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|Título:||Are physical measures good indicators of image quality at low dose levels? A pilot study|
Andersen, E. N.
|Editora:||Hanze University of Applied Sciences|
|Citação:||Lança L, Andersen EN, Carvalho G, Gerwen v. M, Jorge J, Kleiker M, et al. Are physical measures good indicators of image quality at low dose levels? A pilot study. In: Hogg P, Blakeley C, Buissink C, editors. OPTIMAX 2015 – Multicultural team-based research in radiography: a holistic educational approach. Groningen: Hanze University of Applied Sciences; 2016. p. 128-42.|
|Resumo:||Purpose: To evaluate if physical measures of noise predict image quality at high and low noise levels. Method: Twenty-four images were acquired on a DR system using a Pehamed DIGRAD phantom at three kVp settings (60, 70 and 81) across a range of mAs values. The image acquisition setup consisted of 14 cm of PMMA slabs with the phantom placed in the middle at 120 cm SID. Signal-to-noise ratio (SNR) and Contrast-tonoise ratio (CNR) were calculated for each of the images using ImageJ software and 14 observers performed image scoring. Images were scored according to the observer`s evaluation of objects visualized within the phantom. Results: The R2 values of the non-linear relationship between objective visibility score and CNR (60kVp R2 = 0.902; 70Kvp R2 = 0.913; 80kVp R2 = 0.757) demonstrate a better fit for all 3 kVp settings than the linear R2 values. As CNR increases for all kVp settings the Object Visibility also increases. The largest increase for SNR at low exposure values (up to 2 mGy) is observed at 60kVp, when compared with 70 or 81kVp.CNR response to exposure is similar. Pearson r was calculated to assess the correlation between Score, OV, SNR and CNR. None of the correlations reached a level of statistical significance (p>0.01). Conclusion: For object visibility and SNR, tube potential variations may play a role in object visibility. Higher energy X-ray beam settings give lower SNR but higher object visibility. Object visibility and CNR at all three tube potentials are similar, resulting in a strong positive relationship between CNR and object visibility score. At low doses the impact of radiographic noise does not have a strong influence on object visibility scores because in noisy images objects could still be identified.|
|Versão do Editor:||http://usir.salford.ac.uk/38008/1/Ebook%20Hanze%202015.pdf|
|Aparece nas colecções:||ESTeSL - Capítulos ou partes de livros|
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|Are physical measures good indicators of image quality at low dose levels.pdf||8 MB||Adobe PDF||Ver/Abrir|
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