Exam II study guide Flashcards
Shadow; the image of the object we receive:
umbra
Edge gradient; the unsharp area; area around the margins of the object
penumbra
What do we try to minimize in. a radiographic image?
penumbra
How do we minimize penumbra?
by having an increased source to object ratio
Because there are multiple x-ray photons that come and interact with the edges of the object, it creates a blurry margin referred to as:
penumbra
3 factors that affect the quality of the radiograph:
- image sharpnress
- image magnification
- image shape distortion
Equal enlargement:
magnification
unequal enlargement:
shape distortion
enlargement of the radiographic image, compared to the actual size of the object:
magnification
Image shows true shape of object:
magnification
What does magnification have to do with?
the DIVERGENCE due to the distance of the receptor, object, and beam
Variation from the true shape of an object and unequal magnification of certain parts of the object:
shape distortion
What does shape distortion have to do with?
improper alignment/ANGULATION of receptor, object, and beam
3 ways to maximize image sharpness:
- radiation source
- source-to-object distance
- object-to-receptor distance
Discuss the radiation source if we are trying to maximize image sharpness:
radiation source should be as small as possible (smaller focal spot = greater sharpness because there are fewer photons interacting with the object)
Smaller focal spot = ____ sharpness
greater
Smaller radiation source = ____ focal spot = ____ sharpness
smaller; greater
Although a smaller radiation source is a mechanisms to maximize image sharpness, this is not something:
we can control after machinery is bought
Discuss the source-to-object distance if we are trying to maximize object distance:
source-to-object distance should be as long as possible
How can source-to-object distance be controlled when trying to maximize image sharpness?
Can be controlled by length of cone (larger cone = increased sharpness due to decreased divergence)
Larger cone = ____ sharpness due to ____
increased sharpness; decreased divergence
Discuss the objet-to-receptor distance if we are trying to maximize image sharpness:
Object-to-receptor distance should be as short as possible (get tooth as close to image receptor as possible)
If we are trying to increase image sharpness by adjusting the object-to-receptor distance, how do we control this?
can be controlled by where operator places image receptor
When trying to maximize sharpness, discuss what you should do to the following:
- radiation source
- source-to-object distance
- object-to-receptor distance
- radiation source should be as small as possible (can’t be adjusted after buying though)
- source-to-object distance should be as long as possible (controlled by length of cone- larger cone = sharper image)
- object-to-receptor distance should be as short as possible (controlled by operator placement of image receptor)
2 ways to minimize magnification:
- source-to-object distance should be as long as possible
- object-to-receptor distance should be as short as possible
Explain why the object-to-receptor distance should be as short as possible when trying to minimize magnification:
shorter object to image receptor distance results in less magnification and greater sharpness due to LESS DIVERGENCE
Explain what would result from:
longer object to image receptor distance:
greater magnification; less sharpness; due to more divergence
What are 2 ways to minimize distortion?
- object and receptor should be PARALLEL
- beam should be PERPENIDICULAR to both object and receptor
What is the effect of the following on a radiographic image?
- smaller radiation source
- longer source-to-object distance
- shorter object-to-receptor distance
maximized image sharpness
What is the effect of the following on a radiographic image?
- longer source-to-object distance
- shorter object-to-receptor distance
minimized image magnification
What is the effect of the following on a radiographic image?
- object and receptor are PARALLEL
- beam is PERPINDICULAR to both object and receptor
minimized shape distortion
List the 5 rules for accurate image formation:
- focal spot as small as possible
- source-object distance as long as possible
- object-receptor distance as short as possible
- object (tooth) parallel to receptor
- beam perpendicular to object (tooth) and receptor
The 5 rules for accurate image formation include:
- focal spot ____
- source-object distance ___
- object-receptor distance ___
- object (tooth) ____ to receptor
- beam ____ to object (tooth) & receptor
- as small as possible
- as long as possible
- as short as possible
- parallel
- perpendicular
What are the two techniques used for PA radiography?
- paralleling technique
- bisecting angle technique
What type of cone should be used according to the paralleling technique used for PA radiography?
long cone
What is the “preferred” technique for PA radiography?
paralleling technique
Describe the components to the paralleling technique for PA radiography:
- use long cone
- receptor parallel to tooth
- beam perpendicular to tooth and receptor
What problem can we run into when using the paralleling technique for PA radiography?
Can run into problem in MAXILLARY radiographs due to curvature of the palate
What does the paralleling technique for PA radiography violate?
violates rule of increased object-receptor distance so an increased source-receptor distance is utilized (long cone)
Because the paralleling technique for PA radiography violates the rule of increased object-receptor distance, what is done to make up for this? How?
increase source-receptor distance; using a long cone
What technique for PA radiography can be used if the paralleling technique cannot be used?
bisecting angle technique
What type of cone is preferred for the bisecting angle technique for PA radiography?
long cone preferred but short cone can be used
What rule is the bisecting angle technique for PA radiography based on? Explain this rule
Based on rule of isometry: if two triangles have equal angles and a common side, then the two triangles are equal
In the bisecting angle technique for PA radiography, what angle is bisected?
the angle formed by the plane of the tooth and the plane of the receptor
When is the beam directed in the bisecting angle technique for PA radiography?
beam is directed perpendicular to the bisecting line
In the bisecting angle technique for PA radiography, the angle formed by ____ and ___ is bisected and the beam is directed ____ to the ____
the plane of the tooth and the plane of the receptor; perpendicular to the bisecting line
In the bisecting angle technique for PA radiography, what is NOT bisected?
neither the tooth or receptor is bisected
Tube shift method/ buccal object rule can be explained by the:
SLOB rule
SLOB stands for
Same lingual; Opposite buccal
When you move the tube head mesially, and the object moves mesially, where is the object located?
lingually
What causes foreshortening (an error):
tooth not parallel to receptor and beam directed perpendicular to RECEPTOR
Radiographic image of the object (tooth) appears shorter than it actually is:
forshortening
How would the radiographic image appear if foreshortening occurs?
image appears shorter than it actually is
Foreshortening is a result of improper:
VERTICAL angulation
What causes elongation (an error)?
tooth not parallel to receptor and beam is directed perpendicular to TOOTH
Radiographic image of the object (tooth) appears longer than it actually is. Root apices may be cut off:
elongation
Elongation is a result of improper:
VERTICAL angulation
What error causes overlapping of contacts?
improper HORIZONTAL angulation
Reduction of the intensity of an x-ray beam as it traverses matter:
attenuation
absorption =
scatter=
photoelectric effect
coherent & compton scattering
Interactions of x-radiation with matter (attenuation types): (4)
- No interaction (9%)
- Photoelectric effect (27-30%)
- Compton scatter (57-62%)
- Coherent (Thomson) scatter (7%)
What type of interactions with x-radiation (attenuation types) are shown?
A: no interaction (9%)
B: coherent scattering (7%)
C: photoelectric absorption (27-30%)
D: compton scattering (57-62%)
When the x-ray photon enters an object (patient) and exits with no change in its energy:
no interaction (9%)
When the x-ray photons collide with an orbital electron an d lose energy; the ejected photoelectron loses its energy:
photoelectric absorption (27-30%)
In the photoelectric absorption process (27-30%), ____ occurs which results in ___.
ionization; biologic effect
When the x-ray photon collides with an outer orbital electron losing some energy. The x-ray photon continues in a different direction with less energy creating more scatter until all energy is lost:
Compton scattering (57-62%)
In the Compton scattering process (57-62%), ____ occurs which results in ___.
ionization; biologic effect
Rules that govern the probability of photoelectric absorption and compton scatter:
the ionized matter is unstable and seeks a more stable configuration; which may affect biologic structure, or both
X-ray photons of low energy interacts with an outer orbital electron and changes direction:
Coherent scattering
In coherent scattering process (7%), no photoelectron is produced and therefore:
no ionization occurs
How do differential absorption/photoelectric absorption help in image formation?
Produces ___ that generates the detail of the image. Some x0rays are absorbed in the tissue and some pass through the anatomical tissue.
contrast
The process of image formation is a result of:
differential absorption
Varying x-ray intensities exiting the anomic area of interest form the:
latent image
measure of the biological effectiveness of radiation to ionize matter:
QF
Have a threshold and severity is proportional to the dose:
deterministic effects
Describe the curve of deterministic effects of radiation:
is a threshold, non-linear dose curve
Has NO dose threshold. Probability of occurrence is proportion to dose BUT severity of effects does NOT depend on dose:
stochastic effects of radiation
Stochastic effects of radiation on somatic cells results in:
genetic mutations that cause malignancy
Stochastic effects of radiation on germ cells results in:
heritable effects
Describe the curve of stochastic effects:
non-threshold linear
What cancers have the highest risk from dental radiographic exposure?
Leukemia and thyroid cancer
Direct radiation effects on cellular structures its caused by:
rupture in the cell wall of a biologically active molecule
What factors affects radio sensitivity to the greatest degree?
Age
Children aged ____ are ____x more likely of radiation induced cancer
children aged 2-10; 2-6x more likely
Radiation induced tissues changes that are believed to follow these dose-response curves:
Threshold non-linear –>
Linear non-threshold –>
deterministic effects
stochastic effects
Acute radiation syndrome includes: (4)
- prodromal period
- hematopoietic syndrome
- GI syndrome
- CNS/CV syndrome
Prodromal period:
____ R
____Gy
Describe the lethality:
Less than 200 R
Less than 2 Gy
non-lethal
Shortly after exposure to whole body radiation individual may develop nausea, vomiting, diarrhea, and anorexia:
Prodromal period
Describe prodromal period of acute radiation syndrome:
- shortly after exposure to whole body radiation individuals may develop nausea, vomiting, diarrhea, and anorexia
Discussion the timeline of symptom resolution with prodromal period of acute radiation syndrome:
symptoms resolve after several weeks
Hematopoietic syndrome:
____ R
____Gy
Describe the lethality:
200-1000 R
2-10 Gy
Lethal
Irreversible injury to the proliferative capacity of of the spleen and bone marrow with loss of circulating peripheral blood cells:
Hematopoietic syndrome
In hematopoietic syndrome, the person may develop infection from ____ and ____. The person may hemorrhage from ____. The person may develop anemia from _____.
The most lethal part of hematopoietic syndrome is:
lymphopenia & granulocytopenia;
thrombocytopenia;
erythrocytopenia;
sepsis
Describe the timeline with hematopoietic syndrome of acute radiation syndrome:
death within 10-30 days
GI Syndrome:
____ R
____Gy
Describe the lethality:
1000-10k R
10-100 Gy
Supra lethal
Extensive damage to the GI system. Injury to the rapidly proliferating basal epithelial cells of intestine leading to atrophy and ulceration:
GI syndrome
In GI syndrome, the loss of ___ and ____ causes hemorrhage, ulceration, diarrhea, dehydration, weight loss, & infection:
plasma & electrolytes
Describe the timeline with GI syndrome of acute radiation syndrome:
Death within 3-5 days
CNS and CV Syndrome
____ R
____Gy
Describe the lethality:
Greater than 10k R
Greater than 100 Gy
Supralethal
Radiation induced damage to neurons and fine vasculature of the brain. Results in intermittent stupor, incoordination, disorientation, and convulsions:
CNS and CV syndrome
Describe the timeline with CNS and CV syndrome of acute radiation syndrome:
Irreversible damage with death in a few minute to 48 hours
Relative dose ranges to oral tissues from oral cancer radiation treatments:
Total radiation doses to treat malignant tumors ranges from:
6000-8000 Rads or 60-80 Gy
Relative dose ranges to oral tissues from oral cancer radiation treatments:
Solid tumors=
Lymphomas=
Inraoral cancer=
solid tumors = 60-80 Gy
lymphomas= 20-40 Gy
intraoral cancer= 50 Gy
Common dental radiation:
1 Gy=
1 million mSv
Common dental radiation:
Single intraoral radiograph=
FMX=
Pano=
Single= 1.3 mSv
FMX= 33 mSv
Pano= 9 mSv
Potential long term effects of dental ionizing radiation to the head and neck area:
Oral tissue are subjected to high doses of radiation during treatment of malignant tumors or the: (5)
- soft palate
- tonsils
- floor of mouth
- nasopharynx
- hypopharynx
Potential long term effects of dental ionizing radiation to the head and neck area:
Oral tissue are subjected to high doses of radiation during treatment of malignant tumors or the soft palate, tonsils, floor of mouth, nasopharynx and hypo pharynx.
This can have effects on the:
oral mucosa, taste buds, salivary glands, teeth, bone, and muscle
Discuss the potential longer term effects on dental ionizing radiation to the following area: Oral mucosa
mucositis (secondary infections)
Discuss the potential longer term effects on dental ionizing radiation to the following area: Taste buds
lost of taste (hypoguesia)
What results in loss of taste by the 2nd-3rd week of treatment.
- epithelial atrophy
- xerostomia
- mucositis
Epithelial atrophy, xerostomia & mucositis result in loss of taste by the 2nd-3rd week of treatment. When will recovery of taste return?
2-4 months following treatment
Discuss the potential longer term effects on dental ionizing radiation to the following area: Salivary glands:
xerostomia
Describe the loss of salivary secretions causing xerostomia in radiation treatment:
marked and progressive loss
If some of the salivary gland has been spared following radiation treatment, the dryness subsides in:
6 mo-1 year
____ saliva makes the mouth dry and tender, causing difficulty swallowing following radiation
scanty
Residual saliva has a lowered pH from 6.5-5.5 following radiation which can initiate:
decalcification of enamel
Describe the effects of radiation on the buffering capacity of the saliva:
the buffering capacity of saliva is reduced to 40-45%
Pertaining to salivary glands, ____ cells (especially in the ___) are very sensitive to x-rays and replaced by fibrosis and adiposis
parenchymal cells; parotid gland
Parenchymal cells (especially of the parotid glands) are very sensitive to x-rays and are replaced by:
fibrosis & adiposis
Rampant form of decay that may effect individuals who received a course of radiation therapy that include exposure of salivary glands:
radiation caries
Radiation carries is a ___ effect of radiation
INDIRECT
Discuss the potential longer term effects of dental ionizing radiation to the following area: Teeth
lack of or retarded development
Adult teeth are very resistant to the ___ effects of radiation exposure
DIRECT
True/False- There is a discernible effect on the structure of adult teeth and radiation does increase the solubility of teeth.
False- there is NO discernible effect on the structure of adult teeth and radiation DOES NOT increase the solubility of teeth
Describe the potential effects of dental ionizing radiation on erupted teeth:
Only indirect effects to erupted teeth
When primary teeth are irradiated during the development stage, what may occur?
their growth may be severely retarded
Concerning primary teeth, if radiation PRECEDES calcification:
The tooth bud may be destroyed
Concerning primary teeth, if the radiation is AFTER initiation of calcification the teeth may demonstrate:
malformations and arresting general growth
Irradiated primary teeth with altered root formation will still erupt because:
eruptive mechanisms is much more radiation resistant
A dose as low as ___ at the age of 5 months has been reported to cause ___ of enamel
200R; hypoplasia
Discuss the potential longer term effects of dental ionizing radiation to the following area: Bone
Osteoradionecrosis
Primary damage to bone is from irradiation is to:
fine vasculature and bone marrow (affecting vascular and hemopoietic elements)
Discuss the potential longer term effects of dental ionizing radiation to the following area: muscle
fibrosis and inflammation
The fibrosis and inflammation that occur in the muscle from dental ionizing radiation results in:
contracture and truisms in the muscles
Sources of natural and man-made background ionizing radiation exposure to the population:
medical = __mSv
natural = __ mSv
other (man-made) = ___ mSV
medical = 3.2 mSv
natural= 3.0 mSv
other = 0.1 mSV
- consumer produces (TV, Apple Watch, computers)
- medical imaging
- airport scanners
- nuclear fuel cycle
- weapons production
- fall-out from atomic weapons
These are all examples of:
man-made/artificial sources of background ionizing radiation exposure
- external (cosmic, terrestrial)
- internal (radon= majority),
- cosmic
These are all examples of:
natural sources of background ionizing radiation exposure
The majority of manmade exposure of background ionizing radiation =
medical imaging (greater than 50%)
The majority of n natural exposure of background ionizing radiation=
radon (~54%)
Sources of medical imaging radiation exposure are: (4)
What do these add up to a total of?
- CT scanning
- Nuclear medicine
- Radiography
- Interventional
3.2 mSv
The effective dose per individual in the U.S. population (mSv) in the 1980s was ____ and in 2006 was ___
3.6 mSv; 6.2 mSv
Ways to change the EFFECTIVE DOSE of radiation is accomplished by variations in: (4)
- receptor type
- types of exams
- collimation shape
- collimation length
Explain the following- Ways to change the EFFECTIVE DOSE of radiation is accomplished by variations in receptor type:
The faster the receptor type, the less patient exposure
(#1 ways to reduce exposure)
What is the #1 way to reduce radiation exposure to a patient?
Receptor type- faster the receptor type, the less patient exposure
Ways to change the EFFECTIVE DOSE of radiation is accomplished by variations in in type of exams such as:
BW, Pano, PA, CBCT, Etc.
Ways to change the EFFECTIVE DOSE of radiation is accomplished by variations in collimation shape:
rectangular collimator with 2.75” diameter is preferred
Ways to change the EFFECTIVE DOSE of radiation is accomplished by variations in collimator length:
The longer the collimator is, the less patient exposure and sharper the image
The amount of radiation that will not produce any serious, harmful, or deleterious effects on the individual receiving it:
Maximum Permissible Dose (MPD)
The MPD occupational limits =
5 REM/year (5000 mREM)
*50 mSV
The average dental personnel exposure to radiation:
0.2 mSv
The MPD non-occupational limits=
0.5 REM/year (500mREM)
- 5 mSv
The average annual effective dose (natural + man-made) is about:
3.6 mSv
The MPD pregnant occupational limits =
0.5 REM/year (500mREM)
- 5 mSv (at 9 months)
- 0.5 mSv (at 1 month)
In what population are radiographs indicated for acute, painful dental problems only (when outweighs risk vs. benefit)
pregnant women
What cancers have the highest risk from dental x-radiation exposures?
thyroid cancer & leukemia
What is the THRESHOLD radiation erythema dose?
250 Rads
What is the AVERAGE radiation erythema dose?
500 Rads=
What is the MAXIMUM radiation erythema dose?
700 Rads (1st degree burn)
In 1959, how many exposure were required to cause TED?
62 exposures (1250/20)
In 2023, 1/3 of TED is delivered with ~___ intraoral dental exposures at a ___ focal distance
298; 8”
In 2023, using properties of inverse square law, the dose is decreased to ~37% if the focal distance is:
doubled (16”)
~473 exposures
Benefits of dental radiography include: (9)
- interproximal caries diagnosis
- severity (depth) and extent of caries
- periodontal bone loss (alveolar crest)
- root configuration
- periradicular pathology
- basal bone pathology in jaws
- location of 3rd molar roots and IA
- anatomy assessment for implants
- calculus
Compared to visual examination:
- digital bitewings identified ____x more caries
- conventional bitewings identified ___x more caries
3.2x; 2.9x
(6% occlusal decay and 94% interproximal decay)
20% incidence in asian and chinese populations & 10-12% incidence in native North American populations:
Lingual root of mandibular first molars
Basal bone pathology in jaws: hyperdontia is most common in the:
premolar area
What are the goals for maxillofacial and oral radiology?
- reduce radiation exposure
- maintain a high degree of diagnostic efficiency
Its a juggling act to:
reduce a patients radiation exposure yet maintain a high degree of diagnostic efficiency
ALARA:
As Low As Reasonably Achievable
The guiding principle of radiation protection:
ALARA & ALADA
Since the rpbomablility or severity of biological damage increases as the radiation does increases, it is desirable to avoid:
receiving even the smallest dose of unnecessary radiation
With ALARA, what was prioritized?
- Time
- Distance
- Shielding factors
ALADA:
As Low As Diagnostically Acceptable
Why was ALADA created as a a variation of ALARA by Dr. Jerald Bushberg in 2014?
To emphasize the importance of optimization in medical imaging
basically telling these dum ass mf ers to watch they selves
Dose reduction mechanisms in relation to the X-ray tube head include: (2)
- filtration
- collimation
Selective passage of contents through a specified substance:
filtration
Selectively removes a greater proportion of low keV x-ray photons:
filtration
Filtration selectively removes a greater proportion of:
low keV x-ray photons
When filtration selectively removes a greater proportion of low keV x-ray photons, this results in:
increased mean energy of the beam (because its only keeping high keV)
What dose reduction x-ray mechanisms in relation to the X-ray tube head increases the mean energy of the beam?
filtration
In regard to filtration, most of the units are ___ kV.
60kV
In regard to filtration, a higher kv means:
better image quality (but more expensive and requires more filtration)
Collimation describes the:
shape & size of the beam
In regard to collimation, what shape of beam is preferred?
rectangular
In regard to collimation, what is the maximum diameter for intraoral radiation?
2.75” (exit-side beam collimation)
What are the MANDATED requirements for the X-ray tube head?
- filtration
- collimation
a ____ collimator is an OPTIONAL dose reduction mechanism
rectangular
The area exposed is related to:
the maximum size of the beam
- tru-align
- tru-image
- universal rectangular collimator
These are all types of:
rectangular collimators
____ is reflective of the specific technique for common exams
effective dose
(optional) A high kV generator/ transformer allows for a ____
lower dose of radiation
Higher kV units are: (2)
larger & heavier
- rectangular collimator
- higher kV generator
- constant potential (DC) fully-rectified
- increased focal lenght
These are all:
OPTIONAL X-ray tube head dose reduction mechanisms
Discuss how increased of long BID benefits the patient: (3)
- 27% less head volume
- reduced effective dose
- sharper image
Dose reduction mechanisms PRACTICE OPTIONS include: (4)
- film speed
- lead PB thyroid color
- film-holding devices with beam alignment capablity
- time-temperature quality control processing
Film speed includes-
D:
E:
F:
D speed: ultraspeed
E speed: ektaspeed
F speed: insight
List the types of digital receptors that contribute to film speed:
- PSPP (photostimulable phosphor plate)
- CCD (charge coupled device)
- CMOS (complimentary metal oxide semiconductors)
Of the types of digital receptors, which is the most radiation sensitive:
CCD (lowest dose)
Of the types of digital receptors, which is the most common?
CMOS
In regard to image detector speed, the faster the receptor, the ____ the patient exposure
less
What is the #1 way to reduce patient exposure?
using a faster receptor
Film is the ____ receptor but produces the ____ image
slowest; sharpest
- Doesn’t come in an alternating current rather allows a constant potential causing the patient to be LESS exposed because you are ALWAYS producing x-rays so it is more time efficient (faster with less tie exposing patient)
Rectification
X-ray tube head circuitry only producing high energy photons that are good for image production and safer for the patient:
Rectification
What are two important means of patient protection?
- thyroid collar
- lead apron
Discuss the total filtration required for the following:
operating kv of less than 50:
operating kv 50-70:
operating kv of greater than 70:
<50 kV capability= 0.5mm aluminum filter
50-70 kV capability= 1.5mm aluminum filter
> 70 kV capability = 2.5 mm aluminum filter
During an exposure taken with a wall mounted x-ray unit, the operator should stand:
behind a barrier/wall
During an exposure taken with a wall mounted x-ray unit, where should the operator stand if no protective barrier/wall is present:
Atleast 6 feet away at an angle betweenT/ 90-135 degrees to the direction of the useful beam (primary beam)
T/F: It is acceptable to stand in the primary beam of the x-ray when absolutely needed:
False- NEVER stand in the primary beam
T/F: As an x-ray operator, you should NEVER hold the film or other receptors in a patients mouth
true
T/F: Radiation monitoring badges are optional
true (but they are recommended)
When are dosimeter badges worn?
dosimeter badges will be worn by a full-time operator of radiographic equipment while x-ray exposures are being made (these are optional but recommended)
An occupational whole body exposure will not exceed:
50 mSv
Operators who have declared pregnancy will not exceed more than ____ to the embryo or fetus during the term of the pregnancy
5 mSv
What are the nomad and nomad pro?
self-contained, hand-held portable x-ray units
T/F: The use of the nomad x-ray unit violates current radiology statutes
True
What statutes does the nomad x-ray unit violate?
“during each exposure, operator should stand at least 6 feet from patient or behind a protective barrier”
“neither the tube housing nor the position indicating device (cone, cylinder) should be hand-held during the exposure”
What the are the exemptions for licensed hand-held units?
- a backscatter shield must be permanently mounted to the cone and used at all times
- operators must wear a personnel monitoring device that must be evaluated monthly
- all personnel must use training in the use of these x-ray systems and records of the training kept for review
Label the arrows:
top left: back scatter shield
bottom left: end of PID
top right: control panel
bottom right: battery (entire handle)
middle: trigger
When using a nomad, where should the backscatter shield be placed?
at the end of the PID (closest to the patient)
When using a nomad, where should the PID be aligned?
align PID close to the patient
Radiation protection AKA:
dose reduction methods
What is the BEST way to protect patient from radiographic exposure?
Don’t take radiographs at all
What does the “cerebral option” mean?
Not every patient needs the same radiographs every time
According to the cerebral option, who are NOT candidates for dental radiographs:
low caries patients, with good oral hygiene, and no concerns of oral disease
You should never exposure the patient just for:
updating records
Reduce the number of radiographs by: (3)
- collection of patient data
- assimilation of facts
- critical thinking to arrive at a decision
The selection criteria guidelines for radiographs are supported and developed by:
- FDI
- FDA/ADA
FDI indications for imaging states: You need a specific ____ or a ___ task that a radiographic image will produce unique information not readily available from other from other diagnostic means
question; diagnostic task
What entity states “You need a specific question or a diagnostic task that a radiographic image will produce unique information not readily available from other from other diagnostic means”
and “imaging requires justification”
FDI
According to the FDI’s indications for imaging, what is required prior to taking radiographs?
an initial clinical exam is required to make the assessment that they need a radiograph; most regulatory agencies require this
FDA radiograph guidelines were created in ____ and revised in ___, ___.
1987; 2004; 2012
Selection criteria according to the FDA/ADA: (2)
- follows recommendations of FDI
- specific need to supplement clinical information
Individualized radiographic exam consisting of selected periapical/occlusal views and/or posterior bitewings if proximal surfaces cannot be visualized or probed.
Patients without evidence of disease and with open proximal contacts may not require a radiographic exam at this time:
Child with primary dentition- New patient
Posterior bitewings exam at 6-12 month intervals if proximal surfaces cannot be examined visually or with a probe:
Child with primary dentition or Child with transitional dentition or Adolescent with permanent dentition- Recall patient (high risk)
Posterior bitewing exam at 12-24 month intervals if proximal surfaces cannot be examined visually or with a probe:
Child with primary dentition or Child with transitional dentition- Recall patient (no increased risk)
Individualized radiographic exam consisting of posterior bitewings with panoramic exam or posterior bitewings and selected periapical images:
Child with transitional dentition- new patient
Individualized radiographic exam consisting of posterior bitewings with pano or posterior bitewings with selected periapical images.
A FMX is preferred when the patient has clinical evidence of generalized oral disease a history of extensive dental treatment
adolescent with permanent dentition- new patient
Posterior bitewings exam at 6-18 month intervals:
adult dentate or partially edentulous - recall patient (high risk)
Posterior bitewing exam at 18-36 month intervals:
adolescent with permanent dentition- recall patient (Not high risk)
Posterior bitewing exam at 24-36 month intervals:
adult dentate or partially edentulous- recall patient (not high risk)
Individualized radiographic exam, based on clinical signs and symptoms-
adult edentulous- new patient
Clinical situations for which radiographs may be indicated include, but are not limited to: (2)
- positive historical findings
- positive clinical signs and symptoms
Occlusal radiography requires:
Phosphor plate film
What size of sensory is used for occlusal radiography?
2 for child and #4 for adult
What are the types of occlusal radiographies in the maxilla?
- standard cross-sectional
- lateral (right/left) cross-sectional
- anterior topographical
What are the types of occlusal radiographies in the mandible?
- standard cross-sectional
- lateral (right/left) cross-sectional
- anterior topographical
For standard cross-sectional maxilla, the vertical angle is:
The central ray (CR) is at the:
+ 65-70 degrees (pointed downward)
bridge of nose and center of PSP plate
This image shows:
standard cross-sectional maxillary occlusal radiography
A true cross section=
perpendicular image
What features of the palate can be seen with a standard cross-sectional maxillary occlusal radiograph?
entire palate
This image shows what type of radiograph?
standard cross-sectional maxillary occlusal radiography
For lateral cross-sectional maxillary, the vertical angle is:
The central ray (CR) is at the:
vertical angle: + 55-60 (pointed downwards)
central ray: posterior maxillary
What does this image show?
lateral cross-sectional maxillary occlusal radiography
This image shows what type of radiograph?
lateral cross-sectional maxillary occlusal radiograph
For anterior topographical maxillary, the vertical angle is:
The central ray (CR) is at the:
+ 55-60 degrees (pointed downward)
Central ray: 1/4 to 1/2 inches above the tip of the tip of nose
What does this image show?
anterior topographical maxillary occlusal radiography
This image shows what type of radiograph?
anterior topographical maxillary occlusal radiograph
For standard cross-sectional mandibular, the vertical angle is:
The central ray (CR) is at the:
perpendicular to PSP
Central ray: between mandibular first molars; along mid-sagittal plane
What does this image show?
standard cross-sectional mandibular occlusal radiography
For lateral cross-sectional mandibular, the vertical angle is:
The central ray (CR) is at the:
perpendicular to PSP Plate following long axis of first of first molar
Central ray: center of PSP plate @ apex of first molar
For anterior topographical mandibular, the vertical angle is:
The central ray (CR) is at the:
- 55 to 60 degrees (pointed upward); bisecting angle between PSP plate and long axis of incisor teeth
Central ray: below apices of incisors, 1 cm above tip of chin, along midline of chin, directed at center of PSP plate
How occlusal exposure settings when compared to posterior maxillary periapical exposures?
1 (or possible 2) exposure settings higher
- orthodontic encaluations
- orthognathic evaluations
- pathology beyond coverage of standard dental images
These are all indications for:
skull radiography
What are the skull projections in skull radiography (5)?
- lateral cephalogram/cephalometric
- PA cephalogram/cephalometric
- waters’ PA
- Reverse-towne (PA)
- SMV
What are the image enhancers for skull radiography?
- grids (standard, focus, grid ratios)
- air gaps
Reduce amount of scatter radiation exposing film and improves image contrast:
grids with PSPP
What do grids do in skull radiography?
block the scatter photons
What does increasing the tube-to-object distance do for skull radiography?
Improves image sharpness
A lateral cephalogram will identify:
- maxillary sinus
- frontal sinus
- sphenoid sinus
Cephalometric radiography is different because there is a filter to:
capture soft tissue
