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What is the texture index that evaluates the pixel gray-level variations in lumber
spine DXA images? - ANSWER -TBS (Trabecular Bone Score)
When does type 2 primary osteoporosis generally occur? - ANSWER -after age 70
What technique used images of the hand and an aluminum wedge? - ANSWER -
RA (Radiograhic Absorptiometry)
New bone is formed by the ___________? - ANSWER -osteoblasts
Cancellous bone is also known as _______________? - ANSWER -Trabecular
bone
How would you start labeling the vertebral bodies on a PA lumbar scan? -
ANSWER -Start at L4 and count/label up
With changes in rotation of the femoral neck, what happens? - ANSWER -
Increases the BMD
If daily QC fails, what should be your first step of action? - ANSWER --repeat the
scan
-if scan fails again, then call for help
Although the technology is similar with all of the DXA units, the BMD results are
different because.......... - ANSWER --different calibration standards
-algorithms to calculate BMD
,-differences in the ROI
-different databases
The primary mechanism of action of antiresorptive therapies is the direct
interaction with the __________________ - ANSWER -osteoclasts
Which site is preferred for determination of fracture prediction? - ANSWER -
proximal femur
What is one disease not associated with low BMD? - ANSWER -osteopetrosis
DXA results may be influenced by......... - ANSWER --body thickness
-degenerative changes
-fractures
-scan mode
A great forearm scan should include....... - ANSWER --forearm centered
-forearm straight
-free of artifacts
Phantoms that mimic the shape and size of a skeletal region are called
______________________________. - ANSWER -anthromomorphic phantoms
What is the formula used to calculate BMD? - ANSWER -BMD = BMC/Area
How often should you perform the QA on the DXA unit? - ANSWER -everyday
you scan
,Radiogammetry is the measurement of bones using skeletal x-rays/radiographs.
Which site was often used? - ANSWER -metacarpals
With voltage switching units, what type of calibration is used? - ANSWER -
continuous internal calibration--wheel or drum
For low energies, the most common process of absorption is the
________________________ effect. - ANSWER -photoelectric
What are some comparisons to the amount of effective dose given during a central
DXA scan? - ANSWER --less than a day of background radiation
-less than a round trip from Boston to LA
-one-tenth of a chest xray
Why is the non-dominant arm used in bone densitometry? - ANSWER -reference
values reflect non-dominant arm measurements
When measuring the proximal femur, how should the neck ROI be placed? -
ANSWER -the neck ROI should be perpendicular to the femoral neck
What is the bone edge detection methodology? - ANSWER -it tests the machines
ability to distinguish bone from soft tissue
What are the two most common methods for shifting the energies in DXA units? -
ANSWER --energy shifting
-k-edge filters
Why do you use the hip positioner during scanning of the proximal femur? -
ANSWER -to place the femoral neck parallel to the tabletop
Bisphosphonates prevent bone loss by.... - ANSWER -reducing the activity of the
osteoclasts
, If a patient has a history of hyperparathyroidism, what would the preferred site be
for evaluation? - ANSWER -33% or 1/3 of the forearm
What is important for serial monitoring? - ANSWER -precision
What pharmaceutical may be suggested for a woman with a high risk of breast
cancer and elevated lipids? - ANSWER -Evista (Raloxifene)
What year was the Bone Mass Measurement Act proposed? - ANSWER -1997
What type of osteoporosis is a result of menopause? - ANSWER -Primary
Osteoporosis Type 1
What classes of cells are involved in bone remodeling? - ANSWER --osteoclasts
-osteoblasts
-osteocytes
What therapy mimics the effects of estrogen on bone and has antiestrogenic
effects in other tissue? - ANSWER -Raloxifene
In both men and women, bone mass increases until approximately what age? -
ANSWER -30 years
What must be performed in order to compare studies when a new machine is
bought? - ANSWER -cross-calibration
Which acronym best describes the least amount of BMD change that can be
statistically significant? - ANSWER -LSC
What are the 2 types of bone? - ANSWER --cortical
-trabecular