Bone Densitometry
Forearm
Structure that is only scanned with bone densitometry when the spine or hip scans are not obtainable
Loose clothing or gown with no dense objects (zippers or belts)
things that a patient should wear and be instructed to wear for bone densitometry
Osteoclasts
Bone cells that breakdown and reabsorb old bone
Osteoblasts
Bone cells that build new bone and repair bone
Proximal femur
Bone that is best to determine risk factors for hip fractures
3d analysis and true volumetric measurement
Can only be provided by QCT
Lateral
Patient position for assessment of the thoracolumbar spine for vertebral fracture analysis
MSP with midline of table, legs positioned for true AP of the hip, and feet rotated inward
Patient position for bone densitometry of the hip
Supine with MSp to midline of table
Patient position for bone densitometry of the spine
Premenopausal women and men younger than 50
People for whom the Z score is primarily used
30 - 50 %
Percent loss of trabecular bone that will produce the first visible changes on radiographs
Vertebral heights
Are measured and compared with a reference value in vertebral fracture assessment
Risk for fragility fracture
Increases when a patient has a low BMD
High and low x-ray energy
Is commonly used in the technique on a DEXA machine to determine the mass of tissues
Good measurement precision
Is essential for detecting changes in bone mass density
Bone mineral report
Is taken when the site of interest is analyzed with DXA
Vertebral fracture assessment
A new method of bone densitometry that uses software to diagnose current and potential vertebral fractures
BMC (bone mineral content)
A quantity of minerals in the entire bone measured in grams
BMD (bone mineral density)
A ratio of BMC in a specific area of bone
Thoracic hump
A sign of advanced stage osteoporosis
Bone densitometry
A specialty diagnostic modality used to evaluate bone mineral density for diagnosis of osteoporosis
Quantitative computed tomography (QCT)
Alternative modality for bone densitometry that can measure both trabecular and cortical bone and allows three dimensional or volumetric analysis of data
Quantitative ultrasound (QUS)
Alternative modality for bone densitometry that uses nonionizing techniques to evaluate peripheral sites in people that are excessively overweight
BMD and clinical risk factors
Are the most accurate to predict future fractures
Energy switching system or rare earth filters
Are used to achieve the high and low x-ray energies used to determine the mass of tissues
Accuracy
How well the measured value reflects the true or actual value of the object
Osteocytes
Mature bone cells
Peripheral site selection
May be performed with single energy x-ray absorptiometry, central densitometry, or QUS
ALARA principles
Must always be practiced by the technologist when performing bone densitometry
Benefits
Must always outweigh the risks in bone densitometry
Precision (reproducibility)
The ability of a quantitative measurement technique to reproduce the same numerical result when repeatedly performed in an identical fashion
2.7 for each of 1 standard deviation in BMD
The amount that age adjusted relative risk for fracture increases as BMD decreases
30 microSV
The approximate dose range for QCT
QC procedures not updated to ensure accurate results, bone mass to low/ body part to thick, anatomic malformations, previous fracture or metallic prosthesis, new procedures, and pregnancy
The contraindications for bone densitometry
Less than 5 microSv
The effective dose from a bone density exam of both spine and hip
Every 18 months
The frequency of re-examination in most protocols to evaluate change
Gender age, family history, ethnicity, body habitus, lifestyle, estrogen deficiency, nutritional deficiency, frequent falls, alcohol / tobacco abuse, hyperparathyroidism, steroid use for rheumatoid arthritis, GI conditions, and medications
The indications for a bone densitometry procedure
Short term and long term variability of scanner, patient motion, body habitus, and technical factors
The influencing factors that affect precision of DXA
Dual energy x-ray absorptiometry (DEXA or DXA)
The machine used for bone densitometry
Central/ axial
The most common site for bone densitometry
Heel (os calcis)
The most common site for quantitative ultrasound
Greater than or equal to -1.0
The normal T score
Greater than or equal to -2.0
The normal Z score within expected range
T score
The number of SDs the individual's BMD is from the mean BMD of a young normal population of the same sex and ethnic background
Z score
The number of SDs the individual's BMD is from the mean BMD of age appropriate individuals
Measure bone mineral density, detect bone loss, establish diagnosis of osteoporosis, asses risk of fracture, assess response of patient to osteoporosis therapy, and vertebral fracture assessment
The purposes of bone densitometry
T12 - L4
The region of the spine that must be included on bone densitometry of the spine
Inhibitors of bone resorption or stimulants of bone formation
The two types of osteoporosis management drugs
+/- 10%
The typical accuracy of a DXA unit that is sufficient for clinical assessment of fracture risk and diagnosis of osteoporosis
Bone density
Thing that is best evaluated with bone densitometry equipment
Body habitus and soft tissue variations
Things of which a technologist must be aware for each patient to ensure that an appropriate amount of soft tissue is available for adequate scan analysis
Patient's history and associated risk factors
Things on which site selection for bone densitometry is determined
True and measure values expressed and percentage values
Values that are compared to determine the accuracy of a DEXA unit
Bone break
Was the first indicator of osteoporosis before bone densitometry
Various locations of the body or through whole body scan acquisition
Ways in which bone mineral analysis can be performed
Standard radiographs of the dorsal and lumber spine
Were used to determine bone density before bone densitometry. osteoporosis is not visible one these images until later portions of the disease
