Quality Assurance in the Dental Office, Occlusal Localization

when should dental x-ray machines be tested?

annually to test for malfunctions, inadequate collimation, tube head drift, timing errors, inaccurate kV or mA readings

anterior mandibular topographical occlusal projection

anterior: width-wise in front of mouth standard: length-wise to back of mouth lateral: length-wise off centered to one side

if you get a distorted image you should:

assess receptor bending during imaging and check scanner

spatial resolution

capacity for distinguishing fine detail in an image.

if you get a grainy image you should:

check exposure factors and protect PSPs from light

if you get no image you should:

check machine for on status and scanning technique

how to check the strength of the developer solution

compare film densities to a standard using tests such as reference radiograph, stepwedge radiograph, or normalizing device

vertical angulation for lateral

for maxillary teeth = +60 for mandibular teeth = -90 through floor of mouth

vertical angulation of topographical

for maxillary teeth = +65 through nose for mandibular teeth = -55 through chin

vertical angulation for cross sectional

for maxillary teeth = +90 for mandibular teeth = -90

how to check for tube head stability

free of drift and oscillation after 2 seconds

a written monitoring schedule should include:

-all quality control tests and frequency of testing -supplies -film processing -digital imaging

quality administration procedure examples

-description of plan -assignment of duties -monitoring/maintenance schedule -record keeping -evaluation/revision plans -in service training

milliamperes

-flow of electrons from cathode to anode -controls # of electrons produced -increased mA = increased photons = increased density

kilovoltage

-force of electrons accelerating from cathode to anode -increase kV = increased penetrating power of photons

localization techniques help to identify:

-foreign object -fractures -supernumerary impacted tooth in the mouth -eruption patterns -Salivary stones

SLOB rule

-must be a change in the horizontal or vertical angulation -objects on the lingual surface will move in SAME direction as tubehead -objects on the buccal surface will move in the OPPOSITE direction as the tubehead

spatial resolution is determined and affected by:

-pixel size (smaller = increase spatial) -receptor type -focal spot size (smaller = increased sharpness/resolution) -projection geometry of beam -motion blur

a record keeping log should include:

-test performed, date, and test results -processing solutions with dates of replacement, replenishment, and processor or tank cleaning

quality control tests examples

-x-ray machines -film -screens, cassettes for dirt or scratches -darkroom -processing equipment and solutions -digital imaging equipment

annual quality control tests for dental machine covers:

-x-ray output -Kv -timer -HVL -mA -collimation -beam alignment -tubehead stability

two types of localization

1. buccal object rule/clarks rule: 2 images exposed at different angulations 2. right angle: expose normal PA and occlusal image; examine 2 images projected at right angles to each other

primary components of quality assurance

1. equipment (operatory) 2. processing (scanning/darkroom) 3. operator skills (technique)

Occlusal projections identifies:

1. foreign objects 2. eruption pattern 3. retained roots of extracted teeth 4. located pathology in the palate or floor of mouth (salivary cysts, malignancies) 5. trismus 6. pediatric intraoral imaging

optimal temperature for processing solutions

1. manual processing: 68 F 2. automatic processing: 82 F

if a density difference from a coin test is visible, it may be due to:

1. wattage of safelight bulb is too high 2. safelight is too close to counter 3. safelight filter may be faded, damaged, incorrect 4. too many safelights 5. leakage of light *if one of these reasons, you should repeat the test with safelights OFF

localization

2D representation of a 3D area. can locate the object using right angle technique or SLOB

Reference radiograph

A radiograph that is processed under ideal conditions and then used to compare the film densities of radiographs that are processed daily

ALARA

As Low As Reasonably Achievable

Stepwedge Radiographs

Device constructed of layered aluminum steps, placed on film and exposed to x-rays, different densities are seen

slow clearing

If the film does not completely clear in 3 to 4 minutes, the fixer solution is depleted.

Fresh film test

Quality control test that shows a clear film with a slight blue tint, showing that the film is fresh and has been properly stored.

SLOB stands for:

Same Lingual Opposite Buccal

normalizing device

Used to monitor developer strength and film density

unmatched density on stepwedge radiograph

if density on the daily radiograph differs from that on the standard radiograph by more than two steps in the stepwedge the solution is depleted

reference radiograph that shows matched densities

if the densities on the reference radiograph match the densities on the daily radiographs, the developer solution is okay

periodic in service training should include:

training on upgrading and improving x-ray exposure techniques, film processing procedures, and digital imaging

matched density on stepwedge radiograph

use middle density seen on standard stepwedge radiograph for comparison. if density seen matches the density on the daily radiograph, the solution is okay

functioning processor

The unexposed film appears clear and dry and the exposed film appears black and dry

processing solutions must be replenished ___ and changed ___

daily; 3-4 weeks

reference radiograph that shows unmatched densities

darker: the solution is too concentrated or warm lighter: solution is weak or cold

if you get an image with white lines, scratches, or unusual patterns you should:

discard receptor and re-image

if you get a ghost or double image you should:

erase plate completely

darkroom lighting should be checked...

every 6 months; only after the light tightness of the darkroom has been established can the safelighting be checked

____ is one of the most critical areas in quality control and requires daily monitoring

film processing

higher penetrating x-rays produce:

lower contrast

Goal of quality assurance

maintain all systems at a consistently functioning optimal level and prevent detrimental effects on patient services.

anterior occlusal projections of primary teeth

maxillary = +60 with size 2 receptor mandibular = -55 with size 2 receptor

The most critical component in film processing quality control is:

monitoring of processing solutions

when should screens be cleaned?

monthly to check for worn closures, light leaks, warping; after cleaning apply an antistatic solution

checking of processing equipment

needs to be checked daily; check the timer, thermometer, temperature of water bath, developer and fixer solutions.

Fogged film

quality control test that shows an expired film, or a film that has been improperly stored or exposed to radiation. do not use

Fixer strength

removes the unexposed silver halide crystals on the film that results in clear areas on the processed dental image; when the fixer is at full strength a film should clean within 2 mins

developer solution that is weakend or concentrated must be:

replaced

safe lighting test that shows improper safelighting & how to avoid it

shows a fogged background; avoid it by unwrapping film 4 feet away from the safelight

Screen-film contact test showing an adequate contact

shows a wire mesh image on a film with uniform density

safe lighting test that shows proper safelighting

shows no visible image on the processed film

posterior bitewing and PA projections of primary teeth use what size receptor?

size 0

what size receptor does maxillary and mandibular occlusal projections use?

size 4 with active phosphor side facing toward beam

quality assurance

special procedures that are used to ensure the production of high-quality diagnostic images. includes quality control tests and quality administration procedures. dentist is responsible for this.

quality control tests

specific tests used to maintain and monitor dental x-ray units, supplies, film processing, and digital imaging equipment

developer solution that is too cold or warm must be:

temperate must be adjusted

what should be checked in automatic processing equipment?

water circulation system must be checked, and the solution level, the replenishment system and temperature.

the surface of a viewbox should be cleaned ___

weekly