Introduction to Radiography and Medical imaging Flashcards
1
Q
When were x-rays discovered and when was the first one taken?
A
X-rays were discovered on November 1895
First one was taken 22nd December 1895
2
Q
What imaging modalities are used?
A
- Plain film radiography,
- Fluoroscopy,
- Computed tomography (CT)
- Magnetic Resonance Imaging (MRI)
- Ultrasound,
- Nuclear medicine (Radio-Nuclide imaging)
3
Q
What is the role of a radiographic image?
A
To provide anatomical and physiological information achieved by producing a high quality image
4
Q
X-ray interactions with matter
A
- Incident photon is absorbed by K-shell electron(which is then displaced),
- Vacancy is filled by an L-shell electron (resulting in K emission)
- The scattered photon has less energy than the incident proton and may be scattered through any angle.
- The Compton electron (aka recoil electron) always scattered in a forward direction
5
Q
Attenuation
A
- XRay beam is homogenous- one energy level,
- Patient acts as an attenuator (absorber)
- Denser the structure the more X-rays are absorbed therefore the less energy is incident to the receptor.
- Less energy incident to receptor produces a dark area on the image.
6
Q
What does white on an X-ray equal
A
It equals dense structures- Bone
7
Q
What does black on an X-ray equal
A
It equals lucent (None dense) structures-Air.
8
Q
What do shades of grey on an x-ray equal
A
each grey level is a different level of attenuation of the body
9
Q
Plain film Radiography
A
- Uses ionising radiation,
- energy levels between 55 and 150kvp as normal,
- Two projections at 90 degrees to each other,
- Joints- centre over joint,
- Long bones- include joint on either end,
- include soft tissue,
- Demonstrate bony tissue well and some soft tissue structures,
- Department and mobile based
10
Q
Fluoroscopy
A
- Uses X-Rays up to 150KVp,
- produces real time moving images,
- Enables invasive diagnostic, therapeutic and surgical procedures e.g cardio or Neuro,
- Uses Radio-opaque contrast agents.
- Demonstrates bony tissue,
- Using contrast agents good demonstration of some soft tissue structures,
- Normally department based but can be mobile
11
Q
Computed tomography (CT)
A
- Uses ionising radiation up to 150KVp,
- Produces cross sectional images as standard-2D
- Acquired data can be reconstructed in all planes,
- Can be presented as 3D image,
- Can use Contrast agents,
- Higher sensitivity to changes within the densities of the body
- Can demonstrate both Bone and Soft Tissue using computer enhancement processes
- can be used to assess ‘new bleeds’ in the cranium
- Static units or ‘mobile’ in articulated lorry trailer
12
Q
Magnetic Resonance imaging (MRI)
A
- Does not use ionising radiation,
- Computer based imaging modality,
- Produces ‘multi planar’ images,
- Works on the abundance of Hydrogen in the body,
- Utilises magnetic waves and sound waves to produce a signal
- Signal is picked up and converted into image,
- Can demonstrate soft tissue very well- due to water content,
- Doesnt demonstrate hard bone tissue well- little water content,
- Static based or ‘mobile’ in an articulated trailer
13
Q
Ultrasound
A
- Uses non ionising radiation,
- High frequency sound waves,
- Utilised for soft tissue imaging,
- The sound waves penetrate the structure and are reflected back,
- The image is built up from reflected sound waves,
- Doppler-used to calculate blood flow
- Colour can be overlaid to enhance the clarity of image,
- Mobile units can be taken to places only need is an electrical socket
14
Q
Nuclear medicine/Radio Nuclide imaging (RNI)
A
- Uses ionising Radiation- Gamma rays,
- Radioisotope is injected, inhaled or ingested by patient,
- The isotope is attached a pharmaceutical that is targeted for anatomical region.
- Gamma rays are detected by the gamma camera and the image is constructed by the computer.
- (RNI) demonstrates function and physiology mainly
