bone density
Terms
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- DXA
- Dual energy x-ray absorptiometry
- SXA
- single energy x-ray absorptiometry
- RA
- radiographic absorptiometry
- QCT
- quantitative CT
- Does bone densitometry reveal the cause of bone loss?
- NO
- What principle is BMD based on?
- Bone absorbs photons generated by the tube in proportion to the calcium density in the bone
- How is BMD calculated
- A numerical value is obtained by computing the difference in #'s of photons entering and emerging from the body part imaged
- How does QCT measure BMD
- uses calibration phantom and software to measure VERTEBRAL BMD
- which method provides true 3D measurements?
- QCT
- What yields the highest diagnostic accuracy for detection?
- Trabecular
- Pure trabecular yields highest accuracy for what part?
- low VERTEBRAL
- Which method calculates BMD after subtracting the soft tissue absorption?
- DXA
- What sites can DXA measure?
- Central skeletal, Hip, Spine
- How does SXA account for soft tissue?
- Body part is immersed in water bath to simulate uniform soft tissue thickness
- Where is SXA used?
-
Distal skeletal sites
heel, forearm - What part does RA use?
- Fingers
- Which method uses an aluminum step wedge?
- RA
- What does the software average in RA?
- BMD of middle phalanges of 2,3,4th digits
- What can BMD tell you?
-
Detect low bone mass
Predict chance of future fractures
Confirm a Dx
Distinguish osteoporosis fracture from other spinal abnormalities
Monitor effects of treatment