Linked PIC/Monte Carlo simulations for modeling X-ray radiography

Summary form only given. An integrated system simulation capability is under development to examine the fidelity of a dynamic radiographic system. This capability consists of a suite of simulation codes that, individually, model electromagnetic and particle transport phenomena and are linked together in a logical manner to model an entire radiographic event. Our integrated model currently consists of a particle-in-cell (PIC) code to model electron beam dynamics, and a Monte Carlo code to model bremsstrahlung production and photon transport. The photon flux at the detector is used to produce a synthetic radiograph, which is subsequently inverted to reconstruct the imaged object. The reconstructed object is compared to the actual object, thus allowing the system fidelity to be assessed. Our studies show that the electron beam spot size at the bremsstrahlung converter target is an important and direct measure on the accuracy of material edge location in the radiographic process; however, the angular distribution of the electron beam tends to have a much smaller effect on the fidelity. Furthermore, we found that quantitative analysis of material density requires that the full energy spectrum of the imaging photons be accurately modeled in the reconstruction of radiographic image. Incorporating the energy spectrum into the reconstruction algorithms is investigated.