Xray - Week 3 PP Flashcards
Who discovered x-radiation?
Wilhelm Conrad Roentgen, a Bavarian physicist, discovered the X -ray on November 8, 1895
For many years x-rays were referred to as roentgen rays, radiology was referred to as
roentgenology, and radiographs were known as roentgenographs
First radiograph of the human body?
Roentgen placed his wife’s hand on a
photographic plate and exposed her to the rays for 15 minutes to show
that he could capture the outline of her bones permanently.
Otto Walkhoff
produced the first recorded dental
radiograph by exposing a photographic plate in his mouth for 25 minutes in
Dr. C. Edmund Kells
a New Orleans dentist, is credited with the first practical use of radiographs in dentistry, in 1896 Kells, after years of exposing his hands to X-rays every day, eventually lost his fingers, hand, and later his arm as a result of cancerous tumors.
Year of the first intraoral imaging sensor?
1987
An article describing direct digital imaging technology published in U.S. dental literature - what year??
1989
Cone-beam computed tomography was
introduced to dentistry in what year? What does it do?
Cone-beam computed tomography was
introduced to dentistry in 1999; allows for the viewing of oral structures in three dimensions - allows for the diagnosis of disease and image guidance of surgical procedures
Oral and Maxillofacial Radiology (OMFR)
In 1999, the American Dental Association (ADA) recognized its ninth specialty program: Oral and Maxillofacial Radiology (OMFR)
◦ Provides advanced training in radiology of
the oral and maxillofacial region
◦ 2 to 3-year residency term after completion of dental school, followed by an
international board examination
Radiograph
- a picture (a visible photographic record) on film produced by the passage of X-rays through an object or body; also called X-ray film.
- In practice, often called an “x-ray”; this is not correct. X-ray (also x-ray) is a term that refers to a beam of energy
Dental radiograph
- A photographic image produced on film by the passage of X-rays through teeth and related structures
Radiography
- The art and science of making radiographs by the exposure of the film to X-rays
Dental radiography
- The production of radiographs of the teeth and adjacent structures by the exposure of the film to Xrays
Dental radiographer
- Any person who positions, exposes, and processes X-ray film
Image
- A picture or likeness of an object
Image receptor
- A recording medium; examples include x-ray film, phosphor plate, or digital sensor
Dental imaging
- The creation of digital, print, or film representations of anatomic structures for diagnosis
Light & Dark on an x-ray
When the X-rays pass through the mouth, the teeth and bones absorb more of the ray than the gums and soft tissues, so the teeth appear lighter on the final X-ray image (called a radiograph). Areas of tooth decay and infection look darker because they don’t absorb as much of the X-ray
Production of X-radiation
- When the current travels to the x-ray tube, it creates an electron energy within the cathode.
- High speed electrons are accelerated from the cathode to the anode. When they collide with positively charged matter, xradiation is produced.
- Electrons strike the target and their kinetic energy is converted to xrays and heat.
Properties of x-radiation
- They are produced when high-velocity electrons collide with the metal plates, thereby giving the energy as the XRays.
- The X-Ray beam travels through the air and comes in contact with the body tissues, and produces an image on a metal film.
- Soft tissue like organs and skin, cannot absorb the highenergy rays, and the beam passes through them.
- Dense materials inside our bodies, like bones, absorb the radiation.
Radiopaque or Radiolucent
Radiopaque - White areas show the denser tissues, such as bones that have absorbed the X-Rays
Radiolucent - black areas on an X-Ray represent areas where the X-Rays have passed through soft tissues.
X-Ray components
The dental radiographer must be familiar
with dental x-ray equipment and dental xray receptor holders and beam alignment
devices used in digital and film-based
imaging.
The dental radiographer must be familiar
with dental x-ray equipment and dental xray receptor holders and beam alignment
devices used in digital and film-based
imaging.
The Importance of understanding x-rays
An understanding of dental radiography equipment will permit the dental assistant to practice safely, produce diagnostically
acceptable radiographs, and troubleshoot as needed.
where the x-radiation is produced…
X-ray tube head
The Cathode
The cathode consists of a tungsten filament.
* The purpose of the cathode is to supply the electrons necessary to generate xrays.
* Electrons are generated in the x-ray tube at the cathode.
* The hotter the filament becomes; the more electrons that are produced.
The Anode
- The anode is the target for the electrons.
- It is composed of a tungsten target.
- The purpose of the tungsten target is to
serve as a focal spot and convert the
bombarding electrons into x-ray photons.
How X-rays work..
The production of dental x-rays occurs in the x-ray tube. A, When the filament
circuit is activated, the filament heats up, and thermionic emission occurs. B,
When the exposure button is activated, the electrons are accelerated from the
cathode to the anode. C, The electrons strike the tungsten target, and their
kinetic energy is converted to x-rays and heat.
Electrical Currents
Electricity is the energy used to make x-rays
Amperage – a measurement of the number of electrons moving through a conductor
Voltage – measurement of electrical force that causes electrons to move from a negative pole to a positive one.
Transformers
A device that is used to either increase or decrease the voltage in an electrical circuit
Factors Affecting Penetrating Power
- Wavelength:
Shorter wavelengths = greater energy = greater penetrating power. - Distance: from source to object.
Shorter distance = greater penetrating power. - Density: of object to be penetrated.
Less dense object = greater penetrating power
Control Panel
Used to adjust the:
* milliamperage (mA) - amount of electrical current coming out of the cathode
* Usually 10-15mA
* kilovoltage (kV) – amount of current passing from anode to cathode
* Longer exposure (@70kV) = high contrast (Fewer shades of gray - darker)
* Less exposure (@90kV) = low contrast (More shades of gray-lighter)
Types of Radiation
Primary: Useful rays are produced from the xray tube.
Stray: Rays that flow out from parts of the xray tube other than the window. (faulty
tube)
Scatter or Secondary: Reflected rays that have been reflected by objects in its path (patient or dental unit) Less penetrating than primary radiation.
Direct Digital Sensor/Imaging
Solid-state sensor that contains an x-ray sensitive silicon chip with an electronic circuit embedded in the silicon.
- Most commonly used
- Instantly transmits image to computer screen
Indirect Digital Imaging - Phosphor Storage Imaging (PSP)
- Thin, flexible plate that is covered in phosphor crystals
- Plates are the same size as conventional x-ray film
- Phosphor layer stores energy of x-ray photons
- After exposure plates are placed into a scanner
- Scanner laser reads the latent image and converts it to a digital image
- Films are exposed to a bright light to ”erase” the image
Pros/Cons of Digital Radiography
Digital imaging eliminates chemical processing and
hazardous wastes (lead foil, chemicals)
* Requires LESS Radiation to expose
* Allows for digital enhancements, measurements and corrections
* Images can be electronically transferred to other health care providers
* Sensors are VERY expensive
What is a Periapical (PA)
Periapical radiographs show the entire tooth from occlusal surface or incisal edge to about 2-3mm beyond the apex.
* Used to diagnose pathologic conditions of the tooth, root and bone
* Shows tooth formation and eruption
* Essential in endodontics and oral surgery
What is a Bitewing (BW)?
Image shows the upper and lower teeth in
occlusion, only the crowns and a small portion of the root are seen
Used for detecting:
* Interproximal decay
* Early periodontal disease
* Recurrent decay under restorations
* Fit of metallic fillings or crowns
PA Technique
Whether using conventional film, digital
sensors, or a PSP plate, there are two basic
techniques for obtaining periapical images.
- Paralleling Technique Extension cone paralleling technique. (XCP) ALARA
- Bisecting Angle Technique Uses a Snap-A- Ray, not as frequently used.
The Paralleling technique
- Receptor is parallel to long axis of tooth
- X-ray beam is perpendicular to the
long axis of the tooth - Face of cone is parallel with the face of the film.
- Common errors: incorrect placement
and alignment.
Paralleling Technique Steps
- Explain procedure to the patient.
- Position receptor close to midline for a maxillary PA and between the tongue and teeth for a mandibular exposure.
- Position receptor centered on the required anatomy/teeth.
- Position receptor parallel to the long axis of the teeth.
- Seat bite block on the incisal edge or occlusal surface for support.
- Ask patient to relax and slowly close down to support the XCP holder, and breath slowly through their nose.
