panoramic radiology

double image

- real images may be double images -double images are formed in the central region -common double images are hard plate, soft palat, hyoid bone Hyoid Bone Epiglottis Hard Palate Soft Palate

focal trough

-An imaginary three-dimensional curbed zone that is horseshoe shaped and is used to focus panoramic radiographs is the ________

panoramic radiography

-Curvilinear tomographic image capturing both the maxillary and mandibular arches. - Reciprocal movement of x-ray source and an image receptor -many slices of structures are taken and combined into one image -curved surface tomograms

double image

-Structures located in the body's center, between Panoramic Rotational Center and Receptor -X-ray beam passes through structure twice due to rotational center movement - Reversed with respect to each other (mirror) - Examples: hard palate, palatal tori, body of hyoid bone, epiglottis, spinal column, nasal turbinates, greater horn of the hyoid bone

positioning the patient

1. prepare the patient -remove all removable appliances, metallic, hairclips, necklaces, chains, earring etc. -tongue and lip rings should also be removed, if at all possible -explain the procedure to the patient 2. prepare the machine -disinfect the machine -place a new bitestick in the machine 3. position the patient - Patient must be as straight as possible - The patient's neck should be extended - Anterior teeth should be in the notch on the bitestick - Tragus of the ear must be aligned with the plastic guides - Ala - Tragus line should be 50 from level -Panoramic lead apron must be used - Position apron high in front to protect the thyroid - Apron should be lower in back to expose the neck 4. Instruct the patient - Procedure takes less than ½ minute - Patient must remain motionless - The machine will revolve around the patient - Tongue must be kept against the hard palate

panoramic concepts

1.Real Images - Single images - Double images 2.Ghost Images

indications for panoramic radiography

1.evaluation of trauma 2. third molars 3. large lesions 4. generalized disease 5. inability to tolerate intraoral films 6. assessment for surgical procedures

close to the x ray source- big magnification Influence of an object's position on its radiographic size.

A, A mandible is supporting a metal ring positioned at the center of the focal trough. The mandible is positioned at the center of the focal trough by placing the incisal edges of the central incisors in a notch at the end of a bite rod-positioning device. B, Resultant panoramic radiograph shows minimal distortion of the metal ring. C, The mandible and ring are positioned 5 mm away from the focal trough. D, Resultant panoramic radiograph demonstrates horizontal magnification of both the ring and the mandibular teeth. E, The mandible and ring are positioned 5 mm in front of the notch in bite-block. F, Resultant panoramic radiograph demonstrates the horizontal minification of both the ring and the mandibular teeth.

what is this?

Earring ghost image

ghost images

Formed when an object is between the source and the center of rotation. These ghost images usually result from external objects such as earrings, but they may be produced by dense anatomical structures such as the mandible. Appear on opposite side of radiograph • Appear superior to real images • Appear more blurred than real images, but have the same morphology Common ghost images: - L and R from machine - Spine - Earrings - Inferior border of the mandible

positioning

If the patient is positioned to far forward or too far back in the machine, the teeth will be placed facial or lingual to the focal trough and the images of the teeth will be minified or magnified.

what is a problem?

Positioning - chin too far down

positioning

Tilting of the head will result in parts of the anterior teeth being placed outside the focal trough and having their images blurred such that they cannot be seen. distortion: side closer to x-ray source will be magnified

tomography

To view a "slice" of a structure • Useful for examining centrally located structures where overlying structures obscure conventional images • Panoramic radiographs are curved surface tomograms

cranex'd

anterior layer thickness is 50% wider than traditional techniaues. the result is superb anterior image quality -allow for minimal distortion -this is better route togo but expensive

real images

are formed when an object is radiographed between the center of rotation and the film

Ideal positioning evidenced by anterior teeth

black area is submandibular fossa not enough bone so x ray go through them cervical vertebrae right spot

double image

central vertebral hyoid epiglottis

what is problems

cheeck is folded and will form a fold nasal labial fold ghost image (higher up to the original image and horizontally stertching)

what is problems?

closer to dectetor further from x-ray minifize of positionining error mandibular anteriors shortened and blurred

ghost images

earring thyroid apron

what is problems?

error--too far back magnification of teeth when too far posterior magnification is big when the xray close to it

double image

hyoid bone hard plate

midline structure

may appear as single or double images. Single and double images are real images -real images are formed when an object radiographed between center of rotation and film/ sensor -single and double images are real images

typical panoramic system

most panoramic systems have a narrow anterior layer thickness, which leads to difficulty in positioning all of the patient's dentition within the focal trough - we use this system

what is problems?

off centered a lot of interference cervical vetebrae is off pateint not in focal trough not standing right

what is this?

soft palate cervical vertebrate hyoid bone ask pateint to stretch neck out during imaging

panoramic disadvantage

• Resolution is not as good as intraoral films. This results in decreased detail • Only objects in focal trough are seen clearly • Distortion of image - Overlapped teeth - Magnification - Objects of interest outside of focal trough

image layer

• Volume of tissue seen clearly on tomographic image • Three dimensional curved volume • Called the Focal Trough in panoramic radiology • Can vary in thickness • Usually pre-set on panoramic machines with variable settings for different size dental arches • Patient must be positioned precisely in the machine, and machine set correctly so that the dental arches are in the focal trough • Positioning may be difficult due to swelling, pain, and asymmetries - two types of system typical panoramic system, cranex d

panoramic advantages

• Well-tolerated by patients • Minimal time to expose when compared to intraoral radiographs • Broad anatomical coverage • Relatively low patient dose • Useful for patient education (although never exposed only for that purpose!)