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Electromagnetic Radiation. Visible light, radio waves, x-raysNo mass; unaffected by electrical or magnetic fields; constant speed in a given mediumTravels in straight lines; trajectory can be altered by interaction with matterAbsorption removal of the radiationScattering change in trajectory
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1. Radiation and the Atom
2. Electromagnetic Radiation Visible light, radio waves, x-rays
No mass; unaffected by electrical or magnetic fields; constant speed in a given medium
Travels in straight lines; trajectory can be altered by interaction with matter
Absorption – removal of the radiation
Scattering – change in trajectory
4. EM Radiation in Imaging Gamma rays – originate within nuclei of radioactive atoms; used to image the distribution of radiopharmaceuticals
X-rays – produced outside the nucleus; used in radiography and computed tomography
Visible light – produced in detecting x- and gamma rays; used for observation and interpretation of images
Radiofrequency EM in the FM region – used as the transmission and reception signal for MRI
5. EM Wave Characteristics Waves characterized by amplitude, wavelength (?), frequency (?), and period Speed (c), wavelength, and frequency related by Wavelengths typically measured in nanometers (10-9 m); frequency expressed in hertz (Hz) (1 Hz = 1 cycle/sec = 1 sec-1)