1
|
Tahiri M, Benameur Y, Mkimel M, El Baydaoui R, Mesardi MR. Feasibility of size-specific organ-dose estimates based on water equivalent diameter for common head CT examinations: a Monte Carlo study. JOURNAL OF RADIOLOGICAL PROTECTION : OFFICIAL JOURNAL OF THE SOCIETY FOR RADIOLOGICAL PROTECTION 2023; 43:021503. [PMID: 37056156 DOI: 10.1088/1361-6498/acc1f0] [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: 11/22/2022] [Accepted: 03/07/2023] [Indexed: 06/19/2023]
Abstract
Computed tomography dose index (CTDI) is an unreliable dose estimate outside of the standard CTDI phantom diameters (16 and 32 cm). Size-specific dose estimate (SSDE) for head computed tomography (CT) examination was studied in the American Association of Physicists in Medicine Report 293 to provide SSDE coefficient factors based on water equivalent diameter as size metrics. However, it is limited to one protocol and for a fully irradiated organ. This study aimed to evaluate the dependency of normalized organ dose (ND) on water equivalent diameter as a size metric in three common protocols: routine head, paranasal sinus, and temporal bone. CTDIwmeasurements were performed for outlined protocols in the Siemens Emotion 16-slice-configuration scanner. Geant4 Application for Tomographic Emission Monte Carlo simulation platform, coupled with ten GSF patient models, was used to estimate organ doses. CT scanner system was modeled. Helical CT scans were simulated using constructor scan parameters and calculated scan lengths of each patient model. Organ doses provided by simulations were normalized to CTDIvol. The water equivalent diameters (Dw) of patient models were obtained via relationships betweenDwand both effective diameter for a sample of patients' data.NDs received by fully, partially, and non-directly irradiated organs were then reported as a function ofDw. For fully irradiated organs, brain (R2> 0.92), eyes (R2> 0.88), and eye lens (R2> 0.89) correlate well withDw. For the rest of the results, a poor correlation was observed. For partially irradiated organs, the exception was scalp (R2= 0.93) in temporal bone CT. For non-directly irradiated organs, the exception was thyroid (R2> 0.90) and lungs (R2> 0.91) in routine head CT. ND correlates well in routine head CT than other protocols. For the most part, no relationship seems to exist betweenR2and scan percentage coverage. The results have revealed additional factors that may influence the ND andDwrelationship, which explains the need for more studies in the future to investigate the effect of scan conditions and organ anatomy variation.
Collapse
Affiliation(s)
- M Tahiri
- Hassan First University of Settat, High Institute of Health Sciences, Laboratory of Sciences and Health Technologies, Settat, Morocco
| | - Y Benameur
- Hassan First University of Settat, High Institute of Health Sciences, Laboratory of Sciences and Health Technologies, Settat, Morocco
| | - M Mkimel
- Hassan First University of Settat, High Institute of Health Sciences, Laboratory of Sciences and Health Technologies, Settat, Morocco
| | - R El Baydaoui
- Hassan First University of Settat, High Institute of Health Sciences, Laboratory of Sciences and Health Technologies, Settat, Morocco
| | - M R Mesardi
- Hassan First University of Settat, High Institute of Health Sciences, Laboratory of Sciences and Health Technologies, Settat, Morocco
| |
Collapse
|
2
|
Klintström E, Klintström B, Spångeus A, Sandborg M, Woisetschläger M. Trabecular bone microstructure analysis on data from a novel twin robotic X-ray device. Acta Radiol 2022; 64:1566-1572. [PMID: 36373570 PMCID: PMC10088033 DOI: 10.1177/02841851221134973] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Background Bone strength is related to both mineral density (BMD) and the bone microstructure. However, only the assessment of BMD is available in clinical routine care today. Purpose To analyze and study the correlation of trabecular bone microstructure from the imaging data of a prototype Multitom Rax system, using micro-computed tomography (CT) data as the reference method (Skyscan 1176). Material and Methods Imaging data from 14 bone samples from the human radius were analyzed regarding six bone structure parameters, i.e. trabecular nodes, separation, spacing, and thickness as well as bone volume (BV/TV) and structural model index (SMI). Results All six structure parameters showed strong correlations to micro-CT with Spearman correlation coefficients in the range of 0.83–0.93. BV/TV and SMI had a correlation >0.90. Two of the parameters, namely, separation and number, had mean values in the same range as micro-CT. The other four were either over- or underestimated. Conclusion The strong correlation between micro-CT and the clinical imaging system, indicates the possibility for analyzing bone microstructure with potential to add value in fracture assessment using the studied device in a clinical workflow.
Collapse
Affiliation(s)
- Eva Klintström
- Department of Radiology and Department of Health, Medicine and Caring Sciences, Linköping University, Linköping, Sweden
- Center for Medical Image Science and Visualization (CMIV), Linköping University, Linköping, Sweden
| | - Benjamin Klintström
- Department of Biomedical Engineering and Health Systems, KTH Royal Institute of Technology, Stockholm, Sweden
| | - Anna Spångeus
- Department of Acute Internal Medicine and Geriatrics/Department of Endocrinology, Linköping University Hospital, Linköping, Sweden
- Division of Diagnostics and Specialist Medicine, Department of Health, Medicine and Caring Sciences, Linköping University, Linköping, Sweden
| | - Michael Sandborg
- Center for Medical Image Science and Visualization (CMIV), Linköping University, Linköping, Sweden
- Department of Medical Radiation Physics, Department of Health, Medicine and Caring Sciences, Linköping University, Linköping, Sweden
| | - Mischa Woisetschläger
- Department of Radiology and Department of Health, Medicine and Caring Sciences, Linköping University, Linköping, Sweden
- Center for Medical Image Science and Visualization (CMIV), Linköping University, Linköping, Sweden
| |
Collapse
|
3
|
Abdulkadir MK, Shuaib IL, Nasirudin R, Samsudin AHZ, Osman ND. Comparison between Deff and Dw approaches for estimation of size-specific dose in paediatric CT imaging. Radiat Phys Chem Oxf Engl 1993 2022. [DOI: 10.1016/j.radphyschem.2022.110205] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
|
4
|
Zhang Z, Yan W. Spiral Computed Tomography in the Quantitative Measurement of the Adjacent Structure of the Left Atrial Appendage in Patients with Atrial Fibrillation. JOURNAL OF HEALTHCARE ENGINEERING 2021; 2021:9893358. [PMID: 34888024 PMCID: PMC8651432 DOI: 10.1155/2021/9893358] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Revised: 11/10/2021] [Accepted: 11/11/2021] [Indexed: 11/17/2022]
Abstract
Cardiac arrhythmias are common clinical cardiovascular diseases. Arrhythmias are abnormalities in the frequency, rhythm, site of origin, conduction velocity, or sequence of excitation of the cardiac impulses. Arrhythmia mechanisms include foldback, altered autonomic rhythm, and triggering mechanisms. It can cause palpitations, dizziness, black dawn, syncope, and angina pectoris and can worsen a preexisting cardiac disease, reduce the quality of life, and increase mortality. Also, by making it one of the constant challenges for the clinical cardiovascular physician, we can get more information. The study included 94 patients with atrial fibers, including 56 men and 38 women aged 57, 46, 11, and 68 years. There are 80 patients with nonatrial fibers, including 44 men and 36 women aged 56, 10, and 83 years. Those who can perform a normal coronary angiography and exclude congenital heart disease, heart valve disease, and other cardiovascular diseases. In both groups, a 256-layer spiral CT examination was performed. A pulmonary vein scanning protocol was applied to the patients with atrial fibrillation, and this can perform normal coronary angiography and exclude those with cardiovascular diseases such as congenital heart disease and valvular heart disease. The purpose of this study is to investigate the anatomical changes of the left atrium and its adjacent structures by applying the 256 nm spiral CT imaging to visualize the left atrium and its adjacent structures and by applying the MPR technology, VR technology, and simulation endoscope techniques.
Collapse
Affiliation(s)
- Zhen Zhang
- Department of Cardiovascular Medicine, Affiliated Hospital of Youjiang Medical College for Nationalities, Guangxi Baise 533000, China
| | - Wei Yan
- Department of Cardiovascular Medicine, Affiliated Hospital of Youjiang Medical College for Nationalities, Guangxi Baise 533000, China
| |
Collapse
|
5
|
Hardy AJ, Bostani M, Kim GHJ, Cagnon CH, Zankl MA, McNitt-Gray M. Evaluating Size-Specific Dose Estimate (SSDE) as an estimate of organ doses from routine CT exams derived from Monte Carlo simulations. Med Phys 2021; 48:6160-6173. [PMID: 34309040 DOI: 10.1002/mp.15128] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2021] [Revised: 06/11/2021] [Accepted: 07/09/2021] [Indexed: 11/10/2022] Open
Abstract
PURPOSE Size-specific dose estimate (SSDE) is a metric that adjusts CTDIvol to account for patient size. While not intended to be an estimate of organ dose, AAPM Report 204 notes the difference between the patient organ dose and SSDE is expected to be 10-20%. The purpose of this work was therefore to evaluate SSDE against estimates of organ dose obtained using Monte Carlo (MC) simulation techniques applied to routine exams across a wide range of patient sizes. MATERIALS AND METHODS Size-specific dose estimate was evaluated with respect to organ dose based on three routine protocols taken from Siemens scanners: (a) brain parenchyma dose in routine head exams, (b) lung and breast dose in routine chest exams, and (c) liver, kidney, and spleen dose in routine abdomen/pelvis exams. For each exam, voxelized phantom models were created from existing models or derived from clinical patient scans. For routine head exams, 15 patient models were used which consisted of 10 GSF/ICRP voxelized phantom models and five pediatric voxelized patient models created from CT image data. For all exams, the size metric used was water equivalent diameter (Dw ). For the routine chest exams, data from 161 patients were collected with a Dw range of ~16-44 cm. For the routine abdomen/pelvis exams, data from 107 patients were collected with a range of Dw from ~16 to 44 cm. Image data from these patients were segmented to generate voxelized patient models. For routine head exams, fixed tube current (FTC) was used while tube current modulation (TCM) data for body exams were extracted from raw projection data. The voxelized patient models and tube current information were used in detailed MC simulations for organ dose estimation. Organ doses from MC simulation were normalized by CTDIvol and parameterized as a function of Dw . For each patient scan, the SSDE was obtained using Dw and CTDIvol values of each scan, according to AAPM Report 220 for body scans and Report 293 for head scans. For each protocol and each patient, normalized organ doses were compared with SSDE. A one-sided tolerance limit covering 95% (P = 0.95) of the population with 95% confidence (α = 0.05) was used to assess the upper tolerance limit (TU ) between SSDE and normalized organ dose. RESULTS For head exams, the TU between SSDE and brain parenchyma dose was observed to be 12.5%. For routine chest exams, the TU between SSDE and lung and breast dose was observed to be 35.6% and 68.3%, respectively. For routine abdomen/pelvis exams, the TU between SSDE and liver, spleen, and kidney dose was observed to be 30.7%, 33.2%, and 33.0%, respectively. CONCLUSIONS The TU of 20% between SSDE and organ dose was found to be insufficient to cover 95% of the sampled population with 95% confidence for all of the organs and protocols investigated, except for brain parenchyma dose. For the routine body exams, excluding the breasts, a wider threshold difference of ~30-36% would be needed. These results are, however, specific to Siemens scanners.
Collapse
Affiliation(s)
- Anthony James Hardy
- Materials Engineering Division/Non-destructive Evaluation Group, Livermore National Laboratory, Livermore, California, USA
| | - Maryam Bostani
- Department of Radiological Sciences, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, Livermore, USA.,Physics and Biology in Medicine Graduate Program, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California, USA
| | - Grace Hyun J Kim
- Department of Radiological Sciences, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, Livermore, USA
| | - Christopher H Cagnon
- Department of Radiological Sciences, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, Livermore, USA.,Physics and Biology in Medicine Graduate Program, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California, USA
| | - Maria Agnes Zankl
- Institute of Radiation Medicine, Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH, Neuherberg, Germany
| | - Michael McNitt-Gray
- Department of Radiological Sciences, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, Livermore, USA.,Physics and Biology in Medicine Graduate Program, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California, USA
| |
Collapse
|
6
|
Bingyang B, Gang W, Zhiqing S, Li N, Zhou B, Xu S, Li D. A Preliminary Study of Personalized Head CT Scan in Pediatric Patients. Dose Response 2021; 19:1559325820985660. [PMID: 33746652 PMCID: PMC7940743 DOI: 10.1177/1559325820985660] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Revised: 11/30/2020] [Accepted: 12/13/2020] [Indexed: 01/02/2023] Open
Abstract
Objectives: In the present study, we introduced a practical approach to quantify organ-specific radiation doses and investigated whether low-dose head circumference (HC)-based protocols for non-enhanced head computed tomography (CT) could reduce organs-specific radiation dose in pediatric patients while maintaining high image quality. Methods: A total of 83 pediatric patients were prospectively recruited. Without limits to the HC, 15 patients were selected as a convention group (CON group) and underwent non-enhanced head CT scan with standard-dose protocols (tube current-time products of 250mAs). Low-dose group (LD group), including remaining 68 pediatrics were divided into 3 subgroups based on the HC: 54.1-57.0 cm for LD200mAs group (HC-based protocols of 200mAs), 51.1-54.0 cm for LD150mAs group (HC-based protocols of 150mAs), 48.1-51.0 cm for LD100mAs group (HC-based protocols of 100mAs). Subjective and objective image quality was evaluated and measured by 2 experienced radiologists. Radimetrics was used to calculate organs-specific radiation dose, including the brain, eye lenses, and salivary glands. Results: In CON250mAs group, radiation doses in the brain and salivary glands were conversely correlated with HC, and pediatric patients with smaller HC received higher organs-specific radiation dose. Reducing tube current-time product from 250 to 100mAs could significantly reduce the organ-specific radiation dose. The subjective image quality score ≥ 3.0 is acceptable for diagnosis purposes. The signal to noise ratio (SNR) and the contrast to noise ratio (CNR) of bilateral thalamus and centrum semiovale in 3 LD subgroups were not statistically different compared with the CON group. Conclusion: Our research indicated that low-dose HC-based protocols of non-enhanced head CT scan can evidently reduce the organ-specific radiation doses, while maintaining high image quality. HC can serve as a vital tool to guide personalized low-dose head CT scan for pediatric patients.
Collapse
Affiliation(s)
| | - Wang Gang
- Third Hospital of Jilin University, Changchun, China
| | - Shao Zhiqing
- Jilin University First Hospital, Changchun, China
| | - Nan Li
- Jilin University First Hospital, Changchun, China
| | - BoXu Zhou
- Jilin University First Hospital, Changchun, China
| | - ShuJia Xu
- Jilin University First Hospital, Changchun, China
| | - Dan Li
- Jilin University First Hospital, Changchun, China
| |
Collapse
|
7
|
Hardy AJ, Bostani M, Angel E, Cagnon C, Sechopoulos I, McNitt-Gray MF. Reference dataset for benchmarking fetal doses derived from Monte Carlo simulations of CT exams. Med Phys 2020; 48:523-532. [PMID: 33128259 DOI: 10.1002/mp.14573] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2020] [Revised: 07/26/2020] [Accepted: 10/06/2020] [Indexed: 11/09/2022] Open
Abstract
PURPOSE Task Group Report 195 of the American Association of Physicists in Medicine contains reference datasets for the direct comparison of results among different Monte Carlo (MC) simulation tools for various aspects of imaging research that employs ionizing radiation. While useful for comparing and validating MC codes, that effort did not provide the information needed to compare absolute dose estimates from CT exams. Therefore, the purpose of this work is to extend those efforts by providing a reference dataset for benchmarking fetal dose derived from MC simulations of clinical CT exams. ACQUISITION AND VALIDATION METHODS The reference dataset contains the four necessary elements for validating MC engines for CT dosimetry: (a) physical characteristics of the CT scanner, (b) patient information, (c) exam specifications, and (d) fetal dose results from previously validated and published MC simulations methods in tabular form. Scanner characteristics include non-proprietary descriptions of equivalent source cumulative distribution function (CDF) spectra and bowtie filtration profiles, as well as scanner geometry information. Additionally, for the MCNPX MC engine, normalization factors are provided to convert raw simulation results to absolute dose in mGy. The patient information is based on a set of publicly available fetal dose models and includes de-identified image data; voxelized MC input files with fetus, uterus, and gestational sac identified; and patient size metrics in the form of water equivalent diameter (Dw ) z-axis distributions from a simulated topogram (Dw,topo ) and from the image data (Dw,image ). Exam characteristics include CT scan start and stop angles and table and patient locations, helical pitch, nominal collimation and measured beam width, and gantry rotation time for each simulation. For simulations involving estimating doses from exams using tube current modulation (TCM), a realistic TCM scheme is presented that is estimated based upon a validated method. (d) Absolute and CTDIvol -normalized fetal dose results for both TCM and FTC simulations are given for each patient model under each scan scenario. DATA FORMAT AND USAGE NOTES Equivalent source CDFs and bowtie filtration profiles are available in text files. Image data are available in DICOM format. Voxelized models are represented by a header followed by a list of integers in a text file representing a three-dimensional model of the patient. Size distribution metrics are also given in text files. Results of absolute and normalized fetal dose with associated MC error estimates are presented in tabular form in an Excel spreadsheet. All data are stored on Zenodo and are publicly accessible using the following link: https://zenodo.org/record/3959512. POTENTIAL APPLICATIONS Similar to the work of AAPM Report 195, this work provides a set of reference data for benchmarking fetal dose estimates from clinical CT exams. This provides researchers with an opportunity to compare MC simulation results to a set of published reference data as part of their efforts to validate absolute and normalized fetal dose estimates. This could also be used as a basis for comparison to other non-MC approaches, such as deterministic approaches, or to commercial packages that provide estimates of fetal doses from clinical CT exams.
Collapse
Affiliation(s)
- Anthony J Hardy
- Livermore National Laboratory, Materials Engineering Division/Non-destructive Evaluation Group, Livermore, CA, 94550, USA
| | - Maryam Bostani
- Department of Radiology, David Geffen School of Medicine, University of California, Los Angeles, Livermore, CA, 90024, USA.,Physics and Biology in Medicine Graduate Program, David Geffen School of Medicine, University of California, Los Angeles, CA, 90024, USA
| | - Erin Angel
- Canon Medical Systems USA, Inc, Tustin, CA, 92780, USA
| | - Chris Cagnon
- Department of Radiology, David Geffen School of Medicine, University of California, Los Angeles, Livermore, CA, 90024, USA.,Physics and Biology in Medicine Graduate Program, David Geffen School of Medicine, University of California, Los Angeles, CA, 90024, USA
| | - Ioannis Sechopoulos
- Department of Medical Imaging, Radboud University Medical Center, Geert Grooteplein 10, Nijmegen, 6525 GA, The Netherlands.,Dutch Expert Center for Screening (LRCB), Wijchenseweg 101, Nijmegen, 6538 SW, The Netherlands
| | - Michael F McNitt-Gray
- Department of Radiology, David Geffen School of Medicine, University of California, Los Angeles, Livermore, CA, 90024, USA.,Physics and Biology in Medicine Graduate Program, David Geffen School of Medicine, University of California, Los Angeles, CA, 90024, USA
| |
Collapse
|
8
|
Garzón WJ, Aldana DFA, Cassola VF. PATIENT-SPECIFIC ORGAN DOSES FROM PEDIATRIC HEAD CT EXAMINATIONS. RADIATION PROTECTION DOSIMETRY 2020; 191:1-8. [PMID: 32984906 DOI: 10.1093/rpd/ncaa126] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Revised: 08/06/2020] [Accepted: 08/24/2020] [Indexed: 06/11/2023]
Abstract
The aim of this work was to estimate patient's organ absorbed doses from pediatric helical head computed tomography (CT) examinations using the Size-Specific Dose Estimate (SSDE) methodology and to determine organ dose to SSDE conversion coefficients for clinical routine. Patient-specific organ and tissue absorbed doses from 139 Head CT scans performed in pediatric patients from 0 to 15 years old in a Public Hospital in Tunja, Colombia were estimated. The calculations were made through Monte Carlo simulations, based on patient-specific information, dosimetric CT quantities (CTDIvol, DLP) and age-specific computational human phantoms matched to patients on the basis of gender and size. SSDE showed to be a good quantity for estimate patient-specific organ doses from pediatric head CT examinations when appropriate phantom's attenuation-based size metrics are chosen to match for any patient size. Strong correlations between absorbed dose and SSDE were found for skin (R2 = 0.99), brain (R2 = 0.98) and eyes (R2 = 0.97), respectively. Besides, a good correlation between SSDE and absorbed dose to the red bone marrow (tissue extended outside the scan coverage) was observed (R2 = 0.94). SSDE-to-organ-dose conversion coefficients obtained in this study provide a practical way to estimate patient-specific organ head CT doses.
Collapse
Affiliation(s)
- W J Garzón
- Physics Department, Pedagogical and Technological University of Colombia, Avenida Central del Norte 39-115, 150003 Tunja, Colombia
| | - D F A Aldana
- Physics Department, Pedagogical and Technological University of Colombia, Avenida Central del Norte 39-115, 150003 Tunja, Colombia
| | - V F Cassola
- Department of Nuclear Energy, Federal University of Pernambuco, Avenida Professor Luiz Freire 1000 CEP 50740-540, Recife, Pernambuco, Brazil
| |
Collapse
|