Patent ID: 7541590

Claim:
A method to automate and extend the density range for gamma ray attenuation correction algorithms for a non-destructive assay system, the non-destructive assay system for conducting tomographic imaging of an object utilizing a low-intensity transmission beam and a high-intensity transmission beam, the object containing potentially radioactive material, the method comprising: measuring the un-attenuated low-intensity beam to obtain a low-intensity un-attenuated count rate; introducing an attenuating object between the transmitter and detector; measuring the attenuated low-intensity beam to obtain a low-intensity attenuated count rate; determining an attenuation factor; measuring the attenuated high-intensity beam to obtain a high-intensity count rate; determining the high-intensity un-attenuated count rate; determining the ratio using standard deviation estimates; imaging the object with the low-intensity transmission beam to obtain low-beam data; imaging the object with the high-intensity transmission beam to obtain high-beam data; imaging the object by collecting passive emissions to obtain passive-emissions data; creating an emissions map of the object utilizing the passive-emissions data; convolving the low-beam and high-beam data to obtain an attenuation map of the object; and overlaying the emissions map with the attenuation map to obtain a quantitative radiation map of the object.