X-Ray I_o Monitor Device for Primary Intensity Measurement in Computed Tomography (CT) Scanner

摘要

For a Computed Tomography (CT) Scanner used as a Non Destructive Testing (NDT) machine, 3D volume is reconstructed mathematically using un-attenuated (primary I_o) and attenuated (secondary I) intensities. Primary intensity (I_o) values are acquired from area of the imaging detector that is not covered by the object being tested. This procedure is prone to errors due to detector artifacts, nonlinear detector behavior, and scattered radiations detection as primary intensities, etc. This study is an attempt to make this procedure efficient and unimpeachable in which an X-ray I_o monitor device is designed and validated that permit precise detection of the primary intensity to obtain better normalization and consequently higher quality image. Using TSL235 photodiode from Texas Instrument the X-ray intensity measured in current is directly converted into frequency which provides high resolution and precise X-ray detection. The device is designed to be easily integrate with an existing CT machine and could be interfaced and read out with a standard Personal Computer (PC) without any need of additional hardware. Furthermore, this device could also be used for other applications, like direct measurement of scattered radiations to apply correction to data set of scan obtained.