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FLUOROSCOPY QUALITY CONTROL Rev 2014 1. Error Maintenance When errors occur in equipment performance, corrective action must occur. Errors are detected.

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Presentation on theme: "FLUOROSCOPY QUALITY CONTROL Rev 2014 1. Error Maintenance When errors occur in equipment performance, corrective action must occur. Errors are detected."— Presentation transcript:

1 FLUOROSCOPY QUALITY CONTROL Rev

2 Error Maintenance When errors occur in equipment performance, corrective action must occur. Errors are detected by poor equipment performance or poor-quality outcomes. Corrections generally are made by service personnel employed by the vendor.

3 (RHB) Acceptance Testing DAILY PG MONITOR BRIGHTNESS PROTECTIVE DEVICES IN PLACE TOWER LOCKS WORK COMPRESSION DEVICE AUTOMATIC COLLIMATION/SHUTTERS KVP & MA MONINTORING*** ENTERED INTO A LOG….

4 (RHB) Acceptance Testing semi-annually Tube housing 12 “ TPD Filtration Primary barrier Collimation shutters Barrier interlocks 5 min Timer Measure dose rate ma& kvp Max Output TV monitor contrast Scatter measured ABD Focal Spot Size Waveform TV & Video signal

5 (RHB) Acceptance Testing semi-annually Check Aprons Integrity Monitor Dosimeter Reports Distortion TV: Flare (scattered/ reflected light) Image LAG Grid alignment/ uniformity Etc …………………….

6 Fluoro QC Testing Tabletop exposure rates Centering alignment Collimation Kvp accuracy & reproducibility mA accuracy & reproducibility Exposure time accuracy & reproducibility Reproducibility of xray output Half-value layer (filtration) Representative Skin Entrance Doses

7 Fluoro QC Testing IMAGE INTENSIFICATION SYSTEMS Resolution Focusing Distorion Glare Low-contrast performance Physical alignment of camer & collimator lens

8 A fluoroscopy system monitored to achieve good image quality The automatic exposure rate control (AEC) and image quality are important aspects of a fluoroscopy system. Spatial resolution is measured with a contrast-detail test object is used to measure threshold contrast-detail performance. Median limiting spatial resolution was 1.41 lp/mm- 1 for image intensifier fields between 18 and 24 cm in diameter. (7-9”) 8

9 FLUORO OUTPUT MEASURED WITH TYPE OF PHANTOM? MONITORED? RECORDED ? Fluoroscopic ABC should be evaluated annually 9

10 kVp & mAs accuracy what you see is what you get…

11 FLUOROSCOPY QUALITY CONTROL: OUTPUT MONIOTRED – WEEKLY WITH A PHANTOM 7IN LUCITE OF 9” WATER PLACED IN PATH OF BEAM – OUTPUT RECORDED (WITH PATIENTS ) DONE DAILY 11

12 WEAR PROTECTIVE GARMENTS while performing this procedure! Activate the fluoro beam and move the fluoro tower as required in order to center the phantom on Cone down (close) the collimators until only edges of the phantom are visible. 12

13 Phantom Images To ensure that film density, contrast, uniformity, and image quality due to the x-ray imaging system and film processor are maintained at optimum levels. When imaging the phantom for fluoroscopic tests, record the kVp and mA from the meters or displays provided. Any changes in the kVp or mA values for a constant phantom thickness can indicate problems with the fluoroscopic chain, for example, a loss of image intensifier/TV gain. 13

14 Digital fluoro resolution test 14

15 Wet Laser Imager Daily/weekly QC: Monitor each film printed to ensure that it is free from artifacts and matches monitor or desired quality. Print a test pattern from the PACS, or some printers have a built-in test pattern that can be printed by depressing a button on the printer. 15

16 PACS QC Activities ACR also suggests that all of the following tests be carried out with a SMPTE (Society of Motion Pictures and Television Engineers) test pattern to ensure continuity of measurement What does this monitor? (2) 16

17 CONSISTENCY IS THE KEY After each link (x-ray unit, video monitor, laser film printer, processor, darkroom, etc.) in the imaging chain is optimized, a working QA program will provide warning flags to the QA program coordinator when something goes awry. the test or tests must be repeated to verify the results, then corrective action must be taken. The coordinator must be capable of identifying problems and willing to resolve them as they occur, or the QA program will not provide the intended benefits. 17

18 Equipment Warm-up DAILY Each day during the x-ray generator warm- up, and before exposing the first patient to x- rays, check for indicator malfunction (mA, five- minute timer, etc.) and the mechanical and electrical safety of the x-ray system. Malfunctions and unsafe conditions (such as frayed wires) must be corrected promptly. 18

19 NOTE: because this procedure necessitates activation of the fluoroscopic tube, the surveyor should make certain there is something (phantom, cubic water container, etc.) attenuating the useful x-ray beam during operation and wear appropriate protective equipment (lead apron, gloves, thyroid shield, etc.) Equipment Warm-up DAILY 19

20 FOR DIGITAL SYSTEMS: Verify that the window and level settings are set to the pre- established levels. Adjust room lighting conditions to those used clinically. Observe the mesh patterns, line pairs or other test objects under fluoroscopy 20

21 Test Frequency – Weekly Laser Film Printer Quality Control - SMPTE Test Pattern Video Monitor Setup =Must be performed on EACH video monitor (operator’s console, physician’s console, etc.) so that the grays on the monitors all appear similar. Laser Printer Setup 1. Send the SMPTE test pattern to the laser film printer using the largest most commonly used image format (1 on 1 or 4 on 1). 2. Process film if applicable. 3. With the film on a view box and the same image on the monitor, visually compare the film gray scale densities on the film to those on the monitor. 21

22 SMPTE Test Pattern ? Society of Motion Picture and Television Engineers 22 The spatial resolution (linearity) and aliasing (distortion) of your monitor are within acceptable limits if the high contrast bar patterns in the test image are distinct as simple patterns of black and white pairs.

23 Monitor Quality Often the monitor is the weakest link in the digital imaging chain. The monitor has a direct effect on the quality of the image that is presented to the radiologist for reading or to the referring physician for review. Not every computer that is used to view images can have the highest-quality monitor available because of the expense. Monitor Resolution? Conventional vs Digital? 23

24 Monitor Quality Radiologist’s workstation has highest-quality monitor, usually 2K or 3K for computed radiography or digital radiography, 1K or 2K for cross-sectional images, and up to 4K for mammography. Megapixel measurement may be used to determine the appropriate monitor. Generally, physician’s review workstations and technologist’s QC workstations have high-quality commercial monitors. Resolution is usually 1K. 525 for old conventional fluoro units 24

25 VIGNETTING PINCUSION EFFECT The center has the best resolution/detail 25 Veiling glare and pincushion distortion increase with age on an image intensifier.

26 Veiling glare Internal scatter radiation in the form of x-rays, electrons, and particularly light can reduce the contrast of image- intensifier tubes through a process called veiling glare 26

27 DICOM gray scale function window level and width function A photometer to a monitor screen in a check of the monitor's conformance with the DICOM Grayscale Standard Display Function. 27

28 Equipment Visual Checklist Form All foot and hand switches designed to energize the fluoroscopic tube should be tested to ensure that x-ray production is terminated as soon as the switch is released. If switches have multiple positions (example: high level control) each position should be tested. The table, image intensifier, and tube, as applicable, should move smoothly and freely without requiring excessive force. Check all of the locks and centering detents on the tower and table for adequate function. Check all switches, lights and meters on the table, control panel and image intensifier for appropriate function. (i.e. lights should light, meters should move). 28

29 Equipment Visual Checklist Form Lead drapes should be affixed to the image intensifier (under table systems) and have no cracks Bucky moves smoothly along the track and its locking mechanism is functioning. Bucky slot during fluoroscopy is working as designed. 29

30 Equipment Visual Checklist Form If the unit is a portable c-arm, it must be equipped with a spacer on the tube to prevent the patient from being closer than 30 cm to the tube’s target. This spacer must always be used unless it interferes with a sterile field as during surgery. It must not be possible to activate the x-ray tube unless the entire fluoroscopic beam is intercepted by the image receptor. On systems where the image intensifier can be placed in a park position, do so and step on the pedal to assure that this interlock is functioning. Verify that all of the indicators on the control panel are functioning. Check that the fluoro timer emits an audible signal or terminates the exposure after 5 minutes. 30

31 Lead Aprons - annually Examine the integrity of the personnel shielding devices to ensure optimal protection to the patient when positioned properly. NOTE: Lead aprons should never be folded. Cracks in the lead lining can develop at the fold, reducing the useful life of the apron. Do not assume that brand new aprons, gloves, etc. contain no defects. New aprons, gloves, etc. should be examined under x- ray immediately upon arrival and returned to supplier if defects are found. 31

32 Proper storage for apron Hang or lay flat Clean with a damp cloth Cannot be laundered DO NOT FOLD 32

33 Fluoroscopic Systems Intensifier viewing system resolution Intensifier viewing system contrast TV monitors and recorders Automatic brightness control Fluoroscopic ABC should be evaluated _____? LEAD APRONS - CRACKS 33

34 Output ?, Scatter, Leakage ? Check shielding 34

35 OVERFRAMING – Pt dose beam alignment Collimation check An ESE of approximately 200 mR may be assumed for a cassette spot film. An ESE of approximately 100 mR may be assumed for a photofluorospot. 35

36 System Training Each department also has a list of skills that are tested and retrained each year. PACS skills should also be included in this annual training. A training record should be kept for each employee to show proof of the skills in which the employee has been trained. 36

37 37 KEEP I.I. CLOSE TO PATIENT

38 38 Fluoroscopy Quality Control Exposure rate Normal fluoro: ESE ≤ 10 R/min Interventional fluoro: ESE ≤ 20 R/min Cineradiography: unlimited exposure rates Spot-film exposures Cassette ESE approx. 200 mR per spot Photofluorospot ESE approx. 100 mR per spot Automatic brightness control (ABC) Evaluate annually APRON CHECK for cracks …………………..

39 Hand held fluoro device ? 39


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