Imaging Flashcards
Importance of Radiology
Uses medical imaging technology to non-invasively diagnose and guide treatment of medical conditions
Imaging modalities
Radiography Computed Tomography Nuclear Medicine Ultrasounds Magnetic Resonance
Radiation
Energy traveling through space or matter
EM radiation: x rays from atomic shells, gamma rays from nucleus
Particulates: charged and uncharge particles
Projection Imaging
Generate Xrays
Detect transmitted Xrays
Use radiopaque contrast media to visualize structures
Flouroscopy
Real time imaging
Interventional procedure
Concerns about skin dose of radiation
X ray detection
Film measures density
The more dense the whiter it is
Benefits and Drawbacks of Radiography
Low dose radiation Simple, fast, inexpensive High resolution Need multiple projections Limited number of views Cant see 3d
Computed Tomography
Xray source rotates around patient taking multiple shots
Can see in 3D
Table can move during tube rotation for whole body scan
Helical or Spiral CT
Table moves while Xray tube rotates with no loss of information
Multiple Detector CT
Multiple images per one rotation of tube Fast Good for ER Better Quality Good for Cardiac
CT benefits and drawbacks
Fast scanning 3D Good contrast, High Res No need for exploratory surgery Bad soft tissue contrast Higher radiation dose Benefits typically outweigh risks
Nuclear Medicine
Molecular tracers tagged with radioactive atoms
Taken up orally or through IV
Wait a bit
Gamma camera captures emission
Single Photo Emission Computed Tomography
Single photon travels through body to camera
Good only for function
Need CT for anatomical information
Common isotopes for SPECT
Iodine-123 for Thyroid
Indium-111 for Treatment planning
Thallium-201 for Cardiac
Technetium-99m For everything
NM benefits and drawbacks
Sensitivity Functional imaging gives additional info Limited resolution Requires CT for anatomy High patient dose Complex to quantify
PET Scan
Short half life Internal uptake Positron meets electron to form two photons Photons interact in tissue PET is quantitative activity/ml
FDG
Flourodexoyglucose
Most Common Tracer for PET
Taken up in brain kidney and cancer cells
PET Benefits and Drawbacks
Sensitive Functional Limited Resolution Requires CT for anatomy Higher patient dose Expensive
MRI
High magnetic field
Uses non ionizing radiofrequency
Proton spin aligns with magnetic field and RF pulse shifts spin 90 degrees
T1 and T2 Weighted MRI
Longitudinal relaxation (T1) Transverse relaxation (T2)
MRI Drawbacks and Benefits
Good soft tissue High Res Different contrast Non-ionizing radiation Long scan times Expensive Patients may not be eligible Low sensitivity
Ultrasound
Most widely used imaging model
Reflected sound is detected by transducer to indicate depth
Applications of Ultrasound
Anesthesiology Cardiology Gastroenterology Neonatology Obstetrics Urology Musculoskeltal EM
Benefits and Drawbacks of Ultrasound
Inexpensive and fast No radiation dose Portable Limited contrast Difficult to see behind air filled cavities and bone
