Dose 1

Question 1

What is a subjective assessment

Answer 1

Purely personal and likely to be different to that of another individual

Question 2

Objective assessment

Answer 2

Refers to quantity that can be measures and assigned a values. Independent of personal opinion

Question 3

what are 3 means of objective assessment

Answer 3

EI, LEEDS test objects (contrast sensitivity), CDRAD (physical properties)

Question 4

sensitivity

Answer 4

probability of a positive result among those with conditions

Question 5

specificity

Answer 5

Liklihood for negative result for those without condition

Question 6

what is troubleshooting

Answer 6

A logical systematic search for the source of a problem in order to solve it

Question 7

what are the 3 resources for troubleshooting

Answer 7

manufacturer resources (service engineer, applications specialist, equipment manual, user guide), equipment logbook, QC reports

Question 8

6 steps to troubleshooting

Answer 8

1. verify that problem actually exists
2. articulate symptoms
3. determine circumstances where it occurs
4. brainstorm possible causes
5. rank causes in probability
6. investigate causes from most likely

Question 9

what are the 2 types of quality measures in medical imaging

Answer 9

people centred quality (patient care), product centred quality (diagnostic images)

Question 10

what is the goal of QC testing

Answer 10

to detect change in equipment function from the original level of performance

Question 11

what is the QC objective

Answer 11

enable prompt corrective action to maintain image quality and radiation safety

Question 12

what is the QC rationale

Answer 12

degredation in equipment performance is gradual and expected, testing uncovers changes

Question 13

what is the difference between acceptance and compliance testing

Answer 13

acceptance testing measures standards at installation, compliance testing is performed periodically to ensure continued compliance with standards

Question 14

what are the benefits of QC testing

Answer 14

detection of equipment deterioration, ALARA, ensures patient and staff safety, ensures legislative compliance

Question 15

what are the four stages of checks

Answer 15

1. critical examination- ensure safety features working
2. acceptance- verify all equipment Is supplied
3. commissioning- by engineer, ensures equip is safe for clinical use
4. routine performance testing- reg testing throughout lifetime

Question 16

what is the difference between a run chart and a trend chart

Answer 16

a run chart displays data in time sequence, a trend chart is simlar but has ideal central line with upper and lower limits

Question 17

how do you interperate a trend or run chart

Answer 17

look for trends (atleast 3 sets of data in same direction) in same direction. when a first measurement is out of limits it needs to be remeasured, corrective action needs to be performed when a trend indicates that process is out of control

Question 18

what are the QC tests for the xray generator

Answer 18

1. filtration/HVL test
2. radiation output test
3. reproducibility test
4. reciprocity test
5. linearity test

Question 19

what does the HVL test look for, when is it performed and what are the steps

Answer 19

ensures adequate filtration to low dose photons of beam, performed for new XRT and needs to meet manufacturer standard. Steps: collimation set to 0, dosimeter is used and exposures are taken with increasing layers of Al. percentage transmission is calculated as exposures are taken and is plotted against thickness, 50% transmission = ideal amount. cannot fall below 2.3mmAleq

Question 20

what does the radiation output test look for, when is it performed and what are the steps

Answer 20

it assesses the lines voltage compensation and microprocessers of the XRT, and annual testing is required. for indirect reading: rad system with internal filter- one image taken with and one image taken without filter- compares two readings and LUT used to determine what causes different readings. for direct read: output recorded by dosimeter. % accuracy calculation performed. needs to be within 10% of baseline

Question 21

what does the kV reproducibility test look for, when is it performed and what are the steps

Answer 21

measures the ability of the generator to deliver the same output when the same exposure factors are used. dosimeter placed In ray and 5 exposures are taken; reproducibility variance % calculated from the readings. variance must be below 5%

Question 22

what does the reciprocity test look for, when is it performed and what are the steps

Answer 22

it measures the ability of the generator to produce the same output given the same kVp and mAs, with alternating mA and time settings. performed anually. 5 exposures with same kVp and mAs (different combos) are made, dosimeter used to record output. reciprocity variance calculated for max and min measurements, must be below 10% variance

Question 23

what does the linearity test look for, when is it performed and what are the steps

Answer 23

testing of mA and timer separately to determine the proportionality of output with increasing exposure factors. completed annually. mA linearity steps; mA increased while all other factors kept constant. timer linearity test: time increased with all other factors kept constant. 5 exposures are made, reciprocity variance used and must be below 10%

Question 24

what does the xray beam/grid alignment test look for, when is it performed and what are the steps

Answer 24

tests for lateral decentering or tilting of the focussed grid in the bucky. performed annually. lead panel with 5 holes, each hole exposed covering others, middle hole should be most dense. decentering needs to be within 1/2 inch or +/- 2% SID. failed test is remedial

Question 25

what is the xray field IR test, when is it performed and what are the steps

Answer 25

ensures that the x-ray field and IR coincide when XRT and bucky are aligned. performed when grid is replaced or XRT serviced. steps; 24x30 cassette placed in bucky, indicator lights green, 2x sets of exposures taken; one pulling the XRT toward you, one pushing it away. sum of variance of both sides must be less than 2% SID

Question 26

what is the grid uniformity test, when is it performed and what are the steps

Answer 26

ensures grid working effectively, performed annually?, PSP cassette erased, cassette on floor and SID focal range of grid used, collimate to full cassette and expose with tib fib protocol, perform test again with grid on cassette, reprocess with mammography filter and view both images for uniformity- ROI of 5 corners must be within 10% variance

Question 27

what are the 3 components that contribute toward image quality

Answer 27

1. psp cassette (captures latent image) 2. CR reader/digitizer (processes image and applies algorithm) 3. digital electronics (projects image)

Question 28

what are the components of the CR reader

Answer 28

1. mechanical- rollers 2. optical- laser lights 3. computer control- laser tagging (processing of images)

Question 29

when should spot checks of the CR cassette and IP be performed

Answer 29

daily or weekly with cassette chosen at random. inspection/cleaning performed weekly or monthly (disinfectant + microfibre cloth)

Question 30

what is the background noise test, when should it be performed and what are the steps

Answer 30

analyses image for unwanted background noise, 18x24 cassette scanned under hand examination, brightness and contrast scaling performed, 5 ROI measurements performed. EI should be NULL

Question 31

what is the ghosting test, when is it performed and what are the steps

Answer 31

analyses image for ghosting (superimposition of previous image over current image) caused by inability to deactivate detector plate phosphors that were energised on previous exposure. steps; take extremely overexposed phantom image, put psp through normal cycle, put psp through normal cycle again, take ROI and compare. failed test- IP needs to be replaced

Question 32

what is the flat field test, when is it performed and what are the steps

Answer 32

ensuring that there is pixel uniformity in FFD, 35x43 cassette with open collimatioin, process plate with high contrast filter (mammography), view image for non uniformity and ROIs, must be within 10% variance

Question 33

what are the 3 components of the DR system

Answer 33

1. image receptor 2. image detector 3. image processing

Question 34

what is a del and what is the fill factor pixel ratio

Answer 34

the DR image receptor is a configuration of Dels, containing TFT, pixel sensing area and storage. fill factor of pixel is the ratio of sensing area of pixel to area of pixel itself. high fill factor is better

Question 35

what are the 3 stages of detector calibration and why are they performed

Answer 35

offset correction, gain correction and pixel calibration

Question 36

what is offset calibration and how is it performed

Answer 36

ensures that each pixel in the detector measures radiation from the same level. steps; logged in as DR -administrator, system-general-quality assurance, entries for detector calibration and follow screen prompts

Question 37

what is gain calibration and what are the steps for it

Answer 37

ensures that all pixels in the detector generate the same signal value for the same amount of radiation. align xrt to wall stand with 150cm SID, turn key in XRT to manual override, open collimation to 2cm larger than sensing area with 0 filtration, insert 21mm Al filter and no grid, select gain calibration in patient list and perform 10 exposured

Question 38

what is pixel calibration and what are the steps

Answer 38

addresses dead pixels and applies algorithms based on neighbouring pixel values. steps; select pixel calibration from patient list, perform the sequence of 12 exposures

Question 39

what is the SMPTE task for monitor function

Answer 39

assesses if monitor is displaying all signal information w/o loss. steps; patient list- test images- review- spmte. select scaling tool and locate full screen and perform visual inspection. for contrast, black and white squares should be clear. for uniformity, background grey should look uniform. for spatial resolution each corner line pattern should be visible

Question 40

what is the kVp compensation test and what are the steps for it

Answer 40

assesses for consistant level of image quality at different tube potentials. steps; 4 images of test phantom taken with all factors consistant. mean EI and ROI is calculated. EI and ROI of the images must not be more than 20% or less than 15% of average

Question 41

what is the AEC reproducibility test and what are the steps

Answer 41

assesses for consistency of the AEC chambers in recording the signal received. 2 sets of images taken. test 1; phantom placed over central chamber and exposed 5 times, radiation meter records air kerma, mean Is determined of air kerma and EI. smallest and largest value is calculated and expressed as % of avg. test 2; phantom placed over left than right chamber and 2 images taken, air kerma and EI average calculated, smallest of 2 air kerma averages must be within 10% of all other values

Question 42

what is the patient thickness compensation test

Answer 42

determines if AEC is adjusting appropriately for changing patient thickness. test phantoms of varying thicknesses exposed at different kV settings, EI and ROI recorded, average of data recorded. average EI must not differ by more than 20% of the lower two the EI recorded, average central signal value must not differ by more than 20% of the lower two signal values