Control of Scattered Radiation by Air Gap Techniques: Applications to Chest Radiography

Respiratory X-ray imaging enhanced by phase contrast has shown improved airway visualization in animal models. Limitations in current X-ray technology have nevertheless hindered clinical translation, leaving the potential clinical impact an open question. Here, we explore phase-contrast chest radiography in a realistic in silico framework. Specifically, we use preprocessed virtual patients to generate in silico chest radiographs by Fresnel-diffraction simulations of X-ray wave propagation. Following a reader study conducted with clinical radiologists, we predict that phase-contrast edge enhancement will have a negligible impact on improving solitary pulmonary nodule detection (6 to 20 mm). However, edge enhancement of bronchial walls visualizes small airways (< 2 mm), which are invisible in conventional radiography. Our results show that phase-contrast chest radiography could play a future role in observing small-airway obstruction (e.g., relevant for asthma or early-stage chronic obstructive pulmonary disease), which cannot be directly visualized using current clinical methods, thereby motivating the experimental development needed for clinical translation. Finally, we discuss quantitative requirements on distances and X-ray source/detector specifications for clinical implementation of phase-contrast chest radiography.

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“…SI Appendix , Fig. S4 ), which is consistent with the well-known use of air gap techniques ( 33 ) as alternatives to antiscatter grids.…”

Section: Discussionsupporting

confidence: 86%

Phase-contrast virtual chest radiography

Häggmark

Shaker

Nyrén

et al. 2022

Proc. Natl. Acad. Sci. U.S.A.

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“…It enhances image quality, which might make it possible to detect even small changes in valve settings. 12,31 This would be beneficial to the patients´ health even with the increased radiation dose. 24 The three highest scoring imaging techniques are C, B, and H, counting for a 65% of the total scores (table 3).…”

Section: Discussionmentioning

confidence: 99%

Optimization of Codman® Hakim® adjustable valve radiography

Bremnes

Kubosch

Ween

2017

RadOpen

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PurposeCerebrospinal fluid shunt valves are important tools in hydrocephalus treatment. Adjustable valves, sensitive to MRI, are onerous. They need be controlled; in case of re-settings. The vendor give advices for the radiographic procedure; however, hospitals use variations. The purpose was to investigate the different variations. MethodEight images consisting combinations of protocol features, were subjectively and anonymous rated for image quality. The panel consisted of 60 professionals; 50 radiographers and 10 radiologists, from two hospitals doing neurosurgery services. Signal-to-noise ratio compared the level of desired signal to the level of background noise.Results 348 scores were distributed onto all eight images, revealing the image quality difference was within acceptance. Options as valve on the head side near to the detector versus far to; differing geometry, use of head bowl versus not use, air-gap versus grids, were favored by both professional groups and at both hospitals in a clear priority image, given 2.5 times scores over average (108/43). Noise, revealed being the strongest indicator for priority of the best image for shunt evaluation.

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“…Scatter was reduced by an air gap between the phantom and the detector surface, which ranged from 24 cm to 30 cm. According to the study by Gould and Hale (1974), for 100 kV, 30 cm x30 cm field, and absorber thickness of 20 cm (water), an air gap of 26 cm provided a contrast improvement factor of 2.2. In comparison, a 7:1 antiscatter grid provides a contrast improvement factor of 2.1.…”

Section: Phantom Studiesmentioning

confidence: 99%

Cone-beam CT for radiotherapy applications

1995

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Clinical implementation of cone-beam tomography has been hampered by the lack of two-dimensional electronic x-ray detectors that can encompass the full width of the body. We encountered the undersized detector problem in our development of a cone-beam CT system for radiotherapy applications. In order to mitigate the problem, we developed an algorithm which permits an increased reconstruction volume to be imaged using a detector of a given size. We describe the algorithm and report on its implementation using a radiotherapy simulator configured with a digital fluorography unit.

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Control of Scattered Radiation by Air Gap Techniques: Applications to Chest Radiography

Cited by 14 publications

References 5 publications

Phase-contrast virtual chest radiography

Phase-contrast virtual chest radiography

Optimization of Codman® Hakim® adjustable valve radiography

Cone-beam CT for radiotherapy applications

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