Slide 2 - DXA

Question 1

DXA is the

Answer 1

Gold standard for measuring body composition

Question 2

DXA uses

To determine…

Answer 2

Very low radiation x rays

to determine the density of various tissues

Question 3

DXA can measure what types of composition

Answer 3

General

Regional

Question 4

What was DXA originally used for

Answer 4

Measuring bone mineral density

To diagnose osteoporosis

Question 5

What does DXA measure

Answer 5

The attenuation of x rays with HIGH and LOW Photon energies

Question 6

How does DXA work

How many energy peaks

Answer 6

Sends thin invisible beam of LOW DOSE XRAYS

2 distinct energy peaks

Question 7

What do the 2 peaks get absorbed by

Answer 7

One by soft tissue

Other by bone

Question 8

What does attenuation of xrays mean

Answer 8

Weakening of xrays

Question 9

What do the attenuation of xray energies pass through

Answer 9

Bone
Fat
Lean mass

Question 10

What effects the passage of the xrays through bone, fat and lean mass

Answer 10

Thickness
Chemical composition
Density

Question 11

What does the DXA machine featured software display

Answer 11

Bone density
Fat (adipose)
Lean mass

Question 12

What is the radiation in DXA equivalent to

Answer 12

Less than a days exposure to natural radiation

Less than 1/10 dose of chest xray

Question 13

Does radiation remain in patient after the dxa

Answer 13

NO

Question 14

How much does the machine cost

What is the yearly maintenance and repairs

How much is the scan without insurance

Answer 14

80,000 - 275,000

4600

250

Question 15

DXA is a what component model

Answer 15

3 component model

Question 16

What components does DXA measure

Answer 16

Bone mineral content
Fat
Lean tissue

Question 17

What assumptions does the DXA machine make

Answer 17

The amount of fat over bone is the same as the amount of fat over bone-free tissue

Measurements are not affected by the anteroposterior thickness of the body

The hydration and electrolyte content of LEAN TISSUE MASS is CONSTANT

Question 18

What is the change in hydration that does NOT affect the accuracy of measurements

Answer 18

1 kg of water

Question 19

How many water content will affect the %BF by in the DXA

Answer 19

5% change in water

Cause a 1-2.5% change in %BF

Question 20

What is required to test using a DXA

Answer 20

California limited license

No calcium supplements on testing day

No metal on clothing

Low radiation exposure that day

DO NOT SCAN if possibility of pregnancy

Question 21

What errors may occur when doing a DXA scan

Answer 21

Body size = too tall or wide

Body movement

Question 22

What can you still do fine during a dxa scan

Answer 22

Breath normally

Little effect on hydration