, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, 90024, USA
| | - Maryam Bostani
- Department of Radiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, 90024, USA.,Physics and Biology in Medicine Graduate Program, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, 90024, USA
| | - Kyle McMillan
- Formerly with Department of Radiology, Mayo Clinic, Rochester, MN, 55905, USA
| | - Maria Zankl
- Helmholtz Zentrum München, German Research Center for Environmental Health (GmBH) Institute of Radiation Protection, Ingolstaedter Landstrasse 1, Neuherberg, 85764, Germany
| | | | - Chris Cagnon
- Department of Radiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, 90024, USA.,Physics and Biology in Medicine Graduate Program, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, 90024, USA
| | - Michael McNitt-Gray
- Department of Radiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, 90024, USA.,Physics and Biology in Medicine Graduate Program, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, 90024, USA
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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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Pi Y, Liu T, Xu XG. DEVELOPMENT OF A SET OF MESH-BASED AND AGE-DEPENDENT CHINESE PHANTOMS AND APPLICATION FOR CT DOSE CALCULATIONS. RADIATION PROTECTION DOSIMETRY 2018; 179:370-382. [PMID: 29340629 DOI: 10.1093/rpd/ncx296] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2017] [Accepted: 12/14/2017] [Indexed: 06/07/2023]
Abstract
Phantoms for organ dose calculations are essential in radiation protection dosimetry. This article describes the development of a set of mesh-based and age-dependent phantoms for Chinese populations using reference data recommended by the Chinese government and by the International Atomic Energy Agency (IAEA). Existing mesh-based RPI adult male (RPI-AM) and RPI adult female (RPI-AF) phantoms were deformed to form new phantoms according to anatomical data for the height and weight of Chinese individuals of 5 years old male, 5 years old female, 10 years old male, 10 years old female,15 years old male, 15 years old female, adult male and adult female-named USTC-5 M, USTC-5F, USTC-10M, USTC-10F, USTC-15M, USTC-15F, USTC-AM and USTC-AF, respectively. Following procedures to ensure the accuracy, more than 120 organs/tissues in each model were adjusted to match the Chinese reference parameters and the mass errors were within 0.5%. To demonstrate the usefulness, these new set of phantoms were combined with a fully validated model of the GE LightSpeed Pro 16 multi-detector computed tomography (MDCT) scanner and the GPU-based ARCHER Monte Carlo code to compute organ doses from CT examinations. Organ doses for adult models were then compared with the data of RPI-AM and RPI-AF under the same conditions. The absorbed doses and the effective doses of RPI phantoms are found to be lower than these of the USTC adult phantoms whose body sizes are smaller. Comparisons for the doses among different ages and genders were also made. It was found that teenagers receive more radiation doses than adults do. Such Chinese-specific phantoms are clearly better suited in organ dose studies for the Chinese individuals than phantoms designed for western populations. As already demonstrated, data derived from age-specific Chinese phantoms can help CT operators and designers to optimize image quality and doses.
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Affiliation(s)
- Yifei Pi
- School of Nuclear Science and Technology, University of Science and Technology of China, Hefei, Anhui Province 230026, PR China
| | - Tianyu Liu
- Nuclear Engineering Program, Rensselaer Polytechnic Institute, Troy, NY 12180, USA
| | - X George Xu
- School of Nuclear Science and Technology, University of Science and Technology of China, Hefei, Anhui Province 230026, PR China
- Nuclear Engineering Program, Rensselaer Polytechnic Institute, Troy, NY 12180, USA
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de las Heras Gala H, Schöfer F, Schöfer H, Sánchez Casanueva R, Zervides C, Mair K, Al-Zoubi Q, Renger B, de las Heras Gala T, Schlattl H. A patient-centric approach to quality control and dosimetry in CT including CBCT. Phys Med 2018; 47:92-102. [DOI: 10.1016/j.ejmp.2018.02.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/31/2017] [Revised: 12/08/2017] [Accepted: 02/07/2018] [Indexed: 11/16/2022] Open
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Abuhaimed A, Martin CJ. Evaluation of coefficients to derive organ and effective doses from cone-beam CT (CBCT) scans: a Monte Carlo study. JOURNAL OF RADIOLOGICAL PROTECTION : OFFICIAL JOURNAL OF THE SOCIETY FOR RADIOLOGICAL PROTECTION 2018; 38:189-206. [PMID: 29154259 DOI: 10.1088/1361-6498/aa9b9f] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Regular imaging is used throughout image guided radiation therapy to improve treatment delivery. In order for treatment procedures to be optimized, the doses delivered by imaging exposures should be taken into account. CT dosimetry methods based on the CT dose index (CTDI), measured with a 100 mm long pencil ionization chamber (CTDI100) in standard phantoms, are not designed for cone-beam CT (CBCT) imaging systems used in radiotherapy, therefore a modified version has been proposed for CBCT by the International Electrotechnical Commission (CTDIIEC). Monte Carlo simulations based on a Varian On-Board Imaging system were used to derive conversion coefficients that enable organ doses for ICRP reference phantoms to be determined from the CTDIIEC for different scan protocols and different beam widths (80-320) mm. A dose-width product calculated by multiplying the CTDIIEC by the width of the CBCT beam is proposed as a quantity that can be used for estimating effective dose. The variation in coefficients with CBCT beam width was studied. Coefficients to allow estimation of effective doses were derived, namely 0.0034 mSv (mGy cm)-1 for the head, 0.0252 mSv (mGy cm)-1 for the thorax, 0.0216 mSv (mGy cm)-1 for the abdomen and 0.0150 mSv (mGy cm)-1 for the pelvis, and these may be applicable more generally to other CBCT systems in radiotherapy. If data on effective doses are available, these can be used in making judgements on the contributions to patient dose from imaging, and thereby assist in optimization of the treatment regimes. The coefficients can also be employed in converting dosimetry data recorded in patient records into quantities relating directly to patient doses.
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Affiliation(s)
- Abdullah Abuhaimed
- The National Centre for Applied Physics, King Abdulaziz City for Science and Technology, Riyadh, Saudi Arabia
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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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Xie T, Zanotti-Fregonara P, Edet-Sanson A, Zaidi H. Patient-Specific Computational Model and Dosimetry Calculations for PET/CT of a Patient Pregnant with Twins. J Nucl Med 2018; 59:1451-1458. [PMID: 29371408 DOI: 10.2967/jnumed.117.205286] [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: 11/13/2017] [Accepted: 01/12/2018] [Indexed: 11/16/2022] Open
Abstract
The radiation dose delivered to pregnant patients during radiologic imaging procedures raises health concerns because the developing embryo and fetus are considered to be highly radiosensitive. To appropriately weigh the diagnostic benefits against the radiation risks, the radiologist needs reasonably accurate and detailed estimates of the fetal dose. Expanding our previously developed series of computational phantoms for pregnant women, we here describe a personalized model for twin pregnancy, based on an actual clinical scan. Methods: The model is based on a standardized hybrid pregnant female and fetus phantom and on a clinical case of a patient who underwent an 18F-FDG PET/CT scan while expecting twins at 25 weeks' gestation. This model enabled us to produce a realistic physical representation of the pregnant patient and to estimate the maternal and fetal organ doses from the 18F-FDG and CT components. The Monte Carlo N-Particle Extended general-purpose code was used for radiation transport simulation. Results: The 18F-FDG doses for the 2 fetuses were 3.78 and 3.99 mGy, and the CT doses were 0.76 and 0.70 mGy, respectively. Therefore, the relative contribution of 18F-FDG and CT to the total dose to the fetuses was about 84% and 16%, respectively. Meanwhile, for 18F-FDG, the calculated personalized absorbed dose was about 40%-50% higher than the doses reported by other dosimetry computer software tools. Conclusion: Our approach to constructing personalized computational models allows estimation of a patient-specific radiation dose, even in cases with unusual anatomic features such as a twin pregnancy. Our results also show that, even in twins, the fetal organ doses from both 18F-FDG and CT present a certain variability linked to the anatomic characteristics. The CT fetal dose is smaller than the 18F-FDG PET dose.
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Affiliation(s)
- Tianwu Xie
- Division of Nuclear Medicine and Molecular Imaging, Geneva University Hospital, Geneva, Switzerland
| | | | | | - Habib Zaidi
- Division of Nuclear Medicine and Molecular Imaging, Geneva University Hospital, Geneva, Switzerland .,Department of Nuclear Medicine and Molecular Imaging, University Medical Center Groningen, Groningen, Netherlands.,Geneva University Neurocenter, University of Geneva, Geneva, Switzerland; and.,Department of Nuclear Medicine, University of Southern Denmark, Odense, Denmark
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Hoye J, Zhang Y, Agasthya G, Sturgeon G, Kapadia A, Segars WP, Samei E. Organ dose variability and trends in tomosynthesis and radiography. J Med Imaging (Bellingham) 2017; 4:031207. [PMID: 28804729 DOI: 10.1117/1.jmi.4.3.031207] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2017] [Accepted: 06/30/2017] [Indexed: 11/14/2022] Open
Abstract
The purpose of this study was to investigate relationships between patient attributes and organ dose for a population of computational phantoms for 20 tomosynthesis and radiography protocols. Organ dose was estimated from 54 adult computational phantoms (age: 18 to 78 years, weight 52 to 117 kg) using a validated Monte-Carlo simulation (PENELOPE) of a system capable of performing tomosynthesis and radiography. The geometry and field of view for each exam were modeled to match clinical protocols. For each protocol, the energy deposited in each organ was estimated by the simulations, converted to dose units, and then normalized by exposure in air. Dose to radiosensitive organs was studied as a function of average patient thickness in the region of interest and as a function of body mass index. For tomosynthesis, organ doses were also studied as a function of x-ray tube position. This work developed comprehensive information for organ dose dependencies across a range of tomosynthesis and radiography protocols. The results showed a protocol-dependent exponential decrease with an increasing patient size. There was a variability in organ dose across the patient population, which should be incorporated in the metrology of organ dose. The results can be used to prospectively and retrospectively estimate organ dose for tomosynthesis and radiography.
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Affiliation(s)
- Jocelyn Hoye
- Duke University, Carl E. Ravin Advanced Imaging Laboratories, Durham, North Carolina, United States.,Duke University, Department of Radiology, Durham, North Carolina, United States.,Duke University, Medical Physics Graduate Program, Durham, North Carolina, United States.,Duke University Medical Center, Durham, North Carolina, United States
| | - Yakun Zhang
- Duke University, Carl E. Ravin Advanced Imaging Laboratories, Durham, North Carolina, United States.,Duke University, Department of Radiology, Durham, North Carolina, United States.,Duke University Medical Center, Durham, North Carolina, United States
| | - Greeshma Agasthya
- Duke University, Carl E. Ravin Advanced Imaging Laboratories, Durham, North Carolina, United States.,Duke University, Department of Radiology, Durham, North Carolina, United States.,Duke University Medical Center, Durham, North Carolina, United States
| | - Greg Sturgeon
- Duke University, Carl E. Ravin Advanced Imaging Laboratories, Durham, North Carolina, United States.,Duke University, Department of Radiology, Durham, North Carolina, United States.,Duke University Medical Center, Durham, North Carolina, United States
| | - Anuj Kapadia
- Duke University, Carl E. Ravin Advanced Imaging Laboratories, Durham, North Carolina, United States.,Duke University, Department of Radiology, Durham, North Carolina, United States.,Duke University, Medical Physics Graduate Program, Durham, North Carolina, United States.,Duke University Medical Center, Durham, North Carolina, United States
| | - W Paul Segars
- Duke University, Carl E. Ravin Advanced Imaging Laboratories, Durham, North Carolina, United States.,Duke University, Department of Radiology, Durham, North Carolina, United States.,Duke University, Medical Physics Graduate Program, Durham, North Carolina, United States.,Duke University Medical Center, Durham, North Carolina, United States
| | - Ehsan Samei
- Duke University, Carl E. Ravin Advanced Imaging Laboratories, Durham, North Carolina, United States.,Duke University, Department of Radiology, Durham, North Carolina, United States.,Duke University, Medical Physics Graduate Program, Durham, North Carolina, United States.,Duke University Medical Center, Durham, North Carolina, United States
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48
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Niiniviita H, Kiljunen T, Kulmala J. Comparison of Effective Dose and Image Quality for Newborn Imaging on Seven Commonly Used CT Scanners. RADIATION PROTECTION DOSIMETRY 2017; 174:510-517. [PMID: 27522051 DOI: 10.1093/rpd/ncw229] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2016] [Accepted: 07/06/2016] [Indexed: 06/06/2023]
Abstract
This study compares the image quality and the patient doses on seven different computed tomography (CT) scanners for newborn chest imaging. The dose was measured by using an anthropomorphic newborn phantom and thermoluminescence dosemeters (TLDs). The effective dose was estimated separately based on a dose-length-product display, TLD measurements and the ImPACT CT dose calculation software. The image quality was assessed using a signal-to-noise ratio and a contrast-to-noise ratio (CNR). In order to compare the different scanners, a figure of merit (FOM) based on the rate of CNR2 and computed tomography dose index (CTDIvol) was calculated. The organ doses within the scan area ranged between 0.3 and 2.9 mGy and they depended on the organ and used scanner. The highest effective dose (1.1 mSv) was observed on Aquilion 32 and the lowest effective dose was observed on the Aquilion One (0.22 mSv). The lowest organ doses and highest FOM were observed on the Optima 660. With the Aquilion One and the Definition Dual Flash the examination was 71-90% faster when compared with other scanners. Newer devices equipped with novel dose-saving methods provide a lower dose, as well as take better advantage of the radiation in the image formation.
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Affiliation(s)
- Hannele Niiniviita
- Department of Medical Physics, Turku University Hospital, PO Box 52, FI-20521 Turku, Finland
- Department of Diagnostic Radiology, University of Turku, FI-20014 Turun yliopisto, Finland
| | - Timo Kiljunen
- Docrates Cancer Center, Helsinki, Saukonpaadenranta 2, FI-00180 Helsinki, Finland
| | - Jarmo Kulmala
- Department of Oncology, Turku University Hospital, PO Box 52, FI-20521 Turku, Finland
- Department of Radiology, Turku University Hospital, PO Box 52, FI-20521 Turku, Finland
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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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50
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Bostani M, McMillan K, Lu P, Kim GHJ, Cody D, Arbique G, Greenberg SB, DeMarco JJ, Cagnon CH, McNitt-Gray MF. Estimating organ doses from tube current modulated CT examinations using a generalized linear model. Med Phys 2017; 44:1500-1513. [PMID: 28112399 DOI: 10.1002/mp.12119] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2016] [Revised: 12/19/2016] [Accepted: 01/15/2017] [Indexed: 12/16/2022] Open
Abstract
PURPOSE Currently, available Computed Tomography dose metrics are mostly based on fixed tube current Monte Carlo (MC) simulations and/or physical measurements such as the size specific dose estimate (SSDE). In addition to not being able to account for Tube Current Modulation (TCM), these dose metrics do not represent actual patient dose. The purpose of this study was to generate and evaluate a dose estimation model based on the Generalized Linear Model (GLM), which extends the ability to estimate organ dose from tube current modulated examinations by incorporating regional descriptors of patient size, scanner output, and other scan-specific variables as needed. METHODS The collection of a total of 332 patient CT scans at four different institutions was approved by each institution's IRB and used to generate and test organ dose estimation models. The patient population consisted of pediatric and adult patients and included thoracic and abdomen/pelvis scans. The scans were performed on three different CT scanner systems. Manual segmentation of organs, depending on the examined anatomy, was performed on each patient's image series. In addition to the collected images, detailed TCM data were collected for all patients scanned on Siemens CT scanners, while for all GE and Toshiba patients, data representing z-axis-only TCM, extracted from the DICOM header of the images, were used for TCM simulations. A validated MC dosimetry package was used to perform detailed simulation of CT examinations on all 332 patient models to estimate dose to each segmented organ (lungs, breasts, liver, spleen, and kidneys), denoted as reference organ dose values. Approximately 60% of the data were used to train a dose estimation model, while the remaining 40% was used to evaluate performance. Two different methodologies were explored using GLM to generate a dose estimation model: (a) using the conventional exponential relationship between normalized organ dose and size with regional water equivalent diameter (WED) and regional CTDIvol as variables and (b) using the same exponential relationship with the addition of categorical variables such as scanner model and organ to provide a more complete estimate of factors that may affect organ dose. Finally, estimates from generated models were compared to those obtained from SSDE and ImPACT. RESULTS The Generalized Linear Model yielded organ dose estimates that were significantly closer to the MC reference organ dose values than were organ doses estimated via SSDE or ImPACT. Moreover, the GLM estimates were better than those of SSDE or ImPACT irrespective of whether or not categorical variables were used in the model. While the improvement associated with a categorical variable was substantial in estimating breast dose, the improvement was minor for other organs. CONCLUSIONS The GLM approach extends the current CT dose estimation methods by allowing the use of additional variables to more accurately estimate organ dose from TCM scans. Thus, this approach may be able to overcome the limitations of current CT dose metrics to provide more accurate estimates of patient dose, in particular, dose to organs with considerable variability across the population.
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Affiliation(s)
- Maryam Bostani
- Departments of Biomedical Physics and Radiology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, 90024, USA
| | - Kyle McMillan
- Department of Radiology, Mayo Clinic, CT Clinical Innovation Center, Rochester, MN, 55905, USA
| | - Peiyun Lu
- Departments of Biomedical Physics and Radiology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, 90024, USA
| | - Grace Hyun J Kim
- Departments of Biomedical Physics and Radiology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, 90024, USA
| | - Dianna Cody
- Department of Imaging Physics, University of Texas, MD Anderson Cancer Center, Houston, TX, 77030, USA
| | - Gary Arbique
- UT Southwestern Medical Center, Dallas, TX, 75390, USA
| | - S Bruce Greenberg
- Department of Radiology, Arkansas Children's Hospital, Little Rock, AR, 72202, USA
| | - John J DeMarco
- Department of Radiation Oncology, Cedars-Sinai Medical Center, Los Angeles, CA, 90048, USA
| | - Chris H Cagnon
- Departments of Biomedical Physics and Radiology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, 90024, USA
| | - Michael F McNitt-Gray
- Departments of Biomedical Physics and Radiology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, 90024, USA
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