Imaging Flashcards
1
Q
X-ray
A
Produced within x-ray machine
No external radioactive material involved
Current and voltage can be changed to manipulate the properties of x-ray beam being produced
Different beams applied to different arras of the body
Image produced by passing through Pt to digital screen below
2
Q
X-ray beam
A
- X-rays travel in straight lines and a beam of x-rays diverges from its source
- Structures hit by beam first are magnified in relation to those nearer the detector
- To reduce magnification X-ray source can be moved further from the subject
- Structures needing accurate measuring need to be placed close to the detector
3
Q
Absorption- x-ray
A
- Bone absorbs most radiation= least exposure to digital screen= white image
- Air absorbs least radiation= maximum exposure= image appears black
- Between these two extremes, large differential tissue absorption results in grey image
4
Q
X-ray useful for
A
- Chest
- Abdo
- Skeletal system- trauma, spine, Jts, degenerative, metabolic and metastatic disease
- Assessment of fracture healing
5
Q
How- x-ray
A
- May types of plain X-rays
- In most cases the body part is X-rayed from 2 angles
1. Anteroposterior
2. Laterally
6
Q
Fluoroscopy
A
When a continuous low power X-ray beam is passed through the Pt to produce dynamic images (as they are happening) on TV monitor
- Helps to look inside organs, Jts muscles and bons
- Helps to diagnose a health problem (e.g., heart or intestinal disease)
7
Q
Dangers of x-ray
A
- All doses of radiation carry risk, the greater the dose the greater risk
8
Q
X-ray safety
A
- Those referring must provide clinical reason to justify exposure to radiation
- Local rules of X-ray department must be adhered to, ignoring may result in breaking in the law
9
Q
Biological effects of x-ray
A
- Skin damage (dose dependent)
- Development of cancer (random)
- Some body parts are more susceptible to random damage- typically tissues with rapidly dividing cells (stomach- 20x more likely than bone)
- Radiation to reproductive organs carries further potential risk to future generations
- Children more radiosensitive
10
Q
CT scan
A
- Computerised tomography
- Uses X-rays to create detailed image of the inside of the body
- Sometimes referred to as CAT scans
- Can produce detailed images of many structures inside the body |(including int organs, blood vessels, etc)
- X-ray source rotates around Pt
11
Q
CT advantages
A
- Can be done without damage to metal implants
- Bony structures imaged more clearly and detailed
- Rapid exam technique- suitable for ill Pts, less need to hold breath
- Lower cost than MRI
- CT= quicker than MRI
12
Q
Disadvantages of CT
A
- Uses X-radiation to produce images- carcinogen (small risk as low dose)
- Less soft tissue detail than MRI
13
Q
How MRI works
A
- Magnetic resonance imaging
- Produces image of body by utilising magnetic properties of certain nuclei in body
- Pt positioned in scanner, surrounded by large magnet
- High intensity magnetic field displaces nuclei from their position, when they return the nuclei releases energy
- Computer analysis processes energy signals to grey scale image
- Pathological tissue returns different signals compared to normal
14
Q
MRI- useful for
A
- Brain and spinal imaging, internal derangement of Jts
- Primary soft tissues and bone tumours
- Acute and chronic soft tissue injuries to tendons, ligaments and muscle
- Images can be axial, sagittal and coronal
15
Q
MRI advantages
A
- No documented side effects
- Soft tissue pictured in more detail than CT
