Transmission computer tomography

Transmission Computer Tomography 10 pm high resolution for matrix structure no contrast for flow measurments... 

The world average annual impact from natural sources results in 2-3 mSv effective dose half of that dose derives from the radon component, due to the inhalation of radon daughters (UNSCEAR 2000). The contribution of cosmic rays to the natural background can be assessed at 0.35 mSv per year. The dose consequence of a transmission computer tomography for a typical adult patient is about 50 mGy of absorbed dose in the head, and the average individual dose due to an in vivo diagnostic test in nuclear medicine involves 2-5 mSv effective dose. 

Lang TF, Hasegawa BH, Soo Chin L, Keenan Brown J, Blankespoor SC, Reilly SM, Gingold EL, Cann CE. Description of a prototype emission-transmission computed tomography imaging system. JNuclMed 1992 33 1881-1887. 

Neutron or y Sensors Neutron- or y -based sensors are similar in concept to the X-ray sensors. They use different forms of excitation and different detectors, but the basic forms of transmission or backscatter follow the pattern described above. Both normally rely on extensive computation for signal processing called computed tomography, where the detector signals are combined to synthesize an image of the irradiated object. 

With ultrasound velocity tomography the local speed of ultrasound in a cross section of the subject under study is computed from a large set of ultrasound transmission times. These calculations (reconstructions) are based upon a model that describes the propagation of ultrasound in a medium. In its simplest form the ultrasonic pulses are supposed to travel along straight pathways from transmitter to receiver. The measured transmission times depends on the velocity distribution v(jc, y) in the plane of reconstruction ... 

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