Transcript fluroscopy - El Camino College

FLUOROSCOPY
QUALITY CONTROL
Rev 2014
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Error Maintenance
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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.
(RHB) Acceptance Testing
DAILY
PG 104 -105
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MONITOR BRIGHTNESS
PROTECTIVE DEVICES IN PLACE
TOWER LOCKS WORK
COMPRESSION DEVICE
AUTOMATIC COLLIMATION/SHUTTERS
KVP & MA MONINTORING***
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ENTERED INTO A LOG….
(RHB) Acceptance Testing
semi-annually
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Tube housing
12 “ TPD
Filtration
Primary barrier
Collimation shutters
Barrier interlocks
5 min Timer
Measure dose rate
ma& kvp
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Max Output
TV monitor contrast
Scatter measured
ABD
Focal Spot Size
Waveform
TV & Video signal
(RHB) Acceptance Testing
semi-annually
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Check Aprons Integrity
Monitor Dosimeter Reports
Distortion
TV: Flare (scattered/ reflected light)
Image LAG
Grid alignment/ uniformity
Etc …………………….
Fluoro QC Testing
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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
Fluoro QC Testing
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IMAGE INTENSIFICATION SYSTEMS
Resolution
Focusing
Distorion
Glare
Low-contrast performance
Physical alignment of camer & collimator lens
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”)
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FLUORO OUTPUT
 MEASURED WITH TYPE OF PHANTOM?
 MONITORED?
 RECORDED ?
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Fluoroscopic ABC should be evaluated
annually
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kVp & mAs accuracy
what you see is what you
get…
FLUOROSCOPY QUALITY
CONTROL: OUTPUT
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MONIOTRED – WEEKLY WITH A
PHANTOM
7IN LUCITE OF 9” WATER PLACED IN
PATH OF BEAM –
OUTPUT RECORDED
(WITH PATIENTS ) DONE DAILY
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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.
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Phantom Images
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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.
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Digital fluoro resolution test
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Wet Laser Imager
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Daily/weekly QC:
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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.
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PACS
QC Activities
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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
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What does this monitor? (2)
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CONSISTENCY IS THE KEY
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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.
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Equipment Warm-up DAILY
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Each day during the x-ray generator warmup, and before exposing the first patient to xrays,
check for indicator malfunction (mA, fiveminute 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.
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Equipment Warm-up DAILY
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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.)
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FOR
DIGITAL
SYSTEMS:
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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
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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.
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SMPTE Test Pattern ?
Society of Motion Picture and Television Engineers
• 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.
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Monitor
Quality
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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?
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Monitor
Quality
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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.
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Resolution is usually 1K.
525 for old conventional fluoro units
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VIGNETTING
PINCUSION
EFFECT
The center has the
best resolution/detail
Veiling glare and pincushion distortion increase with age on an image
intensifier.
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Veiling glare
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Internal scatter
radiation in the form
of x-rays, electrons,
and particularly light
can reduce the
contrast of imageintensifier tubes
through a process
called veiling glare
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DICOM gray scale function
window level and width function
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A photometer to a
monitor screen in a
check of the monitor's
conformance with the
DICOM Grayscale
Standard Display
Function.
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Equipment Visual Checklist
Form
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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).
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Equipment Visual
Checklist Form
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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.
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Equipment Visual Checklist
Form
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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.
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Lead Aprons - annually
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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.
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Proper storage
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for apron
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Hang or lay flat
Clean with a damp
cloth
Cannot be laundered
DO NOT FOLD
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Fluoroscopic
Systems
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Intensifier viewing system resolution
Intensifier viewing system contrast
TV monitors and recorders
Automatic brightness control
Fluoroscopic ABC should be evaluated
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LEAD APRONS - CRACKS
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Output ?, Scatter, Leakage ?
Check shielding
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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.
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System Training
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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.
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KEEP I.I. CLOSE TO PATIENT
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Fluoroscopy Quality Control
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Exposure rate
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Spot-film exposures
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Cassette ESE approx. 200 mR per spot
Photofluorospot ESE approx. 100 mR per spot
Automatic brightness control (ABC)
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Normal fluoro: ESE ≤ 10 R/min
Interventional fluoro: ESE ≤ 20 R/min
Cineradiography: unlimited exposure rates
Evaluate annually
APRON CHECK for cracks …………………..
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Hand held fluoro device ?
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