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Petsaros S, Chatzipetros E, Donta C, Karaiskos P, Boziari A, Papadakis E, Angelopoulos C. Scattered Radiation Distribution Utilizing Three Different Cone-Beam Computed Tomography Devices for Maxillofacial Diagnostics: A Research Study. J Clin Med 2023; 12:6199. [PMID: 37834843 PMCID: PMC10573760 DOI: 10.3390/jcm12196199] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2023] [Revised: 09/21/2023] [Accepted: 09/24/2023] [Indexed: 10/15/2023] Open
Abstract
This study aimed to estimate scattered radiation and its spatial distribution around three cone-beam computed tomography (CBCT) devices, in order to determine potential positions for an operator to stand if they needed to be inside the CBCT room. The following devices were tested: Morita Accuitomo (CBCT1), Newtom Giano HR (CBCT2), Newtom VGi (CBCT3). Scattered radiation measurements were performed using different kVp, mA, and Field of View (FOV) options. An anthropomorphic phantom (NATHANIA) was placed inside the X-ray gantry to simulate clinical conditions. Scattered measurements were taken with the Inovision model 451P Victoreen ionization chamber once placed at fixed distances from each irradiation isocenter, away from the primary beam. A statistically significant (p < 0.001) difference was found in the mean value of the scattered radiation estimations between the CBCT devices. Scattered radiation was reduced with a different rate for each CBCT device as distance was increased. For CBCT1 the reduction was 0.047 μGy, for CBCT2 it was 0.036 μGy, and for CBCT3 it was 0.079 μGy, for every one meter from the X-ray gantry. Therefore, at certain distances from the central X-ray, the scattered radiation was below the critical level of 1 mGy, which is defined by the radiation protection guidelines as the exposure radiation limit of the general population. Consequently, an operator could stay inside the room accompanying the patient being scanned, if necessary.
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Affiliation(s)
- Sotirios Petsaros
- Department of Oral Diagnosis and Radiology, Faculty of Dentistry, National and Kapodistrian University of Athens, 2 Thivon Street, Goudi, 11527 Athens, Greece; (S.P.); (E.C.); (C.D.); (E.P.)
| | - Emmanouil Chatzipetros
- Department of Oral Diagnosis and Radiology, Faculty of Dentistry, National and Kapodistrian University of Athens, 2 Thivon Street, Goudi, 11527 Athens, Greece; (S.P.); (E.C.); (C.D.); (E.P.)
| | - Catherine Donta
- Department of Oral Diagnosis and Radiology, Faculty of Dentistry, National and Kapodistrian University of Athens, 2 Thivon Street, Goudi, 11527 Athens, Greece; (S.P.); (E.C.); (C.D.); (E.P.)
| | - Pantelis Karaiskos
- Medical Physics Laboratory, Faculty of Medicine, National and Kapodistrian University of Athens, 75 Mikras Asias Street, Goudi, 11527 Athens, Greece;
| | - Argiro Boziari
- Greek Atomic Energy Commission, Agia Paraskevi, 15310 Attiki, Greece;
| | - Evangelos Papadakis
- Department of Oral Diagnosis and Radiology, Faculty of Dentistry, National and Kapodistrian University of Athens, 2 Thivon Street, Goudi, 11527 Athens, Greece; (S.P.); (E.C.); (C.D.); (E.P.)
| | - Christos Angelopoulos
- Department of Oral Diagnosis and Radiology, Faculty of Dentistry, National and Kapodistrian University of Athens, 2 Thivon Street, Goudi, 11527 Athens, Greece; (S.P.); (E.C.); (C.D.); (E.P.)
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Park SW, Yoon RG, Lee H, Lee HJ, Choi YD, Lee DH. Impacts of Thresholds of Gray Value for Cone-Beam Computed Tomography 3D Reconstruction on the Accuracy of Image Matching with Optical Scan. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2020; 17:ijerph17176375. [PMID: 32882986 PMCID: PMC7503962 DOI: 10.3390/ijerph17176375] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Revised: 08/29/2020] [Accepted: 08/31/2020] [Indexed: 12/11/2022]
Abstract
In cone-beam computed tomography (CBCT), the minimum threshold of the gray value of segmentation is set to convert the CBCT images to the 3D mesh reconstruction model. This study aimed to assess the accuracy of image registration of optical scans to 3D CBCT reconstructions created by different thresholds of grey values of segmentation in partial edentulous jaw conditions. CBCT of a dentate jaw was reconstructed to 3D mesh models using three different thresholds of gray value (-500, 500, and 1500), and three partially edentulous models with different numbers of remaining teeth (4, 8, and 12) were made from each 3D reconstruction model. To merge CBCT and optical scan data, optical scan images were registered to respective 3D reconstruction CBCT images using a point-based best-fit algorithm. The accuracy of image registration was assessed by measuring the positional deviation between the matched 3D images. The Kruskal-Wallis test and a post hoc Mann-Whitney U test with Bonferroni correction were used to compare the results between groups (α = 0.05). The correlations between the experimental factors were calculated using the two-way analysis of variance test. The positional deviations were lowest with the threshold of 500, followed by the threshold of 1500, and then -500. A significant interaction was found between the threshold of gray values and the number of remaining teeth on the registration accuracy. The most significant deviation was observed in the arch model with four teeth reconstructed with a gray-value threshold of -500. The threshold for the gray value of CBCT segmentation affects the accuracy of image registration of optical scans to the 3D reconstruction model of CBCT. The appropriate gray value that can visualize the anatomical structure should be set, especially when few teeth remain in the dental arch.
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Affiliation(s)
- Se-Won Park
- Department of Prosthodontics, School of Dentistry, Institute for Translational Research in Dentistry, Kyungpook National University, Daegu 41940, Korea; (S.-W.P.); (Y.-D.C.)
| | - Ra Gyoung Yoon
- Department of Radiology, Nowon Eulji Medical Center, Eulji University, Seoul 01830, Korea;
| | - Hyunwoo Lee
- Department of Dental Clinic, National Medical Center, Seoul 04564, Korea;
| | - Heon-Jin Lee
- Department of Microbiology and Immunology, School of Dentistry, Kyungpook National University, Daegu 41940, Korea;
| | - Yong-Do Choi
- Department of Prosthodontics, School of Dentistry, Institute for Translational Research in Dentistry, Kyungpook National University, Daegu 41940, Korea; (S.-W.P.); (Y.-D.C.)
| | - Du-Hyeong Lee
- Department of Prosthodontics, School of Dentistry, Institute for Translational Research in Dentistry, Kyungpook National University, Daegu 41940, Korea; (S.-W.P.); (Y.-D.C.)
- Correspondence: ; Tel.: +82-53-600-7676
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Rossignol J, Turtos RM, Gundacker S, Gaudreault D, Auffray E, Lecoq P, Bérubé-Lauzière Y, Fontaine R. Time-of-flight computed tomography - proof of principle. Phys Med Biol 2020; 65:085013. [PMID: 32084652 DOI: 10.1088/1361-6560/ab78bf] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Computed tomography has greatly improved over the last decade, especially through x-ray dose exposure reduction while maintaining image quality. Herein, a new concept is proposed to improve the contrast-to-noise ratio (CNR) by including the time-of-flight (TOF) information of individual photons to obtain further insight on the photon's trajectory and to reject scatter contribution. The proof of the concept relies on both simulation and experimental measurements in a cone-beam computed tomography arrangement. Results show a statistical difference between the TOF of scattered and primary photons exploitable in TOF computed tomography. For a large volume of the size of a human abdomen, a scatter reduction from 296% to 4% is achieved in our simulation setup with perfect timing measurements which yields a 110% better CNR, or a dose reduction by a factor of four. Cup artifacts are also reduced from 24.7% to 0.8%, and attenuation inaccuracies are improved from -26.3% to -0.8%. With 100 ps and 10 ps FWHM timing jitters, respectively 75% and 95% of the scatter contribution can be removed with marginal gains below 10 ps. Experimental measurements confirm the feasibility of measuring statistical differences between the TOF of scattered and primary photons.
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Affiliation(s)
- J Rossignol
- Institut Interdisciplinaire d'Innovation Technologique (3IT), Université de Sherbrooke, Sherbrooke, Québec, Canada. Département de Génie Électrique et Génie Informatique, Université de Sherbrooke, Sherbrooke, Québec, Canada
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