oral radiology final

tomography

• Is an imaging technique that allows the imaging of one layer, or section, of the body while blurring the images of structure in other planes

• panoramic imaging process in which the movement of the receptor and tubehead produces an image

what is a panoramic image?

• shows a wide view of the maxilla and the mandible and surrounding structures

• Allows for the visualization of the patients’ oral and facial structures spread out across a flat surface

• structures in a panoramic image are in a 2D curved zone

how is a pan taken?

·       Is an extraoral method of radiography

·       Extraoral receptor is placed and positioned outside the mouth during x-ray exposure

·       Patient is positioned in correct manner

·       Receptor and tube head rotated around patient taking a series of x-ray images that will combine into one

 What rotation occurs when taking panoramic images

·       Both the receptor and tube head rotate around the patient in opposing directions, producing a series of individual images

·       When the images are combined, an overall view of the maxilla and mandible are created

·       tomography

• tubehead rotates BEHIND patient, receptor rotates IN FRONT of patient

Why do we use Pans

·       To evaluate the dentition and supporting structures

·       To evaluate impacted teeth

·       To evaluate eruption patterns, growth, and development

·       To detect diseases, lesions, and conditions of the jaws

·       To examine the extent of large lesion

·       To evaluate trauma

disadvantages of taking panoramic images

• image quality

• focal trough limitations

• distortion

• equipment cost

advantages of taking panoramic images

• field size

• simplicity

• patient cooperation

• minimal exposure

• can aid in detection of

  • jaw fractures, impacted 3rd molars, large lesions in mandible

focal trough

·       Theoretical concept used to determine where the dental arches must be positioned to obtain the sharpest image

·       Image layer

·       Three dimensional curved zone in which structures located within the focal trough appear reasonably well defined on the resulting panoramic image

collimation in pano machine vs collimation in x-ray tubehead

·       In intraoral imaging it is a lead plate with a small round or rectangular opening in the middle while the one used in panoramic imaging is a lead plate with a small opening in the shape of a narrow vertical slit

·       Both are used to restrict the size and shape of the x-ray beam

what are ghost images

·       An artifact seen on a panoramic image that is produced when a metallic or dense object is penetrated twice by the x-ray beam

·       Could obscure diagnostic information

• often appear higher than the counterpart

appearance of ghost images

·       Found on the opposite side of the receptor

·       Appears indistinct, larger, and higher than its actual counterpart

·       Could obscure diagnostic information

What happens if a patient does not close their lips around the bite block when taking a Pan?

A dark radiolucent shadow results that obscures the anterior teeth

What happens on the Pan image if the patients chin is too low?

·       An “exaggerated smile line” is apparent on the image

·       Smaller mandible, teeth, and a high arch can be seen

The patient's chin is too high?

·       A “reverse smile line” is apparent on the image

The patient's teeth are too far forward on the bite block?

·       Anterior teeth appear skinny and out of focus

The patient’s teeth are too far back on the bite block?

Anterior teeth appear fat and out of focus

• big back

When learning about CBCT scans what is multiplanar reconstruction?

·       The sagittal plane is a vertical plane that divides the anatomic features within the FOV into right and left slices

·       When viewed together, axial, coronal, and sagittal images are referred to as this

·       MPR images

What does DICOM stand for?

·       Digital  imaging and communications in medicine

What are common uses of 3-dimensional imaging

• Provides accurate and detailed information regarding the evaluation of pathology

• distances to critical anatomic landmarks

• locations of impacted teeth

• eruption patterns

• other concerns of the oral and maxillofacial complex

What areas of dentistry use 3-dimensional imaging

·       Every single specialty!

o   Public health

o   Orthodontics

o   Oral medicine

o   Endodontics

o   Oral surgery

o   Etc..

What happens on a CBCT scan if the patient has multiple metallic restorations?

·       Beam hardening

·       X-ray beam scatter reduces image quality

Is a uniocular lesion with corticated borders usually benign or malignant?  Fast-growing or slow-growing?

·       This lesion exhibits a thin, well-demarcated radiopaque rim of bone at the periphery

• one compartment, non expansible

·       Usually indicative of a benign, slow-growing process

Unilocular lesions with no corticated borders

·       This lesion does not exhibit a thin radiopaque rim of bone at the periphery

·       The periphery appears fuzzy or poorly defined

·       May represent either a benign or malignant process

What is a Target-lesion?  What do they look like?

·       A well-defined, localized radiopaque area surrounded by a uniform radiolucent halo

What is the definition of Radiation?

·       A form of energy carried by waves or a stream of particles

What is the definition of a Radiograph?

·       An image or picture produced on a receptor by exposure to ionizing radiation; a two dimensional representation of a three dimensional object

Density is defined as?

·       The overall darkness or blackness of an image

What does millamperage control?

·       Controls the quantity of electrons produced

·       KLMN

·       Regulates the temperature of the cathode filament, the higher the setting the more electrons that are produced

What does kilovoltage control?

·       Controls quality of dental x-ray images

·       Regulates the speed and energy of electrons and determines the penetrating ability of the x-ray beam

·       KLMN

When do we use a thyroid collar on a patient?

•   When taking x-rays, radiations is exposed to critical organs of the neck

• A critical organ is an organ that, if damaged, diminished the quality of a persons life

  • Thyroid gland

  • Bone marrow

  • Skin

  • Lens of eye

  • Reproductive organs

  • Lymphocytes

What are the basic principles of the Paralleling technique?

1. receptor placement

2. receptor position

3. vertical angulation

4. horizontal angulation

5. receptor exposure

receptor placement

• the receptor must be positioned to cover the prescribed area of teeth to be examined

receptor position

o   The receptor must be positioned parallel to the long axis of the tooth

o   The receptor and beam alignment device must be placed away from the teeth and toward the middle of the oral cavity

vertical angulation

o   The central ray of the x-ray beam must be directed perpendicular (at a right angle) to the receptor and the long axis of the tooth

horizontal angulation

o   The central ray if the x-ray beam must be directed through the contact areas between the teeth

receptor exposure

o   The x-ray beam must be centered on the receptor to ensure that all areas are exposed

o   failure to center the x-ray beam results in a partial image on the receptor or a cone cut

o   cone cuts can be produced with either a round PID or a rectangular

What is Foreshortening?  How is it corrected?

·       Caused by excessive vertical angulation

·       Appear as short teeth with blunted roots

·       Can be corrected by reducing amount of vertical angulation

What is Elongation?  How is it corrected?

·       Caused by insufficient vertical angulation

·       Appear as long, distorted teeth

·       Can be corrected by increasing the amount of vertical angulation

Contrast

·       Refers to how sharply dark and light areas are differentiated or separated on an image

Mental Ridge

·       A linear prominence of cortical bone located on the external surface of the anterior portion of the mandible

·       Often appears superimposed over the mandibular anterior teeth

·       A thick radiopaque band that extends from the premolar region to the incisor region

 Nasal Spine

·       A sharp projection of the maxilla located at the anterior and inferior portion of the nasal cavity

·       A v-shaped radiopaque area located at the intersection of the floor of the nasal cavity and nasal septum

Zygoma

·       Articulates with the zygomatic process of maxilla

·       A diffuse, radiopaque band extending posteriorly from the zygomatic process of the maxilla

• seen on the maxillary molar and premolar periapicals

Maxillary tuberosity

·       Rounded prominence of bone that extends posterior to the third molar region

·       A radiopaque bulge distal to the third molar region

Mental Foramen

·       An opening or hole in bone located on the external surface of the mandible in the region of the mandibular premolars

·       A small ovoid or round radiolucent area located in the apical region of the mandibular premolars

Maxillary sinuses

·       Paired cavities or compartments of bone located within the maxilla

·       Located above the maxillary premolar and molar teeth

·       A radiolucent area located above the apices of the maxillary premolars and molars

where is the Inverted Y

·       The intersection of the maxillary sinus and the nasal cavity

·       A radiopaque upside-down Y formed by the intersection of the lateral walls of the nasal fossa and the anterior border of the maxillary sinus

·       Above maxillary canine

Where do we see Condensing Osteitis?

·       The most common periapical radiopacity, most commonly in the mandibular third molars

·       More common in women

·       Is seen below the apex of a tooth, varying in shape and size, with a history of pulpitis 

What is Luxation?

·       Is the abnormal displacement of teeth

·       Can be intrusion, the abnormal displacement of teeth into bone or

·       Extrusion, the abnormal displacement of teeth out of bone

Radiopaque

·       Refers to that portion of an image that appears light or white

·       Are dense and absorb or resist the passage of x-ray beam

Radiolucent

·       Refers to that portion of an image that is dark or black

·       A structure that lacks density and permits the passage of x-ray beam with little or no resistance

lamina dura

• the wall of the tooth socket

• made of dense cortical bone

• a dense radiopaque line that surrounds the root of the tooth

frankfort plane is

• parallel with floor

midsagittal plane is

• perpendicular with floor

In panoramic imaging the pivotal point or axis in which our machine rotates is the

• rotation center

The rotation change in a panoramic machine allows the image layer to conform to which shape

• elliptical shape of the dental arches

structures are clearly demonstrated on a panoramic image as a __

• 2-Dimensional, curved image

Which component of a panromic machine tubehead is most different than intraoral tubehead

• collimation- narrow vertical slit 

What is the angulation of a tubehead in a panoramic unit

• slightly negative

Your patient has tooth letter A dislodged, which would be the acceptable x-ray technique for observing

• periapical

why do ghost images appear

• metallic accessories have not been properly removed

if a patients lips arent closed on a bite block, what shadow will appear

• dark radiolucent shadow

What anatomy will appear on a panoramic image that is taken correctly

• posterior teeth are the same size

• anterior teeth should NOT be skinny

• possibly see the hard palate

• should be able to see the pulp chambers on visible teeth

multiplanar reconstruction

• a technique used in medical imaging to create new 2D images from 3D volumetric data

  • axial

  • coronal

  • sagittal

  • oblique

What would a uniocular lesion with corticated borders be indicative of

• benign, slow growing lesion

does most pathology on dental images appear with even thickness or different

• everything will not look the same, they will appear with different varying levels of thickness, and as different shades of grey

radiation

• energy carried by waves or streams of particles

radiography

• the art and science of making radiographs by exposure of film to x-rays

who by law prescribes dental images

• dentist

how often do we need to take a FMX

• every 3 years

how often do we need to take bitewings

• once a year on or past the last appointment date

How much of the apical area should we see on periapical images

• 2-3 mm

angulation for bitewings

• +10 degrees of positive vertical angulation

what do we do when we adjust horizontal angulation

• side-to-side adjustment

why do we use vertical bitewings

• loss of bone in patients with periodontal disease

in periodontal disease, dental images permit the evaluation of pocket depth, soft tissue inflammation, or bone

• bone

where do we see condensing osteitis 

• down in the apical area

• frequently attributed to decay, tooth is nonvital

• focal opacity

• tooth is trying to save itself by condensing the bone around the apices 

PFM appearance

• two components

  • a little or a lot of porcelin

  • solid, fluid metal structure that does not cover the full surface of the tooth

when do we interpret radiographs

• when the patient is in the chair

where do we see post an core restorations

• in endodontically treated teeth

where do we first begin to see decay in teeth

• at contacts or just below

if the interproximal decay does not involve the dentin, but is halfway through the enamel, it is considered

• moderate decay

who do we see rampant decay in

• children and adults with minimal salivary flow (more often elders)

radiology

• the science or study of radiation as used in medicine

what accessories need to be taken out for intraoral imaging

• oral piercings

• nose rings

• glasses

what accessories need to be taken out for extraoral imaging

• everything

  • earrings

  • glasses

  • facial jewelry

  • partial dentures

incipient

• extends less than halfway through the enamel, cannot be found on a dental image

• must be seen clinically

moderate

• extends more than halfway through the enamel but does not involve the dentin

advanced

• extends to or through the dentin but not more than halfway through the pulp

severe

• extends through the enamel, dentin, and more than halfway through the pulp

multiplanar reconstruction

• reconstruction of raw data into images when imported into viewing software to create 3 anatomic planes of the body