Physics basics of Radiology Flashcards
1
Q
What are radiographs?
A
- Images created by x-rays which have been projected through an object and then interacted with a receptor
- Different shades of grey on image correspond to different types of tissue and thickness of tissue involved
2
Q
Why are radiographs useful?
A
- Can see structures within body, particularly mineralised tissues
- Many dental related conditions affect the mineral content of tissues
- Can show normal anatomy and pathology
- Aid diagnosis, treatment planning and monitoring
3
Q
Common intraoral dental radiographs
A
- Periapical
- Bitewing
- Occlusal
4
Q
Common extraoral dental radiographs
A
- Panoramic
- Lateral cephalograms
5
Q
What is electromagnetic radiation?
A
- X-rays are form of electromagnetic radiation
- Flow of energy created by simultaneously varying electrical and magnetic fields
- Schematically represented as a sine wave
6
Q
Name some electromagnetic radiation properties
A
- No mass
- No charge
- Always travel at speed of light = 3x10^8ms^-1= 671million mph
- Can travel in a vacuum
7
Q
What is the electromagnetic spectrum?
A
- Consists of all different types of electromagnetic radiation
- Each type has different properties dependent on its energy/wavelength/frequency
- Divided into 7 main groups
8
Q
What are the 7 main groups of EM radiation?
A
- Gamma ray
- X-ray
- Ultraviolet
- Visible
- Infrared
- Microwave
- Radio
9
Q
What radiation has the shortest wavelength?
A
- Gamma ray
- Shortest wavelength
- Highest frequency
- Highest energy
10
Q
What radiation has longest wavelength?
A
- Radio
- Longest wavelength
- Lowest frequency
- Lowest energy
11
Q
How do you measure frequency from a sine wave?
A
- Need to know however long it took to travel e.g. 4 seconds
- 1 cycle over 4s = 0.25cycles per second = 0.25Hz
- 4 cycles over 4s = 1 cycle per second = 1Hz
12
Q
Definition of frequency
A
Frequency = how many times the waves shape repeats per unit time
- Measured in hertz, Hz
- 1Hz= 1 cycle per second
13
Q
Definition of wavelength
A
Wavelength = distance over which the waves shape repeats
- Measured in metres, m
14
Q
Define speed and how it relates to EM radiation
A
Speed = Frequency x Wavelength
- BUT speed of all EM radiation is constant = 3x10^8ms^-1
- So if frequency increase then wavelength must decrease and vice versa
15
Q
What is energy directly proportional to?
A
- Frequency
- High frequency = high energy
