Room: Exhibit Hall | Forum 8
Purpose: A more accurate peak skin dose (PSD) estimate for fluoroscopy-guided interventional procedures (FGI) can be obtained by accounting for X-ray tube angulation, table positions and patient dimensions. An algorithm for calculating and reporting PSD, which includes these factors, is described and validated.
Methods: A procedure was written describing the process of calculating a PSD (Figure-1) and the assumptions used. Radiation dose management system, Radimetricsâ„¢, is used to query/retrieve the fluoroscopy examâ€™s radiation dose structured report (RDSR) and exports acquisition parameters in a Microsoft Excel format. PSD calculation utilizes parameters within the RDSR including IRP air-kerma, primary and secondary x-ray tube angles, and table coordinates to determine the acquisition-specific source to skin distances (SSD) and skin entrance air-kerma. Field overlap as a function of angulation and patient size is then used to determine the cumulative skin dose from the FGI. Patients are modeled as ellipsoids referring to each patientsâ€™ dimensions obtained from recent CT scans to the FGI region of interest. Validation testing of the PSD calculation method is done by performing FGI on a phantom, with varying levels of complexity. PSD measurements are obtained using radiation detectors positioned on the phantomâ€™s surface (Figure-2). Then, PSD calculations are performed using the new method described above and the traditional â€œdose-conservativeâ€? method. Comparisons between the measured and calculated PSD values determine the level of accuracy the new method provides.
Results: The calculated PSD estimates using the new method, the traditional â€œdose-conservativeâ€? method and the PSD measurements are described and analyzed. Preliminary results suggest that the new method yields more accurate and lower PSD estimates than the â€œdose-conservativeâ€? method, with dose differences of 42%-53%.
Conclusion: Estimated PSD using a new calculation method is more accurate than when the traditional â€œdose-conservativeâ€? method is applied, improving patient follow-up recommendations to performing physicians.