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Anam C, Kusuma Dewi W, Masdi M, Haryanto F, Fujibuchi T, Dougherty G. Investigation of Eye Lens Dose Estimate based on AAPM Report 293 in Head Computed Tomography. J Biomed Phys Eng 2021; 11:563-572. [PMID: 34722401 PMCID: PMC8546161 DOI: 10.31661/jbpe.v0i0.2104-1304] [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: 04/09/2021] [Accepted: 06/22/2021] [Indexed: 11/17/2022]
Abstract
Background: Estimation of eye lens dose is important in head computed tomography (CT) examination since the eye lens is a sensitive organ to ionizing radiation. Objective: The purpose of this study is to compare estimations of eye lens dose in head CT examinations using local size-specific dose estimate (SSDE) based on size-conversion
factors of the American Association of Physicists in Medicine (AAPM) Report No. 293 with those based on size-conversion factors of the AAPM Report No. 220. Material and Methods: This experimental study is conducted on a group of patients who had undergone nasopharyngeal CT examination. Due to the longitudinal (z-axis) dose fluctuation,
the average global SSDE and average local SSDE (i.e. particular slices where the eyes are located) were investigated. All estimates were compared to the measurement
results using thermo-luminescent dosimeters (TLDs). The estimated and measured doses were implemented for 14 patients undergoing nasopharyngeal CT examination. Results: It was found that the percentage differences of the volume CT dose index (CTDIvol), average global SSDE based on AAPM No. 220 (SSDEo,g), average local SSDE based
on AAPM No. 220 (SSDEo,l), average global SSDE based on AAPM No. 293 (SSDEn,g) and average local SSDE based on AAPM No. 293 (SSDEn,l) against the measured TLD doses
were 22.5, 21.7, 15.0, 9.3, and 2.1%, respectively. All comparisons between dose estimates and TLD measurements gave p-values less than 0.001, except for SSDEn,l (p-value = 0.566). Conclusion: SSDE based on AAPM Report No. 293 can be used to accurately estimate eye lens radiation doses by performing the calculations on a number of specific slices containing the eyes.
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Affiliation(s)
- Choirul Anam
- PhD, Department of Physics, Faculty of Sciences and Mathematics, Diponegoro University, Jl. Prof. Soedarto SH, Semarang 50275, Central Java, Indonesia
| | - Winda Kusuma Dewi
- MSc, Department of Physics, Faculty of Sciences and Mathematics, Diponegoro University, Jl. Prof. Soedarto SH, Semarang 50275, Central Java, Indonesia
| | - Masdi Masdi
- BSc, Department of Radiology, Prof. Margono Hospital, Purwokerto, Indonesia
| | - Freddy Haryanto
- PhD, Department of Physics, Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung Jl. Ganesha 10 Bandung 40132, Indonesia
| | - Toshioh Fujibuchi
- PhD, Department of Health Sciences, Faculty of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
| | - Geoff Dougherty
- PhD, Department of Applied Physics and Medical Imaging, California State University Channel Islands, Camarillo, CA 93012, USA
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Yang Y, Zhuo W, Chen B, Lu S, Zhou P, Ren W, Liu H. A new phantom developed to test the ATCM performance of chest CT scanners. JOURNAL OF RADIOLOGICAL PROTECTION : OFFICIAL JOURNAL OF THE SOCIETY FOR RADIOLOGICAL PROTECTION 2021; 41:349-359. [PMID: 33862608 DOI: 10.1088/1361-6498/abf900] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Accepted: 04/16/2021] [Indexed: 06/12/2023]
Abstract
In this study, a new ATCM phantom was developed to test the performance of the automatic tube current modulation (ATCM) of computed tomography (CT) scanners.. Based on the Chinese reference man and Monte Carlo simulations of x-ray attenuation, a more realistic ATCM phantom made of polymethyl methacrylate was developed. The phantom has a length of 20 cm, and it can be used to measure the dose profile along the central axis using 19 real-time MOSFET detectors. The image noise can be calculated slice by slice in the phantom's center. Test experiments showed that the phantom could initiate tube current modulation under different modulation levels of CT scans, and the actual effects of ATCM could be evaluated with the aid of the dose profile measurements. Using the measured dose profiles and image noise, the preferred dose can easily be identified from a choice of different modulation levels. The new phantom developed in this study can be used to test the ATCM performance of CT scanners, and is useful for further studies of the optimization of CT scan protocols with ATCM.
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Affiliation(s)
- Yang Yang
- Institute of Radiation Medicine, Fudan University, Shanghai 200032,People's Republic of China
| | - Weihai Zhuo
- Institute of Radiation Medicine, Fudan University, Shanghai 200032,People's Republic of China
| | - Bo Chen
- Institute of Radiation Medicine, Fudan University, Shanghai 200032,People's Republic of China
| | - Shunqi Lu
- Institute of Radiation Medicine, Fudan University, Shanghai 200032,People's Republic of China
| | - Pei Zhou
- Shanghai United Imaging Healthcare, Shanghai 201807, People's Republic of China
| | - Wenliang Ren
- Shanghai United Imaging Healthcare, Shanghai 201807, People's Republic of China
| | - Haikuan Liu
- Institute of Radiation Medicine, Fudan University, Shanghai 200032,People's Republic of China
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Radioprotection of eye lens using protective material in neuro cone-beam computed tomography: Estimation of dose reduction rate and image quality. Phys Med 2021; 82:192-199. [PMID: 33647602 DOI: 10.1016/j.ejmp.2021.02.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/14/2020] [Revised: 01/02/2021] [Accepted: 02/07/2021] [Indexed: 11/22/2022] Open
Abstract
PURPOSE In cerebral angiography, for diagnosis and interventional neuroradiology, cone-beam computed tomography (CBCT) scan is frequently performed for evaluating brain parenchyma, cerebral hemorrhage, and cerebral infarction. However, the patient's eye lens is more frequently exposed to excessive doses in these scans than in the previous angiography and interventional neuroradiology (INR) procedures. Hence, radioprotection for the lenses is needed. This study selects the most suitable eye lens protection material for CBCT from among nine materials by evaluating the dose reduction rate and image quality. METHODS To determine the dose reduction rate, the lens doses were measured using an anthropomorphic head phantom and a real-time dosimeter. For image quality assessment, the artifact index was calculated based on the pixel value and image noise within various regions of interest in a water phantom. RESULTS The protective materials exhibited dose reduction; however, streak artifacts were observed near the materials. The dose reduction rate and the degree of the artifact varied significantly depending on the protective material. The dose reduction rates were 14.6%, 14.2%, and 26.0% when bismuth shield: normal (bismuth shield in the shape of an eye mask), bismuth shield: separate (two separate bismuth shields), and lead goggles were used, respectively. The "separate" bismuth shield was found to be effective in dose reduction without lowering the image quality. CONCLUSION We found that bismuth shields and lead goggles are suitable protective devices for the optimal reduction of lens doses.
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Radiation dose monitoring in computed tomography: Status, options and limitations. Phys Med 2020; 79:1-15. [DOI: 10.1016/j.ejmp.2020.08.020] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/04/2020] [Revised: 07/21/2020] [Accepted: 08/19/2020] [Indexed: 02/02/2023] Open
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Ebrahiminia A, Asadinezhad M, Mohammadi F, Khoshgard K. EYE LENS DOSE OPTIMIZATION THROUGH GANTRY TILTING IN BRAIN CT SCAN: THE POTENTIAL EFFECT OF THE RADIOLOGICAL TECHNOLOGISTS' TRAINING. RADIATION PROTECTION DOSIMETRY 2020; 189:527-533. [PMID: 32472135 DOI: 10.1093/rpd/ncaa073] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2020] [Revised: 04/16/2020] [Accepted: 04/25/2020] [Indexed: 06/11/2023]
Abstract
This study was designed to evaluate the effect of the radiological technologists' training on optimising the eye lens dose in brain computed tomography (CT) examinations. The lens dose of 50 adult patients was measured using thermoluminescent dosimeters before and after technologists' training. Dose values of lenses, dose length product (DLP), volumetric CT dose index (CTDIvol) as well as image quality in terms of quantitative (contrast to noise ratio and signal to noise ratio) and subjective (artefact) parameters were compared before and after training. Lens dose values were 31.57 ± 9.84 mGy and 5.36 ± 1.53 mGy before and after training, respectively, which was reduced by ~83% (p < 0.05). The values of DLP, CTDIvol and image quality parameters were not significantly different (p > 0.05) and all images were diagnostically acceptable. Excluding the orbits from the scanning range is an efficient approach to optimize the lens dose; the training of the technologists has also a pivotal role in dose reducing.
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Affiliation(s)
- Ali Ebrahiminia
- Department of Medical Physics, School of Medicine, Guilan University of Medical Sciences, Rasht, Iran
| | - Mohsen Asadinezhad
- Department of Radiology Technology, School of Paramedical Sciences, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Fereshteh Mohammadi
- Department of Radiology Technology, School of Paramedical Sciences, Guilan University of Medical Sciences, Rasht, Iran
| | - Karim Khoshgard
- Department of Medical Physics, School of Medicine, Kermanshah University of Medical Sciences, Kermanshah, Iran
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Irdawati Y, Sutanto H, Anam C, Fujibuchi T, Zahroh F, Dougherty G. Development of a novel artifact-free eye shield based on silicon rubber-lead composition in the CT examination of the head. JOURNAL OF RADIOLOGICAL PROTECTION : OFFICIAL JOURNAL OF THE SOCIETY FOR RADIOLOGICAL PROTECTION 2019; 39:991-1005. [PMID: 31272094 DOI: 10.1088/1361-6498/ab2f3e] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The aim of this work was to develop a novel artifact-free eye shield and evaluate its effect on the dose received by the eye lens and the resulting image quality in the CT examination of the head. A new material for an eye shield was synthesised from silicon rubber (SR) and lead (Pb) using a simple method. The percentage of Pb was varied from 0 to 5% wt. An anthropomorphic head phantom was scanned with and without the SR-Pb eye shield, and compared with a tungsten paper (WP) eye shield. The distance from the eye shield and head was varied from 0 to 5 cm. The dose to the eye lens was measured using photo-luminescence detectors (PLDs). The presence of artifacts was determined by measuring CT numbers at different eye lens locations and by subtracting images with and without the eye shield. The dose reduction increases with increasing Pb content in the SR-Pb eye shield. A 5% wt SR-Pb eye shield reduced the eye lens dose by up to 50%, whereas the WP eye shield reduced the dose by up to 86%. The CT numbers in images with the SR-Pb eye shield in the regions of both eyes and the center of the head phantom is similar to those without the eye shield, indicating that there is no artifact in the resulting image. Using the WP eye shield, there is considerable artifact with the CT number increasing by up to 700% in the regions of both eyes and the center of the head. It is found that the distance between the SR-Pb eye shield and the head does not affect either the dose or the resulting images. A SR-Pb-based eye shield can be applied in clinical environments and should be placed directly above the eye surface for dose optimisation.
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Affiliation(s)
- Yulia Irdawati
- Department of Physics, Faculty of Sciences and Mathematics, Diponegoro University, Jl. Prof. Soedarto SH, Tembalang, Semarang 50275, Central Java, Indonesia
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Mohamed A, Augusteyn RC. Human lens weights with increasing age. Mol Vis 2018; 24:867-xxx. [PMID: 30820139 PMCID: PMC6382474] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2018] [Accepted: 12/29/2018] [Indexed: 11/07/2022] Open
Abstract
Purpose To evaluate the changes with age in human lens wet and dry weights. Methods All procedures were performed by the same person in the same environment. Lenses were extracted from donor eyes within a median post-mortem time of 22 h, blotted dry and weighed within 30 min, immediately placed in fixative for 1 week, and then dried at 80 °C until a constant weight was achieved. Results Wet and dry lens weights were obtained from 549 human lenses. Before age 2 years, most of the weight increases are due to a self-limiting process and can be described with logistic equations. The maximum asymptotic wet and dry weights for male lenses are 6.0 and 1.77 mg, respectively, heavier than those for female lenses. After age 3 years, male and female lens weights increase at the same linear rate. Conclusions The data support the biphasic growth model for human lenses. Male lenses are significantly larger than female lenses at the conclusion of the prenatal growth mode, but the rate of weight accrual is constant thereafter. Lens weights increase continuously throughout life and can be described with equations that incorporate terms for prenatal and postnatal growth.
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Affiliation(s)
- Ashik Mohamed
- Ophthalmic Biophysics, L V Prasad Eye Institute, Hyderabad, India,Brien Holden Vision Institute, Sydney, Australia,School of Optometry and Vision Science, University of New South Wales, Sydney, Australia
| | - Robert C. Augusteyn
- Brien Holden Vision Institute, Sydney, Australia,School of Optometry and Vision Science, University of New South Wales, Sydney, Australia,Ophthalmic Biophysics Center, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, FL
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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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