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Kim Y, Lee S, Jo G, Kwon A, Kang J, Kim J, Huh K, Yi W, Heo M, Choi S. Comparative analysis of clinical image evaluation charts for panoramic radiography. Oral Radiol 2024; 40:520-529. [PMID: 38977537 PMCID: PMC11379777 DOI: 10.1007/s11282-024-00765-3] [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: 03/27/2024] [Accepted: 06/30/2024] [Indexed: 07/10/2024]
Abstract
OBJECTIVE To compare and analyze professional (P chart) and simple (S chart) clinical image evaluation charts for evaluating panoramic radiograph image quality. METHODS Ten evaluators assessed 285 clinical panoramic radiograph images. The evaluators were divided into oral and maxillofacial radiologists (OMFR, n = 5) and general dentist (dentists not specializing in oral and maxillofacial radiology, G, n = 5) groups. For image evaluation, P and S charts provided by the Korean Academy of Oral and Maxillofacial Radiology were used. Scores of items for each evaluation chart were used to compare the reliability, correlation, evaluation scores, evaluation time, and preference, and statistical analyses were performed using IBM SPSS Statistics. RESULTS The S chart showed similar levels of evaluation scores at shorter evaluation time, as compared to the P chart. In the results for each evaluation chart, all analyzed correlations were statistically significant. Total score, image density/contrast/sharpness, and overall image quality items showed a very high positive correlation in the P chart. While the overall range of correlation coefficients was relatively lower in the S chart than the P chart, the same items showed high correlation coefficients. In the preference evaluation, both the professional and generalist groups preferred the S chart. CONCLUSIONS A comparative analysis with the P chart, revisions, and upgrades are needed for the S chart items that showed low correlations in this study, such as artifacts, coverage area, and patient movement.
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Affiliation(s)
- Yeonhee Kim
- Department of Oral and Maxillofacial Radiology and Dental Research Institute, School of Dentistry, Seoul National University, Seoul, South Korea
| | - Samsun Lee
- Department of Oral and Maxillofacial Radiology and Dental Research Institute, School of Dentistry, Seoul National University, Seoul, South Korea.
| | - Gyudong Jo
- Department of Oral and Maxillofacial Radiology and Dental Research Institute, School of Dentistry, Seoul National University, Seoul, South Korea
| | - Ahyoung Kwon
- Department of Oral and Maxillofacial Radiology and Dental Research Institute, School of Dentistry, Seoul National University, Seoul, South Korea
| | - Juhee Kang
- Department of Oral and Maxillofacial Radiology and Dental Research Institute, School of Dentistry, Seoul National University, Seoul, South Korea
| | - Joeun Kim
- Department of Oral and Maxillofacial Radiology and Dental Research Institute, School of Dentistry, Seoul National University, Seoul, South Korea
| | - Kyunghoe Huh
- Department of Oral and Maxillofacial Radiology and Dental Research Institute, School of Dentistry, Seoul National University, Seoul, South Korea
| | - Wonjin Yi
- Department of Oral and Maxillofacial Radiology and Dental Research Institute, School of Dentistry, Seoul National University, Seoul, South Korea
| | - Minsuk Heo
- Department of Oral and Maxillofacial Radiology and Dental Research Institute, School of Dentistry, Seoul National University, Seoul, South Korea
| | - Soonchul Choi
- Department of Oral and Maxillofacial Radiology and Dental Research Institute, School of Dentistry, Seoul National University, Seoul, South Korea
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Koivisto J, Wolff J, Pauwels R, Kaasalainen T, Suomalainen A, Stoor P, Horelli J, Suojanen J. Assessment of cone-beam CT technical image quality indicators and radiation dose for optimal STL model used in visual surgical planning. Dentomaxillofac Radiol 2024; 53:423-433. [PMID: 38913866 PMCID: PMC11358642 DOI: 10.1093/dmfr/twae026] [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: 02/05/2024] [Revised: 04/15/2024] [Accepted: 06/12/2024] [Indexed: 06/26/2024] Open
Abstract
OBJECTIVES The aim of this study was to identify cone-beam computed tomography (CBCT) protocols that offer an optimal balance between effective dose (ED) and 3D model for orthognathic virtual surgery planning, using CT as a reference, and to assess whether such protocols can be defined based on technical image quality metrics. METHODS Eleven CBCT (VISO G7, Planmeca Oy, Helsinki, Finland) scan protocols were selected out of 32 candidate protocols, based on ED and technical image quality measurements. Next, an anthropomorphic RANDO SK150 phantom was scanned using these 11 CBCT protocols and 2 CT scanners for bone quantity assessments. The resulting DICOM (Digital Imaging and Communications in Medicine) files were converted into Standard Tessellation Language (STL) models that were used for bone volume and area measurements in the predefined orbital region to assess the validity of each CBCT protocol for virtual surgical planning. RESULTS The highest CBCT bone volume and area of the STL models were obtained using normal dose protocol (F2) and ultra-low dose protocol (J13), which resulted in 48% and 96% of the mean STL bone volume and 48% and 95% of the bone area measured on CT scanners, respectively. CONCLUSIONS The normal dose CBCT protocol "F2" offered optimal bone area and volume balance for STL. The optimal CBCT protocol can be defined using contrast-to-noise ratio and modulation transfer function values that were similar to those of the reference CT scanners'. CBCT scanners with selected protocols can offer a viable alternative to CT scanners for acquiring STL models for virtual surgical planning at a lower effective dose.
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Affiliation(s)
- Juha Koivisto
- Department of Physics, University of Helsinki, 00560 Helsinki, Finland
| | - Jan Wolff
- Department of Dentistry and Oral Health, Section of Oral and Maxillofacial Surgery and Oral Pathology, Aarhus University, DK-8000 Aarhus C, Denmark
| | - Ruben Pauwels
- Department of Dentistry and Oral Health, Aarhus University, DK-8000 Aarhus C, Denmark
| | - Touko Kaasalainen
- HUS Diagnostic Center, Radiology, University of Helsinki, Helsinki, P.O. BOX 224, FI-00029, Finland
| | - Anni Suomalainen
- HUS Diagnostic Center, Radiology, University of Helsinki, Helsinki, P.O. BOX 224, FI-00029, Finland
- Helsinki University Hospital, Helsinki, P.O. Box 63 00014, Finland
| | - Patricia Stoor
- Helsinki University Hospital, Helsinki, P.O. Box 63 00014, Finland
- Department of Oral and Maxillofacial Diseases, Head and Neck Center, University of Helsinki, P.O. BOX 41, FI-00014, Finland
| | | | - Juho Suojanen
- Helsinki University Hospital, Helsinki, P.O. Box 63 00014, Finland
- Department of Oral and Maxillofacial Surgery, Päijät-Häme Joint Authority for Health and Wellbeing, Lahti, P.O. BOX 202, FIN-15101, Finland
- Cleft Palate and Craniofacial Centre, Department of Plastic Surgery, University of Helsinki, Helsinki, P.O. BOX 281 FI-00029, Finland
- Faculty of Medicine, Clinicum, University of Helsinki, P.O. BOX 63, FI-00014, Finland
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Yeom HG, Kim JE, Huh KH, Yi WJ, Heo MS, Lee SS. Development and validation of a clinical phantom reproducing various lesions for oral and maxillofacial radiology research. Imaging Sci Dent 2023; 53:345-353. [PMID: 38174032 PMCID: PMC10761291 DOI: 10.5624/isd.20230129] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2023] [Revised: 08/11/2023] [Accepted: 08/14/2023] [Indexed: 01/05/2024] Open
Abstract
Purpose The objective of this study was to propose a method for developing a clinical phantom to reproduce various diseases that are clinically prevalent in the field of dentistry. This could facilitate diverse clinical research without unnecessarily exposing patients to radiation. Material and Methods This study utilized a single dry skull, which was visually and radiographically examined to evaluate its condition. Existing lesions on the dry skull were preserved, and other relevant lesions were artificially created as necessary. These lesions were then documented using intraoral radiography and cone-beam computed tomography. Once all pre-existing and reproduced lesions were confirmed by the consensus of 2 oral and maxillofacial radiologists, the skull was embedded in a soft tissue substitute. To validate the process, cone-beam computed tomography scans and panoramic radiographs were obtained of the fabricated phantom. All acquired images were subsequently evaluated. Results Most lesions could be identified on panoramic radiographs, although some sialoliths and cracked teeth were confirmed only through cone-beam computed tomographic images. A small gap was observed between the epoxy resin and the bone structures. However, 2 oral and maxillofacial radiologists agreed that this space did not meaningfully impact the interpretation process. Conclusion The newly developed phantom has potential for use as a standardized phantom within the dental field. It may be utilized for a variety of imaging studies, not only for optimization purposes, but also for addressing other experimental issues related to both 2- and 3-dimensional diagnostic radiography.
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Affiliation(s)
- Han-Gyeol Yeom
- Department of Oral and Maxillofacial Radiology and Dental Research Institute, School of Dentistry, Seoul National University, Seoul, Korea
- Department of Oral and Maxillofacial Radiology, School of Dentistry, Wonkwang University, Iksan, Korea
| | - Jo-Eun Kim
- Department of Oral and Maxillofacial Radiology and Dental Research Institute, School of Dentistry, Seoul National University, Seoul, Korea
| | - Kyung-Hoe Huh
- Department of Oral and Maxillofacial Radiology and Dental Research Institute, School of Dentistry, Seoul National University, Seoul, Korea
| | - Won-Jin Yi
- Department of Oral and Maxillofacial Radiology and Dental Research Institute, School of Dentistry, Seoul National University, Seoul, Korea
| | - Min-Suk Heo
- Department of Oral and Maxillofacial Radiology and Dental Research Institute, School of Dentistry, Seoul National University, Seoul, Korea
| | - Sam-Sun Lee
- Department of Oral and Maxillofacial Radiology and Dental Research Institute, School of Dentistry, Seoul National University, Seoul, Korea
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Kang SR, Shin W, Yang S, Kim JE, Huh KH, Lee SS, Heo MS, Yi WJ. Structure-preserving quality improvement of cone beam CT images using contrastive learning. Comput Biol Med 2023; 158:106803. [PMID: 36989743 DOI: 10.1016/j.compbiomed.2023.106803] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2022] [Revised: 02/13/2023] [Accepted: 03/20/2023] [Indexed: 03/29/2023]
Abstract
Cone-beam CT (CBCT) is widely used in dental clinics but exhibits limitations in assessing soft tissue pathology because of its lack of contrast resolution and low Hounsfield Units (HU) quantification accuracy. We aimed to increase the image quality and HU accuracy of CBCTs while preserving anatomical structures. We generated CT-like images from CBCT images using a patchwise contrastive learning-based GAN model. Our model was trained on unpaired CT and CBCT datasets with the novel combination of losses and the feature extractor pretrained on our training dataset. We evaluated the quality of the images generated by our model in terms of Fréchet inception distance (FID), peak signal-to-noise ratio (PSNR), mean absolute error (MAE), and root mean square error (RMSE). Additionally, the structure preservation performance was assessed by the structure score. As a result, the generated CT-like images by our model were significantly superior to those generated by various baseline models in terms of FID, PSNR, MAE, RMSE, and structure score. Therefore, we demonstrated that our model provided the complementary benefits of preserving the anatomical structures of the input CBCT images and improving the image quality to be similar to those of CT images.
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Doriguêtto PVT, de Almeida D, de Lima CO, Lopes RT, Devito KL. Assessment of marginal gaps and image quality of crowns made of two different restorative materials: An in vitro study using CBCT images. J Dent Res Dent Clin Dent Prospects 2022; 16:243-250. [PMID: 37560496 PMCID: PMC10407872 DOI: 10.34172/joddd.2022.039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2022] [Accepted: 10/18/2022] [Indexed: 08/11/2023] Open
Abstract
Background The present study assessed the quality of images and the presence of marginal gaps on cone-beam computed tomography (CBCT) images of teeth restored with all-ceramic and metal-ceramic crowns and compared the gap sizes observed on CBCT images with those obtained on micro-CT images. Methods Thirty teeth restored with metal-ceramic and all-ceramic crowns, properly adapted and with gaps of 0.30 and 0.50 mm, were submitted to micro-CT and CBCT scans. Linear measurements corresponding to the marginal gap (MG) and the absolute marginal discrepancy (AMD) were obtained. The objective assessment of the quality of CBCT images was performed using the contrast-to-noise ratio (CNR), and the subjective assessment was defined by the diagnoses made by five examiners regarding the presence or absence of gaps. Results The measurements were always higher for CBCT, with a significant difference regarding AMD. No significant difference in image quality was observed using CNR between the crowns tested. Low accuracy and sensitivity values could be observed for both crowns. Conclusion Marginal mismatch measures were overestimated in CBCT images. No difference in image quality was observed between the crowns. The correct diagnosis of gaps was considered low, irrespective of crown type and gap size.
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Affiliation(s)
| | - Daniela de Almeida
- School of Dentistry, Federal University of Juiz de Fora, Juiz de Fora, Minas Gerais, Brazil
| | | | - Ricardo Tadeu Lopes
- Nuclear Engineering Department, COPPE, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Karina Lopes Devito
- Department of Dental Clinic, School of Dentistry, Federal University of Juiz de Fora, Juiz de Fora, Minas Gerais, Brazil
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The Effects of Additional Filtration on Image Quality and Radiation Dose in Cone Beam CT: An In Vivo Preliminary Investigation. BIOMED RESEARCH INTERNATIONAL 2022; 2022:7031269. [PMID: 35281593 PMCID: PMC8906961 DOI: 10.1155/2022/7031269] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/22/2021] [Accepted: 02/03/2022] [Indexed: 11/18/2022]
Abstract
Purpose. The aim of this study was to investigate the effect of reduced radiation doses on the image quality of cone-beam computed tomography scans and the suitability of such imaging for orthodontics, oral surgery, dental implantology, periodontology, and endodontology. Materials and Methods. Cone-beam computed tomography scans of a live patient were performed using seven attenuation filters with increased thickness to decrease the effective radiation dose from 22.4 to 1.8 μSv, and the effects of different radiation doses on image quality were further analysed. Quantitative image quality was calculated using dedicated measures, such as signal and contrast-to-noise ratio and sharpness. A panel of five certified raters assessed the cone-beam computed tomography scans qualitatively. Nine anatomical structures relevant to dentistry were identified, and the overall acceptance was assessed. Results. Linear reduction of the effective radiation dose had a nonlinear effect on image quality. A 5-fold reduction in the effective dose led to acceptable quantitative and qualitative image quality measures, and the identification rate of dental anatomical structures was 80% or greater. The use of less than 40% of the reference dose was unacceptable for all dental specialties. Conclusions. The ideal radiation dose for specific diagnostic requirements remains a patient-related and specialty-related decision that must be made on an individual basis. Based on the results of this study, it is possible to reduce exposure in selected patients, and at the same time obtain sufficient quality of images for clinical purposes.
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Yong TH, Yang S, Lee SJ, Park C, Kim JE, Huh KH, Lee SS, Heo MS, Yi WJ. QCBCT-NET for direct measurement of bone mineral density from quantitative cone-beam CT: a human skull phantom study. Sci Rep 2021; 11:15083. [PMID: 34301984 PMCID: PMC8302740 DOI: 10.1038/s41598-021-94359-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2021] [Accepted: 07/12/2021] [Indexed: 02/07/2023] Open
Abstract
The purpose of this study was to directly and quantitatively measure BMD from Cone-beam CT (CBCT) images by enhancing the linearity and uniformity of the bone intensities based on a hybrid deep-learning model (QCBCT-NET) of combining the generative adversarial network (Cycle-GAN) and U-Net, and to compare the bone images enhanced by the QCBCT-NET with those by Cycle-GAN and U-Net. We used two phantoms of human skulls encased in acrylic, one for the training and validation datasets, and the other for the test dataset. We proposed the QCBCT-NET consisting of Cycle-GAN with residual blocks and a multi-channel U-Net using paired training data of quantitative CT (QCT) and CBCT images. The BMD images produced by QCBCT-NET significantly outperformed the images produced by the Cycle-GAN or the U-Net in mean absolute difference (MAD), peak signal to noise ratio (PSNR), normalized cross-correlation (NCC), structural similarity (SSIM), and linearity when compared to the original QCT image. The QCBCT-NET improved the contrast of the bone images by reflecting the original BMD distribution of the QCT image locally using the Cycle-GAN, and also spatial uniformity of the bone images by globally suppressing image artifacts and noise using the two-channel U-Net. The QCBCT-NET substantially enhanced the linearity, uniformity, and contrast as well as the anatomical and quantitative accuracy of the bone images, and demonstrated more accuracy than the Cycle-GAN and the U-Net for quantitatively measuring BMD in CBCT.
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Affiliation(s)
- Tae-Hoon Yong
- grid.31501.360000 0004 0470 5905Department of Applied Bioengineering, Graduate School of Convergence Science and Technology, Seoul National University, Seoul, Korea
| | - Su Yang
- grid.31501.360000 0004 0470 5905Department of Applied Bioengineering, Graduate School of Convergence Science and Technology, Seoul National University, Seoul, Korea
| | - Sang-Jeong Lee
- grid.31501.360000 0004 0470 5905Dental Research Institute, Seoul National University, Seoul, Korea
| | - Chansoo Park
- grid.31501.360000 0004 0470 5905Department of Oral and Maxillofacial Radiology, School of Dentistry, Seoul National University, Seoul, Korea
| | - Jo-Eun Kim
- grid.459982.b0000 0004 0647 7483Department of Oral and Maxillofacial Radiology, Seoul National University Dental Hospital, Seoul, Korea
| | - Kyung-Hoe Huh
- grid.31501.360000 0004 0470 5905Department of Oral and Maxillofacial Radiology and Dental Research Institute, School of Dentistry, Seoul National University, Seoul, Korea
| | - Sam-Sun Lee
- grid.31501.360000 0004 0470 5905Department of Oral and Maxillofacial Radiology and Dental Research Institute, School of Dentistry, Seoul National University, Seoul, Korea
| | - Min-Suk Heo
- grid.31501.360000 0004 0470 5905Department of Oral and Maxillofacial Radiology and Dental Research Institute, School of Dentistry, Seoul National University, Seoul, Korea
| | - Won-Jin Yi
- grid.31501.360000 0004 0470 5905Department of Applied Bioengineering, Graduate School of Convergence Science and Technology, Seoul National University, Seoul, Korea ,grid.31501.360000 0004 0470 5905Department of Oral and Maxillofacial Radiology and Dental Research Institute, School of Dentistry, Seoul National University, Seoul, Korea
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Koivisto J, van Eijnatten M, Ludlow J, Kiljunen T, Shi X, Wolff J. Comparative dosimetry of radiography device, MSCT device and two CBCT devices in the elbow region. J Appl Clin Med Phys 2021; 22:128-138. [PMID: 33811787 PMCID: PMC8130242 DOI: 10.1002/acm2.13245] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2019] [Revised: 03/09/2021] [Accepted: 03/17/2021] [Indexed: 12/27/2022] Open
Abstract
The aim of the study was to estimate and to compare effective doses in the elbow region resulting from four different x-ray imaging modalities. Absorbed organ doses were measured using 11 metal oxide field effect transistor (MOSFET) dosimeters that were placed in a custom-made anthropomorphic elbow RANDO phantom. Examinations were performed using Shimadzu FH-21 HR radiography device, Siemens Sensation Open 24-slice MSCT-device, NewTom 5G CBCT device, and Planmed Verity CBCT device, and the effective doses were calculated according to ICRP 103 recommendations. The effective dose for the conventional radiographic device was 1.5 µSv. The effective dose for the NewTom 5G CBCT ranged between 2.0 and 6.7 µSv, for the Planmed Verity CBCT device 2.6 µSv and for the Siemens Sensation MSCT device 37.4 µSv. Compared with conventional 2D radiography, this study demonstrated a 1.4-4.6 fold increase in effective dose for CBCT and 25-fold dose for standard MSCT protocols. When compared with 3D CBCT protocols, the study showed a 6-19 fold increase in effective dose using a standard MSCT protocol. CBCT devices offer a feasible low-dose alternative for elbow 3D imaging when compared to MSCT.
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Affiliation(s)
- Juha Koivisto
- Department of PhysicsUniversity of HelsinkiHelsinkiFinland
| | - Maureen van Eijnatten
- Department of Oral and Maxillofacial Surgery/Oral PathologyVU University Medical CenterAmsterdamThe Netherlands
| | - John Ludlow
- University of North CarolinaAdams School of DentistryChapel HillNCUSA
| | | | - Xie‐Qi Shi
- Section of Oral Maxillofacial RadiologyDepartment of Clinical DentistryFaculty of Medicine and DentistryUniversity of BergenBergenNorway
| | - Jan Wolff
- Department of Oral Maxillofacial SurgeryUniversity Medical Center Hamburg‐EppendorfHamburgGermany
- Division of Regenerative Orofacial MedicineHamburgGermany
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Correlation of objective image quality and working length measurements in different CBCT machines: An ex vivo study. Sci Rep 2020; 10:19414. [PMID: 33173072 PMCID: PMC7655868 DOI: 10.1038/s41598-020-76424-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Accepted: 10/12/2020] [Indexed: 12/03/2022] Open
Abstract
To investigate potential correlations between objective CBCT image parameters and accuracy in endodontic working length determination ex vivo. Contrast-to-noise ratio (CNR) and spatial resolution (SR) as fundamental objective image parameters were examined using specific phantoms in seven different CBCT machines. Seven experienced observers were instructed and calibrated. The order of the CBCTs was randomized for each observer and observation. To assess intra-operator reproducibility, the procedure was repeated within six weeks with a randomized order of CBCT images. Multivariate analysis (MANOVA) did not reveal any influence of the combined image quality factors CNR and SR on measurement accuracy. Inter-operator reproducibility as assessed between the two observations was poor, with a mean intra-class correlation (ICC) of 0.48 (95%-CI 0.38, 0.59) for observation No. 1. and 0.40 (95%-CI 0.30, 0.51) for observation No. 2. Intra-operator reproducibility pooled over all observers between both observations was only moderate, with a mean ICC of 0.58 (95%-CI 0.52 to 0.64). Within the limitations of the study, objective image quality measures and exposure parameters seem not to have a significant influence on accuracy in determining endodontic root canal lengths in CBCT scans. The main factor of variance is the observer.
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Wang MF, Xie X, Li G, Zhang Z. Relationship between CNR and visibility of anatomical structures of cone-beam computed tomography images under different exposure parameters. Dentomaxillofac Radiol 2020; 49:20190336. [PMID: 32045279 PMCID: PMC7333469 DOI: 10.1259/dmfr.20190336] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2019] [Revised: 02/01/2020] [Accepted: 02/05/2020] [Indexed: 12/26/2022] Open
Abstract
OBJECTIVES The purpose of this study was to investigate the image quality of cone beam CT (CBCT) under different exposure parameters and the relationship between contrast-to-noise and visibility of eight anatomical structures. METHODS CBCT images for the evaluation of subjective image quality were acquired on an anthropopathic phantom containing a human skeleton embedded in soft tissue equivalent materials using 25 exposure protocols. Visibility of eight anatomical structures was evaluated by five independent observers. Using the SEDENTEXCT IQ Image Quality phantom, the contrast-to-noise ratio (CNR) was calculated by ImageJ software. RESULTS A reduction on the visibility of anatomical structures was seen under lower exposure parameters. However, for 84% of the protocols, visibility of anatomical structures remained acceptable even under some lower parameter settings. As CNR increased, the visibility of anatomical structures also increased correspondingly. A change point could be found in the CNR interval 29.42-36.51 after which the visibility of anatomical structures no longer increases with the increase of CNR. CONCLUSIONS Although CNR decrease under a lower exposure parameter, the image quality often remained acceptable at exposure levels below the manufacture's recommended settings. It is possible to standardize subjective image quality by physical factors. Currently, it is not possible to predetermine a change point CNR value due to different CBCT machine and variation of diagnostic tasks.
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Affiliation(s)
- Miss Fei Wang
- Department of oral and maxillofacial radiology, Stomatological Hospital, Peking University, Beijing, China
| | - Xiaoyan Xie
- Department of oral and maxillofacial radiology, Stomatological Hospital, Peking University, Beijing, China
| | - Gang Li
- Department of oral and maxillofacial radiology, Stomatological Hospital, Peking University, Beijing, China
| | - Zuyan Zhang
- Department of oral and maxillofacial radiology, Stomatological Hospital, Peking University, Beijing, China
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Choi JW. Factors affecting modulation transfer function measurements in cone-beam computed tomographic images. Imaging Sci Dent 2019; 49:131-137. [PMID: 31281790 PMCID: PMC6597368 DOI: 10.5624/isd.2019.49.2.131] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2019] [Revised: 03/28/2019] [Accepted: 04/04/2019] [Indexed: 11/18/2022] Open
Abstract
Purpose This study was designed to investigate the effects of voxel size, the oversampling technique, and the direction and area of measurement on modulation transfer function (MTF) values to identify the optimal method of MTF measurement. Materials and Methods Images of the wire inserts of the SedentexCT IQ phantom were acquired, and MTF values were calculated under different conditions (voxel size of 0.1, 0.2, and 0.3 mm; 5 oversampling techniques; simulated pixel location errors; and different directions and areas of measurement). The differences in the MTF values across various conditions were evaluated. Results The MTF 10 values showed smaller standard deviations than the MTF 50 values. Stable and accurate MTF values were obtained in the 0.1-mm voxel images. In the 0.3-mm voxel images, oversampling techniques of 11 lines or more did not show significant differences in MTF values depending on the presence of simulated location errors. MTF 10 values showed significant differences according to the direction and area of the measurement. Conclusion To measure more accurate and stable MTF values, it is better to measure MTF 10 values in small-voxel images. In large-voxel images, the proper oversampling technique is required. MTF values from the radial and tangential directions may be different, and MTF values vary depending on the measured area.
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Affiliation(s)
- Jin-Woo Choi
- Department of Oral and Maxillofacial Radiology, Dankook University College of Dentistry, Cheonan, Korea
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Park HN, Min CK, Kim KA, Koh KJ. Optimization of exposure parameters and relationship between subjective and technical image quality in cone-beam computed tomography. Imaging Sci Dent 2019; 49:139-151. [PMID: 31281791 PMCID: PMC6597377 DOI: 10.5624/isd.2019.49.2.139] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2019] [Revised: 04/10/2019] [Accepted: 04/16/2019] [Indexed: 11/18/2022] Open
Abstract
Purpose This study was performed to investigate the effect of exposure parameters on image quality obtained using a cone-beam computed tomography (CBCT) scanner and the relationship between physical factors and clinical image quality depending on the diagnostic task. Materials and Methods CBCT images of a SedentexCT IQ phantom and a real skull phantom were obtained under different combinations of tube voltage and tube current (Alphard 3030 CBCT scanner, 78–90 kVp and 2–8 mA). The images obtained using a SedentexCT IQ phantom were analyzed technically, and the physical factors of image noise, contrast resolution, spatial resolution, and metal artifacts were measured. The images obtained using a real skull phantom were evaluated for each diagnostic task by 6 oral and maxillofacial radiologists, and each setting was classified as acceptable or unacceptable based on those evaluations. A statistical analysis of the relationships of exposure parameters and physical factors with observer scores was conducted. Results For periapical diagnosis and implant planning, the tube current of the acceptable images was significantly higher than that of the unacceptable images. Image noise, the contrast-to-noise ratio (CNR), the line pair chart on the Z axis, and modulation transfer function (MTF) values showed statistically significant differences between the acceptable and unacceptable image groups. The cut-off values obtained using receiver operating characteristic curves for CNR and MTF 10 were useful for determining acceptability. Conclusion Tube current had a major influence on clinical image quality. CNR and MTF 10 were useful physical factors that showed significantly associations with clinical image quality.
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Affiliation(s)
- Ha-Na Park
- Department of Oral and Maxillofacial Radiology, School of Dentistry, Chonbuk National University, Jeonju, Korea
| | - Chang-Ki Min
- Department of Oral and Maxillofacial Radiology, School of Dentistry, Chonbuk National University, Jeonju, Korea
| | - Kyoung-A Kim
- Department of Oral and Maxillofacial Radiology, School of Dentistry, Chonbuk National University, Jeonju, Korea
| | - Kwang-Joon Koh
- Department of Oral and Maxillofacial Radiology, School of Dentistry, Chonbuk National University, Jeonju, Korea
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Brasil DM, Pauwels R, Coucke W, Haiter-Neto F, Jacobs R. Image quality optimization of narrow detector dental computed tomography for paediatric patients. Dentomaxillofac Radiol 2019; 48:20190032. [PMID: 30864834 DOI: 10.1259/dmfr.20190032] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
OBJECTIVES Dental CBCT exposure parameters should be optimized according to patient-specific indications, mainly for children that are most vulnerable to harmful effects of ionizing radiation. The aim of this study was to determine optimized kV settings for paediatric acquisitions for a dental CBCT device. METHODS Clinical and quantitative evaluations of image quality were performed using 5 and 10 years old (y/o) anthropomorphic phantoms. Technical evaluation was performed with the SEDENTEXCT-IQ phantom. Images were obtained using a PaX-i3D Green CBCT (Vatech, Korea) device, combining tube voltages ranging from 85 to 110 kV and 2 fields of view (FOVs: 21 × 19 and 12 × 9 cm), while maintaining the radiation dose fixed by adjusting the mA accordingly. Clinically, observers assessed images based on overall quality, sharpness, contrast, artefacts, and noise. For quantitative evaluation, mean grey value shift, % increase standard deviation, % beam-hardening and contrast-to-noise ratio were calculated. For technical evaluation, segmentation accuracy, contrast-to-noise ratio and full width at half maximum were measured. Biplot graphs were used to choose representative parameters, from which the best kV was selected for each protocol and evaluation. kV values that had no statistical differences (p > 0.05) with the best kV chosen were considered as having the same quality. RESULTS Clinically, 95 kV was found as a cut-off value. From the quantitative aspect, 85 kV (p < 0.05) showed the worst quality, except in 12 × 9 cm 5 y/o. Technically, 85 and 110 kV in the large FOV showed significantly worse quality for the large FOV. CONCLUSION For paediatric indications, 95 kV or higher (and correspondingly low mA values) was found as optimal.
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Affiliation(s)
- Danieli Moura Brasil
- 1 Department of Oral Diagnosis, Division of Oral Radiology, Piracicaba Dental School, University of Campinas (UNICAMP) , Piracicaba, Sao Paulo , Brazil
| | - Ruben Pauwels
- 2 OMFS-IMPATH Research Group, Department of Imaging and Pathology, Faculty of Medicine, Catholic University of Leuven, and Oral & Maxillofacial Surgery, University Hospitals Leuven , Leuven , Belgium.,3 Department of Mechanical Engineering, Catholic University of Leuven , Leuven , Belgium.,4 Department of Radiology, Faculty of Dentistry, Chulalongkorn University , Bangkok , Thailand
| | - Wim Coucke
- 5 Freelance statistician, Brugstraat 107, 3001 Heverlee , Leuven , Belgium
| | - Francisco Haiter-Neto
- 1 Department of Oral Diagnosis, Division of Oral Radiology, Piracicaba Dental School, University of Campinas (UNICAMP) , Piracicaba, Sao Paulo , Brazil
| | - Reinhilde Jacobs
- 2 OMFS-IMPATH Research Group, Department of Imaging and Pathology, Faculty of Medicine, Catholic University of Leuven, and Oral & Maxillofacial Surgery, University Hospitals Leuven , Leuven , Belgium.,6 Department of Dental Medicine, Karolinska Institutet , Stockholm , Sweden
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Brasil DM, Pauwels R, Coucke W, Haiter-Neto F, Jacobs R. Image quality optimization using a narrow vertical detector dental cone-beam CT. Dentomaxillofac Radiol 2019; 48:20180357. [PMID: 30604636 DOI: 10.1259/dmfr.20180357] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
OBJECTIVES: To determine the optimized kV setting for a narrow detector cone-beam CT (CBCT) unit. METHODS: Clinical (CL) and quantitative (QUANT) evaluations of image quality were performed using an anthropomorphic phantom. Technical (TECH) evaluation was performed with a polymethyl methacrylate phantom. Images were obtained using a PaX-i3D Green CBCT (Vatech, Hwaseong, Korea) device, with a large 21 × 19 and a medium 12 × 9 cm field of view (FOV), and high-dose (HD-ranging from 85 to 110 kV) and low-dose (LD-ranging from 75 to 95 kV) protocols, totaling four groups (21 × 19 cm HD, 21 × 19 cm LD, 12 × 9 cm HD, 12 × 9 cm LD). The radiation dose within each group was fixed by adapting the mA according to a predetermined dose-area product. For CL evaluation, three observers assessed images based on overall quality, sharpness, contrast, artefacts, and noise. For QUANT evaluation, mean gray value shift, % increase of standard deviation (SD), % of beam hardening and contrast-to-noise ratio (CNR) were calculated. For TECH evaluation, segmentation accuracy, CNR, metal artefact SD, metal object area, and sharpness were measured. Representative parameters were chosen for CL, QUANT, and TECH evaluations to determine the optimal kV based on biplot graphs. kV values of the same protocol were compared by the bootstrapping approach. The ones that had statistical differences with the best kV were considered as worse quality. RESULTS: Overall, kV values within the same group showed similar quality (p > 0.05), except for 110 kV in 21 × 19 cm HD and 85 kV in 12 × 9 cm HD of CL score; also 85, 90 kV in 21 × 19 cm HD and 75, 80 kV in 21 × 19 cm LD of QUANT score which were worse (p < 0.05). CONCLUSION: At a constant dose, low and high kV protocols yield acceptable image quality for a narrow-detector CBCT unit.
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Affiliation(s)
- Danieli Moura Brasil
- 1 Department of Oral Diagnosis, Division of Oral Radiology, Piracicaba Dental School, University of Campinas (UNICAMP) , Piracicaba , Brazil
| | - Ruben Pauwels
- 2 Department of Imaging and Pathology, Faculty of Medicine, Catholic University of Leuven , Leuven , Belgium.,3 Department of Oral & Maxillofacial Surgery, University Hospitals Leuven , Leuven , Belgium.,4 Department of Mechanical Engineering, Catholic University of Leuven , Leuven , Belgium.,5 Department of Radiology, Faculty of Dentistry, Chulalongkorn University , Bangkok , Thailand
| | - Wim Coucke
- 6 Freelance statistician , Leuven , Belgium
| | - Francisco Haiter-Neto
- 1 Department of Oral Diagnosis, Division of Oral Radiology, Piracicaba Dental School, University of Campinas (UNICAMP) , Piracicaba , Brazil
| | - Reinhilde Jacobs
- 2 Department of Imaging and Pathology, Faculty of Medicine, Catholic University of Leuven , Leuven , Belgium.,3 Department of Oral & Maxillofacial Surgery, University Hospitals Leuven , Leuven , Belgium.,7 Department of Dental Medicine, Karolinska Institute , Stockholm , Sweden
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Alawaji Y, MacDonald DS, Giannelis G, Ford NL. Optimization of cone beam computed tomography image quality in implant dentistry. Clin Exp Dent Res 2018; 4:268-278. [PMID: 30603109 PMCID: PMC6305941 DOI: 10.1002/cre2.141] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2018] [Revised: 10/02/2018] [Accepted: 10/03/2018] [Indexed: 11/10/2022] Open
Abstract
This study was conducted to optimize the cone beam computed tomography image quality in implant dentistry using both clinical and quantitative image quality evaluation with measurement of the radiation dose. A natural bone human skull phantom and an image quality phantom were used to evaluate the images produced after changing the exposure parameters (kVp and mA). A 10 × 5 cm2 field of view was selected for average adult. Five scans were taken with varying kVp (70-90 kVp) first at fixed 4 mA. After assessment of the scans and selecting the best kVp, nine scans were taken with 2-12 mA, and the kVp was fixed at the optimal value. A clinical assessment of the implant-related anatomical landmarks was done in random order by two blinded examiners. Quantitative image quality was assessed for noise/uniformity, artifact added value, contrast-to-noise ratio, spatial resolution, and geometrical distortion. A dosimetry index phantom and thimble ion chamber were used to measure the absorbed dose for each scan setting. The anatomical landmarks of the maxilla had good image quality at all kVp settings. To produce good quality images, the mandibular landmarks demanded higher exposure parameters than the maxillary landmarks. The quantitative image quality values were acceptable at all selected exposure settings. Changing the exposure parameters does not necessarily produce higher image quality outcomes but does affect the radiation dose to the patient. The image quality could be optimized for implant treatment planning at lower exposure settings and dose than the default settings.
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Affiliation(s)
- Yasmine Alawaji
- Department of Oral Biological and Medical Sciences, Faculty of DentistryThe University of British ColumbiaBritish ColumbiaCanada
| | - David S. MacDonald
- Department of Oral Biological and Medical Sciences, Faculty of DentistryThe University of British ColumbiaBritish ColumbiaCanada
| | - Georgios Giannelis
- Department of Oral Biological and Medical Sciences, Faculty of DentistryThe University of British ColumbiaBritish ColumbiaCanada
| | - Nancy L. Ford
- Department of Oral Biological and Medical Sciences, Faculty of DentistryThe University of British ColumbiaBritish ColumbiaCanada
- Department of Physics and Astronomy, Faculty of ScienceThe University of British ColumbiaBritish ColumbiaCanada
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Koivisto J, van Eijnatten M, Kiljunen T, Shi XQ, Wolff J. Effective Radiation Dose in the Wrist Resulting from a Radiographic Device, Two CBCT Devices and One MSCT Device: A Comparative Study. RADIATION PROTECTION DOSIMETRY 2018; 179:58-68. [PMID: 29040707 DOI: 10.1093/rpd/ncx210] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2017] [Accepted: 09/19/2017] [Indexed: 06/07/2023]
Abstract
The objective of the present study was to assess and compare the effective doses in the wrist region resulting from conventional radiography device, multislice computed tomography (MSCT) device and two cone beam computed tomography (CBCT) devices using MOSFET dosemeters and a custom made anthropomorphic RANDO phantom according to the ICRP 103 recommendation. The effective dose for the conventional radiography was 1.0 μSv. The effective doses for the NewTom 5 G CBCT ranged between 0.7 μSv and 1.6 μSv, for the Planmed Verity CBCT 2.4 μSv and for the MSCT 8.6 μSv. When compared with the effective dose for AP- and LAT projections of a conventional radiographic device, this study showed an 8.6-fold effective dose for standard MSCT protocol and between 0.7 and 2.4-fold effective dose for standard CBCT protocols. When compared to the MSCT device, the CBCT devices offer a 3D view of the wrist at significantly lower effective doses.
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Affiliation(s)
- Juha Koivisto
- Department of Oral and Maxillofacial Surgery, VU University Medical Center, PO Box 7057, 1007 MB Amsterdam, The Netherlands
| | - Maureen van Eijnatten
- Department of Oral and Maxillofacial Surgery, VU University Medical Center, PO Box 7057, 1007 MB Amsterdam, The Netherlands
| | - Timo Kiljunen
- International Docrates Cancer Center, Helsinki, Finland; Saukonpaadenranta 2, FI-00180, Helsinki, Finland
| | - Xie-Qi Shi
- Section of Oral Maxillofacial Radiology, Department of Clinical Dentistry, Faculty of Medicine and Dentistry, University of Bergen, Årstadveien 19, 5009 Bergen, Norway
- Sektionen för bild- och funktionsfysik, C2-63Karolinska Universitetssjukhuset, Huddinge, SE-141 86 Stockholm, Sweden
| | - Jan Wolff
- Department of Oral and Maxillofacial Surgery, VU University Medical Center, PO Box 7057, 1007 MB Amsterdam, The Netherlands
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Influence of patient position and other inherent factors on image quality in two different cone beam computed tomography (CBCT) devices. Eur J Radiol Open 2017; 4:132-137. [PMID: 29159206 PMCID: PMC5675893 DOI: 10.1016/j.ejro.2017.10.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2017] [Accepted: 10/20/2017] [Indexed: 11/23/2022] Open
Abstract
Patient head position can affect the image quality in CBCT-examinations. CNR values can be used to evaluate image quality. Inherent factors influence effective dose variations between CBCT-devices.
Objectives The aim of this in vitro study was to evaluate how a deviation from the horizontal plane, affects the image quality in two different CBCT-devices. Methods A phantom head SK150 (RANDO, The Phantom Laboratory, Salem, NY, USA) was examined in two CBCT-units: Accuitomo 80 and Veraviewepocs 3D R100 (J. Morita Mfg. Corp. Kyoto, Japan). The phantom head was placed with the hard palate parallel to the horizontal plane and tilted 20 ° backwards. Exposures were performed with different field of views (FOVs), voxel sizes, slice thicknesses and exposure settings. Effective dose was calculated using PCXMC 2.0 (STUK, Helsinki, Finland). Image quality was assessed using contrast-to-noise-ratio (CNR). Region of interest (ROI) was set at three different levels of the mandibular bone and soft tissue, uni- and bilaterally in small and large FOVs, respectively. CNR values were calculated by CT-value and standard deviation for each ROI. Factor analysis was used to analyze the material. Results Tilting the phantom head backwards rendered significantly higher mean CNR values regardless of FOV. The effective dose was lower in small than in large FOVs and varied to a larger extent between CBCT-devices in large FOVs. Conclusions Head position can affect the image quality. Tilting the head backward improved image quality in the mandibular region. However, if influenced by other variables e.g. motion artifacts in a clinical situation, remains to be further investigated. Advances in knowledge Image quality assessed using CNR values to investigate the influence of different patient positions and FOVs.
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Koivisto J, van Eijnatten M, Järnstedt J, Holli-Helenius K, Dastidar P, Wolff J. Impact of prone, supine and oblique patient positioning on CBCT image quality, contrast-to-noise ratio and figure of merit value in the maxillofacial region. Dentomaxillofac Radiol 2017; 46:20160418. [PMID: 28306334 DOI: 10.1259/dmfr.20160418] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
OBJECTIVES To assess the impact of supine, prone and oblique patient imaging positions on the image quality, contrast-to-noise ratio (CNR) and figure of merit (FOM) value in the maxillofacial region using a CBCT scanner. Furthermore, the CBCT supine images were compared with supine multislice CT (MSCT) images. METHODS One fresh frozen cadaver head was scanned in prone, supine and oblique imaging positions using a mobile CBCT scanner. MSCT images of the head were acquired in a supine position. Two radiologists graded the CBCT and MSCT images at ten different anatomical sites according to their image quality using a six-point scale. The CNR and FOM values were calculated at two different anatomical sites on the CBCT and MSCT images. RESULTS The best image quality was achieved in the prone imaging position for sinus, mandible and maxilla, followed by the supine and oblique imaging positions. 12-mA prone images presented high delineation scores for all anatomical landmarks, except for the ear region (carotid canal), which presented adequate to poor delineation scores for all studied head positions and exposure parameters. The MSCT scanner offered similar image qualities to the 7.5-mA supine images acquired using the mobile CBCT scanner. The prone imaging position offered the best CNR and FOM values on the mobile CBCT scanner. CONCLUSIONS Head positioning has an impact on CBCT image quality. The best CBCT image quality can be achieved using the prone and supine imaging positions. The oblique imaging position offers inadequate image quality except in the sinus region.
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Affiliation(s)
- Juha Koivisto
- 1 Department of Oral and Maxillofacial Surgery/Oral Pathology and 3D Innovation Lab, VU University Medical Center, Amsterdam, Netherlands
| | - Maureen van Eijnatten
- 1 Department of Oral and Maxillofacial Surgery/Oral Pathology and 3D Innovation Lab, VU University Medical Center, Amsterdam, Netherlands
| | - Jorma Järnstedt
- 2 Medical Imaging Center, Department of Radiology, Tampere University Hospital, Tampere, Finland
| | - Kirsi Holli-Helenius
- 2 Medical Imaging Center, Department of Radiology, Tampere University Hospital, Tampere, Finland
| | - Prasun Dastidar
- 2 Medical Imaging Center, Department of Radiology, Tampere University Hospital, Tampere, Finland.,3 University of Tampere, Medical School, Tampere, Finland
| | - Jan Wolff
- 1 Department of Oral and Maxillofacial Surgery/Oral Pathology and 3D Innovation Lab, VU University Medical Center, Amsterdam, Netherlands
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Al-Okshi A, Theodorakou C, Lindh C. Dose optimization for assessment of periodontal structures in cone beam CT examinations. Dentomaxillofac Radiol 2017; 46:20160311. [PMID: 27910717 PMCID: PMC5606266 DOI: 10.1259/dmfr.20160311] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2016] [Revised: 11/23/2016] [Accepted: 11/28/2016] [Indexed: 11/05/2022] Open
Abstract
OBJECTIVES To investigate the relationship between dose and image quality for a dedicated dental CBCT scanner using different scanning protocols and to set up an optimal imaging protocol for assessment of periodontal structures. METHODS Radiation dose and image quality measurements were made using 3D Accuitomo 170 (J. Morita, Kyoto, Japan) dental CBCT scanner. The SedentexCT IQ phantom was used to investigate the relationship between contrast-to-noise ratio (CNR) and dose-area product. Subjective image quality assessment was achieved using a small adult skull phantom for the same range of exposure settings. Five independent observers assessed the images for three anatomical landmarks using a three-point visual grade analysis. RESULTS When correlating the CNR of each scanning protocol to the exposure parameters used to obtain it, CNR decreased as these parameters decreased, especially current-exposure time product. When correlating to subjective image quality, the CNR level remained acceptable when 5 mA and 17.5 s or greater was selected and 80 kV could be used without compromising the CNR. CONCLUSIONS For a dedicated CBCT unit, changing the rotation angle from 360° to 180° degrades image quality. By altering tube potential and current for the 360° rotation protocol, assessment of periodontal structures can be performed with a smaller dose without substantially affecting visualization.
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Affiliation(s)
- Ayman Al-Okshi
- Department of Oral and Maxillofacial Radiology, Faculty of Odontology, Malmö University, Malmö, Sweden
- Department of Oral Medicine and Radiology, Faculty of Dentistry, Sebha University, Sebha, Libya
| | - Chrysoula Theodorakou
- Christie Medical Physics and Engineering, The Christie NHS Foundation Trust, Manchester Academic Health Science Centre, Manchester, UK
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de Oliveira MVL, Wenzel A, Campos PSF, Spin-Neto R. Quality assurance phantoms for cone beam computed tomography: a systematic literature review. Dentomaxillofac Radiol 2017; 46:20160329. [PMID: 28045345 DOI: 10.1259/dmfr.20160329] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
OBJECTIVES To undertake a systematic review on quality assurance (QA) phantoms for CBCT imaging, including studies on the development and application of phantoms. METHODS The MEDLINE (PubMed) bibliographic database was searched until May 2016 for studies evaluating the development and use of phantoms in CBCT image QA. The search strategy was restricted to English language publications using the following combined terms: (Cone Beam CT) OR (Cone Beam Computed Tomography) OR (Cone-Beam Computed Tomography) OR (CBCT) AND (quality OR phantom). It was assessed which of the six image quality parameters stated by the European Commission could be evaluated with each phantom and which of them actually were. RESULTS The search strategy yielded 37 studies, which had developed and used (25 studies) or only used (12 studies) a phantom in CBCT image QA. According to the literature, in 7 phantoms, it is possible to evaluate 4 or more image quality parameters while in 11 phantoms, merely 1 parameter can be evaluated. Only two phantoms permit the evaluation of the six image quality parameters stated by the European Commission. The parameters, which can most often be evaluated using a phantom, are image density values, spatial resolution and geometric accuracy. The SEDENTEXCT phantom was used most frequently. In two studies, all quality parameters suggested by the European Commission were evaluated. CONCLUSIONS QA phantoms rarely allow all image quality parameters stated by the European Commission to be evaluated. Furthermore, alternative phantoms, which allow all image quality parameters to be evaluated in a single exposure, even for a small field of view, should be developed.
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Affiliation(s)
- Marcus V L de Oliveira
- 1 Department of Health Technology and Biology, Federal Institute of Bahia, Salvador, Brazil.,2 Institute of Health Sciences, Department of Interactive, Processes of Organs and Systems, Federal University of Bahia, Salvador, Brazil
| | - Ann Wenzel
- 3 Oral Radiology, Department of Dentistry and Oral Health, Aarhus University, Aarhus, Denmark
| | - Paulo S F Campos
- 2 Institute of Health Sciences, Department of Interactive, Processes of Organs and Systems, Federal University of Bahia, Salvador, Brazil
| | - Rubens Spin-Neto
- 3 Oral Radiology, Department of Dentistry and Oral Health, Aarhus University, Aarhus, Denmark
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Choi JW. Analysis of the priority of anatomic structures according to the diagnostic task in cone-beam computed tomographic images. Imaging Sci Dent 2016; 46:245-249. [PMID: 28035302 PMCID: PMC5192022 DOI: 10.5624/isd.2016.46.4.245] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2016] [Revised: 07/18/2016] [Accepted: 07/23/2016] [Indexed: 12/04/2022] Open
Abstract
Purpose This study was designed to evaluate differences in the required visibility of anatomic structures according to the diagnostic tasks of implant planning and periapical diagnosis. Materials and Methods Images of a real skull phantom were acquired under 24 combinations of different exposure conditions in a cone-beam computed tomography scanner (60, 70, 80, 90, 100, and 110 kV and 4, 6, 8, and 10 mA). Five radiologists evaluated the visibility of anatomic structures and the image quality for diagnostic tasks using a 6-point scale. Results The visibility of the periodontal ligament space showed the closest association with the ability to use an image for periapical diagnosis in both jaws. The visibility of the sinus floor and canal wall showed the closest association with the ability to use an image for implant planning. Variations in tube voltage were associated with significant differences in image quality for all diagnostic tasks. However, tube current did not show significant associations with the ability to use an image for implant planning. Conclusion The required visibility of anatomic structures varied depending on the diagnostic task. Tube voltage was a more important exposure parameter for image quality than tube current. Different settings should be used for optimization and image quality evaluation depending on the diagnostic task.
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Affiliation(s)
- Jin-Woo Choi
- Department of Oral and Maxillofacial Radiology, Dankook University College of Dentistry, Chungnam, Korea
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Hwang JJ, Park H, Jeong HG, Han SS. Change in Image Quality According to the 3D Locations of a CBCT Phantom. PLoS One 2016; 11:e0153884. [PMID: 27093639 PMCID: PMC4836729 DOI: 10.1371/journal.pone.0153884] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2015] [Accepted: 04/05/2016] [Indexed: 12/22/2022] Open
Abstract
A patient's position changes in every CBCT scan despite patient alignment protocols. However, there have been studies to determine image quality differences when an object is located at the center of the field of view (FOV). To evaluate changes in the image quality of the CBCT scan according to different object positions, the image quality indexes of the Alphard 3030 (Alphard Roentgen Ind., Ltd., Kyoto, Japan) and the Rayscan Symphony (RAY Ind., Ltd., Suwon, Korea) were measured using the Quart DVT_AP phantom at the center of the FOV and 6 peripheral positions under four types of exposure conditions. Anterior, posterior, right, left, upper, and lower positions 1 cm offset from the center of the FOV were used for the peripheral positions. We evaluated and compared the voxel size, homogeneity, contrast to noise ratio (CNR), and the 10% point of the modulation transfer function (MTF10%) of the center and periphery. Because the voxel size, which is determined by the Nyquist frequency, was within tolerance, other image quality indexes were not influenced by the voxel size. For the CNR, homogeneity, and MTF10%, there were peripheral positions which showed considerable differences with statistical significance. The average difference between the center and periphery was up to 31.27% (CNR), 70.49% (homogeneity), and 13.64% (MTF10%). Homogeneity was under tolerance at some of the peripheral locations. Because the CNR, homogeneity, and MTF10% were significantly affected by positional changes of the phantom, an object's position can influence the interpretation of follow up CBCT images. Therefore, efforts to locate the object in the same position are important.
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Affiliation(s)
- Jae Joon Hwang
- Department of Oral and Maxillofacial Radiology, College of Dentistry, Yonsei University, Seoul, Korea
| | - Hyok Park
- Department of Oral and Maxillofacial Radiology, College of Dentistry, Yonsei University, Seoul, Korea
| | - Ho-Gul Jeong
- Department of Oral and Maxillofacial Radiology, College of Dentistry, Yonsei University, Seoul, Korea
| | - Sang-Sun Han
- Department of Oral and Maxillofacial Radiology, College of Dentistry, Yonsei University, Seoul, Korea
- * E-mail:
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Abouei E, Lee S, Ford NL. Quantitative performance characterization of image quality and radiation dose for a CS 9300 dental cone beam computed tomography machine. J Med Imaging (Bellingham) 2015; 2:044002. [PMID: 26587550 DOI: 10.1117/1.jmi.2.4.044002] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2015] [Accepted: 10/16/2015] [Indexed: 11/14/2022] Open
Abstract
This paper aims to characterize the radiation dose and image quality (IQ) performance of a dental cone beam computed tomography (CBCT) unit over a range of fields of view (FOV). IQ and dose were measured using a Carestream 9300 dental CBCT. Phantoms were positioned in the FOV to imitate clinical positioning. IQ was assessed by scanning a SEDENTEXCT IQ phantom, and images were analyzed in ImageJ. Dose index 1 was obtained using a thimble ionization chamber and SEDENTEXCT DI phantom. Mean gray values agreed within 93.5% to 99.7% across the images, with pixel-to-pixel fluctuations of 6% to 12.5%, with poorer uniformity and increased noise for child protocols. CNR was fairly constant across FOVs, with higher CNR for larger patient settings. The measured limiting spatial resolution agreed well with 10% MTF and bar pattern measurements. Dose was reduced for smaller patient settings within a given FOV; however, smaller FOVs obtained with different acquisition settings did not necessarily result in reduced dose. The use of patient-specific acquisition settings decreased the radiation dose for smaller patients, with minimal impact on the IQ. The full set of IQ and dose measurements is reported to allow dental professionals to compare the different FOV settings for clinical use.
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Affiliation(s)
- Elham Abouei
- University of British Columbia , Department of Physics and Astronomy, 6224 Agricultural Road, Vancouver, B.C. V6T 1Z1, Canada
| | - Sierra Lee
- University of British Columbia , Department of Oral Biological and Medical Sciences, 2199 Webrook Mall, Vancouver, B.C. V6T 1Z3, Canada
| | - Nancy L Ford
- University of British Columbia , Department of Physics and Astronomy, 6224 Agricultural Road, Vancouver, B.C. V6T 1Z1, Canada ; University of British Columbia , Department of Oral Biological and Medical Sciences, 2199 Webrook Mall, Vancouver, B.C. V6T 1Z3, Canada
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