mAs and kV

Question 1

What is kV?

Answer 1

• KiloVolt
• A unit of electrical difference

Question 2

What is mAs?

Answer 2

• millimpere-seconds
• the number of milliamps being delivered over a period of time

Question 3

What are the 5 X-ray densities and their colour?

Answer 3

• Black = Air
• Dark grey = Fat
• Mid grey = Soft tissue
• Light grey = Bone
• White = Metal

Question 4

What can low or high mAs do to the density of an X-ray?

Answer 4

• Low mAs = underexposed (too white)
• High mAs = overexposed (too black)

Question 5

What can low or high mAs do to the resolution of an X-ray?

Answer 5

• Low mAs causes low density = pale and poor resolution
• High mAs causes high density = looks dark and better resolution

Question 6

What can low and high kV do to the contrast of an X-ray?

Answer 6

• Low kV causes low tissue penetration = black and white image, too high contrast
• High kV causes high tissue penetration = lots of shades of grey but no white (flat film), too low kV

Question 7

What does ALARP stand for?

Answer 7

• As low as reasonably practicable

Question 8

What are the units milliSieverts used to measure?

Answer 8

• Exposure of biological tissues to ionising radiation