ABSTRACT
X-ray images are acquired by transmitting X-rays through an object and recording the transmitted rays on ‹lm or with electronic detectors. X-rays are attenuated as they travel through an object, similar to the attenuation of visible light as it travels through a semiopaque material. The magnitude of attenuation depends on both the material and the distance the X-rays have to traverse in the material. The recorded intensity of the acquired image, therefore, provides information about the internal structure of the radiographed object. In medical imaging, X-rays have a wide range
CONTENTS
11.1 Introduction ................................................................................................ 203 11.2 What Are X-Rays? ...................................................................................... 204 11.3 Production of X-Rays and X-Ray Spectra ............................................... 205 11.4 Interaction of X-Rays with Matter ........................................................... 207
11.4.1 Rayleigh Scattering ........................................................................ 207 11.4.2 Compton Scattering ....................................................................... 207 11.4.3 Photoelectric Absorption .............................................................. 207 11.4.4 Implications for Medical Imaging ............................................... 209 11.4.5 Attenuation Coef‹cients ............................................................... 209
11.5 Planar X-Ray Imaging and C-arm Systems ............................................ 210 11.6 X-Ray Computed Tomography ................................................................ 212
11.6.1 Representation of CT Images ....................................................... 214 11.6.2 Scan Parameters, Image Quality, and Artifacts......................... 214 11.6.3 Additional X-Ray CT Applications .............................................. 215
11.6.3.1 Dual Energy ..................................................................... 215 11.6.3.2 CT Fluoroscopy ............................................................... 215 11.6.3.3 Perfusion CT .................................................................... 215
11.7 Conclusions ................................................................................................. 216 Suggested Reading .............................................................................................. 216
of applications and provide complementary information to other imaging modalities like magnetic resonance imaging (MRI), positron emission tomography (PET), single-photon emission computed tomography (SPECT), and ultrasound.
