Rayleigh scatter in kilovoltage x-ray imaging: is the independent atom approximation good enough? Export

@article{montecarloscatter_poludniowski_2009, abstract = {Monte Carlo simulation is the gold standard method for modelling scattering processes in medical x-ray imaging. General-purpose Monte Carlo codes, however, typically use the independent atom approximation (IAA). This is known to be inaccurate for Rayleigh scattering, for many materials, in the forward direction. This work addresses whether the IAA is sufficient for the typical modelling tasks in medical kilovoltage x-ray imaging. As a means of comparison, we incorporate a more realistic 'interference function' model into a custom-written Monte Carlo code. First, we conduct simulations of scatter from isolated voxels of soft tissue, adipose, cortical bone and spongiosa. Then, we simulate scatter profiles from a cylinder of water and from phantoms of a patient's head, thorax and pelvis, constructed from diagnostic-quality CT data sets. Lastly, we reconstruct CT numbers from simulated sets of projection images and investigate the quantitative effects of the approximation. We show that the IAA can produce errors of several per cent of the total scatter, across a projection image, for typical x-ray beams and patients. The errors in reconstructed CT number, however, for the phantoms simulated, were small (typically \< 10 HU). The IAA can therefore be considered sufficient for the modelling of scatter correction in CT imaging. Where accurate quantitative estimates of scatter in individual projection images are required, however, the appropriate interference functions should be included.}, author = {Poludniowski, G. and Evans, P. M. and Webb, S.}, citeulike-article-id = {6090794}, citeulike-linkout-0 = {http://dx.doi.org/10.1088/0031-9155/54/22/012}, doi = {10.1088/0031-9155/54/22/012}, journal = {Physics in Medicine and Biology}, keywords = {coherent, iam, medical, monte\_carlo, physics, scattering, x-ray}, number = {22}, pages = {6931--6942}, posted-at = {2009-11-09 22:14:44}, priority = {2}, title = {Rayleigh scatter in kilovoltage x-ray imaging: is the independent atom approximation good enough?}, url = {http://dx.doi.org/10.1088/0031-9155/54/22/012}, volume = {54}, year = {2009} }

TY - JOUR ID - montecarloscatter_poludniowski_2009 L3 - citeulike-article-id:6090794 N2 - Monte Carlo simulation is the gold standard method for modelling scattering processes in medical x-ray imaging. General-purpose Monte Carlo codes, however, typically use the independent atom approximation (IAA). This is known to be inaccurate for Rayleigh scattering, for many materials, in the forward direction. This work addresses whether the IAA is sufficient for the typical modelling tasks in medical kilovoltage x-ray imaging. As a means of comparison, we incorporate a more realistic 'interference function' model into a custom-written Monte Carlo code. First, we conduct simulations of scatter from isolated voxels of soft tissue, adipose, cortical bone and spongiosa. Then, we simulate scatter profiles from a cylinder of water and from phantoms of a patient's head, thorax and pelvis, constructed from diagnostic-quality CT data sets. Lastly, we reconstruct CT numbers from simulated sets of projection images and investigate the quantitative effects of the approximation. We show that the IAA can produce errors of several per cent of the total scatter, across a projection image, for typical x-ray beams and patients. The errors in reconstructed CT number, however, for the phantoms simulated, were small (typically < 10 HU). The IAA can therefore be considered sufficient for the modelling of scatter correction in CT imaging. Where accurate quantitative estimates of scatter in individual projection images are required, however, the appropriate interference functions should be included. IS - 22 JF - Physics in Medicine and Biology EP - 6942 TI - Rayleigh scatter in kilovoltage x-ray imaging: is the independent atom approximation good enough? VL - 54 SP - 6931 KW - coherent KW - iam KW - medical KW - monte_carlo KW - physics KW - scattering KW - x-ray AU - Poludniowski, G AU - Evans, PM AU - Webb, S PY - 2009/// UR - http://dx.doi.org/10.1088/0031-9155/54/22/012 ER -