Comparison of indirect CsI/a:Si and direct a: SE digital radiography: An                assessment of contrast and detail visualization

Fischbach, Frank; Freund, Torsten; Pech, Maciej; Werk, Michael; Bassir, C.; Stoever, B.; Félix, R.; Ricke, Jens

doi:10.1080/02841850312331287769

Cited by 5 publications

(2 citation statements)

References 14 publications

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“…In indirect X-ray detectors, the technology for manufacturing an amorphous silicon (a:Si) photodiode on a thin-film transistor (TFT) array is used, thereby attaching the array to a scintillator. Although X-ray images obtained with a direct-conversion-type detector have superior spatial resolution compared to those obtained with indirect conversion, they have the disadvantage of having low detection sensitivity [7,8]. Therefore, indirect conversion-type X-ray detectors can be safely used at relatively low doses in the medical field.…”

Section: Introductionmentioning

confidence: 99%

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Investigation of Deconvolution Method with Adaptive Point Spread Function Based on Scintillator Thickness in Wavelet Domain

Kim,

Cha,

Jeong

et al. 2024

Bioengineering

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In recent years, indirect digital radiography detectors have been actively studied to improve radiographic image performance with low radiation exposure. This study aimed to achieve low-dose radiation imaging with a thick scintillation detector while simultaneously obtaining the resolution of a thin scintillation detector. The proposed method was used to predict the optimal point spread function (PSF) between thin and thick scintillation detectors by considering image quality assessment (IQA). The process of identifying the optimal PSF was performed on each sub-band in the wavelet domain to improve restoration accuracy. In the experiments, the edge preservation index (EPI) values of the non-blind deblurred image with a blurring sigma of σ = 5.13 pixels and the image obtained with optimal parameters from the thick scintillator using the proposed method were approximately 0.62 and 0.76, respectively. The coefficient of variation (COV) values for the two images were approximately 1.02 and 0.63, respectively. The proposed method was validated through simulations and experimental results, and its viability is expected to be verified on various radiological imaging systems.

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Section: Introductionmentioning

confidence: 99%

“…Therefore, indirect conversion-type X-ray detectors can be safely used at relatively low doses in the medical field. According to Fischbach's study, the indirect FPD system outperforms the direct conversion method in terms of image quality and receiver operating characteristics when the dose is reduced [7].…”

Section: Introductionmentioning

confidence: 99%

Investigation of Deconvolution Method with Adaptive Point Spread Function Based on Scintillator Thickness in Wavelet Domain

Kim,

Cha,

Jeong

et al. 2024

Bioengineering

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Image quality and radiation dose in planar imaging — Image quality figure of merits from the CDRAD phantom

Konst

Weedon‐Fekjær

Båth

2019

J Applied Clin Med Phys

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Purpose A contrast‐detail phantom such as CDRAD is frequently used for quality assurance, optimization of image quality, and several other purposes. However, it is often used without considering the uncertainty of the results. The aim of this study was to assess two figure of merits (FOM) originating from CDRAD regarding the variations of the FOMs by dose utilized to create the x‐ray image. The probability of overlapping (assessing an image acquired at a lower dose as better than an image acquired at a higher dose) was determined. Methods The CDRAD phantom located underneath 12, 20, and 26 cm PMMA was imaged 16 times at five dose levels using an x‐ray system with a flat‐panel detector. All images were analyzed by CDRAD Analyser, version 1.1, which calculated the FOM inverse image quality figure (IQFinv) and gave contrast detail curves for each image. Inherent properties of the CDRAD phantom were used to derive a new FOM h, which describes the size of the hole with the same diameter and depth that is just visible. Data were analyzed using heteroscedastic regression of mean and variance by dose. To ease interpretation, probabilities for overlaps were calculated assuming normal distribution, with associated bootstrap confidence intervals. Results The proportion of total variability in IQFinv, explained by the dose (R2), was 91%, 85%, and 93% for 12, 20, and 26 cm PMMA. Corresponding results for h were 91%, 89%, and 95%. The overlap probability for different mAs levels was 1% for 0.8 vs 1.2 mAs, 5% for 1.2 vs 1.6 mAs, 10% for 1.6 vs 2.0 mAs, and 10% for 2.0 mAs vs 2.5 mAs for 12 cm PMMA. For 20 cm PMMA, it was 0.5% for 10 vs 16 mAs, 13% for 16 vs 20 mAs, 14% for 20 vs 25 mAs, and 14% for 25 vs 32 mAs. For 26 cm PMMA, the probability varied from 0% to 6% for various mAs levels. Even though the estimated probability for overlap was small, the 95% confidence interval (CI) showed relatively large uncertainties. For 12 cm PMMA, the associated CI for 0.8 vs 1.2 mAs was 0.1–3.2%, and the CI for 1.2 vs 1.6 mAs was 2.1–7.8%. Conclusions Inverse image quality figure and h are about equally related to dose level. The FOM h, which describes the size of a hole that should be seen in the image, may be a more intuitive FOM than IQFinv. However, considering the probabilities for overlap and their confidence intervals, the FOMs deduced from the CDRAD phantom are not sensitive to dose. Hence, CDRAD may not be an optimal phantom to differentiate between images acquired at different dose levels.

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Single-exposure dual-energy subtraction chest radiography: Detection of pulmonary nodules and masses in clinical practice

et al. 2007

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The purpose of this retrospective study was to evaluate the impact of energy subtraction (ES) chest radiography on the detection of pulmonary nodules and masses in daily routine. Seventy-seven patients and 25 healthy subjects were examined with a single exposure digital radiography system. Five blinded readers evaluated first the nonsubtracted PA and lateral chest radiographs alone and then together with the subtracted PA soft tissue images. The size, location and number of lung nodules or masses were registered with the confidence level. CT was used as standard of reference. For the 200 total lesions, a sensitivity of 33.5-52.5% was found at non-subtracted and a sensitivity of 43.5-58.5% at energy-subtracted radiography, corresponding to a significant improvement in four of five readers (p<0.05). However, in three of five readers the rate of false positives was higher with ES. With ES, sensitivity, but not the area under the alternative freeresponse receiver operating characteristics (AFROC) curve, showed a good correlation with reader experience (R=0.90, p=0.026). In four of five readers, the diagnostic confidence improved with ES (p=0.0036). We conclude that single-exposure digital ES chest radiography improves detection of most pulmonary nodules and masses, but identification of nodules <1 cm and false-positive findings remain a problem.

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Comparison of indirect CsI/a:Si and direct a: SE digital radiography: An assessment of contrast and detail visualization

Abstract: Image quality of a:Si flat panel digital radiography proved to be superior to a:Se drum digital radiography using low-dose settings. If the primary target is dose reduction indirect flat panel technology should be used.

Cited by 5 publications

References 14 publications

Investigation of Deconvolution Method with Adaptive Point Spread Function Based on Scintillator Thickness in Wavelet Domain

Investigation of Deconvolution Method with Adaptive Point Spread Function Based on Scintillator Thickness in Wavelet Domain

Image quality and radiation dose in planar imaging — Image quality figure of merits from the CDRAD phantom

Single-exposure dual-energy subtraction chest radiography: Detection of pulmonary nodules and masses in clinical practice

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