Boltz, Thomas

BackgroundPhysicians use fixed C‐arm fluoroscopy equipment with many interventional radiological and cardiological procedures. The associated effective dose to a patient is generally considered low risk, as the benefit‐risk ratio is almost certainly highly favorable. However, X‐ray‐induced skin injuries may occur due to high absorbed patient skin doses from complex fluoroscopically guided interventions (FGI). Suitable action levels for patient‐specific follow‐up could improve the clinical practice.There is a need for a refined metric regarding follow‐up of X‐ray‐induced patient injuries and the knowledge gap regarding skin dose‐related patient information from fluoroscopy devices must be filled. The most useful metric to indicate a risk of erythema, epilation or greater skin injury that also includes actionable information is the peak skin dose, that is, the largest dose to a region of skin.Materials and MethodsThe report is based on a comprehensive review of best practices and methods to estimate peak skin dose found in the scientific literature and situates the importance of the Digital Imaging and Communication in Medicine (DICOM) standard detailing pertinent information contained in the Radiation Dose Structured Report (RDSR) and DICOM image headers for FGI devices. Furthermore, the expertise of the task group members and consultants have been used to bridge and discuss different methods and associated available DICOM information for peak skin dose estimation.ResultsThe report contributes an extensive summary and discussion of the current state of the art in estimating peak skin dose with FGI procedures with regard to methodology and DICOM information. Improvements in skin dose estimation efforts with more refined DICOM information are suggested and discussed.ConclusionsThe endeavor of skin dose estimation is greatly aided by the continuing efforts of the scientific medical physics community, the numerous technology enhancements, the dose‐controlling features provided by the FGI device manufacturers, and the emergence and greater availability of the DICOM RDSR. Refined and new dosimetry systems continue to evolve and form the infrastructure for further improvements in accuracy. Dose‐related content and information systems capable of handling big data are emerging for patient dose monitoring and quality assurance tools for large‐scale multihospital enterprises.

The purpose of this study is to evaluate a direct measure of calcium burden by using dual‐energy computed tomography (DECT) during contrast‐enhanced coronary imaging, potentially eliminating the need for an extra noncontrast X‐ray acquisition. The ambiguity of separation of calcium from contrast material on contrast‐enhanced images was solved by using virtual noncontrast images obtained by DECT. A new threshold CT number was required to detect the calcium carrying potential risk for adverse coronary events on virtual noncontrast images. Two methods were investigated to determine the 130 HU threshold for DECT scoring. An in vitro anthropomorphic phantom with 29 excised patient calcium plaques inserted was used for both a linear and a logistic regression analysis. An IRB approved in vivo prospective study of six patients was also performed to be used for logistic regression analysis. The threshold found by logistic regression model to define the calcium burden on virtual noncontrast images detects the calcium carrying potential risk for adverse coronary events correctly (2.45% error rate). DECT calcium mass and volume scores obtained by using the threshold correlates with both conventional Agatston and volume scores . A conventional CT cardiac exam requires two scans, including a noncontrast scan for calcium quantification and a contrast‐enhanced scan for coronary angiography. With the ability to quantify calcium on DECT contrast‐enhanced images, a DECT cardiac exam could be accomplished with one contrast‐enhanced scan for both calcium quantification and coronary angiography.PACS numbers: 87.57.Q, 87.57.N

The current work describes an anthropomorphic beating heart phantom constructed as a tool for the assessment of technological advances in cardiac X‐ray computed tomography (CT). The phantom is comprised of a thorax, a compressor system, an ECG system, a beating heart with tortuous coronary arteries, and the option to add or remove pathologies such as aberrant beats, stents, and plaques. Initial trials with the phantom have shown its utility to assess temporal resolution, spatial resolution, radiation dose, iodine contrast, stents, and plaques.PACS numbers: 87.59.Fm, 87.57.Ce