Transcript Medical Imaging - Davidson College
Medical Imaging
Allison Amore April Barnado May 5, 2004
Types of Medical Imaging
• Ultrasound • X-ray • CAT or CT Scan • PET Scan • NMR • MRI
Ultrasound
• How does it work?
–
Pulse-echo technique
• • •
use of transducer d = tv measurement of distances and intensities
• Uses – One of most common medical imaging – important for monitoring fetal development
Ultrasound: Pulse Echo Technique
Ultrasound
• How does it work?
–
Pulse-echo technique
• • •
use of transducer d = tv measurement of distances and intensities
• Uses – One of most common medical imaging – important for monitoring fetal development
Evolution of Ultrasound
X-Rays
• Wavelength: 10 -9 to 10 -11 meters
– Cathode (heated filament and current) – Anode (Tungsten)
• Uses – Detecting bone injuries
CAT or CT Scan
• CT = Computerized Tomography • CAT = Computerized Axial Tomography • Basic procedure • How is image formed?
• Uses – Detect brain tumors, vascular injuries – Can show soft tissue, blood vessels, and bone all on the same image
CAT Scans
CAT Scans
CAT or CT Scan
• CT = Computerized Tomography • CAT = Computerized Axial Tomography • Basic procedure • How is image formed?
• Uses – Detect brain tumors, vascular injuries – Can show soft tissue, blood vessels, and bone all on the same image
PET Scans
• • Positron Emission Tomography • Detects radiation emitted by radioactive substances • Substances injected into body are tagged – usually 11 C, 18 F, 15 O, or 13 N http://science.howstuffworks.com/nuclear medicine2.htm
11
C
5 11
C
6
e
e
e
2 • can show blood flow and other biological processes
How a PET Scan Works
NMR
• NMR = Nuclear Magnetic Resonance • Magnets – Spin – Energy split – hf = ∆E = kB
MRI
• MRI = Magnetic Resonance Imaging • Use of Hydrogen • Magnetic and RF coils • Image detection
MRI
MRI
• 3 types of magnets – Resistive – Permanent – Superconducting • Most commonly used • Strength of magnet – 0.5 - 2.0 tesla – Earth’s field = 0.5 * 10 -4 tesla
References
• http://science.howstuffworks.com/ultrasou nd1.htm
• http://science.howstuffworks.com/nuclear medicine2.htm
• http://science.howstuffworks.com/x ray2.htm
• http://www.phy.davidson.edu/history.html
• http://www.gehealthcare.com/rad/us/4d/the nnow.html
References
• http://www.doctorspiller.com/Dental%20_X-Rays.htm
• Giancoli, Douglas.
Physics: Principles with Applications.
5 th edition. Prentice Hall, NJ, 1998.
• • Rubin, Rita. “Dental X-rays in pregnancy linked to low birth weight.”
USA Today
. Front page, April 29, 2004. http://www.radiologyinfo.org/content/ct_of_the_head.htm
• Hobbie, Russell K. Intermediate
Physics for Medicine and Biology.
3 rd edition. Springer-Velager, NY, 1997.
The End
How X-rays work?
Early X-Rays
Interesting Facts
• Full-mouth x-rays: 1.6 milligrays – Equivalent to atmospheric radiation received from 16 round trip flights from New York to London • “bitewing” series – Equivalent of just 2 roundtrips