Radiology
Chapter 38
Foundations of Radiology,
Radiographic Equipment, and
Radiologic Safety
Uses of Dental Radiographs
• Detect dental caries in the early stages
• Identify bone loss in the early stages
• Locate abnormalities in the surrounding
hard and soft tissues
• Evaluate growth and development
• Provide information during dental
procedures (ie root canal)
• Document a patient’s condition at a
specific time
Properties of Radiographs
• X-rays are a form of energy
• X-rays belong to a group classified as
Electromagnetic radiation
• Electromagnetic radiation is made up of
photons that travel through space at the
speed of light in a straight line with
wavelike motion
• Shorter the wavelength the Greater its
energy
Dental X-ray Machine
• Tubehead—tightly sealed—contains tube
• X-ray tube—in the heart of the system
– Cathode—negative electrode
– Anode—positive electrode
• Position Indicator Device (PID)
• Extension Arm
• Control Panel
–
–
–
–
Master Switch and indicator lights
Exposure Button
Milliamperage
Kilovoltage selector
Types of Radiation
• Primary
– X-rays that come from the target to the x-ray tube,
(the useful beam)
• Secondary
– Created when the primary beam interacts with matter
(less penetrating, not useful)
• Scatter
– Form of secondary, that is deflected from path in all
directions (dangerous to all)
• Leakage
Characteristics of Radiograph
Beam
• Quality, quantity and intensity of beam
• Determine contrast, density and image
detail (good x-ray)
Radiolucent and Radiopaque
Characteristics
• Radiolucent
– Structures that radiation can pass through
easily (dark)
– Such as:
• Radiopaque
– Structures that radiation cannot pass through
easily (light)
– Such as:
Contrast
•
•
•
•
Images appear in a range of shades
Black to white
Ideal?
Higher kVp produces more penetrating
radiograph and lower contrast
• 90 kVp requires less exposure time and
produces low contrast on x-ray (more shades of
gray
• 70 kVp requires slightly longer exposure and
gives high contrast (fewer shades of gray)
Density
• Overall blackness or darkness of a film
• Should enable view of air spaces (black)
and enamel, dentin and bone (white) and
tissue (gray)
• mAs control amount of time given to the
exposure of x-ray
Other factors that Influence Density
• Distance from the x-ray tube to the patient
– It changes the exposure setting and will be
light or less dense
• Developing time temperature
– Process time too long, will appear dark
• Body size of patient
– Very small/thin—requires less rad than
heavier patient
Geometric Characteristics
• Sharpness
– Reproduction of fine details, and/or outlines
– Such as TV control (fuzzy) referred to as
penumbra
– Focal spot size
– Film composition
– Movement
Geometric cont
• Distoration
– Disproportional change in size of images
– Too much or too little vertical angulation
• Magnification
– Proportional enlargement of radiographic
image
Radiation Effects
• ALL ionizing radiation is harmful
• Tissue damage—radiation that is absorbed can
result in chemical changes and biologic damage
– Ionization—can cause disruption of cellular
metabolism and permanent damage to living cells and
tissue
• Biologic effects—can take many years to
become evident
– Cumulative effect– tissues can repair some damage,
tissue does not return to their original state
Effects cont.
– Acute and chronic rad exposure
• Acute—large does in short period of time
• Chronic—small amounts absorbed repeatedly over
long period of time
– Genetic and somatic effects
• Genetic- (sperm and ova) passed on to
succeeding generations, genetic mutations
• Somatic- (body) not passed on to future
generations
Effects cont.
• Critical Organs
– Skin—seen as reddening or erythema
• Thyroid gland—(how do you protect)
• Lens of eye—can cause cataracts
• Bone Marrow--leukemia
Radiation Measurement
• Traditional system or standard system
(older system of measurement)
– Roentgen (R) radiation absorbed dose (rad)
and roentgen equivalent in human (rem)
• System Internationale (newer system)
– Metric equivalent
– Coulombs per kilogram (C/kg), gray (Gy), and
sievert (Sv)
– UNDERSTAND each system
• Maximum Permissible Dose
Occupation persons = 5.0 rem per year
Non-occupation persons = 500 mrem per year
Radiation Safety
• Background radiation—comes from
natural sources
• Protective devices
– Aluminum filtration ?
– Collimator ?
– Position Indicator device ?
Safety cont.
• Patient protection
– Lead apron and thyroid collar
– Fast-speed film
– Film-holding devices
– Exposure factor
– Proper technique
• What does the ADA and FDA state
regarding pregnancy and dental radiation?
Safety cont
• Operator protection and monitoring
– What are the rules ?
• Never stand in direct path of primary beam
• Always stand behind lead barrier or stand at right
angles from beam
• Never stand closer than 6 feet from the x-ray unit
Safety
• Equipment monitoring
– What are the rules
What is the ALARA concept?
Chapter 39
Dental Film and Processing
Radiographs
• What is a film holder ?
• Explain some of the few holding systems
that are available
Dental Film
• Understand the following
– Film composition
– Latent image
– Film speed
Intraoral Film
• Understand the following
– Film packet
• Packet info, wrapper and lead sheet, package
positioning, package disposal
– Outer packet
• Tube side, label side
– Film sizes
• #’s 0, 1, 2, 3, 4 (what is each size used for)
Extraoral film
• Film packaging ?
• Film cassette ?
• Intensifying screen ?
• How and where do you store film ?
• If you were duplicating film what
equipment would be needed?
Film Processing
• What are the five steps in processing film
• What are the requirements for a film
processing darkroom?
• Know the techniques/steps for Manual and
Automatic film processing
Errors
• Fully understand the possible errors that
can take place while processing films
• How would you correct or prevent these
errors
Chapter 40
Legal Issues, Quality
Assurance, and Infection
Control
• Quality assurance
– Regular testing to detect equipment
malfunctions, planned monitoring and
scheduled maintenance
Legal Considerations
• Federal and State regulations ?
• Licensure requirements ?
• Risk management—polices and
procedures that reduce chance of lawsuits
– Key areas
• Patient consent, patient records, liability issues
and patient education
• Informed Consent
• Liability
Cont
• Patient records
• Patient Refusal
• Patient Education
(Understand all of the above)
Quality Assurance
• What is a quality control test and what
does it monitor?
• There is a lot of information under Quality
Assurance, make sure that you
understand each type and the steps
involved
Administrative Quality Control
Steps
• Develop and maintain a written description
of the quality assurance plan
• Assign specific duties to staff members
and ensure that each individual is
thoroughly trained
• Maintain records of monitoring and
maintenance
• Review the plan periodically and revise if
needed
Infection Control
• There is a high risks for crosscontamination
• CDC has guideline for Infection control
(make sure you know them)
• There is a checklist for Infection Control
during radiographs, be familiar with these
steps
ICE
• There are procedures that can be
performed for equipment and supplies
– Understand these procedures, such as how to
handle film, film packets, holders.
• Procedures during and after exposure
must be followed:
– What are these procedures; such as drying
exposed film, etc.
Infection Control
Steps
• There are several steps to practice during
film exposure
– Some are common sense and others are not
– Read and think about the many ways you can
practice this.
• Such as barriers for operatory, washing hands,
how to unwrap an exposed film or how to transport
an exposed film
Chapter 41
Intraoral Radiography
• Steps to quality radiographs
– Placement
– Exposure
– Processing
– = Quality radiographs
Full Mouth Series
• Intra oral films
• What type of x-rays are take in FMX
• Two types of methods for exposing intra
oral films
Paralleling Technique
• Five basic rules
– Film Placement—cover teeth involved
– Film Position—parallel to long axis of tooth
– Vertical Angulation—central ray perpendicular
to film and long axis
– Horizontal Angulation central ray directed
through contact areas
– Central Ray—beam must be centered on the
film
Guidelines for Placement
• There are seven (fill them in below)
• Patient Preparation
– Make sure that you read over the procedure
in your book
• Exposure sequence for film placement
– Make sure you understand what teeth should
be present in what x-ray
Producing Full Mouth
• There is a whole procedure outline in your
book for each tooth/teeth
– Be very familiar with each section
Bisecting Technique
• Based on the geometric principle of
equally dividing a triangle
• Places film directly against the teeth to be
radiographed, so teeth and film are not
parallel but are at a right angle
• Film holders are used rather then the XCP
• Understand patient positioning
– Beam alignment
Bite Wing Technique
• Shows the crowns and interproximal areas
of max and mand teeth and the areas of
the crestal bone
• Basic principles
– Placed parallel to the crowns of upper and
lower
– Stabilized when the patient bites on the tab or
holder
– Central beam is directed through contacts of
teeth using +10 degrees vertical angulation
Occlusal Technique
• Take an x-ray of entire maxillary or entire
mandibular arch at one time
Mounting Radiographs
• You need to be able to recognize
anatomic landmarks
– If I showed you an x-ray with a Nutrient canal
and Lingual foramen on it, would you be able
to tell me that this is a mandibular anterior xray????
Guidelines for Mounting
• Handle films by the edges
• Learn normal anatomy
• Label and date film mount before
mounting films
• Mount immediately
• Use clean dry hands
• Use order of teeth to distinguish right from
left
cont
• Use definite order for mounting
• Mount bite-wings with the curve of Spee
upward (makes a smile)
Chapter 42
Extraoral and Digital
Radiography
• Extraoral—large areas of skull or jaw
must be examined (outside of mouth)
Panoramic—entire dentition and structures
on single fillm
Why would they be used?
What type of equipment is used
What would be some errors that could
take place
Advantages and Disadvantages
•
•
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Field size
Ease of use
Patient acceptance
Less radiation
Image sharpness
Focal trough limitations
Distoration
Cost of equipment
• Cephalometric films
– Takes side view of skull
– Used mostly in orthodontics and surgery
Digital Radiography
• Advances in computers have made this
the way of the future
• Filmless
• Records images
• What is the basic concept?
• Understand types of digital imaging
Advantages and Disadvantages
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Gray-scale resolution
Reduced radiation exposure to the patient
Faster viewing of images
Lower equipment and film costs
Patient education
Initial set-up costs
Quality of images
Sensor size
Infection control