Introduction to Imaging Flashcards
What is an X-Ray
An electromagnetic packet of energy with an extremely short wavelength between 0.1-10 nm
How many shells do electrons have. Name them
2
Outer
Inner
Which shell from electrons produces X-Rays
Inner
What does the intensity of X-rays depend on
Tube current
Atomic number of the target
Tube voltage.
What is attenuation
The process by which radiation loses power as it travels through matter and interacts with it.
What does emulsion contain and explain its function
Silver halide
Clumps form, after exposure to light generated on luminescent screens
Explain how an ultrasound works
The machine transmits high frequencies of 1-5 megahertz sound pulses
The soundwaves travel into the body and will hit a boundary between tissues (e.g. fluid and soft tissue or soft tissue and bone)
Some of the waves will be reflected to the probe and others will travel further till they reach another boundary and get reflected
It’s the reflected waves which are picked up by the probe and relayed to the machine
What is barium
A radio-opaque contrast agent used for outlining the gastro-intestinal tract
It has a high atomic number which absorbs more X-Ray photons than surrounding tissues.
How can barium be used in clinical investigations
To study:
Oesophagus, stomach and duodenum by swallow and meal
Large bowl using enemas
What are some of the complications of Barium use
Bowel disturbance
Colonic perforation (1:25,000)
Both are uncommon
What does CT stand for
Computed Tomography
How does a CT work
It is a rotaing X-Ray tube which has multiple beams on a single axis of rotation
What are patients often given with a CT
Iodinated contrast
What are the advantages and disadvantages of CT scans
Helpful: In traumas Cancer staging and response to treatment As a guidance for procedures in defining bony detail
Disadvantage:
Exposure to radiation
What is radiation
The process of emitting energy, in the form of either particles or waves
