![Basic panoramic radiograph](https://upload.wikimedia.org/wikipedia/commons/5/5c/Basic_panoramic_radiograph.jpg)
A panoramic radiograph is a
panoramic scanning
dental X-ray
Dental radiographs, commonly known as X-rays, are radiographs used to diagnose hidden dental structures, malignant or benign masses, bone loss, and cavities.
A radiographic image is formed by a controlled burst of X-ray radiation which penetrate ...
of the upper and lower
jaw
The jaw is any opposable articulated structure at the entrance of the mouth, typically used for grasping and manipulating food. The term ''jaws'' is also broadly applied to the whole of the structures constituting the vault of the mouth and serv ...
. It shows a
two-dimensional view of a
half-circle from
ear to ear. Panoramic radiography is a form of
focal plane tomography
In radiography, focal plane tomography is tomography (imaging a single plane, or slice, of an object) by simultaneously moving the X-ray generator and X-ray detector so as to keep a consistent exposure of only the plane of interest during image ac ...
; thus, images of multiple
planes
Plane(s) most often refers to:
* Aero- or airplane, a powered, fixed-wing aircraft
* Plane (geometry), a flat, 2-dimensional surface
Plane or planes may also refer to:
Biology
* Plane (tree) or ''Platanus'', wetland native plant
* ''Planes' ...
are taken to make up the composite panoramic image, where the
maxilla
The maxilla (plural: ''maxillae'' ) in vertebrates is the upper fixed (not fixed in Neopterygii) bone of the jaw formed from the fusion of two maxillary bones. In humans, the upper jaw includes the hard palate in the front of the mouth. The t ...
and
mandible
In anatomy, the mandible, lower jaw or jawbone is the largest, strongest and lowest bone in the human facial skeleton. It forms the lower jaw and holds the lower tooth, teeth in place. The mandible sits beneath the maxilla. It is the only movabl ...
are in the focal trough and the structures that are superficial and deep to the trough are blurred.
Other nonproprietary names for a panoramic radiograph are dental panoramic radiograph and pantomogram; Abbreviations include PAN, DPR, OPT, and OPG (the latter, based on genericizing a trade name, are often avoided in medical editing).
Types
Dental
panoramic radiography
Radiography is an imaging technique using X-rays, gamma rays, or similar ionizing radiation and non-ionizing radiation to view the internal form of an object. Applications of radiography include medical radiography ("diagnostic" and "therapeut ...
equipment consists of a horizontal rotating arm which holds an X-ray source and a moving
film
A film also called a movie, motion picture, moving picture, picture, photoplay or (slang) flick is a work of visual art that simulates experiences and otherwise communicates ideas, stories, perceptions, feelings, beauty, or atmosphere ...
mechanism (carrying a film) arranged at opposed extremities. The patient's
skull
The skull is a bone protective cavity for the brain. The skull is composed of four types of bone i.e., cranial bones, facial bones, ear ossicles and hyoid bone. However two parts are more prominent: the cranium and the mandible. In humans, the ...
sits between the X-ray generator and the film. The
X-ray
An X-ray, or, much less commonly, X-radiation, is a penetrating form of high-energy electromagnetic radiation. Most X-rays have a wavelength ranging from 10 picometers to 10 nanometers, corresponding to frequencies in the range 30&nb ...
source is rectangular
collimated beam. Also the height of that beam covers the
mandible
In anatomy, the mandible, lower jaw or jawbone is the largest, strongest and lowest bone in the human facial skeleton. It forms the lower jaw and holds the lower tooth, teeth in place. The mandible sits beneath the maxilla. It is the only movabl ...
s and the
maxilla
The maxilla (plural: ''maxillae'' ) in vertebrates is the upper fixed (not fixed in Neopterygii) bone of the jaw formed from the fusion of two maxillary bones. In humans, the upper jaw includes the hard palate in the front of the mouth. The t ...
regions. The arm moves and its movement may be described as a rotation around an instant center which shifts on a dedicated
trajectory
A trajectory or flight path is the path that an object with mass in motion follows through space as a function of time. In classical mechanics, a trajectory is defined by Hamiltonian mechanics via canonical coordinates; hence, a complete traj ...
.
The manufacturers propose different solutions for moving the arm, trying to maintain constant distance between the teeth to the film and generator. Also those moving solutions try to project the teeth
arch
An arch is a vertical curved structure that spans an elevated space and may or may not support the weight above it, or in case of a horizontal arch like an arch dam, the hydrostatic pressure against it.
Arches may be synonymous with vaul ...
as
orthogonal
In mathematics, orthogonality is the generalization of the geometric notion of ''perpendicularity''.
By extension, orthogonality is also used to refer to the separation of specific features of a system. The term also has specialized meanings in ...
ly as possible. It is impossible to select an ideal movement as the anatomy varies very much from person to person. Finally a
compromise is selected by each manufacturer and results in
magnification
Magnification is the process of enlarging the apparent size, not physical size, of something. This enlargement is quantified by a calculated number also called "magnification". When this number is less than one, it refers to a reduction in siz ...
factors which vary strongly along the film (15%-30%). The patient positioning is very critical in regard to both sharpness and distortions.
Films
There are two kinds of film moving mechanisms, one using a sliding flat
cassette
Cassette may refer to:
Technology
* Cassette tape (or ''musicassette'', ''audio cassette'', ''cassette tape'', or ''tape''), a worldwide standard for analog audio recording and playback
** Cassette single (or "Cassingle"), a music single in the ...
which holds the film, and another using a rotating cylinder around which the film is wound. There are two standard sizes for dental panoramic films: 30 cm × 12 cm (12″ × 5″) and 30 cm x 15 cm (12″ × 6″). The smaller size film receives 8% less X-ray
dosage on it compared to the bigger size.
Digital
Dental X-rays' radiology is moving from film technology (involving a chemical developing process) to
digital X-ray technology, which is based on electronic sensors and
computer
A computer is a machine that can be programmed to Execution (computing), carry out sequences of arithmetic or logical operations (computation) automatically. Modern digital electronic computers can perform generic sets of operations known as C ...
s. One of the principal advantages compared to film based systems is the much greater
exposure latitude
Exposure latitude is the extent to which a light-sensitive material can be overexposed or underexposed and still achieve an acceptable result. This measure is used for digital and analogue processes, e.g. optical microlithography or photography.
D ...
. This means many fewer repeated scans, which reduces costs and also reduces patient exposure to
radiation
In physics, radiation is the emission or transmission of energy in the form of waves or particles through space or through a material medium. This includes:
* ''electromagnetic radiation'', such as radio waves, microwaves, infrared, visi ...
. Lost X-rays can also be reprinted if the digital file is saved. Other significant advantages include instantly viewable images, the ability to enhance images, the ability to email images to practitioners and clients (without needing to digitize them first), easy and reliable document handling, reduced X-ray exposure, that no
darkroom
A darkroom is used to process photographic film, to make prints and to carry out other associated tasks. It is a room that can be made completely dark to allow the processing of the light-sensitive photographic materials, including film and ph ...
is required, and that no
chemicals are used.
One particular type of digital system uses a
photostimulable phosphor plate Photostimulated luminescence (PSL) is the release of stored energy within a phosphor by stimulation with visible light, to produce a luminescent signal. X-rays may induce such an energy storage. A plate based on this mechanism is called a photostimu ...
(aka PSP - Phosphor Plate) in place of the film. After X-ray exposure the plate (sheet) is placed in a special
scanner where the
latent formed image is retrieved point by point and
digitized
DigitizationTech Target. (2011, April). Definition: digitization. ''WhatIs.com''. Retrieved December 15, 2021, from https://whatis.techtarget.com/definition/digitization is the process of converting information into a digital (i.e. computer- ...
, using a laser light scanning. The digitized images are stored and displayed on the computer screen. This method is in between old film based technology and the current direct digital imaging technology. It is similar to the film process because it involves the same image support handling and differs because the chemical development process is replaced by the scanning process. This is not much faster than film processing and the
resolution
Resolution(s) may refer to:
Common meanings
* Resolution (debate), the statement which is debated in policy debate
* Resolution (law), a written motion adopted by a deliberative body
* New Year's resolution, a commitment that an individual mak ...
and sensitivity performances are contested. However it has the clear advantage of being able to fit with any existing equipment without any modification because it replaces just the existing film.
Also sometimes the term "digital X-rays" is used to designate the scanned film documents which further are handled by computers.
The other types of digital imaging technologies use electronic sensors. A majority of them first convert the X-rays in light (using a GdO2S or
CsI layer) which is further captured using a
CCD or a
CMOS
Complementary metal–oxide–semiconductor (CMOS, pronounced "sea-moss", ) is a type of metal–oxide–semiconductor field-effect transistor (MOSFET) fabrication process that uses complementary and symmetrical pairs of p-type and n-type MOSFE ...
image sensor. Few of them use a hybrid
analog-to-digital arrangement which first converts the X-ray into
electricity
Electricity is the set of physical phenomena associated with the presence and motion of matter that has a property of electric charge. Electricity is related to magnetism, both being part of the phenomenon of electromagnetism, as described ...
(using a
CdTe
Cadmium telluride (CdTe) is a stable crystalline compound formed from cadmium and tellurium. It is mainly used as the semiconducting material in cadmium telluride photovoltaics and an infrared optical window. It is usually sandwiched with cadmi ...
layer) and then this electricity is rendered as an image by a reading section based on CMOS technology.
In current state-of-the-art digital systems, the image quality is vastly superior to conventional film-based systems. The latest advancements have also seen the addition on Cone Beam 3D Technology to standard digital panoramic devices.
Indications
![JawCyst (with arrows)](https://upload.wikimedia.org/wikipedia/commons/c/c9/JawCyst_%28with_arrows%29.jpg)
Orthopantomograms (OPTs) are used by health care professionals to provide information on:
*
Impacted wisdom teeth
Impacted wisdom teeth is a condition where the third molars (wisdom teeth) are prevented from erupting into the mouth. This can be caused by a physical barrier, such as other teeth, or when the tooth is angled away from a vertical position. Com ...
diagnosis and treatment planning - the most common use is to determine the status of wisdom teeth and trauma to the jaws.
*
Periodontal bone
A bone is a Stiffness, rigid Organ (biology), organ that constitutes part of the skeleton in most vertebrate animals. Bones protect the various other organs of the body, produce red blood cell, red and white blood cells, store minerals, provid ...
loss and periapical involvement.
* Finding the source of dental
pain
Pain is a distressing feeling often caused by intense or damaging stimuli. The International Association for the Study of Pain defines pain as "an unpleasant sensory and emotional experience associated with, or resembling that associated with, ...
, and when carrying out tooth-by-tooth diagnosis.
* Assessment for the placement of dental
implant
Implant can refer to:
Medicine
*Implant (medicine), or specifically:
** Brain implant
** Breast implant
**Buttock implant
**Cochlear implant
**Contraceptive implant
**Dental implant
** Fetal tissue implant
**Implantable cardioverter-defibrillator ...
s
*
Orthodontic assessment. pre and post operative
* Diagnosis of developmental anomalies such as
cherubism
Cherubism is a rare genetic disorder that causes prominence in the lower portion in the face. The name is derived from the temporary chubby-cheeked resemblance to putti, the chubby-faced infants featured in Renaissance paintings, which were often m ...
,
cleido cranial dysplasia
*
Carcinoma
Carcinoma is a malignancy that develops from epithelial cells. Specifically, a carcinoma is a cancer that begins in a tissue that lines the inner or outer surfaces of the body, and that arises from cells originating in the endodermal, mesodermal ...
in relation to the jaws
*
Temporomandibular joint dysfunction
Temporomandibular joint dysfunction (TMD, TMJD) is an umbrella term covering pain and dysfunction of the muscles of mastication (the muscles that move the jaw) and the temporomandibular joints (the joints which connect the mandible to the skul ...
s and
ankylosis.
* Diagnosis of
osteosarcoma,
ameloblastoma, renal
osteodystrophy affecting jaws and hypophosphatemia.
* Diagnosis, and pre- and post-surgical assessment of
oral
The word oral may refer to:
Relating to the mouth
* Relating to the mouth, the first portion of the alimentary canal that primarily receives food and liquid
**Oral administration of medicines
** Oral examination (also known as an oral exam or oral ...
and
maxillofacial trauma, e.g. dentoalveolar fractures and
mandibular fractures.
* Salivary stones (
Sialolithiasis
Sialolithiasis (also termed salivary calculi, or salivary stones) is a crystallopathy where a calcified mass or ''sialolith'' forms within a salivary gland, usually in the duct of the submandibular gland (also termed "Wharton's duct"). Less common ...
).
* Other diagnostic and treatment applications.
Mechanism
Normally, the person bites on a plastic
spatula so that all the teeth, especially the
crowns
A crown is a traditional form of head adornment, or hat, worn by monarchs as a symbol of their power and dignity. A crown is often, by extension, a symbol of the monarch's government or items endorsed by it. The word itself is used, partic ...
, can be viewed individually. The whole orthopantomogram process takes about one
minute
The minute is a unit of time usually equal to (the first sexagesimal fraction) of an hour, or 60 seconds. In the UTC time standard, a minute on rare occasions has 61 seconds, a consequence of leap seconds (there is a provision to insert a nega ...
. The patient's actual radiation exposure time varies between 5.5 and 22 seconds for the machine’s excursion around the skull.
The
collimation of the machine means that, while rotating, the X-rays project only a limited portion of the
anatomy
Anatomy () is the branch of biology concerned with the study of the structure of organisms and their parts. Anatomy is a branch of natural science that deals with the structural organization of living things. It is an old science, having its ...
onto the film at any given instant but, as the rotation progresses around the skull, a composite picture of the maxillo-facial block is created. While the arm rotates, the film moves in a such way that the projected partial skull image (limited by the beam section) scrolls over it and exposes it entirely. Not all of the overlapping individual images projected on the film have the same magnification because the beam is
divergent and the images have differing focus points. Also not all the element images move with the same
velocity
Velocity is the directional speed of an object in motion as an indication of its rate of change in position as observed from a particular frame of reference and as measured by a particular standard of time (e.g. northbound). Velocity is a ...
on the target film as some of them are more distant from and others closer to the instant rotation center. The velocity of the film is controlled in such fashion to fit exactly the velocity of projection of the anatomical elements of the dental arch side which is closest to the film. Therefore, they are recorded sharply while the elements in different places are recorded blurred as they scroll at different velocity.
The dental panoramic image suffers from important distortions because a vertical
zoom
Zoom may refer to:
Technology Computing
* Zoom (software), videoconferencing application
* Page zooming, the ability to magnify or shrink a portion of a page on a computer display
* Zooming user interface, a graphical interface allowing for image ...
and a horizontal zoom both vary differently along the image. The vertical and horizontal zooms are determined by the relative position of the recorded element versus film and generator. Features closer to the generator receive more vertical zoom. The horizontal zoom is also dependent on the relative position of the element to the focal path. Features inside the focal path arch receive more horizontal zoom and are blurred; features outside receive less horizontal zoom and are blurred.
The result is an image showing sharply the section along the mandible arch, and blurred elsewhere. For example, the more radio-opaque anatomical region, the cervical vertebrae (neck), shows as a wide and blurred vertical pillar overlapping the front teeth. The path where the anatomical elements are recorded sharply is called "focal path".
Principal advantage of panoramic images
* Broad coverage of facial bone and teeth
* Low patient radiation dose
* Convenience of examination for the patient (films need not be placed inside the mouth)
* Ability to be used in patients who cannot open the mouth or when the opening is restricted e.g.: due to
trismus
* Short time required for making the image
* Patient's ready understandability of panoramic films, making them a useful visual aid in patient education and case presentation.
* Easy to store compared to the large set of intra oral x-rays which are typically used.
Preparation
Persons who are to undergo panoramic radiography usually are required to remove any earrings, jewellery, hair pins, glasses,
dentures or
orthodontic appliances.
If these articles are not removed, they may create artifacts on the image (especially if they contain metal) and reduce its usefulness. There is also a need for the person to stay absolutely still during the 18 or so second cycle it takes for the machine to expose the film. For this reason, radiographers often explain to the person beforehand how the machine will move.
Adverse effects
Like any medical imaging utilizing
ionizing radiation
Ionizing radiation (or ionising radiation), including nuclear radiation, consists of subatomic particles or electromagnetic waves that have sufficient energy to ionize atoms or molecules by detaching electrons from them. Some particles can travel ...
, there will be a minute degree of direct ionizing damage and indirect damage from
free radicals created during the ionization of water molecules within cells. A rough estimate of the risk of fatal cancer from a panoramic radiograph is about 1 in 20,000,000.
The age of the person being imaged also alters the risk, with younger people having a slightly higher risk. E.g. the 1 in 20,000,000 risk would be doubled for someone in the 1-10 age group (1 in 10,000,000).
History
Historical milestones for digital panoramic systems
1985–1991 – The first attempt to build a dental digital panoramic was of McDavid et al. at
UTHSCSA. Their idea was based on a linear pixel array(single pixel column) sensor which was not appropriate for such an application because: a) there is no tomographic effect; b) huge difficulties to collimate the X-rays beam and to control the X-ray dose delivered to the patient; c) poor generator efficiency.
![RotatingPan](https://upload.wikimedia.org/wikipedia/commons/1/17/RotatingPan.gif)
1995 – DXIS, the first dental digital panoramic X-rays system available on the market, created by Catalin Stoichita a
Signet (France) DXIS targeted to retrofit all the panoramic models.
1997 – SIDEXIS, of
Siemens
Siemens AG ( ) is a German multinational conglomerate corporation and the largest industrial manufacturing company in Europe headquartered in Munich with branch offices abroad.
The principal divisions of the corporation are ''Industry'', '' ...
(currentl
Sirona Dental Systems Germany) offered a digital option for Ortophos Plus panoramic unit, DigiPan of Trophy Radiology (France) offered a digital option for the OP100 panoramic made by Instrumentarium (Finland).
1998–2004 – many panoramic manufacturers offered their own digital systems.
Research
Panoramic radiographs have the capability to demonstrate a portion of the neck and display atheromas (calcifications in the
carotid artery Carotid artery may refer to:
* Common carotid artery, often "carotids" or "carotid", an artery on each side of the neck which divides into the external carotid artery and internal carotid artery
* External carotid artery, an artery on each side of t ...
) which are an indication of both local and generalized (systemic)
atherosclerosis. Atherosclerosis of the
coronary arteries
The coronary arteries are the arterial blood vessels of coronary circulation, which transport oxygenated blood to the heart muscle. The heart requires a continuous supply of oxygen to function and survive, much like any other tissue or organ of ...
leading to
myocardial infarction
A myocardial infarction (MI), commonly known as a heart attack, occurs when blood flow decreases or stops to the coronary artery of the heart, causing damage to the heart muscle. The most common symptom is chest pain or discomfort which may ...
(heart attack), and atherosclerosis of the carotid artery leading to
stroke
A stroke is a medical condition in which poor blood flow to the brain causes cell death. There are two main types of stroke: ischemic, due to lack of blood flow, and hemorrhagic, due to bleeding. Both cause parts of the brain to stop functionin ...
are the number one and number three most common causes of death in the United States.
[American Heart Association’s Heart Disease and Stroke Statistics—2010 Updat]
/ref>
There is interest to look at panoramic radiographs as a screening tool, however further data is needed with regards if it is able to make a meaningful difference in outcomes.
Epidemiology: general public and high risk groups
Additional research projects have further determined the prevalence rate of these atheromas in the general population (3–5%) and among high-risk groups (over 25% in: recent stroke victims, individuals with obstructive sleep apnea
Obstructive sleep apnea (OSA) is the most common sleep-related breathing disorder and is characterized by recurrent episodes of complete or partial obstruction of the upper airway leading to reduced or absent breathing during sleep. These episod ...
syndrome, postmenopausal women, type 2 diabetics
Type 2 diabetes, formerly known as adult-onset diabetes, is a form of diabetes mellitus that is characterized by high blood sugar, insulin resistance, and relative lack of insulin. Common symptoms include increased thirst, frequent urination, ...
, individuals with dilated cardiomyopathy,[ and among individuals who have received ]radiotherapy
Radiation therapy or radiotherapy, often abbreviated RT, RTx, or XRT, is a therapy using ionizing radiation, generally provided as part of cancer treatment to control or kill malignant cells and normally delivered by a linear accelerator. Radia ...
directed at the neck,). These findings have been corroborated by other several other researchers.[
]
Dental infection and atherosclerosis
Atherosclerosis is attributed to risk factors that include cigarette smoking, hyperlipidemia, obesity
Obesity is a medical condition, sometimes considered a disease, in which excess body fat has accumulated to such an extent that it may negatively affect health. People are classified as obese when their body mass index (BMI)—a person's we ...
, diabetes mellitus
Diabetes, also known as diabetes mellitus, is a group of metabolic disorders characterized by a high blood sugar level ( hyperglycemia) over a prolonged period of time. Symptoms often include frequent urination, increased thirst and increased ap ...
, and hypertension
Hypertension (HTN or HT), also known as high blood pressure (HBP), is a long-term medical condition in which the blood pressure in the arteries is persistently elevated. High blood pressure usually does not cause symptoms. Long-term high bl ...
(high blood pressure). These factors, however, do not fully account for the risk of disease. Atherosclerosis has been conceptualized as a chronic inflammatory response to endothelial cell
The endothelium is a single layer of squamous endothelial cells that line the interior surface of blood vessels and lymphatic vessels. The endothelium forms an interface between circulating blood or lymph in the lumen and the rest of the vessel ...
injury and dysfunction possibly arising from chronic dental infection. In 2010, using the previously validated Mattila panoramic radiographic index to quantify the totality of dental infection (i.e., periapical and furcal lesions, pericoronitis sites, carious tooth roots, teeth with pulpal caries, and vertical bony defects), Friedlander’s group determined that individuals with carotid artery atheromas on their panoramic radiographs had significantly greater amounts of dental infection/inflammation than atherogenic risk-matched controls devoid of radiographic atheromas. While the Mattila index had been previously used to relate the extent of dental infection to coronary artery disease
Coronary artery disease (CAD), also called coronary heart disease (CHD), ischemic heart disease (IHD), myocardial ischemia, or simply heart disease, involves the reduction of blood flow to the heart muscle due to build-up of atherosclerotic pla ...
, this research is the first to link the full range of dental disease that it measures to panoramic radiographs evidencing calcified carotid artery atherosclerosis.
See also
*Oral and maxillofacial radiology
Oral and maxillofacial radiology, also known as dental and maxillofacial radiology, is the specialty of dentistry concerned with performance and interpretation of diagnostic imaging used for examining the craniofacial, dental and adjacent structur ...
References
{{medical imaging
Dentistry
Projectional radiography