Week 3 Introduction to Medical Imaging Flashcards
How does radiography work?
X-rays are shot through a body part, but only some make it through (based on electron density). The ones that do are captured on the other end and recorded as an image
What are benefits of radiogrpahy (2)?
fast, great resolution
what are the limitations of radiography? (2)
poor tissue contrast, radiation
how does CT work? what does CT stand for?
Computed tomography. makes use of computer-processed combinations of many X-ray images taken from different angles to produce cross-sectional (tomographic) images (virtual “slices”) of specific areas
how does radiography show tissue differences?
different electron density
how does CT scan show tissue differences?
different attenuation of X-rays relative to water
what is a benefit of the CT scan?
has very good contrast (all tissue densities show up)
what are some negatives of the CT?
huge amount of radiation
How does an MRI work? what does MRI stand for/
Magnetic resonance imaging. essentially a huge magnetic sends a signal to the nucleus and then the rate at which the nuclei of different tissues is recorded.
what type of energy does MRI use?
radiofrequency waves
how does MRI show tissue differences
different rates of nuclear relaxation
what are benefits to MRI (2)?
best tissue contrast. no radiation
what are some limits to MRI (3)
slow, expensive, magnet danger
how does ultrasound work?
a sound signal is sent, bounces of objects, and is recorded. (dolphins, sonar)
what type of energy does ultrasound use?
sound waves
how does ultrasound show tissue differences?
different acoustic impedance
what are 2 benefits of ultrasound?
real time imaging, no radiation
what are two limits to ultrasound?
user dependent, many artifacts
how does nuclear medicine work?
radioactive material is taken in and then a special camera takes pictures of the material inside your body
what is the source of energy in nuclear medicine?
gamma-rays
how does nuclear medicine show tissue differences?
different levels of radioactivity
what is the benefit to nuclear medicine?
see physiology and pathophysiology in action
what are two limitations to nuclear medicine?
worst resolution, radiation
