DXA

Question 1

strengths of SXA, pDXA

Answer 1

low radiation dose
low cost
portable

Question 2

limitations of SXA, pDXA

Answer 2

use on appendicular sites only

cannot measure trabcular and cortical bone seperately

Question 3

scan time SXA, pDXA

Answer 3

3-5 minutes

Question 4

strengths of DXA

Answer 4

low raditaion dose
multiple assessment sites possible
strongest predictor of hip fracture

Question 5

limitations of DXA

Answer 5

cost

size

Question 6

scan time of DXA

Answer 6

1/2 - 6 mins

Question 7

strengths of QCT

Answer 7

gives volumetric densities

discriminates trabular from cortical bone

Question 8

limitations of QCT

Answer 8

radiation dose
capital and running cost
N/A to the proximal femur
rigorous QC and slow

Question 9

scan time of DXA

Answer 9

10 minutes

Question 10

strengths of QUS

Answer 10

no radiation exposure 
small and postable 
fast 
easy to use 
low cost

Question 11

limitation of QUS

Answer 11

limited to calcaneus, radius and tibia

Question 12

sacn time of QUS

Answer 12

1-5 minutes

Question 13

principles of DXA

Answer 13

utilise xray tube
emits a narrowly collimated beam of xray at 2 different energies
differeniated between soft tissue and bone

Question 14

why lift legs slightly when scanning lumbar spine

Answer 14

flattens spine

prevent vertebrate tilt

Question 15

how is osteoarthrtis idenitfied in images

Answer 15

white patches

Question 16

what do you do to the hip to improve image

Answer 16

twist hip to enlongate femoral neck

ensure there is sufficietn soft tissue surronding the hip

Question 17

how much can the femoral neck chnage by due to meds

Answer 17

2-4%

Question 18

how much can the size of the hip be altered due to positioning

Answer 18

9%

Question 19

z score calculatoion

Answer 19

patient BMD - age matched mean/age matched SD

Question 20

t score calculation

Answer 20

patient BMD - young normal mean/ young adult SD

Question 21

use of risk factors

Answer 21

help clincians idenfity those who may be at risk

• histroy of atraumic fracture
• xray osteopenia
• medical conditions or use of meds known to affect bone metabolism
• premature menopause
• family history of osetoprosis
• low BMI
• current smoking habit

Question 22

normal t score

Answer 22

T>-1SD

Question 23

osteopenic t score

Answer 23

T>-1SD to

Question 24

osteoporotic t score

Answer 24

T