Bone Densitometry Review Exam
Questions with Solutions
The term DXA stands for: - -Dual-energy x-ray absorptiometry
-The two anatomic sites typically used for central DXA scanning are: - -
Lumbar spine and proximal femur
-Two different types of bone in the skeletal region are: - -cortical and
trabecular
-Radiation exposure for a typical DXA scan is - -1 to 5 mrem (millirems)
-The T-score is directly related to: - -young adult population
-The Z-score is directly related to: - -age-matched population
-Bone mineral density (BMD) is calculated by the following equation: - -BMC
divided by area
-What medical condition is an indication for scanning the forearm? - -
Hyperparathyroidism
-Three factors directly related to radiation safety in DXA scanning are: - -
Time, distance, and shielding
-One of the correct scanning procedures for precision testing is as follows. -
-Scan 30 patients twice
-Describe the process of bone remodeling and its two main components. - -
Old bone is replaced with new bone. Osteoclasts are the bone-destroying
cells. Osteoblasts are the bone-building cells.
-What is the purpose of vertebral fracture assessment (VFA)? - -Vertebral
fracture assessment (VFA) is performed for the sole purpose of detecting
vertebral fractures, not measuring bone density.
-Describe the attenuation method used in BMD calculation. - -Eliminate the
contribution of soft tissue, and measure the attenuation due to bone alone.
Scan at two different x-ray photon energies, and mathematically manipulate
the recorded signal. The density of the isolated bone is calculated on the
principle that denser, more mineralized bone produces more x-ray
attenuation.
, -Why is a baseline scan so important in diagnosis and follow-up? - -All
follow-up scans are compared to the baseline scan. The baseline scan must
be acquired and analyzed correctly so that when serial scanning is done, the
serial can scan can be directly compared to the baseline. Precision and
accuracy in both scans are vital to assure correct diagnosis and follow-up.
-How often should you perform a phantom scan? - -A phantom scan is
performed daily before any patients are scanned.
-Name one contraindication to performing a central DXA scan. - -Recent
barium studies or other contrast media studies, pregnancy
-Describe the difference between accuracy and precision in bone
densitometry - -Accuracy is equipment dependent and relates to the ability
to measure the true BMD. Precision is technologist related and involves the
ability to reproduce positioning.
-What does ALARA stand for? - -As Low As Reasonably Achievable
-What is the minimal distance a DXA scan operator should be from he x-ray
source of a fan-beam DXA scanner? - -9 ft or 3 meters
-Define the difference between primary and secondary osteoporosis - -
Primary osteoporosis is related to postmenopausal status (type I) or aging
(type II). Secondary osteoporosis is caused by other factors, such as
medications or disease processes.
-What is the correct procedure to follow after there has been a failed quality
assurance test on any DXA scanner? - -Repeat the test and record the
problem or corrective action. If the test fails a second time, call the
manufacturer's help or applications service line. Cancel all appointments
until the problem can be corrected.
-Describe FRAX and why it is used. - -The FRAX tool has been developed by
the World Health Organization (WHO) to evaluate fracture risks of patients. It
is based on individual patient models that integrate the risks associated with
clinical risk factors as well as bone mineral density (BMD) at the femoral
neck. The algorithm gives the 10-year probability of fracture.
-What is the primary reason a serial DXA scan is done? - -The primary
reason to do a serial scan is to determine treatment or monitoring response
to therapy.
-According to the World Health Organization (WHO), what T-score level
indicates osteoporosis? - --2.5 or less
Questions with Solutions
The term DXA stands for: - -Dual-energy x-ray absorptiometry
-The two anatomic sites typically used for central DXA scanning are: - -
Lumbar spine and proximal femur
-Two different types of bone in the skeletal region are: - -cortical and
trabecular
-Radiation exposure for a typical DXA scan is - -1 to 5 mrem (millirems)
-The T-score is directly related to: - -young adult population
-The Z-score is directly related to: - -age-matched population
-Bone mineral density (BMD) is calculated by the following equation: - -BMC
divided by area
-What medical condition is an indication for scanning the forearm? - -
Hyperparathyroidism
-Three factors directly related to radiation safety in DXA scanning are: - -
Time, distance, and shielding
-One of the correct scanning procedures for precision testing is as follows. -
-Scan 30 patients twice
-Describe the process of bone remodeling and its two main components. - -
Old bone is replaced with new bone. Osteoclasts are the bone-destroying
cells. Osteoblasts are the bone-building cells.
-What is the purpose of vertebral fracture assessment (VFA)? - -Vertebral
fracture assessment (VFA) is performed for the sole purpose of detecting
vertebral fractures, not measuring bone density.
-Describe the attenuation method used in BMD calculation. - -Eliminate the
contribution of soft tissue, and measure the attenuation due to bone alone.
Scan at two different x-ray photon energies, and mathematically manipulate
the recorded signal. The density of the isolated bone is calculated on the
principle that denser, more mineralized bone produces more x-ray
attenuation.
, -Why is a baseline scan so important in diagnosis and follow-up? - -All
follow-up scans are compared to the baseline scan. The baseline scan must
be acquired and analyzed correctly so that when serial scanning is done, the
serial can scan can be directly compared to the baseline. Precision and
accuracy in both scans are vital to assure correct diagnosis and follow-up.
-How often should you perform a phantom scan? - -A phantom scan is
performed daily before any patients are scanned.
-Name one contraindication to performing a central DXA scan. - -Recent
barium studies or other contrast media studies, pregnancy
-Describe the difference between accuracy and precision in bone
densitometry - -Accuracy is equipment dependent and relates to the ability
to measure the true BMD. Precision is technologist related and involves the
ability to reproduce positioning.
-What does ALARA stand for? - -As Low As Reasonably Achievable
-What is the minimal distance a DXA scan operator should be from he x-ray
source of a fan-beam DXA scanner? - -9 ft or 3 meters
-Define the difference between primary and secondary osteoporosis - -
Primary osteoporosis is related to postmenopausal status (type I) or aging
(type II). Secondary osteoporosis is caused by other factors, such as
medications or disease processes.
-What is the correct procedure to follow after there has been a failed quality
assurance test on any DXA scanner? - -Repeat the test and record the
problem or corrective action. If the test fails a second time, call the
manufacturer's help or applications service line. Cancel all appointments
until the problem can be corrected.
-Describe FRAX and why it is used. - -The FRAX tool has been developed by
the World Health Organization (WHO) to evaluate fracture risks of patients. It
is based on individual patient models that integrate the risks associated with
clinical risk factors as well as bone mineral density (BMD) at the femoral
neck. The algorithm gives the 10-year probability of fracture.
-What is the primary reason a serial DXA scan is done? - -The primary
reason to do a serial scan is to determine treatment or monitoring response
to therapy.
-According to the World Health Organization (WHO), what T-score level
indicates osteoporosis? - --2.5 or less
