14. QA/QC and equipment testing (the role of the MIT) Flashcards
what is the life cycle of x-ray equipment
equipment specification
tender and purchase
installation
critical examination
in terms of x-ray testing what is critical examinations
installer must ensure that the equipment is radiologically safe once it has been installed
in terms of x-ray testing what is acceptance testing
the installer must demonstrate that the equipment meets specifications of purchase contract
in terms of x-ray testing what is commissioning tests
carried out by the purchaser representative to ensure that the equipment is fit for use and is optimised for clinical use
baseline values are established to allow for comparison with future measurement
in terms of x-ray testing what is routine performance testing (quality control)
these are performed on a regular basis, as well as following maintenance or repair to ensure that the equipment still operates safely and is optimised for use
in terms of x-ray testing what is tender
looking for something available on the market
in terms of x-ray testing what is commission
make sure machine does what it needs to do consistently
what is the x-ray measurement for the output
mGy/mAs at 1 meter
what are the 3 things that are checked as part of x-ray measurements
kV and filtration accuracy
functionality of ABC/AEC/Dose modulation
DAP meter/displayed dose
what are the 5 areas where radiation safety checks are performed
warning lights
interlocks
emergency stop
tube leakage
shielding
to test image quality using phantoms what 4 factors are evaluated
uniformity
contrast
resolution
artefacts
what is the CAT fan phantom
cylindrical module with different nodules inside used to set baselines and troubleshoot problems that come up with time
How many dots we can see of different contrast and check HU accuracy and how accurately its identifying different materials
are phantoms qualitative or quantitative
why
qualitative as they are subjective
what is MTF
modular transfer function
quantitative way of assessing resolution
what are 3 quantitive ways of analysing images
noise = standard deviation of uniform region
noise power spectrum
modular transfer function
what should x-ray room design ensure
that people in surrounding areas will not receive radiation doses above permitted levels
what is protection normally provided by for room shielding
3 examples
concrete
lead
leaded glass
ALARP ensure that doses are high enough to ___ and low enough that ___
high enough to obtain adequate quality images
no higher than necessary to minimise risk of harm
what are the exposure limits for radiation staff per year
20mSv/year
what are the exposure limits for the general public per year
1mSv/year
what are 5 places scatter can occur in
x-ray tube assembly
patient
bed
detector
housing
what are 3 ways to limit radiation exposure
increase distance from source
reduce exposure time
increase shielding
how does increasing the distance from the source limit the radiation exposure
exposure reduces with distance squared
how does reducing exposure time limit the radiation exposure
spend as little time as possible in the x-ray room while the beam is on
how does increasing the shielding limit the radiation exposure
x-rays are absorbed by any material they pass through so exposure behind a barrier is lower
what is the optimization process
data collection -> assess dose and assess image quality
assess dose = compare to standards/DRLS
assess image quality = quantitative and qualitative
make a change in the dose, process or settings
