Introduction to radiology and imaging Flashcards
What is radiology
Medical discipline that uses imaging to diagnose and treat disease
Different types of imaging that radiologists use
- xray
- Ultrasound
- Computed tomography
- MRI
- Nuclear medicine
What are the types of imaging that use ionising radiation
- Plain xray
- Computerised tomography
- Fluoroscopy
- Nuclear medicine
What type of imaging uses high frequency sound waves
Ultrasound
What type of imagine uses high strength magnet field and radio frequency waves
MRI
What structures are well visualised by ultrasound
Soft tissue, fat and fluid filled structures
Benefits of CT scans
- quick scanning of large areas of the body
- Provides good anatomical information in multiple planes
- Appropriate to assess for most acute clinical problems
Drawbacks of CT scans
- Can involve large doses of ionising radiation
- Risk of allergy to iodine based contrast
- Poor at assessing the spinal cord and reproductive organs
Benefits of fluoroscopy
- Real time anatomical assessment
- COmmonly used for interventional procedures
- Low radiation dose
Drawbacks of fluoroscopy
- Always require use of contrast agents
- Poor soft tissue assessment and overlapping anatomy
Benefits of MRI
- Doesnt use ionising radiation
- Excellent anatomical detail
- MUltiple phases enable some functional assessment of tissues
Drawbacks of MRI
Time consuming and expensive
- Safety issues regarding metallic implants
- Claustraphobic
Benefits of ultrasound
- Real time assessment
- Doesn’t involve ionising radiation
- Used for paediatric and antenatal imaging
Drawbacks for ultrasound
- Poor assessment of air filled structures and bone
- More heavily operator/patient dependent
- Attenuation of sound waves limits scan depth
Benefits of Nuclear Medicine
- large number of tracers available to assess different tissues
- Provides anatomical and functional information
- Allows more definitive assessment of pathology identified on other modalities
Drawbacks of Nuclear Medicine
- Scan acquisition is time consuming
- Poor resolution compared to alternative cross-sectional imaging
- Radiation exposure continues after termination of examination
Different between deterministic and stochastic effects
Deterministic- There is a threshold dose for symptoms of radiation
Stochastic- Assumes there is no threshold dose as the effects are not clear because of other cancer promoting factors such as drinking and smoking
Three laws to do with radiation
Ionising Radiation Regulations (IRR) = protection of employees against exposure
Ionising Radiation Medical Exposure Regulations (IRMER)
=Protects patients
ALARP Principle = acceptable region, tolerable region and unacceptable region
