Deck 19: Bone Densitometry

Question 1

Radiation dose for DXA scans is:

A) twice as much as for a diagnostic lumbar x-ray.
B) half as much as for a lumbar CT examination.
C) similar to natural background radiation.
D) similar to a diagnostic hand x-ray.

Answer 1

similar to natural background radiation.

Question 2

Peak bone mass is reached at about age _____ years.

A) 10 to 20
B) 20 to 30
C) 30 to 40
D) 40 to 50

Answer 2

20 to 30

Question 3

The measurement of bone density uses two different beam energies,allowing the separation of soft tissue and bone due to:

A) filtration differences in the beam.
B) mass attenuation coefficient differences.
C) BMD population calculations.
D) the two-dimensional area.

Answer 3

mass attenuation coefficient differences.

Question 4

The bone densitometry parameters reported on the DXA printouts include which two of the following? (Select all that apply.)

A) Area in centimeters squared (cm²)
B) Mass attenuation coefficient
C) BMD in g/cm²
D) Volumetric density

Question 5

Accuracy in bone densitometry relates to the ability of the system to:

A) measure the true value of an object.
B) reproduce the same results in repeat measurements of the same object.
C) reflect the bone measurement by the scanner software.
D) measure the variability of the spread of data values around the mean.

Question 6

The T-score is used to assess:

A) the reference population.
B) fracture risk for the patient.
C) if the measured BMD is reasonable.
D) patient age and bone loss.

Question 7

Precision relates to the ability of the system to:

A) measure the true value of an object.
B) reproduce the same results in repeat measurements of the same object.
C) reflect the bone measurement by the scanner software.
D) measure the variability of the spread of data values around the mean.

Question 8

DXA calculations are based on:

A) body position and bone density.
B) bone density only.
C) soft tissue only.
D) soft tissue and bone.

Question 9

The most common osteoporotic fracture is found in the:

A) hips.
B) femurs.
C) vertebrae.
D) ankles.

Question 10

What is the chief benefit of using a high and low x-ray energy source with a DXA system?

A) Reduces patient dose significantly.
B) Reduces wear and tear on the x-ray tube to change energies.
C) Demonstrates attenuation difference between bone and soft tissue.
D) Reduces postprocessing time of bone for the digital image.

Question 11

The Z-score is used to determine:

A) the reference population.
B) fracture risk for the patient.
C) if the measured BMD is reasonable.
D) patient age and bone loss.

Question 12

The purpose of bone densitometry is to:

A) establish the diagnosis of osteoporosis.
B) assess the response to osteoporosis therapy.
C) measure bone mineral density.
D) do all of the above.

Question 13

Bone-destroying cells are called:

A) osteoblasts.
B) osteoclasts.
C) cancellous.
D) cortical.

Question 14

All are risk factors for osteoporosis,except:

A) daily physical activity.
B) alcohol consumption.
C) low body weight.
D) low calcium intake.

Question 15

Which vertebral region(s)is (are)analyzed during a DXA scan?

A) T12
B) T7 to L1
C) L1 to L5
D) L4 to S2

Question 16

A BMD measurement from a patient is most useful when it can be compared statistically to:

A) the same patient age population.
B) a population living in the same area.
C) multiple scans on the same patient.
D) an appropriate sex-matched reference population.