Radiology Flashcards
What is a radiograph?
A radiograph is a projection all image generated by a passage of x-rays through an object.
How is an X-ray image generated?
Am Image is generated on a detector plate called x-ray detector.
This detector plate is like a put=topographic film. When x-rays hit the plate, it turns black. Amount of blackness depends on the number of x-rays hitting the plate.
X-rays are are stopped by materials with lots of electrons / dense materials like bone / metals so, they appear white.
What are the advantages of x-rays?
Quick
Readily available
Inexpensive
What are the disadvantages of x-rays?
Involve radiation
Poor soft tissue information
What are the roles of x-rays in the imaging of MSK system?
- They are are initial imaging of choice for skeletal muscle trauma / acute bone or joint injury. Eg:
Fractures
Joint dislocations - X-rays are also used for the evaluation of chronic bone or joint pathologies. Eg:
Chronic osteomyelitis
Chronic joint arthritis
Chronic septic arthritis
What is a fracture?
A complete or incomplete break in the continuity of the bone.
What different types of fractures can you get?
Most fractures have fracture lines / unenthusiastic lines on a radiograph. -These will be transverse / oblique or spiral fractures.
You can also get spinal compression fractures. I’m these, it is difficult to find a fracture line, bone is just crushed or deformed.
I’m childhood, you can get:
- Greenstick fractures / buckle fractures
- Epiphyseal separation fractures.
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What is a CT scan?
Computerise Tomography (CT) or Computerised Axial tomography (CAT) scanning is a diagnostic imaging procedure that uses radiation to build cross sectional images (slices) of the body.
What does CT do?
CT scans provide thin sections of the MSK system. These slices give detailed information about the bone structure and pathology.
The soft tissue detail is better than plain radiographs (X-ray).
Subtle, un-displaced fractures are better seen on CT scans.
Spinal fractures and other complex fractures (eg pelvic) are seen in greater detail.
Slices can be reformatted to give 3D construction.
What are the advantages of CT scans?
Cross sectional. Think slices of the body.
Excellent in assessment of complex bone trauma.
Fast.
Miltiplanar and 3D reconstruction.
What are some disadvantages of CT scan?
Involves significant radiation
There is poor soft tissue detail (better than x-rays). ]]]]]]]]]]]]]]]]
What is hounsfield units / density?
This is the colour seen on a CT.
Water has 0 HU.
Below 0 U -dark on CT image.
0-40 U -shades of grey
+100 -white on CT.
What is the role of MRI scanning in MSK imaging?
This is a non-invasive method of mapping the internal structures of the body.
How does MRI scanning work?
MRI utilises magnetic resonance of the hydrogen nuclei to produce high quality cross-sectional images of the body in any plane.
There is no use of ionising radiation. Instead, it utilise radio frequency radiation in presence of carefully controlled magnetic fields.
What are the fundamental objectives of MRI MSK imaging?
Definition of normal anatomy
Detection of pathology