Radiographic Safety Flashcards Preview

Year 2 Pro Skills > Radiographic Safety > Flashcards

Flashcards in Radiographic Safety Deck (33)
Loading flashcards...
1

What are the two effects of ionising radiation?

Deterministic effects
Stochastic effects

2

What are deterministic effects?

Tissue reaction related to cell death- skin burns, cataracts, bone marrow suppression, sterility

3

What are stochastic effects?

Cell manipulation related to DNA damage- cancer induction, birth defects

4

What is the size of the filter that must be fitter to radiography machines?

2.5mm aluminium

5

What feature must radiographs have for safety?

Must have light beam diaphragm

6

What should radiation leakage not exceed?

1mGy/hour

7

Where should the exposure button be placed?

Outside control area, behind suitable barrier, more than 2m from primary beam source

8

What dosage needs to be investigated?

15mSv per year
2mSv in one dose

9

What size should the radiography room be?

Large enough for people to be 2m away or behind the screen

10

What should the boundary shielding be?

Scattered- 0.5mm
2mm for primary beam

11

What is the relevant radiation safety legislation?

Ionising radiation regulations 1999

12

How are X-rays produced?

By tube- electrons produced by heating of filament in vacuum, producing electron, accelerated by potential difference to collide with anode which gives out X-rays

13

What does the primary X-ray beam first pass through?

Perspex window

14

How is the size and shape of the primary beam controlled?

Lead collimators

15

What are the tube variables?

Kilovolt peak
Milliamps
Seconds

16

What is the kilovolt peak?

Voltage potential difference between anode and cathode
Increasing kVP accelerated electrons and collide with higher velocity

17

What is milliamps?

Current in the tube circuit- number of electrons accelerated

18

What is mAs?

Milliamps a second

19

What are the two types of radiation produced from the production of X-rays?

Bremsstrahlung- 'breaking' radiation
Characteristic radiation

20

What is bremsstrahlung radiation?

electrons pass close to nucleus and are deflected and slowed, lost energy results in X-ray photon production
Protons have spectrum of energy dependent on speed and amount of slowing

21

What is characteristic radiation?

Incoming electron displaces electrons from shell, incoming electron has higher energy, vacancy filled by electron from outer shell moving down, this emits X-ray photon

22

What is the anode made of?

Rotating disk of tungsten/rhenium-tungsten

23

How is the beam filtered?

Low energy x-ray photons removed by aluminium filter and the beam is 'hardened'

24

What is inherent filtration?

Filtration that occurs due to machine structure- perspex window

25

What do collimators do?

Control the size of area of irradiated by primary beam
By a pair of lead shutters

26

What is the function of the light beam diaphragm?

Shows the area going to irradiated by using light source and angled mirror with the collimators to show size and shape

27

What is attenuation and how does it occur?

Weakening of the primary beam by structures between the tube and X-ray detector- via photoelectric absorption or scatter

28

What is photoelectric absorption?

When an X-ray photon is absorbed and an electron is ejected
affected by atomic number
Origin of all radiographic contrast

29

What is scatter?

Photon continues in a different direction with lower energy and results in random film image blackening

30

What is Compton scatter?

Outer shell of electrons deflected on collision (ionised) and continues with lower energy, predominantly medium high energy photons