Quantitative scatter measurement in digital radiography using a photostimulable phosphor imaging system

Floyd, Carey E.; Lo, Joseph Y.; Chotas, H.; Ravin, Carl E.

doi:10.1118/1.596687

Cited by 44 publications

(33 citation statements)

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“…Most profoundly, the slot-scan system, with a low scatter fraction and no antiscatter grid, shows a reverse rank ordering relative to full-field systems when comparing the DQE and eDQE results shown in Figures 5 and 6. These findings are consistent with earlier theoretical estimations of eDQE values for that system, given the differences in the phantoms used (23). The relevance of eDQE as a metric of image quality is further demonstrated with the subjective example provided in Figure 7, showing that the ThoraScan system, with a higher eDQE but lower DQE, offers improved conspicuity of a simulated retrocardiac lesion.…”

Section: Medical Physics: Detective Quantum Efficiency and Digital Rasupporting

confidence: 79%

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Detector or System? Extending the Concept of Detective Quantum Efficiency to Characterize the Performance of Digital Radiographic Imaging Systems

Samei¹,

Ranger²,

Mackenzie³

et al. 2008

Radiology

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Purpose:To develop an experimental method for measuring the effective detective quantum efficiency (eDQE) of digital radiographic imaging systems and evaluate its use in select imaging systems. Materials and Methods:A geometric phantom emulating the attenuation and scatter properties of the adult human thorax was employed to assess eight imaging systems in a total of nine configurations. The noise power spectrum (NPS) was derived from images of the phantom acquired at three exposure levels spanning the operating range of the system. The modulation transfer function (MTF) was measured by using an edge device positioned at the anterior surface of the phantom. Scatter measurements were made by using a beamstop technique. All measurements, including those of phantom attenuation and estimates of x-ray flux, were used to compute the eDQE. Results:The MTF results showed notable degradation owing to focal spot blur. Scatter fractions ranged between 11% and 56%, depending on the system. The eDQE(0) results ranged from 1%-17%, indicating a reduction of up to one order of magnitude and different rank ordering and performance among systems, compared with that implied in reported conventional detective quantum efficiency results from the same systems. Conclusion:The eDQE method was easy to implement, yielded reproducible results, and provided a meaningful reflection of system performance by quantifying image quality in a clinically relevant context. The difference in the magnitude of the measured eDQE and the ideal eDQE of 100% provides a great opportunity for improving the image quality of radiographic and mammographic systems while reducing patient dose. Note: This copy is for your personal, non-commercial use only. To order presentation-ready copies for distribution to your colleagues or clients, use the Radiology Reprints form at the end of this article. Image quality is an important attribute of an imaging system, as it can have a measurable effect on the diagnostic utility and clinical usability of a system. To ensure sufficient and consistent performance, it is necessary to be able to assess image quality quantitatively so that it can be optimized and monitored to maintain a high level of clinical care. In the past few years, the most recognized and comprehensive metric of image quality performance for digital radiographic and mammographic systems has been the detective quantum efficiency (DQE), a measure of the efficiency of a detector when using the input signal-to-noise ratio (SNR) provided by a limited number of x-ray photons to form an image at a certain exposure or dose level. With measurement methods largely standardized (1-5), a number of studies have reported the variations in DQE performance of these imaging systems (6-9).While the DQE provides a quantitative measure of image quality per unit of exposure to the detector, it does not include some important attributes of the total system that affect the quality of images captured clinically. Clinical images are affected by the presence of scattered radiation, ...

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Section: Medical Physics: Detective Quantum Efficiency and Digital Rasupporting

confidence: 79%

“…The scatter properties of the systems in the nine operating modes (Table 1) were measured by using a beam-stop array device (23,24) placed adjacent to the anterior surface of the phantom (Figure 2c). The phantom was centered in the field of view and adjacent to the detector cover plate.…”

Section: Scatter Measurementsmentioning

confidence: 99%

Detector or System? Extending the Concept of Detective Quantum Efficiency to Characterize the Performance of Digital Radiographic Imaging Systems

Samei¹,

Ranger²,

Mackenzie³

et al. 2008

Radiology

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“…(3) Transmission factor (TF nb ). This was measured under narrow beam conditions with the Radcal Table 1 and a beam stop technique described by Floyd et al [40]. The beam stop consists of an array of 224 lead beam stops, each of 6 mm in thickness and 3 mm in diameter, 25 mm apart, suspended on a 1-mmthick PMMA sheet.…”

Section: Other Practical Measurementsmentioning

confidence: 99%

Correlation of the clinical and physical image quality in chest radiography for average adults with a computed radiography imaging system

Moore¹,

Wood²,

Beavis³

et al. 2013

BJR

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Objective: The purpose of this study was to examine the correlation between the quality of visually graded patient (clinical) chest images and a quantitative assessment of chest phantom (physical) images acquired with a computed radiography (CR) imaging system. Methods:The results of a previously published study, in which four experienced image evaluators graded computer-simulated posteroanterior chest images using a visual grading analysis scoring (VGAS) scheme, were used for the clinical image quality measurement. Contrast-to-noise ratio (CNR) and effective dose efficiency (eDE) were used as physical image quality metrics measured in a uniform chest phantom. Although optimal values of these physical metrics for chest radiography were not derived in this work, their correlation with VGAS in images acquired without an antiscatter grid across the diagnostic range of X-ray tube voltages was determined using Pearson's correlation coefficient.Results: Clinical and physical image quality metrics increased with decreasing tube voltage. Statistically significant correlations between VGAS and CNR (R50.87, p,0.033) and eDE (R50.77, p,0.008) were observed. Conclusion:Medical physics experts may use the physical image quality metrics described here in quality assurance programmes and

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“…33 The resulting DRR images were validated quantitatively with a chest phantom and real patient CR images. Signal-to-noise ratio (SNR) values of the DRR images in the lung, spine and diaphragm regions agreed to within 15% (mean55%) across the diagnostic energy range when compared with the CR images.…”

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Use of a digitally reconstructed radiograph-based computer simulation for the optimisation of chest radiographic techniques for computed radiography imaging systems

Moore¹,

Avery²,

Balcam³

et al. 2012

BJR

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Objectives: The purpose of this study was to derive an optimum radiographic technique for computed radiography (CR) chest imaging using a digitally reconstructed radiograph computer simulator. The simulator is capable of producing CR chest radiographs of adults with various tube potentials, receptor doses and scatter rejection. Methods: Four experienced image evaluators graded images of average and obese adult patients at different potentials (average-sized, n550; obese, n520), receptor doses (n510) and scatter rejection techniques (average-sized, n520; obese, n520). The quality of the images was evaluated using visually graded analysis. The influence of rib contrast was also assessed. Results: For average-sized patients, image quality improved when tube potential was reduced compared with the reference (102 kVp). No scatter rejection was indicated. For obese patients, it has been shown that an antiscatter grid is indicated, and should be used in conjunction with as low a tube potential as possible (while allowing exposure times ,20 ms). It is also possible to reduce receptor air kerma by 50% without adversely influencing image quality. Rib contrast did not interfere at any tube potential. Conclusions: A virtual clinical trial has been performed with simulated chest CR images. Results indicate that low tube potentials (,102 kVp) are optimal for average and obese adults, the former acquired without scatter rejection, the latter with an antiscatter grid. Lower receptor (and therefore patient doses) than those used clinically are possible while maintaining adequate image quality.

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Quantitative scatter measurement in digital radiography using a photostimulable phosphor imaging system

Cited by 44 publications

References 0 publications

Detector or System? Extending the Concept of Detective Quantum Efficiency to Characterize the Performance of Digital Radiographic Imaging Systems

Detector or System? Extending the Concept of Detective Quantum Efficiency to Characterize the Performance of Digital Radiographic Imaging Systems

Correlation of the clinical and physical image quality in chest radiography for average adults with a computed radiography imaging system

Use of a digitally reconstructed radiograph-based computer simulation for the optimisation of chest radiographic techniques for computed radiography imaging systems

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