Scattered radiation in chest radiography

Niklason, Loren T.; Sorenson, James A.; Nelson, James A.

doi:10.1118/1.595027

Cited by 67 publications

(39 citation statements)

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“…An important factor in image quality improvement in X-ray imaging is the elimination of scattered radiation, which would otherwise reduce the image contrast and affect the detectability of subtle signals [1,2].…”

Section: Introductionmentioning

confidence: 99%

Comparison of anti-scatter grids for digital imaging with use of a direct-conversion flat-panel detector

Mizuta

Sanada

Akazawa

et al. 2011

Radiol Phys Technol

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Our purpose in this study was to establish a selection standard for anti-scatter grids for a direct conversion flat-panel detector (FPD) system. As indices for grid evaluation, we calculated the selectivity, Bucky factor, and the signal-to-noise ratio improvement factor (SIF) by measuring rates of scatter transmission, primary transmission, and total transmission (based on the digitally displayed measurement values of the FPD system), by using 4 acrylic phantoms of different thicknesses. The results showed that the SIF was less than 1.0 when the phantom thickness was 5 cm. When the phantom thickness was 25 cm and the grid ratio was 16:1, the SIF was 1.505 and 1.518 (maximum value) at 90 and 120 kV, respectively. Compared with the grid ratio of 12:1, the SIF at the grid ratio 16:1 was improved by 6.1% at 90 kV, and by 7.0% at 120 kV. In a direct-conversion FPD system, the grid ratio of 16:1 is considered adequate for eliminating the scattered-radiation effect when much scattered radiation is present, such as with a thick imaged object or a high X-ray tube voltage.

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Section: Introductionmentioning

confidence: 99%

Comparison of anti-scatter grids for digital imaging with use of a direct-conversion flat-panel detector

Mizuta

Sanada

Akazawa

et al. 2011

Radiol Phys Technol

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“…This has long been recognized as a main cause for degraded image quality in projection imaging as it decreases both the image contrast and contrast-to-noise ratio ͑CNR͒ for low-contrast objects in the image. [18][19][20][21] Various techniques have been implemented and investigated to reject scattered radiation during image acquisition. [22][23][24] Due to its simplicity, the anti-scatter grid method has by far been the most widely used technique in radiographic and fluoroscopic procedures with various area detectors, including the screen-film ͑S/F͒ combinations, image intensifier-video camera chains, storage phosphors or more recently flat-panel detectors.…”

Section: Introductionmentioning

confidence: 99%

Scatter rejection and low‐contrast performance of a slot‐scan digital chest radiography system with electronic aft‐collimation: A chest phantom study

et al. 2008

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Anti-scatter grids have been widely used to reject scatter and increase the perceptibility of lowcontrast object in chest radiography; however they also attenuate the primary x-rays, resulting in a substantial degradation of primary information. Compensation for this degradation requires the use of higher exposure technique hence higher dose to the patient. A more efficient approach to reject scatter is the slot-scan imaging technique which employs a narrow scanning x-ray fan beam in conjunction with a slit or slot shaped solid state detector or an area detector used with an aftcollimator. With this approach, scatter can be rejected effectively without the need to attenuate primary x-rays. This paper demonstrates an electronic aft-collimation method, referred to as the alternate line erasure and readout ͑ALER͒ technique, for implementing the slot-scan digital radiography with a modern flat-panel detector. With this technique, instead of first exposing the detector and then reading the image line by line, the image line on the leading edge of the scanning fan beam is reset to erase the scatter accumulated prior to the arrival of the fan beam x-rays, while the image line on the trailing edge of the scanning fan beam is read out to acquire the image signals following the fan-beam exposure. These reset and readout processes are alternated and repeated as the x-ray fan beam scans across the detector. An anthropomorphic chest phantom was imaged to evaluate the scatter rejection ability and the low-contrast performance for the ALER technique and compare them with those for the anti-scatter grid method in full-field chest imaging. With a projected beam width of 16 mm, the slot-scan/ALER technique resulted in an average reduction of the scatter-toprimary ratios by 81%, 84%, 82%, and 86% versus 65%, 73%, 74%, and 73% with the anti-scatter grid method in the lungs, mediastinum, retrocardium, and subdiaphragm, respectively. The average CNR for the slot-scan/ALER technique was found to improve by 135%, 133%, 176%, and 87% versus 15%, 15%, 38%, and −11% with the anti-scatter grid method in the mediastinum, retrocardium, subdiaphragm, and lungs, respectively. These results demonstrated that the slot-scan/ALER technique can be used to achieve equally effective scatter rejection but substantially higher lowcontrast performance than the anti-scatter grid method.

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“…The scatter fraction (SF) is defined as the ratio of the intensity of scattered radiation to that of total (scattered plus primary) radiation recorded on the image. Niklason et al [38] and Floyd et al [39] measured average scatter fractions of 0.55, 0.81 and 0.91 in the lung, retrocardiac and mediastinum regions of chest radiographs, respectively. Scatter in chest radiography is therefore not negligible and must be present in images produced for optimisation.…”

Section: Scatter Measurement and Addition To Drrmentioning

confidence: 99%

A method to produce and validate a digitally reconstructed radiograph-based computer simulation for optimisation of chest radiographs acquired with a computed radiography imaging system

Moore¹,

Liney²,

Beavis³

et al. 2011

BJR

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Objectives: The purpose of this study was to develop and validate a computer model to produce realistic simulated computed radiography (CR) chest images using CT data sets of real patients. Methods: Anatomical noise, which is the limiting factor in determining pathology in chest radiography, is realistically simulated by the CT data, and frequency-dependent noise has been added post-digitally reconstructed radiograph (DRR) generation to simulate exposure reduction. Realistic scatter and scatter fractions were measured in images of a chest phantom acquired on the CR system simulated by the computer model and added post-DRR calculation. Results: The model has been validated with a phantom and patients and shown to provide predictions of signal-to-noise ratios (SNRs), tissue-to-rib ratios (TRRs: a measure of soft tissue pixel value to that of rib) and pixel value histograms that lie within the range of values measured with patients and the phantom. The maximum difference in measured SNR to that calculated was 10%. TRR values differed by a maximum of 1.3%. Conclusion: Experienced image evaluators have responded positively to the DRR images, are satisfied they contain adequate anatomical features and have deemed them clinically acceptable. Therefore, the computer model can be used by image evaluators to grade chest images presented at different tube potentials and doses in order to optimise image quality and patient dose for clinical CR chest radiographs without the need for repeat patient exposures.

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Scattered radiation in chest radiography

Cited by 67 publications

References 0 publications

Comparison of anti-scatter grids for digital imaging with use of a direct-conversion flat-panel detector

Comparison of anti-scatter grids for digital imaging with use of a direct-conversion flat-panel detector

Scatter rejection and low‐contrast performance of a slot‐scan digital chest radiography system with electronic aft‐collimation: A chest phantom study

A method to produce and validate a digitally reconstructed radiograph-based computer simulation for optimisation of chest radiographs acquired with a computed radiography imaging system

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