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Xray > Xray - Week 2 PP > Flashcards

Xray - Week 2 PP Flashcards

1
Q

Importance of Dental Images

A

In dentistry, dental images enable the
dental professional to identify many
conditions that may otherwise go
undetected and to see conditions that
cannot be identified clinically.
Many dental diseases and conditions have no clinical signs or symptoms and may go undetected without the use of dental images.

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2
Q

Uses of Dental Images

A
  1. Detect lesions
  2. Confirm or classify suspected disease
  3. Localize lesions or foreign objects
  4. Provide information during dental procedures
  5. Evaluate growth and development
  6. Illustrate changes secondary to caries,
    periodontal disease, trauma
  7. Document the condition of a patient
  8. Aid in development of a clinical treatment plan
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3
Q

Dental Assistant’s Role for Xrays

A
  1. The dental assistant must have a thorough knowledge and understanding of the importance and uses of dental imaging
  2. Dental imaging enables the dentist to see
    conditions that are not visible in the oral cavity
  3. The dental assistant must understand the
    fundamental concepts of atomic and molecular structure and have a working knowledge of ionizing radiation and the properties of x-rays
  4. Radiation used to produce dental
    radiographs has the capacity to cause
    damage to all types of living tissues
  5. Any exposure to radiation, no matter how
    small, has the potential to cause biologic
    changes to the operator and the patient
  6. The dental assistant must have a thorough understanding of the characteristics of radiation to minimize radiation exposure to both the dental patient and the operator
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4
Q

Biological Effects of X-Radiation

A

Short-Term and Long-Term Effects
* Radiation effects can be classified as either short-term or long-term effects.
* After the latent period, effects that are seen within minutes, days, or weeks are termed short-term effects.
* Short-term effects are associated with large amounts of radiation absorbed in a short time (e.g., exposure to a nuclear accident or the atomic bomb). Acute radiation syndrome (ARS) is a short-term effect and includes nausea, vomiting, diarrhea, hair loss, and hemorrhage.
Short-term effects are not applicable to dentistry.

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5
Q

Various Effects of Radiation

A

Effects that appear after years, decades, or
generations are termed long-term effects.
Long-term effects are associated with small
amounts of radiation absorbed repeatedly over a long period.
Repeated low levels of radiation exposure are linked to the induction of cancer, birth abnormalities, and genetic defects.

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6
Q

Genetic Effects

A

Genetic effects are not seen in the
irradiated person but are passed on to
future generations.
Genetic damage cannot be repaired.

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7
Q

Radiation Effects on Tissues & Organs

A

In dentistry, some tissues and organs are designated as “critical” because they are exposed to more radiation than others during imaging procedures.
A critical organ is an organ that, if damaged, diminishes the quality of a person’s life. Critical organs exposed during
dental imaging procedures in the head and neck region
include the following:
1. Thyroid gland
2. Bone marrow
3. Skin
4. Lens of the eye

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8
Q

ALARA Concept

A

ALARA concept means as low as reasonably
achievable
◦ Every possible method of reducing exposure to radiation
should be employed

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9
Q

Personal Monitoring Dosimeter

A

Given to health care professionals exposed to radiation and monitored by Health Canada. It is linked to your Social Insurance Number. It tracks the amounts of radiation you are exposed to. If you go above the recommended amount, Health Canada will contact you to investigate.

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10
Q

Radiation Monitoring

A
  • Equipment monitoring
    ◦ Dental x-ray machines must be monitored for leakage radiation
  • Personnel monitoring
    ◦ A radiation monitoring badge can be worn at waist level when taking images
    ◦ It is mailed along with a control badge to the monitoring company once a month for evaluation
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11
Q

Safety Code 30

A

Safety Code 30 indicates personnel only need to use dosimeters in certain circumstances, however, Alberta’s Occupational Health and Safety Code (OHS Code) requires all workers who use or are exposed to radiation to use
them.
* In Alberta, we follow the OHS Code as it takes precedence. S. 291.5 requires that “a worker who uses or may be exposed to radiation through the use of any ionizing radiation equipment” must use a monitoring device.

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12
Q

Prescribing Dental Images

A

The first important step in limiting the amount of x-radiation received by a dental patient is the proper prescribing, or order, of dental images.
The person responsible for prescribing dental images is the dentist. The dentist uses professional judgment to make decisions about the number, type, and frequency of dental images

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13
Q

Proper Equipment

A

Another important step in limiting the amount of xradiation a dental patient receives is the use of proper equipment. The dental x-ray tube head must
be equipped with appropriate aluminum filters, a lead collimator (rectangular), and a position indicating device.
Compared with a short (8-inch) position indicating device (PID), the longer (16-inch) PID is preferred because it produces less
divergence of the x-ray beam

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14
Q

Rectangular Collimeter

A

Collimators must now be rectangular instead of circular.
* Safety Code 30 s. A.3.2.2, 2 states
“Rectangular collimation of the X-ray beam
must be used, except in occlusal protocols, as it significantly reduces the dose to the patient compared to circular collimation.”

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15
Q

Patient Protection measures during exposure

A

Patient protection measures are used before and during x-ray exposure.
A thyroid collar, lead apron, digital sensors or fast film, and beam alignment devices are all used during x-ray exposure to limit the amount of radiation received by the patient. Proper selection of exposure factors and good technique further protect the patient from excessive exposure to x-radiation.

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16
Q

Thyroid collar

A

The thyroid collar is a flexible lead shield that is placed securely around the patient’s neck to protect the thyroid gland
from scattered radiation The lead prevents radiation from reaching the gland and protects the highly radiosensitive
tissues of the thyroid.
It is recommended for all intraoral exposures
It is not recommended for extraoral exposures

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17
Q

The lead apron

A

The lead apron is a flexible
shield placed over the patient’s
chest and lap to protect the
reproductive and bloodforming tissues from scatter radiation; the lead prevents the
radiation from reaching these
radiosensitive organs Use of a
lead apron is recommended
for both intraoral and extraoral
exposures.

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18
Q

Beam Alignment Device

A

Stabilizes the receptor in the mouth and
reduces the chance for movement
◦ Eliminates the need for the patient to hold the
receptor in position with a finger, reducing
unnecessary exposure

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19
Q

Image Receptors

A

Compared with traditional film radiography, digital image receptors require less radiation exposure to the patient. The use of a digital receptor is the most
effective method of reducing a patient’s radiation exposure.
The lowered absorbed dose is significant with regard to patient protection from excessive radiation

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20
Q

Exposure Factor Selection

A

Adjustment of kVp, milliamperage, and time
settings on the control panel to limit the amount of x-radiation exposure received by the patient
On most units, the kilovolt peak and milliamperage are preset by the manufacturer and cannot be
adjusted

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21
Q

Proper Technique

A

The proper technique helps create a diagnostic image and reduce the amount of exposure a patient receives. Images that are nondiagnostic must be retaken; this results in additional exposure of the patient to radiation.
The re-exposure of an image, or retake, must be avoided at all times.
To produce diagnostic images, the radiographer must have a thorough knowledge of the techniques used in dental imaging

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22
Q

After Exposure

A

Proper receptor handling
◦ Artifacts caused by improper film handling result in nondiagnostic films
* Proper film processing/image retrieval
◦ Improper film processing may require retakes, needlessly exposing the patient to excess xradiation

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23
Q

Operator Protection

A
  1. The dental radiographer must use proper
    protection measures to avoid occupational
    exposure to x-radiation (e.g., primary radiation, leakage radiation, scatter radiation).
  2. The use of proper operator protection techniques can minimize the amount of radiation that a dental radiographer receives.
  3. Operator protection measures include following protection guidelines and using radiation monitoring devices.
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24
Q

Distance and Position recommendations

A
  1. The dental radiographer must stand at
    least 6 feet (2 meters) away from the
    x-ray tube head during x-ray exposure
  2. The dental radiographer must never
    hold a receptor in place for a patient.
  3. The dental radiographer must never
    hold or stabilize the x-ray tube head
25
Q

Shielding recommendations

A

Whenever possible, the dental radiographer should stand behind a protective barrier, such as a wall, during x-ray exposure.
Most dental offices incorporate adequate shielding in walls through the use of several thicknesses of common construction materials such as drywall.
A leaded glass window or the use of a mirror is beneficial to monitor the patient during exposure.
At SAIT we stand behind a glass window.

26
Q

Maximum Permissible Dose (MPD)

A

MPD is the maximum dose equivalent that a
body is permitted to receive in a specific
period
◦ MPD for occupationally exposed persons is 50 mSv/year (0.05 Sv/year or 5.0 rem/year)
◦ For nonoccupationally exposed persons it is 1mSv/year (0.1 rem/year)
◦ For occupationally exposed pregnant women, MPD is 0.5 mSv per month during the pregnancy months

27
Q

Cumulative Occupational Dose

A

Cumulative occupational dose is the dose
accumulated over a lifetime
◦ An individual’s cumulative occupational effective dose should not exceed the worker’s age multiplied by 10 mSv

(50 years old x 10 mSv = 500 mSv)

28
Q

Panoramic Imaging

A

◦ Shows a wide view of the upper and lower jaws

Panoramic imaging is used to examine the upper and lower jaws on a single projection

Extraoral technique

  • An overall image of the maxilla and mandible
    ◦ Often used to supplement bite-wing and selected periapical images
29
Q

Advantages of Panoramic Radiography

A
  1. Numerous anatomical structures can be
    viewed on a panoramic image at one time.
  2. Learning how to expose a panoramic image is relatively easy.
  3. Most patients prefer panoramic imaging
    because they don’t have to hold the
    uncomfortable film in their mouths.
30
Q

Disadvantages of Panoramic Radiography

A
  1. The images seen on a panoramic are not as sharp as those seen on an intraoral
    radiograph.
  2. Structures must be within the focal trough, or they will appear out of focus.
  3. A panoramic unit is much more expensive than the cost of an intraoral radiograph unit.
31
Q

Panoramic Images are used to:

A
  1. evaluate the dentition and supporting structures
  2. evaluate impacted teeth
  3. evaluate eruption patterns
  4. growth, and development
  5. detect diseases
  6. lesions
  7. conditions of the jaws,
  8. examine the extent of large lesions,
  9. evaluate trauma.
32
Q

Fundamentals of Panoramic Radiography

A

In panoramic imaging, the receptor and x-ray tube head move around the
patient
◦ The x-ray tube rotates around the patient’s head in one direction while the receptor rotates in the opposite direction
◦ The patient may stand or sit in a stationary position
* The movement of the receptor and the tube head produces an image through the process known as tomography
* Tomography
◦ This is an imaging technique that allows the imaging of one layer or section of the body while blurring images from structures in other planes

33
Q

Rotation Center

A

The pivotal point, or axis, around which the cassette carrier and x-ray tube head rotate is the “rotational center”
◦ Modern panoramic x-ray units use a continuously moving center of rotation rather than multiple fixed center locations

34
Q

Focal Trough

A
  • Can be defined as a three-dimensional curved zone in which structures are clearly
    demonstrated on a panoramic image
  • Theoretical concept used to determine where the dental arches must be positioned to obtain the sharpest image
35
Q

Real Image (panoramic)

A

Results when a structure lies between the
receptor and moving rotation center

36
Q

Ghost Image

A

Results when an anatomic structure or object is located outside of the focal plane and close to the x-ray source

Problem
◦ If all metallic or radio dense objects are not removed before exposure, a ghost image results that obscure diagnostic information
* Solution
◦ The dental radiographer must instruct the patient to remove all radio dense objects in the head and neck region prior to positioning the patient

37
Q

Panoramic Equipment

A

There are a number of different panoramic xray units
◦ All have similar components
A. X-ray tube head
B. Head positioner
C. Exposure controls

38
Q
  • X-ray tube head & Collimator (pan)
A

Tube Head - Similar to an intraoral x-ray tube head

Collimators - Differs from the collimator used in the intraoral xray tube head
▪ The collimator used in the panoramic x-ray machine is a lead plate with an opening in the shape of a narrow vertical slit

The x-ray beam emerges from the panoramic tube head through the collimator as a narrow band
◦ It passes through the patient and exposes the receptor through another vertical slit in the cassette carrier
◦ The vertical angulation is fixed so that the x-ray beam is directed slightly upward

39
Q

Head Positioner

A

A chin rest, notched biteblock, forehead rest, and lateral head supports or guides
Used to align the patient’s teeth as accurately as possible

40
Q

Exposure Factors

A
  1. Suggested exposure factors for milliamperage and kilovoltage are provided by the manufacturer and can be varied to accommodate patients of different sizes
  2. Exposure time can be adjusted based on the type of image obtained
41
Q

Image Receptors for PAN

A
  • In panoramic x-ray units, the image receptor may be a direct digital sensor, a PSP plate, or a film
  • Extraoral screen film is used in film-based
    panoramic imaging
    ◦ It is sensitive to the light from an intensifying screen
    ◦ It is placed between two intensifying screens in a cassette holder
42
Q

Instructions/Info to give to client for PAN (MUST KNOW FOR EVALUATION)

A

Ensure the patient understands the following:
a. This is a radiograph that is used to evaluate larger areas such as your jaw.
b. This film is taken outside of the mouth.
c. I will help position you in the equipment.
d. The equipment will rotate around your head.
e. You will need to keep still while the machine rotates.

43
Q

Patient Preparation for PAN

A
  1. Explain the imaging
    procedures
  2. Place a lead apron without a
    thyroid collar on the patient
    and secure it
  3. A double-sided lead apron is
    recommended
  4. Remove all objects from the
    head and neck area that may
    interfere with the procedure
44
Q

Patient Positioning for PAN

A
  1. Instruct the patient to sit or stand “as tall as possible” with the back straight and erect
  2. Instruct the patient to bite on the plastic biteblock
  3. Position the Frankfort plane parallel with the floor
  4. Position the midsagittal plane perpendicular to the floor
  5. Instruct the patient to position the tongue on the roof of the mouth and keep the tongue in that position during exposure to the receptor
  6. Instruct the patient to close the lips around the bite-block
  7. Instruct the patient to remain still while the machine is rotating during exposure
  8. Expose the receptor and proceed with receptor processing
45
Q

Imagining Artifact

A

An imaging artifact is seen on a panoramic
image that is produced when a metallic or
dense object is penetrated twice by the x-ray beam
◦ It is found on the opposite side of the receptor
◦ It appears indistinct, larger, and higher than its actual counterpart

46
Q

Diagnostic Panoramic Image

A

Results when the equipment preparation, patient preparation, and patient
positioning are completed correctly
2. Ideally, should be free from all errors
3. Must demonstrate accurate anatomic features and proper exposure
resulting in correct density and contrast

47
Q

Common Errors in PAN

A
  1. Patient preparation errors
  2. Patient positioning errors
48
Q

Lead Apron Artifact

A

Problem
◦ A radiopaque cone-shaped artifact that obscures diagnostic information results if the lead apron is incorrectly placed, or if a lead apron with a thyroid collar is used
* Solution
◦ The dental radiographer must always use a lead apron without a thyroid collar when exposing a panoramic projection

49
Q

Common Patient Positioning Errors

A
  1. Positioning of the lips and tongue
  2. Chin tipped up
  3. Chin tipped down
  4. Teeth anterior to the focal trough
  5. Teeth posterior to the focal trough
  6. Head turned
  7. Slumped posture
50
Q

Positioning of the Lips & Tongue

A
  • Problem
    ◦ If the patient’s lips are not closed on the bite-block during the exposure of a panoramic projection, a dark radiolucent shadow results that obscures the anterior teeth
    ◦ If the tongue is not in contact with the palate during exposure of a panoramic projection, a dark radiolucent shadow results that obscures the apices of the maxillary teeth
  • Solution
    ◦ Instruct the patient to close the lips around the biteblock and swallow and raise the tongue up to the palate during the exposure of the receptor
51
Q

Chin Tipped up in PAN

A

Problem
◦ If the patient’s chin is positioned too high a “reverse smile line” is apparent on the image
* Solution
◦ Position the patient so the Frankfort plane is parallel with the floor

52
Q

Chin Tipped Down in PAN

A
  • Problem
    ◦ If the patient’s chin is positioned too low or is tipped down an “exaggerated smile line” is apparent on the image
  • Solution
    ◦ Position the patient so that the Frankfort plane is parallel with the floor
53
Q

Teeth Anterior to Focal Trough in PAN

A

Problem
◦ If the patient’s teeth are positioned too far forward on the bite-block or anterior to the focal trough, the anterior teeth appear “skinny” and out of focus
* Solution
◦ Position the patient so that the anterior teeth are placed in an end-to-end position in the groove on the bite-block

54
Q

Teeth Posterior to the Focal Trough in PAN

A

Problem
◦ If the patient’s teeth are positioned too far forward on the bite-block or anterior to the focal trough, the anterior teeth appear “skinny” and out of focus
* Solution
◦ Position the patient so that the anterior teeth are placed in an end-to-end position in the groove on the bite-block

55
Q

Head Turned in PAN

A

Problem
◦ If the patient’s head is not centered, the ramus and posterior teeth appear unequally magnified on the panoramic image
▪ The side farthest from the receptor appears magnified
* Solution
◦ Position the patient’s head so that the midsagittal plane is perpendicular to the floor while the midline is centered on
the bite-block

56
Q

Slumped Posture

A

Problem
◦ If the patient is not standing or sitting with a straight spine, the cervical spine appears as a radiopacity in the center of the receptor and obscures diagnostic information
* Solution
◦ Instruct the patient to stand or sit “as tall as possible” with a straight back

57
Q

CBCT

A

CBCT – Cone Beam Computed Tomography (3D imaging)
Allows the viewing of the head and neck in 3
dimensions

58
Q

How CBCT Works

A

The xray arm rotates around the patients head in a complete 360-degree rotation, while doing so it takes 200-600 2D images which the software collects and then digitally combines to form a 3D image.
* 1 scan is equivalant to 3-4 FMS
* Takes between 7-30 seconds to expose
* Images can be colorized, adjusted and
manipulated on the computer

59
Q

Advantages of CBCT

A

Due to other images being 2D they cannot
provide and information about buccal or lingual width or locations. They also cannot distinguish between types of soft tissues.
This information is vital for:
* The exact placement of implants
* The buccal/lingual placement of impacted
teeth
* Determining the location of the mandibular nerve before surgery

Xray (21 decks)

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