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RAD 231 - Unit 4

QC questions

8 (9) Penny Collimator Test is also known as: p113 Papp X-ray/light field congruency test or Light Field-Radiation Field Alignment (Congruence)
What does the light field congruency test measure? how well the collimator regulates the field size and whether the area illuminated by the positioning light and area exposed by x-rays are the same
What tools do you need for the light field-radiation field alignment test? 8 or 9 coins
What are the acceptance limits for the x-ray/light field congruency test? Deviation within +/- 2% of the SID for light field/x-ray field alignment.
What is the purpose of the nine-penny collimator test? to assure the x-ray field and light field are congruent
Which test measures x-ray/light field congruency? 8 (9) penny collimator test
What is the purpose of the Beam Perpendicularity test? To assure that the x-ray tube is mounted in its housing so that the central ray is perpendicular to the plane of the IR
What equipment is needed for the beam perpendicularity test? A Wisconsin Beam alignment Test Tool - (clear Plexiglas cylinder containing 2 1/6" diameter steel balls separated by 6") OR Beam alignment test tool - cylinder of Lucite with lp/mm test tool embedded in center of top (Papp p115)
What are the acceptance limits for the Beam Perpendicularity test? beam must be within 1 degree of perpendicular (>0.4" must be reported)
What is the name of the test that ensures filtration of the x-ray beam is adequate in 2 exposures? Beam Quality Test - Filter Ratio Method
What tools are needed for the Filter Ratio method test? Dosimeter, sheets of lead rubber, sponges and 2.3mm Aluminum filtration
What are the acceptance limits for the Beam quality test - filter ratio method? The acceptable range of the filter ratio is 0.50 - 0.75. Less than 0.50 indicates that filtration is insufficient. Greater than .75 indicates excessive filtration.
What is the purpose of the Filter Ratio method test? to assure that filtration of the x-ray beam is adequate to reduce patient exposure to low-energy radiation and assures that the filters are in place.
Describe the purpose of the Generator Linearity test. To assure that sequential increases in milliampere-seconds produce the same sequential increase in exposure.
Name the tools required for the generator linearity test. Dosimeter, sheets of lead rubber
What are the acceptance limits for the generator linearity test? Papp p111 federal regulations state that the linearity should not exceed +/- 10%. Problems in the x-ray generator, such as timer circuitry, or rectifier failure, can cause the linearity variance to exceed accepted limits.
What is the purpose of the Generator - Reproducibility test? To assure that exposure received for the same mAs and kVp is the same from exposure to exposure.
What equipment is needed for the Generator - reproducibility test? dosimeter sheets of lead rubber
What are the acceptance limits for the generator - reproducibility test? the reproducibility for each technique should be maintained within plus or minus 5%.
What are the three components of QC for radiographic units? Visual Inspection - p101 Papp; Environmental Inspection - p102 Papp; Performance Testing - p103 Papp
Describe the frequency of QC testing. PP p2 Upon installation, annually, during service (repairs); based on usage (8-10yrs may be increased from annual to biannual) age of machine; high volume production (may increase required # of tests based on patient scan volume)
What are the types of maintenance? PP p3 CORRECTIVE maintenance - performed by engineer or radiation physicist (equip adjustments and repairs); PREVENTATIVE maintenance - prevents unexpected breakdowns of equip and interruptions of dept routines (some tests can be performed by techs or engine
When performing a visual inspection, what do you need to check? Papp p101 Inspect the control console, overhead tube crane, radiographic table, protective lead apparel, and miscellaneous equipment
Describe REPEAT ANALYSIS. Papp p129 Performance of reject, retake or repeat analysis. REJECT includes ALL rejected images - including repeats REPEAT includes patient images repeated, resulting in addtl patient exposure You MUST repeat a QC test that fails in order to validate the data
What is the process for REPEAT ANALYSIS for QC testing? PP p4 1) repeat failed QC test to validate data 2) notify proper authority (show test results) 3) document adjustments/repairs after completion (engineer resp) 4) retest to ensure normal operation/document results of retest (engineer responsible)
Describe PREVENTATIVE MAINTENANCE. PP p3 -Process cleaning/maintenance (CR Reader) -Walk-through inspections -Inspection of mobile units and specialty equip -Check mechanical/electrical components for strength (foot board) -Visual inspection of entire room (include ceiling)
What is the process of TROUBLESHOOTING? PP p4 IMPORTANT - saves money by reducing unnecessary service calls; 1. Trace the problem 2. Finding a cause 3. Taking the appropriate action
What is Phase 1 Troubleshooting? -make a list of common operational problems -speak with radiographers/prof service engineers; -as problems are identified, find several solutions to problem -"what do I do if...?"
What is Phase 2 Troubleshooting? -Develop a medium to convey troubleshooting communications. *post a troubleshooting list in each room *include in new employee orientation
What is Phase 3 Troubleshooting? PP p6 -Evaluates radiographers on use of list *test tech on problems that may occur with equipment *take note of proper and improper troubleshooting when equip problems occur
What is the new name of the Bureau of Radiological Health? Papp p4 National Center for Devices and Radiologic Health
What is a QA manual? Quality Assurance manual incl EVERYTHING Located with RSO, Exec Direc -goals/objectives for program -indiv duties/Responsibilities -tests/sched -descrip of each test procedure used -provides master plan -generates awareness of obj, functions, admin
What is contained in QA manual? -goals/objectives for program -list of indiv duties/Responsibilities -list of tests/testing schedule -description of each test procedure used in dept -provides master plan -generates awareness of obj, functions, admin -specific data about each unit
What is contained in QA manual log books? PP p7 Each radiographic unit includes *tube rating chart *equipment operating instructions *record of test results *log of equipment service
What is the purpose of QC - performance testing of radiographic equipment? measures radiation output
Describe TYPES of tools used for radiation measurement. PP p8 Papp p103-104 Most performance testing performed with gas-filled chamber detectors 3 diff types of detectors *ion chamber (most common) DOSIMETER *Proportional counter (nuc med) (drop into well, counts) *Geiger-Mueller counter (nuc med) (survey meter)
State the name of the test that demonstrates the same technical factors always produce the same radiation output. PP p9 X-Ray Generator - Reproducibility of Exposure
What does the Reproducibility of Exposure test evaluate? Papp p104 x-ray generator - a specific technique always produces the same radiation output
What is the testing tool used to measure that the same technical factors always produce the same radiation output? PP p9 dosimeter
What is the acceptable range for the Reproducibility of Exposure test? PP p9 no more than +/- 5% variation from expected output
What is the formula for the Reproducibility of Exposure (exposure or air kerma max - exposure or air kerma min) / (exposure of air kerma max + exposure or air kerma min) X 100 OR (exposure or air kerma max - exposure or air kerma min) / 2 then divide that answer by the average of the measured air kerma X 100
Is intensity of radiation a qualitative or quantitative measurement? QUANTITATIVE; the only thing that is a qualitative measurement is kVp
State the name of the test that measures how much low energy radiation is in the x-ray beam. PP p10 QC Packet #3 Beam Quality Test - Filter Ratio Method
What does the filtration test measure? measures filtration by determining the HVL (Half Value Layer)
What testing tool does the filtration test utilize? radiation dosimeter 1 mm Aluminum filter(s)
What is the acceptable range/value for HVL? MINIMUM HVL is 2.3 mm aluminum equivalent at 80kVp Papp p107
What is the formula used for computing average of filter ratio test results? PP p10 Aluminum filter / no filter = filter ratio
What does the x-ray generator - Kilovolt (Peak) Accuracy test measure? that the kVp on the control panel equals the kVp output of the actual beam
What testing tool is utilized to measure kVp output of the beam? a) Wisconsin Test Cassette (we don't have) b) digital kVp meter
What is the purpose of the measuring kVp output? to ensure exposures are accurately penetrating anatomy while maintaining ALARA
What is the acceptable range/value for kVp? Variations between stated kVp and actual x-ray beam quality must be withing +/- 5%
?????? What formula is used to calculate whether Reproducibility results are acceptable? Meter reading - control panel kVp / control panel kVp X 100 =
Describe the test to measure VOLTAGE WAVEFORM. Papp p107-108 Using an oscilloscope, a specially trained physicist, biomedical engineer or service engineer, can measure many aspects of generator performance by visualizing the voltage waveform while a detector is placed within the beam.
State the name of the test that uses a spinning top or a digital timer. Papp p108-109 Orth p376 X-ray generator -timer accuracy
What testing tool does Timer Accuracy use? PP p12 a) spinning top (manual for single phase, synchronous for 3-phase) b) digital timer (3-phase only)
What is the purpose of measuring timer accuracy? accurate exposure timer measurements are critical for acquiring properly exposed images with ALARA
What variability is acceptable for timer accuracy? QC Packet - Timer Test, Motorized Sychronous Top +/- 5% for exposure times over 10 ms; +/- 20% for exposure times less than 10 ms
KNOW What formula do you use to calculate time for half-wave time? count number of dots / 60 = time; 60 cycles per second (1 per complete sine wave)
KNOW What formula do you use to calculate time for full-wave time? count number of dots / 120 = time 60 cycles per second (2 positive waves per complete sine wave)
What is the purpose of PBL? PP p18 Papp p113-114 Automatic collimation regulates the size of the x-ray exposure field; significant role in determining patient dose; impacts image contrast (more or less scatter based on amt of anatomy exposed)
When are QC tests performed? a) upon acceptance; b) annually; c) service or repair performed ALL QC TESTS PERFORMED EACH TIME
In a Beam Alignment Test Tool, will the two balls be completely superimposed? Why or why not? Due to OID, one ball will be slightly magnified. However, if they are both within the circle, the test passes. If one ball is outside the inner circle, then test fails and must be repeated.
What happens to image quality if beam alignment fails? a) shape distortion b) must repeat study (increase patient dose)
Describe components of AEC. COMPARATOR - electronic circuit that receives current signal sent by sensor and terminates exposure when specific rad amt has been measured; DETECTORS - sensors, cells, chambers > can be photodetectors, ion chambers, solid state detectors
What is grid latitude? PP p33 margin of error in centering x-ray beam to center of grid before significant grid cut-off appears in resulting image
Describe grids PP p32 most common device for controlling scattered radiation; improper use can cause "grid cut-off" resulting in an underexposed radiograph or artifact
What are the grid variables? PP p32 grid UNIFORMITY; grid ALIGNMENT
What is a portable xray generator? can be carried ex...military battlefield use
What is a mobile xray generator? can be pushed (what we use in clinical);
Types of mobile x-ray generator... DIRECT POWER UNIT (fluctuations in power, need outlet); CAPACITOR DISCHARGE (high tension capacitor that must pre-charge before exposure, need outlet, must make x-ray ASAP) CORDLESS (battery powered)
Created by: Larobbins