Lecture 3 Flashcards
(20 cards)
What are the objectives to be attained by a QA program?
Maintain quality of diagnostic images
Minimum radiography exposure to patient and staff
Cost effective
Difference between accuracy and precision?
Accuracy = random error
Precision = systematic
What are the differnt types of distributions that measurements can fall under?
Normal
Positively and negatively skewed
Bimodal
What do we have to make sure of when measuring?
Keeping all variables constant except one
The extraneous variables and the effect on results
Account for and correct for the uncontrollable things
How do we monitor drift in measurements?
With set limits that shouldn’t be exceeded
So we find the coefficient of variance
COV = SD/mean
Precision = COV x 100 to get percentage
Name the different QC tests
Acceptance testing of equipment
Regulatory compliance
Preventive maintenance and repair
Routine quality control
What is acceptance testing?
Done on new, or refurbished equipment
To show that it works within set specifications and criteria
To detect defects
To establish baseline used as ref point in furutre testing
What is regulatory compliance testing?
EPA compliance tests are specific and they demonstrate X-ray equipment performance within specifications and creiteria for registration of ionising radiation apparatus
What is preventive maintenance and repair?
Done to prevent unexpected breakdowns due to failing of equipment
What is routine quality control?
Tests are performed after a certain period of usage to show optimum performance is being kept so that it doesn’t come up on scans
This tests image quality, patient safety and dose, state safety and dose
Examples of routine quality checks and standards?
AS/NZ
ARPANSA
NSW EPA
Go through what is done during RQC?
It’s non invasive and simple test, and involves visual checks
X-ray generator and tube performance
AEC performance
Image receptor performance
System checks
Display devices/viewing conditions
Patient dose and image quality assessment
Name the non invasive and simple tests that are done during RQC
Tube warm up
Mechanical checks
Visual safety checks
Explain what’s tube warm up
Objective= are anode and other components of X-ray machine experiencing shock and stress from sudden heat, as this can cause fail
Procedure= large focal spot, expose with low kVp (60-70), mA (100), 1-2 s , do 3 exposures with 30 sec intervals
Outcome = unusual noise means DO NOT USE and record on fault sheet
Explain what’s meant by mechanical checks
Obj= are all components of system working properly and is it stable?
Procedure=
Check cable condition, locks, Bucky movement
Collimation, integrated detectors
Control panel indicator
Correct selection of chambers
Grid and portable detectors condition and operation
Explain what are visual safety checks. Done quarterly
Objective= to take adequate radiation safety measures to protect patients and staff
Procedure= Check radiation warning sign Radiation warning light Radiation shielding labels Lead aprons, gloves, collars condition Patient shield
Explain what is meant by the X-ray tube and generator performance
Waveform KVp accuracy Timer accuracy KVp, time and output reproducibility Output linearity HVL Focal spot assessment Collimation (X-ray and light filed alignment) Leakage radiation
Name all the tests conducted in a test equipment set up
Wave firm check KVp accuracy Timer accuracy KVp, timer and radiation output reproducibility Radiation output linearity HVL (beam filtration)
Explain what’re wave form checks
Obj= is the applied voltage smooth? And meeting specifications?
Procedure= set multimeter to around 100 cm from focus, connect the meter to a laptop (software to record waveform), set exposure factors (70-80 kVp, 200 mA)
Outcome= waveform should be free of spikes or kinks
Explain KVp accuracy testing
Obj= X-ray generated in terms of KVp selected
Procedure=
