Dose efficiency and the effects of resolution and noise on detail perceptibility in radiographic magnification

Wagner, Louis K.; Cohen, Gerald; Wong, W. H.; Amtey, Sharad R.

doi:10.1118/1.594902

Cited by 7 publications

(2 citation statements)

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“…Field of view ͑FOV͒ and effective pixel size influence 2D localization precision by determining the sampling densities of the marker's projection when converted to a digital image. 37 X-ray scatter, by decreasing the contrast-to-noise ͑CNR͒ ratio, 38 affects the precision as well. The precision of the 2D marker localization ultimately determines the precision of the 3D localization.…”

Section: Iic Analysis Of 2d Localization Precisionmentioning

confidence: 99%

Error analysis of marker‐based object localization using a single‐plane XRII

et al. 2008

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The role of imaging and image guidance is increasing in surgery and therapy, including treatment planning and follow-up. Fluoroscopy is used for two-dimensional (2D) guidance or localization; however, many procedures would benefit from three-dimensional (3D) guidance or localization. Three-dimensional computed tomography (CT) using a C-arm mounted x-ray image intensifier (XRII) can provide high-quality 3D images; however, patient dose and the required acquisition time restrict the number of 3D images that can be obtained. C-arm based 3D CT is therefore limited in applications for x-ray based image guidance or dynamic evaluations. 2D-3D model-based registration, using a single-plane 2D digital radiographic system, does allow for rapid 3D localization. It is our goal to investigate-over a clinically practical range-the impact of x-ray exposure on the resulting range of 3D localization precision. In this paper it is assumed that the tracked instrument incorporates a rigidly attached 3D object with a known configuration of markers. A 2D image is obtained by a digital fluoroscopic x-ray system and corrected for XRII distortions (+/- 0.035 mm) and mechanical C-arm shift (+/- 0.080 mm). A least-square projection-Procrustes analysis is then used to calculate the 3D position using the measured 2D marker locations. The effect of x-ray exposure on the precision of 2D marker localization and on 3D object localization was investigated using numerical simulations and x-ray experiments. The results show a nearly linear relationship between 2D marker localization precision and the 3D localization precision. However, a significant amplification of error, nonuniformly distributed among the three major axes, occurs, and that is demonstrated. To obtain a 3D localization error of less than +/- 1.0 mm for an object with 20 mm marker spacing, the 2D localization precision must be better than +/- 0.07 mm. This requirement was met for all investigated nominal x-ray exposures at 28 cm FOV, and for all but the lowest two at 40 cm FOV. However, even for those two nominal exposures, the expected 3D localization error is less than +/- 1.2 mm. The tracking precision was +/- 0.65 mm for the out-of-plane translations, +/- 0.05 mm for in-plane translations, and +/- 0.05 degrees for the rotations. The root mean square (RMS) difference between the true and projection-Procrustes calculated location was 1.07 mm. It is believed these results show the potential of this technique for dynamic evaluations or real-time image guidance using a single x-ray source and XRII detector.

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Section: Iic Analysis Of 2d Localization Precisionmentioning

confidence: 99%

Error analysis of marker‐based object localization using a single‐plane XRII

et al. 2008

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“…Combined objective and subjective studies can determine the quality of an X-ray imaging system. Based on the Rose model of human visual perception [8], an experimental technique to evaluate object detectability at the threshold of human visibility in medical images was developed [9,10]. The detectability of lowcontrast objects of various sizes is expressed graphically as a contrast-detail curve, which relates the threshold contrast necessary to perceive an object as a function of the object's size.…”

Section: Introductionmentioning

confidence: 99%

Impacts of Filtration on Contrast‐Detail Detectability of an X‐ray Imaging System

Zhang

Rong

et al. 2006

International Journal of Biomedical Imaging

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The purpose of this study is to investigate the impacts of added filtration on the contrast-detail detectability of a digital X-ray imaging system for small animal studies. A digital X-ray imaging system specifically designed for small animal studies was used. This system is equipped with a micro X-ray source with a tungsten target and a beryllium window filtration and a CCD-based digital detector. Molybdenum filters of 0 mm, 0.02 mm, and 0.05 mm in thickness were added. The corresponding X-ray spectra and contrast-detail detectabilities were measured using two phantoms of different thicknesses simulating breast tissue under different exposures. The added Mo filters reduced the low-energy as well as the high-energy photons, hence providing a narrowband for imaging quality improvement. In the experiments with a 1.15 cm phantom, the optimal image detectability was observed using 22 kVp and the 0.05 mm Mo filter. With the 2.15 cm phantom, the best detectability was obtained with 22 kVp and the 0.02 mm Mo filter. Our experiments showed that appropriate filtrations could reduce certain low- and high-energy components of X-ray spectra which have limited contributions to image contrast. At the same time, such filtration could improve the contrast-detail detectability, particularly at relatively low kVp and high filtration. Therefore, optimal image quality can be obtained with the same absorbed radiation dose by the subjects when appropriate filtration is used.

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