Radiology Flashcards
Radiology basics
-coventional radiographs
-ultrasound
-computated tomography
-MRI
-bone scans
Conventional radiography/ X-Rays
-are a form of energy
-2D image of 3D structure
-electromagnetic spectrum
What are the indications for X-rays?
-trauma
-infective processes
-skeletal survey
-follow up after Rx
what are the advantages of X-Rays
-easily accessible
-quick
-does not require special assessment
-inexpensive
-bed side
What are the disadvantages of X-Rays?
-overlap of tissues
-ionizing radiation increases risk of malignancy
caution for pregnant patients
Ultrasound
-a beam of high frequency is shot into soft tissue
-the sound returns to same probe
-various tissues bounce the signal back creating an image
-gel is used to reduce air because sound waves cannot travel through air
-this reduces reflection and acoustic impedence which allows for a clear picture
-used in solid and fluid-containing structures
-not for air containing structures and bone
Types of ultrasound probes
-curvilinear probes have lower frequency and penetrate deeper
-linear probes have higher frequency and for superficial structures
What are the indications for ultrasound?
-abdominal and pelvic organs
-muscles and tendons
-thyroid
-cranial sonar
-vascular and cardiac
What are the Advantages of Ultrasound?
-portable and relatively cheap
-no ionizing radiation, so safe for pregnant patients
-real time imaging
-doppler studies
-user independent
Computated Tomography
-an X-Ray tube that spins pt around very fast with row of receptors on other side spinning on same axis
-attenuation is constantly recorded at various angles
-allows 3D imags from multi planar and volume rendering
-uses hounsfield unit to measure radiodensity
-0 (water)- 1000 (air)
What are the advantages of CT?
-very quick
-gold standard for trauma and lung
-good for calcification
-staging malignancies
What are the disadvantages of CT?
-high dose ionizing radiation
-not bedside
-motion artefacts
-caution in pregnant and pediatrics
-no contrast medium in renal failure
Contrast vs. no contrast
-non-contrast includes bleeds and stones
-contrast includes infections, malignancies and vascular pathology
-CT angiograms indicate aneurysms, dissections and injuries
MRI
-align all H+ atoms that interact with radiowaves
-protons flip back into OG direction and give off radio waves
-coils detect the radiowaves
-characteristics of tissues determine signal retrieved
What are the advantages of MRI?
-best soft tissue resolution
-brain, SC and MSK
-no radiation
-contrast not iodine based, more renal friendly
