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Flashcards in Introduction to Imaging Deck (20)
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1
Q

What is an X-Ray

A

An electromagnetic packet of energy with an extremely short wavelength between 0.1-10 nm

2
Q

How many shells do electrons have. Name them

A

2
Outer
Inner

3
Q

Which shell from electrons produces X-Rays

A

Inner

4
Q

What does the intensity of X-rays depend on

A

Tube current
Atomic number of the target
Tube voltage.

5
Q

What is attenuation

A

The process by which radiation loses power as it travels through matter and interacts with it.

6
Q

What does emulsion contain and explain its function

A

Silver halide

Clumps form, after exposure to light generated on luminescent screens

7
Q

Explain how an ultrasound works

A

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

8
Q

What is barium

A

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.

9
Q

How can barium be used in clinical investigations

A

To study:
Oesophagus, stomach and duodenum by swallow and meal
Large bowl using enemas

10
Q

What are some of the complications of Barium use

A

Bowel disturbance
Colonic perforation (1:25,000)
Both are uncommon

11
Q

What does CT stand for

A

Computed Tomography

12
Q

How does a CT work

A

It is a rotaing X-Ray tube which has multiple beams on a single axis of rotation

13
Q

What are patients often given with a CT

A

Iodinated contrast

14
Q

What are the advantages and disadvantages of CT scans

A
Helpful:
In traumas
Cancer staging and response to treatment
As a guidance for procedures
in defining bony detail

Disadvantage:
Exposure to radiation

15
Q

What is radiation

A

The process of emitting energy, in the form of either particles or waves

16
Q

What is ionising radiation

A

When a particle or wave has sufficient energy to ‘ionise’ a neutral atom or molecule and leave them with either a positive or negative charge

17
Q

Why is ionising radiation important in health care

A

The process of ionisation can lead to the disruption of chemical bonds within living tissue

18
Q

What is a sievert

A

A unit that is used for describing the absorption of radiation by the human body

19
Q

How can exposure to radiation be minimised

A

Increasing the distance from a radiation source
Minimising the time exposed to radiation
Using a shield to protect staff and patients

20
Q

How can x-rays interact with matter

A

Absorption
Transmission
Scatter