Micro‐angiography for neuro‐vascular imaging. II. Cascade model analysis

Ganguly, Arundhuti; Rudin, Stephen; Bednarek, Daniel R.; Hoffmann, Kenneth R.

doi:10.1118/1.1617550

Cited by 47 publications

(59 citation statements)

References 17 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Parallel processes occur when x-ray converting phosphors are implemented, resulting from the emission and reabsorption of secondary x rays. 38,46 Parallel processes also occur in photoconductive ͑direct͒ x-ray detectors. 47 Cascaded linear systems theory has been an extremely useful tool for characterizing and optimizing detector performance and has been used to accurately predict the signal and noise transfer properties of a wide variety of digital x-ray imaging technologies.…”

Section: Iia Theoretical Development Of the Noise-response Methodsmentioning

confidence: 99%

“…Additional details can be seen in a number of works. [33][34][35][36][37][38][39][40] Amplification processes may involve binary selection or conversion of quanta from one form to another. The signal at the output of stage i of an amplification process is described by…”

Section: Iia Theoretical Development Of the Noise-response Methodsmentioning

confidence: 99%

“…Parallel events may occur ͑depending on the x-ray energy and phosphor͒ as a result of the production of secondary x rays. 46,47 The signal and NPS at the output of stage 2 can be written as 38 ⌽ 2 ͑u,v͒ = g 1 ⌽ 0 T 2 ͑u,v͒W…”

Section: Iia2 Stage 2 X-ray-to-light Conversionmentioning

confidence: 99%

“…[37][38][39][40] Careful inspection of the resultant noise response of such systems from a theoretical framework, as described by the two-dimensional noise power spectrum ͑NPS͒, indicates that the resolution response ͑i.e., the MTF͒ is inherently included in such information. 41,42 In this work, we present an exact relationship using a generalized cascaded linear systems analysis.…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Accurate MTF measurement in digital radiography using noise response

et al. 2010

Self Cite

View full text Add to dashboard Cite

Purpose:The authors describe a new technique to determine the system presampled modulation transfer function ͑MTF͒ in digital radiography using only the detector noise response. Methods: A cascaded-linear systems analysis was used to develop an exact relationship between the two-dimensional noise power spectrum ͑NPS͒ and the presampled MTF for a generalized detector system. This relationship was then utilized to determine the two-dimensional presampled MTF. For simplicity, aliasing of the correlated noise component of the NPS was assumed to be negligible. Accuracy of this method was investigated using simulated images from a simple detector model in which the "true" MTF was known exactly. Measurements were also performed on three detector technologies ͑an x-ray image intensifier, an indirect flat panel detector, and a solid state x-ray image intensifier͒, and the results were compared using the standard edge-response method. Flat-field and edge images were acquired and analyzed according to guidelines set forth by the International Electrotechnical Commission, using the RQA 5 spectrum. Results: The presampled MTF determined using the noise-response method for the simulated detector system was in close agreement with the true MTF with an averaged percent difference of 0.3% and a maximum difference of 1.1% observed at the Nyquist frequency ͑f N ͒. The edgeresponse method of the simulated detector system also showed very good agreement at lower spatial frequencies ͑less than 0.5 f N ͒ with an averaged percent difference of 1.6% but showed significant discrepancies at higher spatial frequencies ͑greater than 0.5 f N ͒ with an averaged percent difference of 17%. Discrepancies were in part a result of noise in the edge image and phasing errors. For all three detector systems, the MTFs obtained using the two methods were found to be in good agreement at spatial frequencies less than 0.5 f N with an averaged percent difference of 3.4%. Above 0.5 f N , differences increased to an average of 20%. Deviations of the experimental results largely followed the trend seen in the simulation results, suggesting that differences between the two methods could be explained as resulting from the inherent inaccuracies of the edgeresponse measurement technique used in this study. Aliasing of the correlated noise component was shown to have a minimal effect on the measured MTF for the three detectors studied. Systems with significant aliasing of the correlated noise component ͑e.g., a-Se based detectors͒ would likely require a more sophisticated fitting scheme to provide accurate results. Conclusions: Results indicate that the noise-response method, a simple technique, can be used to accurately measure the MTF of digital x-ray detectors, while alleviating the problems and inaccuracies associated with use of precision test objects, such as a slit or an edge.

show abstract

Section: Iia Theoretical Development Of the Noise-response Methodsmentioning

confidence: 99%

Section: Iia Theoretical Development Of the Noise-response Methodsmentioning

confidence: 99%

Section: Iia2 Stage 2 X-ray-to-light Conversionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Accurate MTF measurement in digital radiography using noise response

et al. 2010

Self Cite

View full text Add to dashboard Cite

show abstract

“…These descriptors have become common for 2D imaging systems, may be determined by experimental measurements 1,2 and by theoretical calculations ͑e.g., cascaded systems analysis͒, [3][4][5] and have been proven useful in system design and optimization. [6][7][8][9][10][11][12][13][14][15][16][17] These metrics can be described similar to 3D imaging, including tomosynthesis and CBCT. [18][19][20][21][22][23][24][25] With a knowledge of the imaging task and an appropriate model observer, these metrics can be extended to a description of task performance as described by ICRU Report No.…”

Section: Introductionmentioning

confidence: 99%

Noise aliasing and the 3D NEQ of flat-panel cone-beam CT: Effect of 2D/3D apertures and sampling

Tward

Siewerdsen

2009

Med. Phys.

View full text Add to dashboard Cite

The ability to tune an imaging system to be optimal for a specific task is an essential component of image quality. This article discusses the ability to tune the noise-equivalent quanta ͑NEQ͒ of cone-beam computed tomography ͑CBCT͒ by managing noise aliasing through binning of data at different points in the reconstruction cascade. The noise power spectrum, modulation transfer function, and NEQ for CBCT are calculated using cascaded systems analysis. Binning is treated as a modular process, insertable between any two stages ͑in both the 2D projection domain and in the 3D reconstruction domain͒, consisting of the application of an aperture, followed by the resampling of data ͑which introduces noise aliasing͒. Several conditions were examined to demonstrate the validity of the model and to describe the effect on the image quality of some common reconstruction and visualization techniques. It was found that when downsampling data for increased reconstruction speed, binning in 2D results in a superior low-frequency NEQ, while binning in 3D results in a superior high-frequency NEQ. Furthermore, visualization procedures such as slice averaging were found not to degrade the NEQ provided the sampling interval is unchanged. Finally methods for reducing noise aliasing by oversampling are examined, and a method to eliminate noise aliasing without increasing reconstruction time is proposed. These results demonstrate the ease with which the NEQ of CBCT can be modified and thus optimized for specific tasks and show how such analysis can be used to improve image quality.

show abstract

Cone-beam CT with a flat-panel detector: From image science to image-guided surgery

Siewerdsen

2011

Nuclear Instruments and Methods in Physics Research Section A:

View full text Add to dashboard Cite

The development of large-area flat-panel x-ray detectors (FPDs) has spurred investigation in a spectrum of advanced medical imaging applications, including tomosynthesis and cone-beam CT (CBCT). Recent research has extended image quality metrics and theoretical models to such applications, providing a quantitative foundation for the assessment of imaging performance as well as a general framework for the design, optimization, and translation of such technologies to new applications. For example, cascaded systems models of Fourier domain metrics, such as noise-equivalent quanta (NEQ), have been extended to these modalities to describe the propagation of signal and noise through the image acquisition and reconstruction chain and to quantify the factors that govern spatial resolution, image noise, and detectability. Moreover, such models have demonstrated basic agreement with human observer performance for a broad range of imaging conditions and imaging tasks. These developments in image science have formed a foundation for the knowledgeable development and translation of CBCT to new applications in image-guided interventions - for example, CBCT implemented on a mobile surgical C-arm for intraoperative 3D imaging. The ability to acquire high-quality 3D images on demand during surgical intervention overcomes conventional limitations of surgical guidance in the context of preoperative images alone. A prototype mobile C-arm developed in academic-industry partnership demonstrates CBCT with low radiation dose, sub-mm spatial resolution, and soft-tissue visibility potentially approaching that of diagnostic CT. Integration of the 3D imaging system with real-time tracking, deformable registration, endoscopic video, and 3D visualization offers a promising addition to the surgical arsenal in interventions ranging from head-and-neck / skull base surgery to spine, orthopaedic, thoracic, and abdominal surgeries. Cadaver studies show the potential for significant boosts in surgical performance under CBCT guidance, and early clinical trials demonstrate feasibility, workflow, and image quality within the surgical theatre.

show abstract

Micro‐angiography for neuro‐vascular imaging. II. Cascade model analysis

Cited by 47 publications

References 17 publications

Accurate MTF measurement in digital radiography using noise response

Accurate MTF measurement in digital radiography using noise response

Noise aliasing and the 3D NEQ of flat-panel cone-beam CT: Effect of 2D/3D apertures and sampling

Cone-beam CT with a flat-panel detector: From image science to image-guided surgery

Contact Info

Product

Resources

About