Quality Assurance Basics Exam 62 Questions with Verified Answers,100% CORRECT

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Quality Assurance Basics Exam 62 Questions with Verified Answers Why do we need Quality Assurance? (primary objective) - CORRECT ANSWER To enable prompt and accurate image diagnosis What are the... 3 secondary objectives to QA? - CORRECT ANSWER 1. To maintain the quality of diagnostic images 2. to minimise the radiation exposure to patient and staff 3. to be cost effective Who is Responsible for Quality Assurance Programs? - CORRECT ANSWER Radiologist in charge But ultimately everyone is actively involved. QC responsibility is often delegated to: - CORRECT ANSWER Chief Radiographer Radiology Physicist QA Radiographer Radiation Safety Officer Measurement Accuracy How would we get THE ERROR from the measurements we get from any experiment? - CORRECT ANSWER Get MORE measurement to get an idea of the spread of results (which is the error) How would you use the BULLSEYE concept to 1. Precision 2. Accuracy - CORRECT ANSWER Precision - darts (measurements) are much closer together but further away from the bullseye Accuracy - darts (measurements) more spread out but closer to the bullseye When TESTING and taking measurements we also need to take account of VARIABILITIES such as... - CORRECT ANSWER temperature - affecting the x-ray tube - ionisation chambers are sensitive to temperature and pressure - if the daily temp is rising it may affect the measurements taken for the output Variation and limit FORMULA Coefficient of variance: (what do you do the answer to get precision?) - CORRECT ANSWER COV = st dev/ mean x100 to get PRECISION Type of QC Tests What are the 4 types? - CORRECT ANSWER 1. Acceptance testing of equipment 2. Regulatory compliance 3. Preventive maintenance and Repair 4. Routine Quality Control Acceptance Testing What is acceptance testing? Why is acceptance testing needed? - CORRECT ANSWER - it is performed on new equipment or - equipment that has undergone major repairs * to demonstrate equipments are performing within the manufacturer's specifications and criteria * meets purchasing requirements * detect any defects that may exist * to establish BASELINE that may be used as reference point in future testing What is the condition that goes along with Acceptance Testing and use in clinical practice? - CORRECT ANSWER - Acceptance testing should be performed by MEDICAL PHYSICIST in the presence of the supplier/ engineer before the equipment is used for clinical work >>Regulatory Compliance Testing Who is responsible? Under what law? - CORRECT ANSWER EPA (Environment protection Authority) Radiation Control Act What are >>EPA Regulatory Compliance Tests? - CORRECT ANSWER tests performed by state accredited CRES (consulting radiation experts) - to demonstrate that x-ray equipment is performing within the EPA specifications and criteria for registration of the ionising radiation apparatus used in diagnostic imaging We should not pay the supplier until equipment has passed ACCEPTANCE TESTING and STATE REGULATORY REQUIREMENTS - CORRECT ANSWER YAS >>Preventative Maintenance and Repair Why is preventative maintenance and repair needed? - CORRECT ANSWER - to prevent unexpected breakdowns due to falling of equipment - follow manufacturer's specifications for routine cleaning and maintenance - address problems identified during routine scans and quality control >> Routine Quality Control What are Routine Quality Control tests? - CORRECT ANSWER - specific tests done on equipment in use after a certain period of time - records should be kept to show authority Why is it carried out? - CORRECT ANSWER - to verify (equipment is performing within previously accepted standards) - to diagnose any changes in performance (before becoming radiographically apparent) - to further test (if any malfunctions) for rectifying problem >> Routine QC What should we test? What are the factors that affect the EXTENT of the RQC? - CORRECT ANSWER * Size of practice * Modality * Use/ age of equipment * Manpower and testing equipment available (QC costs money) To what standards should RQC's be tested to? - CORRECT ANSWER 1. AS/ NZ 2. ARPANSA 3. NSW EPA To organise all this STUFF!! What do we need? (hint hint: its a big book) - CORRECT ANSWER Establish a ... Quality assurance manual What goes in the Quality assurance manual? - CORRECT ANSWER * List of quality control tests to be performed * Objective * Frequency of testing * Equipment required * Procedure to follow * analysis * Action limits/ corrective action * Forms/ spreadsheets * Sample reports Routine Quality Checks may include: - CORRECT ANSWER - non invasive and simple tests including visual checks - x-ray generator and tube performance - AEC performance - Image receptor performance (These tests will be covered in the next lecture) - System checks - Display devices/ Viewing conditions - Patient dose and image quality assessment QC Testing Levels 1. Non invasive and simple tests WHO 2. X-ray equipment performance testing requiring test equipment 3. Invasive and complex WHO - CORRECT ANSWER - any radiographer - QA radiographer/ medical physicist specially trained in QC procedures - by engineers or engineers and physicists together Non invasive and Simple Tests There are 3 - CORRECT ANSWER 1. Tube warm up 2. Mechanical Checks 3. Visual Safety checks TUBE WARM UP Why is it done? - CORRECT ANSWER - to assure anode & other components do not get damaged by excessive heat TUBE WARM UP How is it done? - CORRECT ANSWER - use large focal spot - expose using low kVp (60-70) and low mA (~100) 1-2s MECHANICAL CHECKS Why is it done? - CORRECT ANSWER To assure all components of radiographic x-ray system works properly To assure system is mechanically stable MECHANICAL CHECKS Procedure? - CORRECT ANSWER All parts (cables, locks, bucky movement, collimators, control panel indicators, grid and portable detectors) VISUAL SAFETY CHECKS Why is it needed? Procedure? Frequency? - CORRECT ANSWER To assure patients and staff are safe from radiation dose Check all radiation safety signs, labels, shields for correct functioning Quarterly >>X-ray Tube and Generator Performance Name 9 features to be checked? - CORRECT ANSWER 1. Waveform 2. kVp accuracy 3. timer accuracy 4. kVp, time and output reproducibility 5. Output linearity 6. HVL (half value layer) 7. Focal Spot assessment 8. Collimation (X-ray and light field alignment) 9. Leakage radiation What are the equipment required? - CORRECT ANSWER - Multifunction meters/ devices - Metal coins/ paper clips - Tape measure - Focal spot tool/ resolution gauge - High purity aluminium - Lead sheet Waveform Checks Objective: - CORRECT ANSWER To assure applied voltage/ output is smooth and meets the manufacturer specifications What are the steps to the procedure? - CORRECT ANSWER 1. Set the multi meter at about 100 cm from the focus 2. Connect the meter to a laptop 3. Set exposure to 70-80 kVp/ 200mA/ 100ms 3. Expose and analyse the waveform Analysis? - CORRECT ANSWER Waveform should be free from any spikes or kinks Frequency? - CORRECT ANSWER Acceptance/ Annual/ After major generator service/ at tube replacement kVp accuracy Objective? - CORRECT ANSWER to ensure the x-ray generator is producing the kVp as selected on the control panel Procedure? - CORRECT ANSWER 1. position ionisation chamber at distance recommended by manufacturer 2. place a sheet of lead under the chamber to absorb backscatter 3. Collimate to size 4. Fix mAs 5. Make a series of exposure using the clinical kV range Analysis - CORRECT ANSWER Measure kvP average This should be within +- 5% of nominal kV Frequency - CORRECT ANSWER Acceptance/ Annual/ after major service/ tube replacement How do you calculate the accuracy of the measured kVp? (within 5% nominal value) - CORRECT ANSWER accuracy = kVp (set) - Av kVp / kVp (set) x 100 (%) Timer Accuracy Objective? - CORRECT ANSWER To ensure that x-ray generator is capable of terminating the exposure after a pre-selected time interval What are the steps in the Procedure? - CORRECT ANSWER 1. Set up same as for kVp accuracy 2. Fix kVp, mA (70-80 kvp, 200mA) 3. Make a series of exposures in the clinical range What would we want to measure? - CORRECT ANSWER Measured times must be within +-5% of the nominal values or within +/- 1 pulse (for short exposures, single phase generator) Frequency: - CORRECT ANSWER Acceptance, annual, after major generator service/ tube replacement Reproduciblility Objective? - CORRECT ANSWER - To ensure that the selected kVp, time and radiation output is reproducible Procedure? - CORRECT ANSWER 1. set up same as for kVp accuracy 2. Fix kVp mA and exposure time (70-80 kVp 200mA 100ms) 3. Expose and record the measured kVp, time and radiation output 4.Repeat 5 times 5. Calculate average of the five measurement, standard deviation and coefficient of variation Analysis? Frequency is same as previous - CORRECT ANSWER *All measured kVp values must be withiin +-2%, *timer andoutput values within +-5% of the average value Coefficient of variation = Average/ SD - CORRECT ANSWER Radiation Output linearity Objective? - CORRECT ANSWER To ensure that the radiation output is LINEAR over a range of set current (mA) and exposure time (ms) at each focus What does the procedure entail? - CORRECT ANSWER 1. Set up as same for kVp accuracy 2. For mA linearity fix kVp and exposure time (70-80 kvp, 100ms) 3. Measure output over clinically used mA range (50,100,200) 4. Repeat for each focus 5. Repeat the above procedure at fix kVp and mA (70kvp, 200ma) 6. Calculate Output/ mAs and coefficient of linearity Analysis - CORRECT ANSWER Coefficient of linearity must be within 10% What is the HVL for Al for diagnostic units operatin above 70kVp? - CORRECT ANSWER ~ 2.5 mm Al HVL Objective? - CORRECT ANSWER To ensure that there is sufficient filtration in the beam to remove low energy photons Procedure? - CORRECT ANSWER 1. Remove any additional filters 2. Set up same as for kVp accuracy 3. Fix kVp, mA, exposure time (70kVp 200mA 100ms) 4.Expose and record the measured kVp and radiation output (uGy) without any additional filtration in the beam 5. Repeat by adding 1, 2, 3 .. mm Al on the face of collimator till the radiation output reduces to one half 6. Plot the values on a semi log graph 7. Calculate mm Al corresponding to 50% of the initial output Analysis - CORRECT ANSWER HVL must be > 2.1 mm Al at 70kVp Focal Spot Assessment What are the 4 different methods? - CORRECT ANSWER 1. pinhole camera 2. slit camera 3. Star pattern 4. Resolution bar pattern Objective? - CORRECT ANSWER To ensure that system resolution is not compromised by poor focal spot geometry Procedure - CORRECT ANSWER 1. place the line pair gauge directly on the CR cassette 2. Place an absorber 3. Expose at 70kV, 200ma, 0.1 s, repeat for each focus 4. Record the number of lp/mm clearly visible Analysis - CORRECT ANSWER Compare results against baseline X-ray and Light Field Alignment Objective? - CORRECT ANSWER To ensure mean alignment and collimator accuracy Procedure - CORRECT ANSWER 1. position CR plate/ digital detector at 100cm from focus of the tube 2. Open the collimator to say 20x20cm field of view 3. Place metal markers on each light field edge and one to identify side and orientation (say on anode side) 4. Place a perpendicularity tool in the centre 5. Expose using 50kVp 5-10 mAs 6. estimate the difference in x-ray and light field Analysis - CORRECT ANSWER x-ray and light field alignment must be within 1% of focus to detector distance [Show More]

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