Optimal kVp selection for dual‐energy imaging of the chest: Evaluation by task‐specific observer preference tests

Abstract

Human observer performance tests were conducted to identify optimal imaging techniques in dual-energy (DE) imaging of the chest with respect to a variety of visualization tasks for soft and bony tissue. Specifically, the effect of kVp selection in low- and high-energy projection pairs was investigated. DE images of an anthropomorphic chest phantom formed the basis for observer studies, decomposed from low-energy and high-energy projections in the range 60-90 kVp and 120-150 kVp, respectively, with total dose for the DE image equivalent to that of a single chest radiograph. Five expert radiologists participated in observer preference tests to evaluate differences in image quality among the DE images. For visualization of soft-tissue structures in the lung, the [60/130] kVp pair provided optimal image quality, whereas [60/140] kVp proved optimal for delineation of the descending aorta in the retrocardiac region. Such soft-tissue detectability tasks exhibited a strong dependence on the low-kVp selection (with 60 kVp providing maximum soft-tissue conspicuity) and a weaker dependence on the high-kVp selection (typically highest at 130-140 kVp). Qualitative examination of DE bone-only images suggests optimal bony visualization at a similar technique, viz., [60/140] kVp. Observer preference was largely consistent with quantitative analysis of contrast, noise, and contrast-to-noise ratio, with subtle differences likely related to the imaging task and spatial-frequency characteristics of the noise. Observer preference tests offered practical, semiquantitative identification of optimal, task-specific imaging techniques and will provide useful guidance toward clinical implementation of high-performance DE imaging systems.

Feasibility of markerless tumor tracking by sequential dual-energy fluoroscopy on a clinical tumor tracking system

“…Improved contrast of lung lesions after DE subtraction, resulting in significant improvement in markerless tumor localization, has been reported by several groups [16][17][18][19]. In this study, we evaluate the feasibility of markerless tumor tracking through the implementation of DE subtraction imaging into the current clinical RTTT workflow, using the implanted fiducials as a benchmark.…”

Assessment of image quality in soft tissue and bone visualization tasks for a dedicated extremity cone-beam CT system

“…Studies involved two types of tests, performed by expert radiologists: (i) diagnostic satisfaction rating [18], in which the ability to perform a given visualization task was assessed with respect to a single displayed image; and (ii) preference rating [19], in which the ability to perform a given task was assessed with respect to two images displayed side-by-side.…”

“…Preference scores were evaluated in terms of the median, quartiles, and range displayed as box-and-whisker plots. To compute the normalized preference score [19], raw scores were converted to a binary preference (i.e., preferred or not preferred), and for cases with a raw score of 0 (no preference), both the control and test images were considered as equally preferred. Therefore, raw scores of 0, + 1, and +2 were "binarized" simply as "preferred" for the test case, and raw scores of 0, − 1, and −2 as "preferred" for the control case.…”

Digital breast tomosynthesis: studies of the effects of acquisition geometry on contrast-to-noise ratio and observer preference of low-contrast objects in breast phantom images

“…without the time-consuming task of examining each factor individually. Preference studies have been used by investigators to determine the optimal kVps for dual energy digital radiography of the chest (Shkumat et al , 2008; Williams et al , 2007), to evaluate radiologists’ visual judgments of the similarity of masses and/or microcalcifications in mammograms (Muramatsu et al , 2007; Tourassi et al , 2013), and to compare digital with screen-film radiography. (Hamers et al , 2001)…”