The purpose of this study was to develop and validate a projection-based dose metric that enables computationally efficient dose estimation. The two physical quantities determining dose, absorbed energy and mass, were estimated in projection space. The absorbed energy was estimated using the difference between the imparted energy and detected energy. The mass was estimated using the area under the attenuation profile. A series of phantom simulations were conducted to test the metric’s applicability for multi-material phantoms, different kVp settings, and bowtie filters. Projection-based dose estimates were benchmarked against results from the Monte Carlo (MC) simulation. The projection-based dose metric shows a strong linear correlation with MC dose estimates (R² > 0.96). The prediction errors for projection-based dose metric are below 14%. This study demonstrates a computationally efficient and relatively accurate dose estimation method based on the projection data. It further suggests the possibility to achieve real-time and patient-specific dose optimization when applied prior to a CT scan.

Date Published: 19 March 2013
PDF: 9 pages
Proc. SPIE 8668, Medical Imaging 2013: Physics of Medical Imaging, 866829 (19 March 2013); doi: 10.1117/12.2008051

Published in SPIE Proceedings Vol. 8668:
Medical Imaging 2013: Physics of Medical Imaging
Robert M. Nishikawa; Bruce R. Whiting; Christoph Hoeschen, Editor(s)