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**Chapter 0**

**Chapter 6**

**Recent Developments on Compton Scatter**

T. T. Truong and M. K. Nguyen

http://dx.doi.org/10.5772/50012

**1. Introduction**

[35, 47].

(or positron) radio-activity density for PET.

properly cited.

Additional information is available at the end of the chapter

**Tomography: Theory and Numerical Simulations**

Progress in nuclear physics acquired during World War II has naturally led many scientists to devote their research activities to the field of tomographic imaging techniques using ionizing radiation. This was, in the post-war booming economy, particularly of great importance for medical diagnostic as well as for industrial non destructive evaluation (NDE). As the objective is to extract information on the inner part of objects of interest, penetrating radiation was the most appropriate agent for this purpose. With the availability of high quality X-ray and gamma-ray sources (either directly originated from nuclear transitions or from pair annihilation) and the emergence of sensitive detectors, three types of imaging have been introduced and developed throughout half a century. Nowadays they have emerged as

These are: a) the X-ray transmission Computed Tomography (CT), which exploits the physical law of radiation attenuation in matter, b) the Single Photon Emission Tomography (SPECT), which uses the possibility of implanting radiation sources inside objects, c) the Positron Emission Tomography (PET), which uses the possibility of implanting positron sources in objects and exploits the properties of electron-positron pair annihilation. Milestones of their sensational evolution throughout decades are vividly recalled in recent reviews, see *e.g.*

It is observed that all three cited imaging methods deal exclusively with primary (or non-deviated) radiation. The physical quantity, which is non-uniformly distributed over an object and responsible for the imaging process, is respectively: the linear attenuation coefficient for CT, the *γ*-ray radio-activity density inside the object for SPECT, and the *β*+-ray

However right at the start, scientists were also attracted by the idea of using scattered radiation by Compton effect (the scattering of X- or gamma photons by an electron) to image the inner parts of an object by reconstructing its electron density map. While this last imaging technology has not yet reached the same level of maturity as the three quoted above, it has

and reproduction in any medium, provided the original work is properly cited.

©2012 Truong and Nguyen, licensee InTech. This is an open access chapter distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is

© 2012 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution,

mature standard investigation methods for several domains of application.

