Advanced Biomedical Imaging. Dr. Azza Helal A. Prof. of Medical Physics Faculty of Medicine Alexandria University. Intended learning outcomes of the course (ILOS). To understand physical principles of imaging modalities. Aiming to apply these modalities in a safe and effective way.
Dr. Azza Helal
A. Prof. of Medical PhysicsFaculty of MedicineAlexandria University
1.(+ve nuc. & –ve e).
Prevent ele. from leaving atom
Electron mass 1800 time < p or n
K shell, L,M,N,O
Dr Azza Helal
X Rays are high-energy EM radiation and part of EM spectrum
High-speed electrons suddenly slowed down releasing part of their energy as X-Rays.
Dr Azza Helal
Copper anode block
Tungsten target (high Z material)
high melting point
high thermal conductivity
More efficient X-Ray production
Therapeutic x-ray tube: Mega electron volts (MeV) are used, a higher conversion of electrons into photons, high KV, larger focal spot, longer duration & stationary anode.
Diagnostic x ray tube: (KeV), there is more conversion of the electrons to heat, low KV, small focal spot, short duration & rotating anode.
Total number of electrons converted to heat is 99%.
Only 1% of the electrons are converted to photons
Probing patient from different directions during 360
rotations with x-ray beam of known intensity (I0) &
measuring it after it has passed the pt (I).
Attenuation depends thickness and density of tissues
or multiple films
New technologies are
characteristics of the interfaces.
Time between pulse emission and echo return determines depth
Velocity =Distance/ Time
DR Azza Helal
One student will be selected for assignment
David Sutton’s Radiology
Physics for medical imaging by RF Fare & PJ Allisy-Roberts.
Mention different components of x ray tube?