Radiology chapter 17: Panoramic examination

P I D used with the panoramic tube head is in a fixed vertical position pointing up slightly, about ___ degrees

-8

Panoramic x-ray machines have guides to aid in positioning the patient within the focal trough

-Biteblock or bite pin -Forehead or chin rest -Beams of light that, when activated, shine on the patient's face

All panoramic x-ray machines have four basic components:

-Rotational x-ray tube head -Cassette holder (for film or phosphor plate) or digital image receptor -Head positioner guides -Exposure control panel

The three dimensions of the focal trough are:

1.Anterior- posterior 2.Lateral or left-right 3.Superior-inferior or up-down

how much magnification is typically found on panoramic radiographs?

10-30%

Panormics take ____ to ____ seconds to take

15 to 20

Why is it important that the pt places the tongue against the hard palate when taking a pano?

Because it will interfere with the mandibular teeth

**Patient preparation: 1.Inform the patient of the need for the panoramic radiograph. Explain the procedure, answer patient concerns/questions regarding the procedure, and obtain patient's consent. 2.Request that the patient remove items from the oral cavity and the head, neck, and shoulders that may interfere with the procedure such as removable dental appliances, eyeglasses, necklaces, hair barrettes, ear and facial jewelry (tongue, lip piercing adornments), and scarves or a hooded sweatshirt. 3.Place the lead/lead-equivalent cape or apron without a thyroid collar over the patient. Ensure that the lead apron will not impede the rotation of the tube head and image receptor assembly. 4. Disinfect biteblock and use barrier

Explaining procedure: Explain why you are taking the panoramic and if it's okay that you continue and receive consent

For the superior-inferior position: _____ plane which is line with orbital ridge will be in a position parallel to the plane of the floor ___ ____ line which is line from ala of the nose is positioned 5 degrees down

Frankfort Ala-tragus

____ imaging plate: Panoramic photostimulable phosphor (P S P) imaging plates are available in sizes that approximate panoramic film sizes. Plate is placed into a cassette to shield it from prolonged light exposure and attached to the cassette holder on the panoramic machine. Plate captures the panoramic image and is then removed from the cassette and placed into a laser scanner.

PSP

Arches too far ____ results in blurred and diminished appearance of anterior teeth and prominent imaging of spinal column on both sides

anterior

Most panoramic machines have a relatively narrow focal trough in the ____ region Requires precision in locating the forward and backward dimension of image sharpness

anterior

A biteblock aids in locating the correct ____ ____ dimension; side positioner guides aid in locating the correct lateral dimension Beams of light shine on the patient's face to aid in positioning the arches in the focal trough

anterior posterior

Extraoral film for use with panoramic radiography comes in two sizes: ▪5 × 12 inch ▪6 × 12 inch Film-based panoramic x-ray machines use extraoral film in conjunction with a pair of intensifying screens housed within a light-tight _____ These are available as a rigid box or a flexible sleeve

cassette

We do not prescribe panoramic radiographs for opportunistic screening uses but two possible opportunistic screening uses for the panoramic are detection of ____ ____ and _____

catorid stenosis and osteoporosis

A L A R A dictates the fastest speed screen-film combination be used to reduce the amount of radiation exposure to the patient Slight reduction in image ____ produced by rare-earth screens is considered acceptable to reduce the radiation dose to the patient.

clarity

X-rays of a panoramic machine emerge from a narrow vertical slit opening in the tube head and are constricted to form a narrow band It _____ (constricts) the beam so a limited amount of tissue is irradiated at a time

collimates

The ____ panoramic sensor shares the same technology as CCD and CMOS-APS solid state sensors used in digital intraoral imaging Major differences between intraoral sensors and panoramics is the ___ ____ because the panoramic x-ray beam is collimated to expose only a narrow band of tissues at a time so the vertical portion of the sensor is only a few pixels wide The digital image receptor is usually built into the unit

digital pixel arrangement

Panoramics provide a broad view of the dental arches. However, the image has inherent ____ and ghost images

distoration

**Patient positioning: 1. To position the arches into the focal trough's anterior/posterior dimension, instruct the patient to bite on the biteblock guide with the anterior teeth occluding ___ __ ____, or to place the chin completely forward into the chin rest or forehead against the forehead rest. If using a panoramic machine with light indicators, align the laser light beam at the interproximal space recommended by the machine manufacturer 2. To position the arches into the focal trough's lateral (right-left) dimension, close the side head positioner guides or if using a panoramic machine with light indicators, align the laser light beam recommended by the machine manufacturer. If using a panoramic machine with a mirror, instruct the patient to view reflection in the mirror to align the midsagittal plane perpendicular to the floor 3. To position the arches into the focal trough's superior-inferior dimension, adjust the patient's chin up or down in the chin rest until the Frankfort plane is parallel to the plane of the floor or until the ala-tragus line is approximately positive 5 degrees to the plane of the floor. If available use the indicator lines engraved on the side head positioner guides or if using a panoramic machine with light indicators, align the laser light beam as recommended by the machine manufacturer.

edge to edge

The focal trough or ___ ____ is an estimated position between the x-ray source and the image receptor where the dental arches must be positioned to be recorded distinctly on the panormaic radiograph. Objects that are located at various distances from the center of the focal trough become less sharp the farther away they are located

focal layer

Panoramic imaging errors result from: Incorrectly preparing the patient for the procedure Incorrectly positioning the patient and dental arches in the ___ ____ Incorrectly handling, exposing, and processing the image receptor

focal trough

Most panoramic machines available today utilize a continuous moving rotational center to refocus the x-ray beam during movement to produce an image This keeps inherent ____ and _____ magnification of the image relatively constant.

horizontal and vertical

Arches too ____ result in a characteristic exaggerated "smile" appearance Arches too ____ result in a characteristic exaggerated "frown" appearance

inferior superior

Arches too _____ (chin tipped down) causes root apices of mandibular anterior teeth to slant out of focal trough Arches too _____ (chin tipped up) causes root apices of maxillary anterior teeth to slant out of focal trough.

inferior superior

Panoramic radiographs may aid in the evaluation of caries and periodontal diseases but the Imagery is not as sharp and detailed as the images produced by _____ radiographs.

intraoral

which of these is an advantage of a pano radiograph as compared to an intraoral radiograph? larger region recorded distoration eliminated definition is improved

larger region recorded

The patient must stand or sit up straight, and avoid a slumped posture When the arches are correctly positioned within the three dimensions of the focal trough, all teeth and supporting structures are recorded and there is less unequal ______ and unsharpness over all parts of the radiographic image.

magnification

Focal trough is determined and set by the machine _____ Use the head positioner guides the panoramic machine to position a patient correctly. These guides provide very specific and precise direction . The exposure control panel will usually allow for selection of the mA and kV as recommended by the manufacturer

manufacturer

Arches tilted too far to one or the other side of focal trough results in a _____ appearance of teeth on the side closer to the image receptor and a _______ of teeth on the side closer to the x-ray tube

narrowed magnification

_____ radiography refers to a technique for producing a broad view image of the entire dentition of the maxilla and mandible with the surrounding alveolar bone, the sinuses, and the temporomandibular joints on a single radiograph It is probably the most common extraoral projection used in general oral health care practice

panoramic

For the lateral position: The midsagittal plane that divides a patient's head into a right and left side must be positioned ____ to the floor

perpendicular

Arches too far _____ results in widened and magnified anterior teeth

posterior

in panoramics the anterior teeth are more narrower and require much more ____ than posterior teeth a mistake of 3 to 4 mm of positioning of the anteriors can cause magnification

precision

a panoramic radiograph is valuable when diagnosing each of the following EXCEPT which one cyst impacted molar recurrent caries supernumerary tooth

recurrent caries

Fundamentals of panoramic radiography: Cassette with image receptor and the x-ray tube head move in directions opposite each other while the patient stands or is seated in a _____ position X-ray tube head moves around the back of the patient while the cassette with image receptor moves around the front X-ray beam enters the patient's tissues from the back of the head penetrating through to exit the front tissues and strike the image receptor

stationary

focal trough is ____ dimensional and its actual shape varies depending on the manufacturer's equipment design

three

Panoramic x-ray machines operate on the basis of _____ with the patient positioned between the x-ray tube head and a cassette that holds the image receptor Exposure is made as the tube head and cassette rotate slowly around the patient's head during the operational cycle

tomography

_____ is a special radiographic technique used to record images of structures located within a selected plane of tissue, while blurring structures outside the selected plane making them less visible

tomography

If the anterior teeth are blurry and narrowed in size this means the focal trough was

too far forward

Panoramic means "_____ view" Plays valuable role in: ▪Examining large areas of the face and jaws ▪Locating impacted teeth or retained root tips ▪Evaluating trauma, lesions, and diseases of the jaws ▪Assessing growth and development

wide