MEDICAL IMAGING Dr Hugh Blanton ENTC 4390 Lecture

MEDICAL IMAGING Dr. Hugh Blanton ENTC 4390

Lecture 1 EM Introduction

Mass • Mass Measure of the resistance of a body to acceleration. • eg. • Newton’s 2 nd Law Dr. Blanton - ENTC 4337 - Lab 2 3

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 4337 - Lab 2 4

Energy • Energy The ability to do work. • • For electrical forces: • Dr. Blanton - ENTC 4337 - Lab 2 5

Electron-Volt • For 1 electron moving in a 1 V potential difference, • • Define this as 1 electron-Volt (e. V) Dr. Blanton - ENTC 4337 - Lab 2 6

Conservation of Mass • • c is the speed of light • Dr. Blanton - ENTC 4337 - Lab 2 7

• Dr. Blanton - ENTC 4337 - Lab 2 8

EM Radiation

• 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 4337 - Lab 2 10

Waves • Longitudinal waves—disturbance in the direction of propagation. • eg. sound Animation courtesy of Dr. Dan Russell, Kettering University Dr. Blanton - ENTC 4337 - Lab 2 11

• Transverse waves—disturbance perpendicular to direction of propagation. • eg. waves in the ocean Animation courtesy of Dr. Dan Russell, Kettering University Dr. Blanton - ENTC 4337 - Lab 2 12

• Regardless of the type of wave, they can be characterized by: • • • wavelength (l) frequency (f) phase (f) velocity (n) amplitude Dr. Blanton - ENTC 4337 - Lab 2 13

• Wave characteristics of EM radiation: • EM radiation can be seen to be a transverse wave of particular oscillations of electric and magnetic fields. oscillatory electric field (force) Dr. Blanton - ENTC 4337 - Lab 2 perpendicular magnetic field (force) wavelength 14

• EM radiation has wave characteristics such as: • reflection • refraction • interference Dr. Blanton - ENTC 4337 - Lab 2 15

Dr. Blanton - ENTC 4337 - Lab 2 16

• 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 perpendicular magnetic field (force) oscillatory electric field (force) wavelength Dr. Blanton - ENTC 4337 - Lab 2 17

• h is Planck’s constant Dr. Blanton - ENTC 4337 - Lab 2 18

Example • What is the frequency and l for 100 ke. V photons? Dr. Blanton - ENTC 4337 - Lab 2 19

• What is the frequency and l for 100 ke. V photons? Dr. Blanton - ENTC 4337 - Lab 2 20

EM Radiation Low E, long l—Acts like wave. High E, short l—Acts like particles. Dr. Blanton - ENTC 4337 - Lab 2 21

• 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 4337 - Lab 2 22

• 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. Dr. Blanton - ENTC 4337 - Lab 2 23