MEDICAL IMAGING Dr. Hugh Blanton ENTC 4390
Lecture 1 EM Introduction
Dr. Blanton - ENTC Lab 2 3 Mass Mass Measure of the resistance of a body to acceleration. eg. Newton’s 2 nd Law
Dr. Blanton - ENTC Lab 2 4 Mass kg (kilograms) is a lot of mass in the nuclear physics world. Define 1 atomic mass unit (amu) = 1/12 mass of 1 atom of Carbon 12
Dr. Blanton - ENTC Lab 2 5 Energy Energy The ability to do work. For electrical forces:
Dr. Blanton - ENTC Lab 2 6 Electron-Volt For 1 electron moving in a 1V potential difference, Define this as 1 electron-Volt (eV)
Dr. Blanton - ENTC Lab 2 7 Conservation of Mass c is the speed of light
Dr. Blanton - ENTC Lab 2 8
EM Radiation
Dr. Blanton - ENTC Lab 2 10 Two ways to transfer energy from one body to another: particle—kinetic energy wave—propagation of a disturbance. EM radiation has properties of both of these—the wave/particle duality.
Dr. Blanton - ENTC Lab 2 11 Waves Longitudinal waves—disturbance in the direction of propagation. eg. sound Animation courtesy of Dr. Dan Russell, Kettering University
Dr. Blanton - ENTC Lab 2 12 Transverse waves—disturbance perpendicular to direction of propagation. eg. waves in the ocean Animation courtesy of Dr. Dan Russell, Kettering University
Dr. Blanton - ENTC Lab 2 13 Regardless of the type of wave, they can be characterized by: wavelength frequency (f) phase velocity amplitude
Dr. Blanton - ENTC Lab 2 14 Wave characteristics of EM radiation: EM radiation can be seen to be a transverse wave of particular oscillations of electric and magnetic fields. wavelength oscillatory electric field (force) perpendicular magnetic field (force)
Dr. Blanton - ENTC Lab 2 15 EM radiation has wave characteristics such as: reflection refraction interference
Dr. Blanton - ENTC Lab 2 16
Dr. Blanton - ENTC Lab 2 17 Particle characteristics of EM radiation: Particles of EM radiation are called quanta or photons. Photons can be thought of as wave packets of electric and magnetic fields wavelength oscillatory electric field (force) perpendicular magnetic field (force)
Dr. Blanton - ENTC Lab 2 18 h is Planck’s constant
Example What is the frequency and for 100 keV photons? Dr. Blanton - ENTC Lab 2 19
What is the frequency and for 100 keV photons? Dr. Blanton - ENTC Lab 2 20
Dr. Blanton - ENTC Lab 2 21 EM Radiation Low E, long —Acts like wave. High E, short —Acts like particles.
Dr. Blanton - ENTC Lab 2 22 Scientists have observed that electromagnetic radiation has a dual "personality." Besides acting like waves. It acts like a stream of particles (called "photons") that have no mass. The photons with the highest energy correspond to the shortest wavelengths.
Dr. Blanton - ENTC Lab 2 23 Electromagnetic waves are produced by the motion of electrically charged particles. These waves are also called "electromagnetic radiation" because they radiate from the electrically charged particles. They travel through empty space as well as through air and other substances.