Radiography/radiology

Question 1

Pink Camels Collect Extra Large Apples

Answer 1

P=Positioning (Position part of interest as close to the image receptor, must be parallel NOT oblique or else image will distort. No movement or superimposition)
C= Centering (centre the primary beam over the area of interest, esp in LA)
C= Collimation (collimate beam size to minimum necessary to see desired area to reduce scattered radiation)
E= Exposure (use the right exposure factors
L= Labelling (patient details and date in software, area radiographed DV, VD, RLat, Llat etc. Always expose side marker (R/L)
A= Artefacts (Check there is nothing thaty could cause artefact)

Question 2

kV

Answer 2

affects the quality and intensity

Question 3

mA

Answer 3

affects the intensity only
- if increased, tube current increases, number of electrons increases
- therefore, there is a greater number of x-rays produced.

Energy of the xrays is unchanged

Question 4

what substance appears black on radiograph

Answer 4

Air

Question 5

Appears grey on radiograph

Answer 5

fat (darkest grey)
Water (Lighter grey in comparison to fat)

Question 6

what structures appear white on radiograph

Answer 6

Bone
Metal (more vibrant white in comparison to bone)

Question 7

Why do different structures show up as different colours on a radiograph

Answer 7

different tissues absorb differetn amounts of radiation

Fat absorbes less than bone

Question 8

what happens when you increase kV

5

Answer 8

• the overall amount of radiation emerging from the patient and reduces the difference between different structures
• increased electron acceleration
• increased energy of electrons
• greater number of x rays produced
• xrays have increased energy = increased penetrating power

Question 9

What happens when you decrease the kV

Answer 9

decreases the amount of exposure of the image receptor and increases the difference between different structures

Question 10

What happens when you increas mAs

Answer 10

Increase the overall amount of radiation emerging from the pation

increases plate exposure

Question 11

What happens when you increas mAs

Answer 11

Increase the overall amount of radiation emerging from the pation

increases plate exposure

Question 12

What happens when you decrease mAs

Answer 12

Decreases the overall amount of radiation emerging from the patient

decrease plate exposure

Question 13

What does it mean if you see a blackk area on a radiograph

Answer 13

the X-rays ahve penetrated through the body and have not been stopped

white means X-rays have been absorbed by body

Question 14

What is the term for taking 2 images at right angles to eachother

Answer 14

orthogonal views

necessary bc rads are 2D and patient is 3D, 2 views gives full picture

Question 15

What are X-rays?

Answer 15

a form of electromagnetic radiation
they have a high energy and a short wavelength
can lead to ionisation (damaging to living tissues)

Question 16

How are X-rays produced

5

Answer 16

• the interaction of electrons with an atom
• the cathode (-ve) in an X-ray tube generates a stream of electrons
• these hit and interact with the atoms within the target area of the anode(+), resulting in the release of X-rays
• the number of electrons generated at the cathode is determined by the mA and Exposure time
• the energy of the electrons striking the anode is determined by the kV applied

Question 17

Properties of the X-ray beam

2

Answer 17

QUALITY: the penetrating power of the beam
INTENSITY: amount of radiation in the beam

Question 18

effect of exposure time

Answer 18

increasing time of exposure increases number of xrays
mA x sec = mAs

Question 19

Source of image-receptor distance (SID)

Answer 19

• the closer to the x-ray tube the image-receptor is, the more concentrated the xray beam will be and vice versa
• the exposure vaires according to the inverse square law

Question 20

How do you reduce scattered radiation

Answer 20

• good collimation
• use of a low kV
• use of a radiographic grid if necessary

Question 21

What should a good radiograoh show

3

Answer 21

• accurate portrayal
• easy perception (sharp shadows, wide range of shades of grey)
• no misleading artefacts

Question 22

Where do you look on a radiograph to assess if you have axial rotation in a thoracic view

Answer 22

the dorsocaudal ribheads (must overlie eachother)

NOT where the rib bodies lie