Evaluation of a commercial cardiac motion phantom for dual‐energy chest radiography

Abstract

Misregistration due to cardiac motion causes artifacts in two‐exposure dual‐energy subtraction images, in both the soft‐tissue‐only image and the bone‐only image. Two previous investigations have attempted to avoid misregistration artifacts by using cardiac gating of the first and second exposures. The severity of misregistration was affected by the heart rate, the time interval between the low‐ and high‐energy exposures, the total duration of the two exposures, and the phase of the cardiac cycle at the start of the exposure sequence. We sought to determine whether a commercial phantom with a simulated beating heart can be use to investigate the factors affecting misregistration in dual‐energy chest radiography. We made dual‐energy images of the phantom in postero–anterior orientation using the indirect digital radiography system (GE XQ/i). We acquired digital images at heart rates between 40 beats per minute and 120 beats per minute and transferred them to a computer, where the area of the artifact on the silhouette of the heart was measured from both soft‐tissue‐only and bone‐only images. For comparison, we measured misregistration in clinical dual‐energy subtraction images by the same method. Generally speaking, without synchronization of the exposure sequence with the cardiac cycle, the area of the misregistration artifact increased with heart rate for both the phantom and clinical images. However, the phantom exaggerated the magnitude of misregistration relative to clinical images. Although this phantom was designed for horizontal operation and computed tomography imaging, it can be use in an upright configuration to simulate heart motion for investigation of dual‐energy misregistration artifacts and control.PACS numbers: 87.59.bf, 87.57.cf, 87.57N

Coronary calcium visualization using dual energy chest radiography with sliding organ registration

“…Using a commercial dynamic cardiac phantom (multipurpose chest phantom N1 "LUNGMAN", Kyoto Kagaku) [14] , DE images were captured by a GE Discovery XR656 system (with the same DE output as the GE XRd system) with 120-kV and 60-kV exposures within 150-ms interval. We tuned the cardiac motion parameters in the phantom to acquire DE exposures under 4 different heart rates (bpm=60, 70, 80, 90).…”