Basics of Radiology Flashcards
What is the rough risk for children from CT Scans?
- 1:10’000 increased risk for children >5yrs old
- 1:1000 risk <5yo
- Most commonly brain tumours and leukaemia
What simple measures can be used to allow babies to have CT scans?
- Ensure the baby is fed before the scan
- Swaddling the baby
- Pacifier if used
- Music playing ie a lullaby
- Simple analgesia ie paracetamol or sucrose
What ionizing scan has the least radiation for the diagnosis of PE in pregnancy?
If going to use an ionizing radiation scan in pregnancy then perfusion only VQ scan has the least radiation
- VQ has injected radioactive material and inhaled radioactive material
- Need perfusion aspect to see the VTE
What is the conversion between Sieverts and Greys in terms of radiation? What do they each represent?
Greys (Gy)
- The mean absorbed dose of radiation
- Alternatively measured as j/kg
Sieverts (Sv)
- The equivalent or effective dose
- Also measured as j/kg
Difference
- Sv takes into account the overall dose of radiation from different types ie alpha/beta particles and photons
- Gy is per unit/mass of tissue
- The difference occurs when a patient is exposed to multiple types of radiation and thus different areas have different exposure
- In medicine usually only photons are used so 1Gy = 1Sv
- If alpha particles were used then the Sv would be much higher
What are the 2 types of damage that can occur to foetuses from radiation?
Tissue effects
- AKA non-stochastic
- Multicellular damage that occurs when a threshold is passed
- Short term relatively obvious changes ie organ damage, CNS damage, FDIU
- Damage does not occur below the radiation threshold
Stochastic effects
- Damage to a single cell
- May lead to m
What is the rough risk from CT scan contrast for reactions?
Type I hypersensitivity (severe)
- 0.01-0.04% ie 1/2000 - 1/10,000
Mild non-hypersensitivity
- 0.5 - 3% ie 1/500 - 1/30
