ARRT Bone Density Exam Study Set

According to the WHO criteria, what is the diagnosis of osteoporosis based on the measurement of bone density?

2.5 SD or more below the young adult peak bone density

What is the gold standard technique for measuring bone density?

DXA

Cancellous bone is also know as?

Trabecular Bone

What is the anatomical landmark on the proximal femur that gives the best visual indication of the degree of rotation of the proximal femur?

Lesser Trochanter

Which lumbar vertebra is described as having a characteristic shape of an X or and H on a DXA PA spine scan?

L4

Is Forteo a bisphosphonate?

NO

Quantitative Computated Tomography (QCT)

-measurements are volumetric

-trabecular bone can be isolated from cortical bone

-accuracy may be affected by marrow fat

Peripheral BMD measurements are advocated for _____________?

Screening

What is the most important clinical consequence of osteoporosis?

Fracture

What is the name of the tool that integrates clinical information in a quantitative manner to predict a 10-year probability of major osteoporotic fracture for both men and women?

FRAX

What is the major source of precision error in clinical practice?

Technologist

What is the percentage of trabecular bone in the skeleton?

20 %

The forearm is not used to monitor the effects of therapy for osteoporosis because.......

rate of change in BMD is too slow

What site is mostly composed of cortical bone?

Proximal forearm

What are the advantages of QUS over x-ray methodologies for BMD measurement?

-ultrasound is comparatively inexpensive

-patients are not subjected to ionizing radiation

-ultrasound exams are quick to perform

What is the name of the isotope that was used in SPA?

Iodine-125

What is the texture index that evaluates the pixel gray-level variations in lumber spine DXA images?

TBS (Trabecular Bone Score)

When does type 2 primary osteoporosis generally occur?

after age 70

What technique used images of the hand and an aluminum wedge?

RA (Radiograhic Absorptiometry)

New bone is formed by the ___________?

osteoblasts

Cancellous bone is also known as _______________?

Trabecular bone

How would you start labeling the vertebral bodies on a PA lumbar scan?

Start at L4 and count/label up

With changes in rotation of the femoral neck, what happens?

Increases the BMD

If daily QC fails, what should be your first step of action?

-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..........

-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 __________________

osteoclasts

Which site is preferred for determination of fracture prediction?

proximal femur

What is one disease not associated with low BMD?

osteopetrosis

DXA results may be influenced by.........

-body thickness

-degenerative changes

-fractures

-scan mode

A great forearm scan should include.......

-forearm centered

-forearm straight

-free of artifacts

Phantoms that mimic the shape and size of a skeletal region are called ______________________________.

anthromomorphic phantoms

What is the formula used to calculate BMD?

BMD = BMC/Area

How often should you perform the QA on the DXA unit?

everyday you scan

Radiogammetry is the measurement of bones using skeletal x-rays/radiographs. Which site was often used?

metacarpals

With voltage switching units, what type of calibration is used?

continuous internal calibration--wheel or drum

For low energies, the most common process of absorption is the ________________________ effect.

photoelectric

What are some comparisons to the amount of effective dose given during a central DXA scan?

-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?

reference values reflect non-dominant arm measurements

When measuring the proximal femur, how should the neck ROI be placed?

the neck ROI should be perpendicular to the femoral neck

What is the bone edge detection methodology?

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?

-energy shifting

-k-edge filters

Why do you use the hip positioner during scanning of the proximal femur?

to place the femoral neck parallel to the tabletop

Bisphosphonates prevent bone loss by....

reducing the activity of the osteoclasts

If a patient has a history of hyperparathyroidism, what would the preferred site be for evaluation?

33% or 1/3 of the forearm

What is important for serial monitoring?

precision

What pharmaceutical may be suggested for a woman with a high risk of breast cancer and elevated lipids?

Evista (Raloxifene)

What year was the Bone Mass Measurement Act proposed?

1997

What type of osteoporosis is a result of menopause?

Primary Osteoporosis Type 1

What classes of cells are involved in bone remodeling?

-osteoclasts

-osteoblasts

-osteocytes

What therapy mimics the effects of estrogen on bone and has antiestrogenic effects in other tissue?

Raloxifene

In both men and women, bone mass increases until approximately what age?

30 years

What must be performed in order to compare studies when a new machine is bought?

cross-calibration

Which acronym best describes the least amount of BMD change that can be statistically significant?

LSC

What are the 2 types of bone?

-cortical

-trabecular

What parameters are used to calculate rate of change for a follow-up scan?

BMD

The shoulders of a patient should be squared with their ________.

pelvis

What are the preferred sites for the measurement of bone density in children?

spine and total body less head

What percentage of the skeletal body mass is cortical bone?

80%

Bone mineral density is expressed as.........

g/cm squared

How many times should you scan a patient with in-vivo precision study?

-30 patients scanned twice

-15 patients scanned 3 times

When analyzing the PA spine, what should you not mess with?

Width of ROI box

How many places to the right of the decimal point is used in reporting BMD?

3

The name of the forearm sites are based on what?

the location of the site on the bone in relationship to the overall length

A postmenopausal woman with a femoral neck T-score of -2.0 SD below a young adult is to be classified as.......

osteopenia

What happens when there is an imbalance or uncoupling of the remodeling cycle?

the usual result is a net loss in the bone mass

A technologist should perform a precision study in order to calculate _______________.

LSC (Least Significant Change)

A DXA scanner that uses a single detector and a pinhole collimator is a........

pencil beam scanner

Regarding Shewart Rules, the control limits are based on what percentage of the average values?

1.5% (3 SD)

What is the sum of the data values divided by the number of values?

mean

A DXA system that employs a rare earth filtered x-ray source uses what type of detector?

pulse counting

The characteristic shapes of the vertebrae seen on the DXA image are primarily based on the appearance of the ____________ elements.

posterior

Accuracy

-ability to measure true value

-most important for diagnosis

-less important for serial monitoring

-affected by the technology

Cortical bone makes up what?

outer cover of bones

What percentage of trabecular bone is found in the PA spine?

66%

the forearm, pelvis, and scapula all belong to which skeletal classification?

appendicular

The WHO criteria for diagnosing osteoporosis was initially to apply to only........

postmenopausal Caucasian women

In order to do a compare analysis...

-the patient must have a previous scan done on the same anatomy

-you must retrieve the baseline study

-patient position must be consistent

How many degrees should you rotate the femur when positioning for a proximal femur scan?

15-25 degrees

When should Z-scores be used to make a diagnosis instead of T-scores?

males or females under age 20

What is the name of the isotope used in DPA?

Gadolinium-153

What bone parameter is measured in grams?

BMC

The region of the proximal femur lying on the border of the femoral neck and the greater trochanter is termed the..............

Ward's Area

What are the diagnosis guidelines for children?

-z-scores are used

-"low for age" is used instead of "osteopenia"

-pediatric software is highly recommended

What is the age range used with FRAX?

40-90 years

What is the number which the precision error is multiplied to determine the LSC at 95% confidence level?

2.77

What skeletal site may be preferred for assessing early menopause following an oophorectomy?

spine

An increase in the overall bone mass of a patient is closely related to an accelerated rate of bone ___________ and a reduced amount of _______________.

formation; resorption

What scan measures the most trabecular bone?

QCT of the spine

What are 2 types of exercise that are great for your bones?

-weight bearing

-weight resistence

What are the 4 classifications that apply to the heel?

-appendicular

-peripheral

-predominantly trabecular

-weight bearing

What is the most accurate method to determine a patient's response to therapy for osteoporosis?

Serial DXA measurements of the proximal femur and spine

DXA results may be influenced by

-body thickness

-degenerative changes

-fractures

-scan speed/mode

Sunlight is the main source of vitamin _____

D

All follow up DXA scans should be compared to the ________scan

baseline

With long term use of steroids, what type of bone would be affected?

Trabecular

If a patient has a history of a laminectomy, how would that affect the results?

Decrease BMD

How many people are affected with low bone mass in the US?

54 million

The _____ is the only validated skeletal site for the clinical use of QUS in osteoporosis.

heel

Standard Deviation (SD)

measure of the variability or the spread of data around the mean

As _______ increases, the risk for a hip fracture increases independent of the BMD

HAL (hip axis length)