Estimating patient peak skin dose with fluoroscopic procedures

Abstract: During image guided interventional radiology (IR) procedures, acute X-ray induced skin injuries may occur due to high absorbed patient skin dose. These procedures are highly dependent on X-ray imaging both for guiding fluoroscopy and high quality diagnostic image acquisitions. A dose metric that quantifies the peak absorbed skin dose (PSD) is therefore of great importance, both in terms of patient specific follow-up and for imaging protocol optimization. Presently, the cumulative interventional reference point (IRP) air Kerma is the most common skin dose estimation metric in use. This metric lacks several important dose contributions, such as pre-patient attenuation, air-to-skin medium correction, scattering from the patient and the support table, and fluence correction for actual source-to-skin distance. In this manuscript, we present a novel methodology for estimating the maximum absorbed skin dose by using dose related X-ray equipment parameters, such as peak tube voltage, support table position and IRP air Kerma obtained from radiation dose structured reports (RDSR) generated by modern IR equipment. In particular, Siemens Artis Zee (Siemens Healthineers, Erlangen, Germany) and Philips Allura Clarity (Philips, Amsterdam, Netherlands). The calculation process was automated by the development of a series of programming scripts in the PythonTM programming language v3.6 (Python Software Foundation), together with a database storing correction factors and machine specific parameters such as half-value layer (HVL). The proposed calculation model enables the implementation of a dose metric which corresponds better to absorbed skin dose than IRP air Kerma in clinical settings. However, extensive future work is required for a complete PSD implementation, in particular, the development of a skin dose map in which the spatial location of each irradiation event is tracked.