P023] Estimating patient peak skin dose with fluoroscopic procedures

Abstract

Purpose Deterministic radiation induced patient skin injuries may be caused by time consuming and complex fluoroscopic procedures. Post-procedure dose analysis can provide valuable feedback for optimisation of exposures in interventional radiology and follow-up of individual patients. However, lack of accuracy when estimating patient peak skin dose (PSD) can lead to inappropriate action levels and follow-up routines. It is common to use action levels entirely based on the interventional reference point (IRP) cumulative Air kerma, spatially located 15 cm from the irradiation geometry isocentre. This metric lacks influence of physical effects needed to estimate PSD, e.g., specifics of the irradiation event, conversion of Air kerma to absorbed skin dose, scattered radiation, and pre-patient attenuation. Modern radiologic equipment commonly reports irradiation event details in a radiation dose structured report (RDSR), as described by the NEMA DICOM standard. For fluoroscopy equipment the RDSR contains important information, e.g., X-ray beam field size, IRP Air kerma, number of images, X-ray beam filtration and X-ray tube voltage. The RDSR is thus a useful data source for estimation of PSD with fluoroscopic procedures. Methods Pertinent correction methods and data for PSD estimation were summarized by literature review and beam quality- and geometry dependent functions were developed in the PythonTM programming language v3.6 (Python Software Foundation). The RDSR from two different fluoroscopic devices; Siemens Artis Zee (Siemens Healthineers, Erlangen, Germany) and Philips Allura Clarity (Philips, Amsterdam, Netherlands), were examined and information required as input for the developed functions was identified. Results This work resulted in an open source Python™ script for RDSR parsing and patient PSD estimation; including table-top and mattress attenuation, Air kerma to absorbed skin dose conversion, forward and back scatter. PSD estimates were verified and compared to IRP Air-kerma. Conclusions The estimation of patient PSD with fluoroscopic procedures is greatly assisted by information found in fluoroscopy device RDSR. With refined dose metrics the specificity of patient PSD estimates may be increased, e.g., compared to the IRP Air kerma. Combining RDSR information and novel methods for refining patient dose metrics found in the literature can improve the management of patients after interventional radiology procedures.