14. QA/QC and equipment testing (the role of the MIT)

Question 1

what is the life cycle of x-ray equipment

Answer 1

equipment specification

tender and purchase

installation

critical examination

Question 2

in terms of x-ray testing what is critical examinations

Answer 2

installer must ensure that the equipment is radiologically safe once it has been installed

Question 3

in terms of x-ray testing what is acceptance testing

Answer 3

the installer must demonstrate that the equipment meets specifications of purchase contract

Question 4

in terms of x-ray testing what is commissioning tests

Answer 4

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

Question 5

in terms of x-ray testing what is routine performance testing (quality control)

Answer 5

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

Question 6

in terms of x-ray testing what is tender

Answer 6

looking for something available on the market

Question 7

in terms of x-ray testing what is commission

Answer 7

make sure machine does what it needs to do consistently

Question 8

what is the x-ray measurement for the output

Answer 8

mGy/mAs at 1 meter

Question 9

what are the 3 things that are checked as part of x-ray measurements

Answer 9

kV and filtration accuracy

functionality of ABC/AEC/Dose modulation

DAP meter/displayed dose

Question 10

what are the 5 areas where radiation safety checks are performed

Answer 10

warning lights

interlocks

emergency stop

tube leakage

shielding

Question 11

to test image quality using phantoms what 4 factors are evaluated

Answer 11

uniformity

contrast

resolution

artefacts

Question 12

what is the CAT fan phantom

Answer 12

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

Question 13

are phantoms qualitative or quantitative

why

Answer 13

qualitative as they are subjective

Question 14

what is MTF

Answer 14

modular transfer function

quantitative way of assessing resolution

Question 15

what are 3 quantitive ways of analysing images

Answer 15

noise = standard deviation of uniform region

noise power spectrum

modular transfer function

Question 16

what should x-ray room design ensure

Answer 16

that people in surrounding areas will not receive radiation doses above permitted levels

Question 17

what is protection normally provided by for room shielding

3 examples

Answer 17

concrete

lead

leaded glass

Question 18

ALARP ensure that doses are high enough to ___ and low enough that ___

Answer 18

high enough to obtain adequate quality images

no higher than necessary to minimise risk of harm

Question 19

what are the exposure limits for radiation staff per year

Answer 19

20mSv/year

Question 20

what are the exposure limits for the general public per year

Answer 20

1mSv/year

Question 21

what are 5 places scatter can occur in

Answer 21

x-ray tube assembly

patient

bed

detector

housing

Question 22

what are 3 ways to limit radiation exposure

Answer 22

increase distance from source

reduce exposure time

increase shielding

Question 23

how does increasing the distance from the source limit the radiation exposure

Answer 23

exposure reduces with distance squared

Question 24

how does reducing exposure time limit the radiation exposure

Answer 24

spend as little time as possible in the x-ray room while the beam is on

Question 25

how does increasing the shielding limit the radiation exposure

Answer 25

x-rays are absorbed by any material they pass through so exposure behind a barrier is lower

Question 26

what is the optimization process

Answer 26

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