(Tuesday, 7/16/2019) 9:30 AM - 10:00 AM
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, Radimetrics™, is used to query/retrieve the fluoroscopy exam’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 patients’ 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 phantom’s surface (Figure-2). Then, PSD calculations are performed using the new method described above and the traditional “dose-conservative� 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 “dose-conservative� 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 “dose-conservative� method, with dose differences of 42%-53%.
Conclusion: Estimated PSD using a new calculation method is more accurate than when the traditional “dose-conservative� method is applied, improving patient follow-up recommendations to performing physicians.
Keywords
Fluoroscopy, Surface Dose, Modeling
Taxonomy
IM- Radiation dose and risk: General (Most Aspects)
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