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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

The impact of image test bank construction on radiographic interpretation outcomes: A comparison study

Hardy, Maryann L., Flintham, K., Snaith, Beverly, Lewis, Emily F. 22 October 2015 (has links)
Assessment of image interpretation competency is commonly undertaken through review of a defined image test bank. Content of these image banks has been criticised for the high percentage of abnormal examinations which contrasts with lower reported incidences of abnormal radiographs in clinical practice. As a result, questions have been raised regarding the influence of prevalence bias on the accuracy of interpretive decision making. This article describes a new and novel approach to the design of musculoskeletal image test banks. Three manufactured image banks were compiled following a standard academic menu in keeping with previous studies. Three further image test banks were constructed to reflect local clinical workload within a single NHS Trust. Eighteen radiographers, blinded to the method of test bank composition, were randomly assigned 2 test banks to review (1 manufactured, 1 clinical workload). Comparison of interpretive accuracy was undertaken. Inter-rater agreement was moderate to good for all image banks (manufactured: range k = 0.45–0.68; clinical workload: k = 0.49–0.62). A significant difference in mean radiographer sensitivity was noted between test bank designs (manufactured 87.1%; clinical workload 78.5%; p = 0.040, 95% CI = 0.4–16.8; t = 2.223). Relative parity in radiographer specificity and overall accuracy was observed. This study confirms the findings of previous research that high abnormality prevalence image banks over-estimate the ability of observers to identify abnormalities. Assessment of interpretive competency using an image bank that reflects local clinical practice is a better approach to accurately establish interpretive competency and the learning development needs of individual practitioners.
2

Renal stone detection using a low kilo-voltage paediatric CT protocol – A porcine phantom study

Mussmann, B., Hardy, Maryann L., Jung, H., Ding, M., Osther, P.J., Fransen, M.L., Greisen, P.W., Graumann, O. 18 June 2021 (has links)
yes / Introduction: Reducing tube voltage is an effective dose saving method in computed tomography (CT) assuming tube current is not concurrently increased. Recent innovations in scanner technology now enable CT tube voltage reduction to 70 kV thereby increasing opportunities for dose reduction in paediatric patients, but it is unclear if the increased image noise associated with 70 kV impacts on ability to visualise renal stones accurately. The purpose was to assess detectability of nephrolithiasis using a bespoke paediatric phantom and low kV, non-contrast CT and to assess inter-observer agreement. Methods: Forty-two renal stones of different size and chemical composition were inserted into porcine kidneys and positioned in a bespoke, water-filled phantom mimicking a 9-year-old child weighing approximately 33kg. The phantom was scanned using 120 and 70 kV CT protocols, and the detectability of the stones was assessed by three radiologists. Absolute agreement and Fleiss’ kappa regarding detectability were assessed. Results: The mean diameter of renal stones as measured physically was 4.24 mm ranging from 1 to 11 mm. Four stones were missed by at least one observer. One observer had a sensitivity of 93 and 95% at 70 and 120 kV, respectively, while the sensitivity for observers 2 and 3 was 98% at both kV levels. Specificity was 100% across readers and kV levels. Absolute agreement between the readers at 70 kV was 92% (kappa = 0.86) and 98% (kappa = 0.96) at 120 kV indicating a strong agreement at both kV levels. Conclusions: The results suggest that lowering the kV does not affect the detection rate of renal stones and may be a useful dose reduction strategy for assessment of nephrolithiasis in children.
3

The Low-dose Limits of Lung Nodule Detectability in Volumetric Computed Tomography

Silverman, Jordan 15 February 2010 (has links)
Purpose. Low-dose computed tomography is an important imaging modality for screening and surveillance of lung cancer. The goal of this study was to determine the extent to which dose could be minimized while maintaining diagnostic accuracy through knowledgeable selection of reconstruction techniques. Methods. An anthropomorphic phantom was imaged on a 320-slice volumetric CT scanner. Detectability of small solid lung nodules was evaluated as a function of dose, patient size, reconstruction filter and slice thickness by means of 9-alternative forced-choice observer tests. Results. Nodule detectability decreased sharply below a threshold dose level due to increased image noise. For large body habitus, optimal (smooth) filter selection reduced dose by a factor of ~3. Nodule detectability decreased for slice thicknesses larger than the nodule diameter. Conclusions. Radiation dose can be reduced well below current clinical protocols. Smooth reconstruction filters and avoidance of large slice thickness permits lower-dose techniques without tradeoff in diagnostic performance.
4

The Low-dose Limits of Lung Nodule Detectability in Volumetric Computed Tomography

Silverman, Jordan 15 February 2010 (has links)
Purpose. Low-dose computed tomography is an important imaging modality for screening and surveillance of lung cancer. The goal of this study was to determine the extent to which dose could be minimized while maintaining diagnostic accuracy through knowledgeable selection of reconstruction techniques. Methods. An anthropomorphic phantom was imaged on a 320-slice volumetric CT scanner. Detectability of small solid lung nodules was evaluated as a function of dose, patient size, reconstruction filter and slice thickness by means of 9-alternative forced-choice observer tests. Results. Nodule detectability decreased sharply below a threshold dose level due to increased image noise. For large body habitus, optimal (smooth) filter selection reduced dose by a factor of ~3. Nodule detectability decreased for slice thicknesses larger than the nodule diameter. Conclusions. Radiation dose can be reduced well below current clinical protocols. Smooth reconstruction filters and avoidance of large slice thickness permits lower-dose techniques without tradeoff in diagnostic performance.
5

Alveolar bone loss in radiographic modalities for diagnosis of periodontal disease / Periodonto ligų diagnozavimas: dantinės ataugos pokyčių analizė, taikant skirtingus rentgeninio tyrimo metodus

Ivanauskaitė, Deimantė 21 June 2011 (has links)
Radiographic modalities are used in addition to clinical methods to gain information about the patients. In the examination of the periodontium, which is comprised of the gingiva, alveolar bone, periodontal ligament, and cementum, the radiographic examination plays an integral role for diagnosis of periodontal disease. The diagnosis periodontitis is based on a finding of alveolar bone loss. Changes of the alveolar bone can be assessed by different radiographic modalities, such as intraoral radiography (bitewing and periapical radiography) and panoramic radiography. Analysis of alveolar bone loss (alveolar bone level, detection of vertical bone defect and furcation involvement) in radiographic modalities and a systematic review could be helpful to suggest the more applicable radiographic methods for diagnosis of periodontal disease. The purpose of the present study was to examine diagnostic properties of panoramic radiography for the assessment of alveolar bone loss for the diagnosis of periodontal diseases as compare to posterior bitewing radiography. For 96 patients panoramic and posterior bitewing radiographs were performed and results of analysis of visibility of radiographic images and assessment of alveolar bone loss were compared. Also, the systematic review on diagnostic properties of panoramic radiography in the assessment of alveolar bone loss was performed. Based on the results of this study, recommendations for clinical practice and for research were proposed. / Rentgeniniai tyrimo metodai taikomi, kad būtų papildyti klinikinio tyrimo duomenys. Tiriant periodontą, kurį sudaro dantenos, dantinė atauga, periodonto raiščiai ir cementas, rentgeninis tyrimas svarbus diagnozuojant periodonto ligas, nes jo metu nustatomi dantinės ataugos pokyčiai. Dantinės ataugos pokyčiams vertinti daromos rentgeno nuotraukos taikant vidinių burnos rentgeno nuotraukų darymo metodus, t. y. kandimo ar dantų šaknų rentgeno nuotraukų darymo metodus, ir išorinės burnos rentgeno nuotraukos darymo metodą, t. y. panoraminės rentgeno nuotraukos darymo metodą. Atlikus dantinės ataugos pokyčių (kaulo lygio arba rezorbcijos, kaulo defekto ir tarpšaknio kaulo pažeidimų) analizę, taikant rentgeninius metodus, ir padarius sisteminę literatūros apžvalgą, galima būtų pasiūlyti tinkamiausią rentgeno metodą periodonto ligoms diagnozuoti. Šio darbo tikslas – ištirti ir palyginti panoraminės rentgeno nuotraukos ir kaplių bei krūminių dantų rentgeno nuotraukų darymo metodų diagnostikos ypatybes vertinant dantinės ataugos pokyčius periodonto ligoms diagnozuoti. Kiekvienam, iš 96 pacientų įtrauktų į tyrimą, buvo padaryta panoraminė rentgeno nuotrauka ir kaplių bei krūminių dantų kandimo rentgeno nuotraukos. Atlikta dantinės ataugos rentgeno atvaizdo vizualioji kokybė analizė ir vertinimai skirtingose rentgeno nuotraukose bei palyginti rezultatai. Padaryta sisteminė literatūros apžvalga apie panoraminės rentgeno nuotraukos vertę diagnozuojant periodonto ligas. Pagal šio tyrimo... [toliau žr. visą tekstą]
6

Periodonto ligų diagnozavimas: dantinės ataugos pokyčių analizė, taikant skirtingus rentgeninio tyrimo metodus / Alveolar bone loss in radiographic modalities for diagnosis of periodontal diseases

Ivanauskaitė, Deimantė 21 June 2011 (has links)
Rentgeniniai tyrimo metodai taikomi, kad būtų papildyti klinikinio tyrimo duomenys. Tiriant periodontą, kurį sudaro dantenos, dantinė atauga, periodonto raiščiai ir cementas, rentgeninis tyrimas svarbus diagnozuojant periodonto ligas, nes jo metu nustatomi dantinės ataugos pokyčiai. Dantinės ataugos pokyčiams vertinti daromos rentgeno nuotraukos taikant vidinių burnos rentgeno nuotraukų darymo metodus, t. y. kandimo ar dantų šaknų rentgeno nuotraukų darymo metodus, ir išorinės burnos rentgeno nuotraukos darymo metodą, t. y. panoraminės rentgeno nuotraukos darymo metodą. Atlikus dantinės ataugos pokyčių (kaulo lygio arba rezorbcijos, kaulo defekto ir tarpšaknio kaulo pažeidimų) analizę, taikant rentgeninius metodus, ir padarius sisteminę literatūros apžvalgą, galima būtų pasiūlyti tinkamiausią rentgeno metodą periodonto ligoms diagnozuoti. Šio darbo tikslas – ištirti ir palyginti panoraminės rentgeno nuotraukos ir kaplių bei krūminių dantų rentgeno nuotraukų darymo metodų diagnostikos ypatybes vertinant dantinės ataugos pokyčius periodonto ligoms diagnozuoti. Kiekvienam, iš 96 pacientų įtrauktų į tyrimą, buvo padaryta panoraminė rentgeno nuotrauka ir kaplių bei krūminių dantų kandimo rentgeno nuotraukos. Atlikta dantinės ataugos rentgeno atvaizdo vizualioji kokybė analizė ir vertinimai skirtingose rentgeno nuotraukose bei palyginti rezultatai. Padaryta sisteminė literatūros apžvalga apie panoraminės rentgeno nuotraukos vertę diagnozuojant periodonto ligas. Pagal šio tyrimo... [toliau žr. visą tekstą] / Radiographic modalities are used in addition to clinical methods to gain information about the patients. In the examination of the periodontium, which is comprised of the gingiva, alveolar bone, periodontal ligament, and cementum, the radiographic examination plays an integral role for diagnosis of periodontal disease. The diagnosis periodontitis is based on a finding of alveolar bone loss. Changes of the alveolar bone can be assessed by different radiographic modalities, such as intraoral radiography (bitewing and periapical radiography) and panoramic radiography. Analysis of alveolar bone loss (alveolar bone level, detection of vertical bone defect and furcation involvement) in radiographic modalities and a systematic review could be helpful to suggest the more applicable radiographic methods for diagnosis of periodontal disease. The purpose of the present study was to examine diagnostic properties of panoramic radiography for the assessment of alveolar bone loss for the diagnosis of periodontal diseases as compare to posterior bitewing radiography. For 96 patients panoramic and posterior bitewing radiographs were performed and results of analysis of visibility of radiographic images and assessment of alveolar bone loss were compared. Also, the systematic review on diagnostic properties of panoramic radiography in the assessment of alveolar bone loss was performed. Based on the results of this study, recommendations for clinical practice and for research were proposed.

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