1_Introduction to Medical Imaging (1)

Introduction to Medical Imaging – Chapter 1
Radiation and the Atom – Chapter 2
17-Feb-20
Contrast – What does it depend on?
Radiation must interact with the body’s various tissues in
some differential manner to provide contrast
X-ray/CT: differences in e - density (e - /cm 3 = r ∙ e - /gr)
Ultrasound: differences in acoustic impedance (Z = r·c)
MRI: endogenous and exogenous differences
endogenous: T1, T2, r H , flow, perfusion, diffusion
exogenous: TR, TE, and TI
NM: concentration (r) of radionuclide or b + emitter
Contrast agents exaggerate natural contrast levels
Iodinated (x-ray/CT)
Paramagnetic (MRI)
Microspheres (US)
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Radiation and the Physics of Medical Imaging
“Without radiation, life itself would
be impossible” – Prof. Stewart
“Radiation is all around us. From
natural sources like the Sun to
man made sources that provide
life saving medical benefits,
smoke detectors, etc...”
- nuclearactive.com
“You’re soaking in it” – Madge,
Palmolive spokeswoman
“10 mGy/day keeps the Dr. away”
"It’s not the volts that’ll get ya, it’s
the amps.“ – Billy Crystal,
Running Scared
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BME HCMUT 12