Module 5 Flashcards
BD takes advantage of X-ray energy and body composition process by using a blank technique
Subtraction
What type of equipment used a water bath to emulate soft tissue during scanning
Absorptiometry scanners
How is the value of bmd calculated
Determining the BMC and dividing it by the area of bone that was scanned
Refers to the binding energy of the K shell electron which varies for different materials
K edge
What type of filter does the GE system use
CERIUM
What type of filter does a Norland system use
Samarium
What type of energy does hologic use
A patent energy switch in system to generate beams with the 2 distinct photo electric pics
Where is the detector
The scanner arm that passes over the patient
What are 3 common physics problems that occur with DXA
Beam hardening, scintillating detector pillup, and cross over
This problem is from increased absorption shifts the distribution of photons towards high energy x-rays
Is beam hardening
This affects K edge filtration systems because they pulse counting detector can only process one photo at a time, if it’s not processed quickly enough and incoming photon can be missed
Scintillating detector pile up
This problem occurs because high energy photons can sometimes lose energy when passing through the body and be counted as low energy photons by the detector
Crossover
Travels back-and-forth in a rectilnear pattern across the scan area
Pencil beam
This scanner has a slit shaped colometer and a multi element detector the scanning motion only moves along one access
Is fan beam or fan array
What is a Disadvantage of fan beam technology
It can magnify and distort the outer edges of the scan area
This is a process by which the lateral projections of the spine are analyzed and measured, Answer is not VFA
Morphometric Absorptiometry
The ability of a test to measure the correct value of the thing it’s measuring
Accuracy
The likelihood a test can achieve the same result when It is repeated on the same subject and under the same conditions
Precision
How is the operator’s precision assist through in vivo
Scan of 15 patients 3 times or 30 patients 2 times
This error is expressed mathematically as a standard deviation with the most common results falling in the middle of a range and the less frequent results to the edge
Random error
A wide standard deviation indicates
Low precision
This measures how closely the results of the test match an external reference value
Trueness
What are the 2 factors of in vivo studies
The variability of a patient’s anatomy and the skill and attentiveness of the technologist
LSC
Least significant change is the minimum change in a patient’s measured bone density that reflects a real change in the patient rather than an error by the technologist or scanner
The minimum accuracy for the lumbar spine is ____ part technologist with an associated LSC of _____
1.9% and 5.3%
The minimum Accuracy for a scan of a total hip is ______ with a LSC of ______
1.8% and 5%
The minimum accuracy for a scan of the femoral neck is _____ with an LSC of _____
2.5% and 6.9%
What are the 4 speeds of the hologic system
Fast array 30 seconds
array 60 seconds
high definition a 120 seconds
Turbo 10 seconds
What modes do GE And Norland have
Thick standard thin and quick view modes
Slow shifts in blank are a much greater concern because they can affect many patient scans before being noticed
Accuracy
DEXA uses a blank technique that eliminates soft tissue from the scan results
Subtraction
K edge filter crossover occurs when high energy photons lose energy passing through the body and are
Registered as photons from the low energy beam
What value measures how closely the results of the test match an external reference value
Truness
What type of patient is most appropriate for precision testing
One that represents the facility’s population
DXA equipment calibration effects which values
Precision and truness
