scholarly journals Relationship between CNR and visibility of anatomical structures of cone-beam computed tomography images under different exposure parameters

2020 ◽  
Vol 49 (5) ◽  
pp. 20190336
Author(s):  
Miss Fei Wang ◽  
Xiaoyan Xie ◽  
Gang Li ◽  
Zuyan Zhang
Keyword(s):  
Image Quality ◽  
Change Point ◽  
Cone Beam Ct ◽  
Cone Beam ◽  
Physical Factors ◽  
Anatomical Structures ◽  
Subjective Image Quality ◽  
Computed Tomography Images ◽  
Tissue Equivalent ◽  
Imagej Software

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.

scholarly journals An investigation into dose optimisation for imaging root canal anatomy using cone beam CT

2020 ◽  
Vol 49 (7) ◽  
pp. 20200072
Author(s):  
Margarete B McGuigan ◽  
Christie Theodorakou ◽  
Henry F Duncan ◽  
Jonathan Davies ◽  
Anita Sengupta ◽  
...  
Keyword(s):  
Image Quality ◽  
Root Canal ◽  
Image Quality Assessment ◽  
Cone Beam Ct ◽  
Threshold Level ◽  
Cone Beam ◽  
Subjective Image Quality ◽  
Dose Area Product ◽  
Junior Staff ◽  
Root Canal Anatomy

Objectives: To identify a dose as low as diagnostically acceptable and a threshold level of image quality for cone beam CT (CBCT) imaging root canals, using maxillary first molar (M1M) second mesiobuccal (MB2) canals of varying complexity for two CBCT scanners. Methods: Dose–area product (DAP) and contrast-to-noise ratio (CNR) were measured for two scanners at a range of exposure parameters. Subjective-image-quality assessment at the same exposures was performed for three M1Ms of varying MB2 complexity, positioned in an anthropomorphic phantom. Nine raters (three endodontists, three dental radiologists and three junior staff) assessed canal visibility, using a 5-point confidence scale rating. Results: Identification of simple-moderate MB2 canal complexity was achieved at a range of protocols, with DAP values of ≥209.3 and ≥203.2 mGy cm² and CNRs of 3 and 7.6 for Promax®3D and Accuitomo-F170® respectively. For complex canal anatomy, target subjective image quality was not achieved, even at the highest DAP values for both scanners. Junior staff classified significantly more images as undiagnostic compared with senior staff (p = 0.043). Conclusions: In this first study to address optimisation of CBCT imaging of root canal anatomy, a similar threshold dose for both scanners was identified for M1Ms with simple-moderate MB2 canal complexity. Increasing dose to enhance visualisation of more complex canal anatomy was ineffective. Selection of standard protocols (while avoiding lower kV/mA protocols) instead of high-resolution scans was a practical means of reducing patient dose. CNR is not a transferable measure of image quality.

scholarly journals Estimation of contrast-to-noise ratio in CT and CBCT images with varying scan settings in presence of different implant materials

2019 ◽  
Vol 48 (8) ◽  
pp. 20190139
Author(s):  
Emine Şebnem Kursun-Cakmak ◽  
Husniye Demirturk Kocasarac ◽  
Seval Bayrak ◽  
Gülbahar Ustaoğlu ◽  
Marcel Noujeim
Keyword(s):  
Image Quality ◽  
Imaging Modality ◽  
Cone Beam Ct ◽  
Medical Systems ◽  
Plastic Container ◽  
Implant Materials ◽  
Different Types ◽  
Noise Ratio ◽  
Titanium Grade ◽  
Imagej Software

Objectives: To assess the contrast-to-noise ratio (CNR) of four different types of dental implant materials in CT and cone beam CT (CBCT) images with varying scan settings. Methods: Four different types of implants: zirconium (Zr), titanium (Ti) Grade 4 and 5 and titanium–zirconium (Ti–ZrO2) alloy were placed in a 3% gelatin phantom in a cylindrical plastic container and scanned with two different CT machines (GE Medical systems and Toshiba Medical Systems) and one CBCT machine (I-CAT, Imaging Sciences International) with different voxel sizes of 0.2, 0.25, 0.3 and 0.4 mm. Images were analyzed using ImageJ software with the purpose of estimating the CNR. Results: The CNR obtained from images acquired with CT was lower than the CBCT with all voxel sizes tested. 0.3 and 0.4 mm voxel sizes exhibited the highest CNR (p < 0.05) that gives the best image quality. Among the implant materials tested, titanium Grade 5 has the highest levels of CNR while Zirconium has the lowest (p < 0.05). Conclusions: The optimum protocol for radiographic follow-up in areas near implants on the I-CAT is low-resolution settings (0.3 and 0.4 mm voxel sizes) which gave the highest CNR thus image quality. In presence of Zr implants, an alternative imaging modality (i.e., MRI) may be considered to avoid low-quality images.

Dose and Image Quality Evaluation of a Dedicated Cone-Beam CT System for High-Contrast Neurologic Applications

2010 ◽  
Vol 194 (2) ◽  
pp. W193-W201 ◽  
Author(s):  
Lifeng Yu ◽  
Thomas J. Vrieze ◽  
Michael R. Bruesewitz ◽  
James M. Kofler ◽  
David R. DeLone ◽  
...  
Keyword(s):  
Image Quality ◽  
Quality Evaluation ◽  
Cone Beam Ct ◽  
Cone Beam ◽  
High Contrast ◽  
Image Quality Evaluation ◽  
Ct System

A 3D printed phantom for Image Quality Assessment in Cone-beam CT

2018 ◽  
Vol 52 ◽  
pp. 170
Author(s):  
James O’Halloran ◽  
Paddy Gilligan ◽  
Sinead Cleary ◽  
Susan Maguire ◽  
Gerald O’Connor ◽  
...  
Keyword(s):  
Image Quality ◽  
Quality Assessment ◽  
Image Quality Assessment ◽  
Cone Beam Ct ◽  
Cone Beam ◽  
3D Printed

Improved image quality of cone beam CT scans for radiotherapy image guidance using fiber-interspaced antiscatter grid

2014 ◽  
Vol 41 (6Part1) ◽  
pp. 061910 ◽  
Author(s):  
Uros Stankovic ◽  
Marcel van Herk ◽  
Lennert S. Ploeger ◽  
Jan-Jakob Sonke
Keyword(s):  
Image Quality ◽  
Image Guidance ◽  
Cone Beam Ct ◽  
Ct Scans ◽  
Cone Beam ◽  
Antiscatter Grid

scholarly journals Oral and maxillofacial anatomical structures acknowledgment through cone beam computed tomography images – a teaching practice experience

2019 ◽  
Vol 19 (3) ◽  
pp. 163-171
Author(s):  
Solange Kobayashi-Velasco ◽  
Fernanda Cristina Sales Salineiro ◽  
Ivan Onone Gialain ◽  
Wellington Hideaki Yanaguizawa ◽  
Marcelo Gusmão Paraiso Cavalcanti
Keyword(s):  
Computed Tomography ◽  
Cone Beam Computed Tomography ◽  
Teaching Practice ◽  
Cone Beam ◽  
Anatomical Structures ◽  
Practice Experience ◽  
Computed Tomography Images

O objetivo deste estudo foi relatar uma metodologia de ensino de tomografia computadorizada de feixe cônico (TCFC) aplicada a estudantes de graduação, avaliando o conhecimento de estruturas anatômicas do complexo dentomaxilofacial. Os estudantes foram orientados quanto às estruturas anatômicas e às aplicações clínicas da TCFC em aulas teóricas e práticas, compreendendo 45 horas de aula. Foram submetidos a duas avaliações, a primeira na metade do semestre, e a segunda no término do semestre. Os escores das avaliações (três variáveis: 1) nome, 2) lado - esquerdo/direito e 3) reconstruções multiplanares (RMP) - imagens ortogonais de identificação) foram comparados para verificar se houve melhora na aprendizagem. Testes de medianas e Wilcoxon compararam os exames intermediário e final. Os valores medianos para a variável 1 foram 6,0 (intermediário) e 8,0 (final). Em relação à variável 2, a mediana variou de 9,0 (intermediário) a 10,0 (final). Quando os resultados da variável 3 foram analisados, ambas as medianas foram 10,0. Houve diferença significativa (teste de Wilcoxon, p<0,05) quando foram comparados os exames intermediário e final, nas três categorias. Correlações lineares foram estabelecidas entre as três categorias e foram estatisticamente significantes para duas associações (“nome da estrutura anatômica” com “lado da estrutura anatômica” e “nome da estrutura anatômica” com “imagens da MPR”). Os estudantes de graduação apresentaram uma melhora em termos do reconhecimento correto das estruturas anatômicas, nome e lado, bem como imagens de MPR quando comparadas as duas avaliações.

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