Medical Imaging Flashcards
What are the 4 types of radiation in X-Rays?
- Primary
- Scatter
- Absorbed
- Remnant
What is attenuation regarding to X-Rays?
The degree to which density relates to absorption of radiation
Name 3 conditions that can be identified using an X-Ray
- Bone fractures
- Lung consolidation/infection
- Volvulus
- Vascular narrowing
What are the negatives of using X-Rays?
- Ionising radiation
- 2D imaging
- Poor for soft tissue
Describe the 5 positioning terms in radiology
Superior - Top Inferior - Bottom Anterior - Front Posterior - Back Medial - Towards the midline Lateral - Away from the midline
What are the 3 planes of imaging?
- Coronal
- Transverse/Axial
- Sagitta
Name 2 organs that lie to the left and two that lie to the right hand side
Left - Spleen/stomach/heart
Right - Appendix/liver
What are the units of attenuation?
Hounsfield Unit
How is a CT scan achieved?
Uses x-rays to create a 3D image by continuous rotation of X-ray tube and detectors
What are the issues of CT scans?
- High ionising radiation
- Poor soft tissue detail
What view does a Ct scan show?
Uses transverse sections to produce an axial view looking from feet end up
Name 3 common images and conditions identified by CT scans
Head - tumour/bleed
Chest - PE
Abdomen - bowel obstruction
Pelvis - bladder stone
What is Fluoroscopy?
Serial x-rays taken in a sequence with contrast showing dynamic flow through a system
What does PET stand for?
Position Emission Tomography
What is PET combined with and what does it show?
Combined with CT scanning to give a 3D view of metabolically active tissue using radioactively labelled glucose
How does an MRI produce an image?
- Measures spin of hydrogen atoms using strong magnet
- Unmatched atoms emit energy which sends a signal to the computer producing an image
Name 3 uses of an MRI scan
Head - CVA
Spine - slipped disc
Liver - gallstones
Knee - torn ligament
Name 2 advantages and disadvantages of MRI
Advantages - High detail and no radiation
Disadvantages - Expensive, Noisy, Can’t be used with metal implants
What effect is used in ultrasound and how does it work?
- Piezoelectric Crystal Effect
- Pressure on crystals by reflection generates current for the computer
What is the difference between high and low frequency?
High - short wavelength/penetration with good resolution
Low - long wavelength/penetration with poor resolution
Name two advantages and disadvantages of ultrasound
Advantages - dynamic, quick
Disadvantages - poor detail, can’t see past air
