MedPhys
Physik für FCRC
Physik für FCRC
piezoelectric effect
- quartz produces electric when compressed or expand
- lose the prperties when heated
acustic impedance
- Impedance = density x speed of sound
- Z = p x c
- independant to frequency f
- large Z = more reflexion
- small Z = less reflexion
Acustic impredance
- Total reflexion at air, because Zair is 0, and the difference of Z is large.
transducer
- linear
- curvilinear
- phased
- annular
ultrasound: A-mode
- Amplitude Mode
B-Mode
- Brightness mode
ultrasound quality
spatial resolution
- high frequency = high axial resolution (along the axis of the beam)
- focus the beam, more scan lines = high lateral resolution
ultrasound: doppler effect
- louder, when the object is moving towards
- less louder, when object is moving away
power doppler
- amplitude is the amount of the red blood calls, not the velocity
- quantity of the blood flow
Doppler with colors
- red = flow towards the transducer
- blue = flow away the transducer
- turbulence = green / yellow
harmonic frequency
- transducer frequency is the the 1st
- it changes through the tissue, so the harmonic frequencies are produced
ultrasound m-mode
- motion mode
ultrasound artefarct: speckle
- many small structures
- textured appearance
ultrasound artefarct: reverberation
- strong the reflector near the surface
- series of delayed echoes
ultrasound artefarct: double reflection
- diaphragma as a mirror
ultrasound artefarct:shadowing
- bowel gas, stone, bone
ultrasound artefarct: enhancement
- cyst, bladder
ultrasound artefarct:refraction
different velocity through the tissus
at the border
ultrasound artefarct: aliasing
- caused by under sampling
- colour change, and wrapped around
ultrasound contrast agent
- air-filledd (vascular, thrombosis)
- perfluorocarbon (liver, spleen, metastase)
- gold (combined with antibodies)
Nucleus
protons and neutrons
Atomic mass (A)
protons + neutrons
Atomic number
number of protons
nuclides
same protons = same element
Isotope
same chemical properties, but different physical properties
electron orbit
K: 2
outer orbit shell
valence
determines the chemical, electrical and thermal properties of the element
ion
electrons <> protons
electron excitation
gains energy and moves to higher energy outer shell
Binding energy E and atomic number Z of
Iodine?
Barium?
Tungsten?
Lead?
energy to remove the electron from the an atom
high, as Z=atomic number is high
high for electron in the inner shell, closer to the nucleus
Binding energy = E
energy to remove an electron from the shel
E increase = atomic numbre Z increase
E increase = K shell, near to the nucleus
Electromagnetic radiation (EMR)
speed of light in vacuum
3 x 108 m/s
magnetic and electric components
wave and particle component
X-Ray
EMR from the electron
Gamma ray
from the nucleus
EMR
the wave model
f = 1 Hz = 1/s
in different media f constant----- speed changes
EMR
the particle model
photon
Wave equation
v = f x λ
velocity = frequency x wavelength
Planck-Einstein equation
E = h x f
Photon energy = Planck constant x frequency
E=h x c /λ = 1,24 /λ
photon fluence
number of photons in a slice of the beam
energy fluence
energy of all the photons in a fluence
-
- 1 / 172
-
Cartes-fiches
power doppler
- amplitude is the amount of the red blood calls, not the velocity
- quantity of the blood flow
Doppler with colors
- red = flow towards the transducer
- blue = flow away the transducer
- turbulence = green / yellow
harmonic frequency
- transducer frequency is the the 1st
- it changes through the tissue, so the harmonic frequencies are produced
ultrasound m-mode
- motion mode
ultrasound artefarct: speckle
- many small structures
- textured appearance
ultrasound artefarct: reverberation
- strong the reflector near the surface
- series of delayed echoes
ultrasound artefarct: double reflection
- diaphragma as a mirror
ultrasound artefarct:shadowing
- bowel gas, stone, bone
ultrasound artefarct: enhancement
- cyst, bladder
ultrasound artefarct:refraction
different velocity through the tissus
at the border
ultrasound artefarct: aliasing
- caused by under sampling
- colour change, and wrapped around
ultrasound contrast agent
- air-filledd (vascular, thrombosis)
- perfluorocarbon (liver, spleen, metastase)
- gold (combined with antibodies)
