Absorbed Dose Estimation for Computed Tomography by Method of Characteristics Deterministic Simulation


Organ dose estimation in CT scanning is very important. Monte Carlo methods are considered gold standard in patient dose estimation, but the computation time is formidable for routine clinical calculations. A more efficient approach to estimate the absorbed dose is to solve the linear Boltzmann equation numerically. In this study, an axial CT scan is modeled with the deterministic code TRANSFX, which solves the linear Boltzmann equation using the method of characteristics. The CT scanning model includes 16 X-ray sources, beam collimators, flat filters, and bowtie filters. The phantom is the standard 32 cm CTDI phantom. A Monte Carlo simulation was performed to benchmark the TRANSFX simulations. Comparisons of simulation results were made between TRANSFX and Monte Carlo methods. The deterministic simulation results are in good agreement with the Monte Carlo simulation. It has been found that the method of characteristics underestimates the flux near the periphery of the phantom (i.e. high dose region). The simulation results show that deterministic method can be used to estimate the absorbed dose in CTDI phantom. The accuracy of the method of characteristics is close to that of a Monte Carlo simulation at low dose region. The benefit of the method of characteristics is its potentially faster computation speed. Further optimization of this method in routine clinical CT dose estimation is expected to improve its accuracy and speed.

Meeting Name

Mathematics and Computations, Supercomputing in Nuclear Applications and Monte Carlo International Conference, M and C+SNA+MC 2015 (2015: Apr. 19-23, Nashville, TN)


Nuclear Engineering and Radiation Science

Keywords and Phrases

Boltzmann equation; Computerized tomography; Estimation; Intelligent systems; Tomography; Absorbed dose; Computation speed; Computation time; Deterministic methods; Deterministic simulation; Dose estimations; Linear Boltzmann equation; Method of characteristics; Monte Carlo methods; Absorbed dose; Computed tomography

International Standard Book Number (ISBN)


Document Type

Article - Conference proceedings

Document Version


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© 2015 American Nuclear Society (ANS), All rights reserved.

Publication Date

01 Apr 2015