Introduction to Imaging Flashcards Preview

Principles of Disease > Introduction to Imaging > Flashcards

Flashcards in Introduction to Imaging Deck (20)
Loading flashcards...
1

What is an X-Ray

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

2

How many shells do electrons have. Name them

2
Outer
Inner

3

Which shell from electrons produces X-Rays

Inner

4

What does the intensity of X-rays depend on

Tube current
Atomic number of the target
Tube voltage.

5

What is attenuation

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

6

What does emulsion contain and explain its function

Silver halide
Clumps form, after exposure to light generated on luminescent screens

7

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

8

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.

9

How can barium be used in clinical investigations

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

10

What are some of the complications of Barium use

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

11

What does CT stand for

Computed Tomography

12

How does a CT work

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

13

What are patients often given with a CT

Iodinated contrast

14

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

15

What is radiation

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

16

What is ionising radiation

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

Why is ionising radiation important in health care

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

18

What is a sievert

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

19

How can exposure to radiation be minimised

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

20

How can x-rays interact with matter

Absorption
Transmission
Scatter