Radiology FINAL

List the four basic ingredients for the fixer solution.

fixing agent, perseverative, accelerator, restrainer

List the factors that influence sharpness

focal spot size, film composition, movement

describe latent image

halid crystal pattern of stored energy on the exposed film that cannot be seen

recognize dental x ray machines used for intraoral exposures

heliodent plus planmeca prox portable

Discuss the difference between high contrast and low contrast.

high: the dark light areas are strikingly different low: doesn't have very dark or very light images but instead, many shades of grey

Describe the use of intensifying screens and cassettes.

intensifying screens: devices that transfers xray energy into visible light, in turn, exposes the screen film cassettes: special device that is used to hold the extraoral film and the intensifying screens

list the 3 different types of xray film used in dentistry

intraoral, extraoral, duplicating

Describe the mechanisms and theories of radiation injury.

ionization and free radical formation theories: - direct theory of radiation injury suggests that cell damage results when ionizing radiation directly hits critical areas, or targets, within the cell. - indirect theory of radiation injury suggests that x-ray photons are absorbed within the cell and cause the formation of toxins, which in turn damage the cell

Describe the care and maintenance of the processing solutions, equipment, and equipment accessories used in manual film processing.

keep all equipment very clean

List the factors that influence density and contrast.

kilovoltage, milliamperage, exposure time

Briefly describe how a latent image becomes a visible image.

latent imaging remains invisible within the emulsion until it undergoes chemical processing procedures

Discuss the advantages of automatic film processing.

less processing time required, time and temp are auto controlled, less equipment is used, less space

describe the purpose of collimating devices

may be retrofired onto the end of a standard PID to restrict the size of the x-ray beam and limit radiation exposure

List the three geometric characteristics of the radiographic image.

sharpness, magnification, distortion influence

state the 5 rules of the paralleling technique

- receptor placement - receptor position - vertical angulation - horizontal angulation - receptor exposure

C. Edmund Kells

first practical use of radiographs in dentistry in 1896

Calculate an example of radiation intensity using the inverse square law.

original intensity / new intensity = new distance squared / original distance squared

Discuss proper film storage and protection.

- kept in cool, dry, place - must be stored in areas that are adequately shielded from sources of radiation and should not be stored in areas where patients are exposed to radiation - lead lined or radiation resistant film protectors are ideal to prevent smog

recognize dental x ray machines used for extraoral exposures

orthophos XG3 orthophos XG3D Ready

Describe how kilovoltage, milliamperage, exposure time and sourced-to-receptor distance influences the intensity of the x-ray beam.

- kilovoltage: higher kilovoltage settings produce an xray beam with more energy and shorter wavelengths - milliamperage: higher settings produce a beam with more energy - exposure time: longer exposure time produces more xray and beam intensity

List and describe the possible interactions of x-rays with matter.

- no interaction - absorption or photoelectric effect - Compton and coherent scatter

List the two types of ionizing radiation and give examples of each.

- particulate radiation: cathode rays in xray tube - electromagnetic radiation: gamma rays, microwaves

summarize the importance of dental images

detection

Define the units of measurement used in radiation exposure.

• Roentgen (R) • Radiation absorbed dose (rad) • Roentgen equivalent (in) man (rem) The SI units of radiation measurement include the following: • Coulombs/kilogram (C/kg) • Gray (Gy) • Sievert (Sv)

Describe the effects of radiation exposure on cells, tissues, and organs and identify the relative sensitivity of a given tissue to x-radiation.

- A cell that is sensitive to radiation is termed radiosensitive; one that is resistant is termed radioresistant. The response of a cell to radiation exposure is determined by the following: • Mitotic activity: Cells that divide frequently or undergo many divisions over time are more sensitive to radiation. • Cell differentiation: Cells that are immature or are not highly specialized are more sensitive to radiation. • Cell metabolism: Cells that have a higher metabolism are more sensitive to radiation. - Radiosensitive organs are composed of radiosensitive cells and include the lymphoid tissues, bone marrow, testes, and intestines. Examples of radioresistant tissues include the salivary glands, kidney, and liver.

Describe the sequence of radiation injury and list the determining factors for radiation injury.

- A latent period can be defined as the time that elapses between exposure to ionizing radiation and the appearance of observable clinical signs. - period of injury occurs. A variety of cellular injuries may result, including cell death, changes in cell function, breaking or clumping of chromosomes, formation of giant cells, cessation of mitotic activity, and abnormal mitotic activity. - The last event in the sequence of radiation injury is the recovery period.

Discuss risk and risk estimates for radiation exposure.

- A risk can be defined as the likelihood of adverse effects or death resulting from exposure to a hazard.

Name and describe two types of digital sensors (CCD and CMOS).

- CCD: charged couple device, the common receptor used in digital imaging. Relies on a specialized and costly fabrication process. - CMOS: complimentary metal oxide semiconductor, a solid state detector similar to the CCD that has built in control functions, similar pixel size, and lower power requirements

Discuss the short-term and long-term effects as well as the somatic and genetic effects of radiation exposure.

- Following the latent period, effects that are seen within minutes, days, or weeks are termed short-term effects. associated with large amounts of radiation absorbed in a short time - Effects that appear after years, decades, or generations are termed long-term effects. associated with small amounts of radiation absorbed repeatedly over a long period. - Somatic cells are all the cells in the body except the reproductive cells -The reproductive cells (e.g., ova, sperm) are termed genetic cells

Discuss the different types of filtration, and state the recommended total filtration for dental x-ray machines operating above and below 70kV.

- Inherent filtration takes place when the primary beam passes through the glass window of the x-ray tube, the insulating oil, and the tubehead seal. - Added filtration refers to the placement of aluminum disks in the path of the x-ray beam between the collimator and the tubehead seal in the dental x-ray machine - Dental x-ray machines operating at or below 70 kilovoltage (kV) require a minimum total of 1.5 mm aluminum filtration, and machines operating above 70 kV require a minimum total of 2.5 mm aluminum filtration

Describe the importance of receptor handling and processing after patient exposure to x-radiation.

- Proper receptor handling is necessary to produce diagnostic images and to limit patient exposure to x-radiation. - Proper film processing (developing) and proper retrieval of digital images are also necessary to produce diagnostic images and to limit patient exposure to x-radiation

Describe the conditions that must be present for disease transmission to occur.

- a susceptible host - a pathogen with sufficient infectivity and numbers to cause infection

Describe the care and maintenance of the automatic film processor and automatic processing solutions.

- automatic: daily or weekly cleaning - processing solutions: replace replenisher every 2-6 weeks

Describe how kilovoltage affects the density and contrast of the image.

- density: if kilovoltage is increased while other exposure factors stay constant, the resulting image exhibits an increased density and appears lighter - contrast: lower kilovoltage used, high contrast image will result

Discuss waste management of items used in the darkroom.

- developer: down regular drain - fixer: hazardous - film: recycle or send back. not in regular trash

Describe the three possible routes of disease transmission.

- direct contact with pathogens present in saliva, blood, respiratory secretions, or lesions - indirect contact with contaminated objects or instruments - direct contact with airborne contaminants present in spatter or aerosols of oral and respiratory fluids

Explain other types of digital radiography that are available?

- direct digital imaging: a method of obtaining a digital image using an intraoral sensor that is exposed to the xradiation to transfer information directly to a computer with imaging software

List and describe the two types of digital imaging.

- direct digital sensor: sends image instantly to the computer - indirect digital: uses phosphorous coated plate

describe film composition

- film base - adhesive layer - film emulsion - protective layer

define intraoral film and describe the packaging

- film that is placed inside the mouth during xrays - packing to protect film from light. made of 4 items - xray film - paperfilm wrapper - lead foil sheet - outer film wrapping

Describe the infection control procedures that are necessary for film processing.

- film transport: placed in a labeled disposable container after use, container touched with ungloved hands. take to the darkroom - darkroom supplies: paper towels and gloves in darkroom. Paper envelopes, cups labeled with patients name

Describe film contrast and subject contrast.

- film: characteristics of the film that influence radiographic contrast - subject: characteristics of the subject that influence radiographic contrast

what modification should be used for a shallow palate, bony growths such as tori, or a sensitive premolar region when using the paralleling technique?

- for a maxillary torus, the receptor must be placed on the far side of the torus, not on the torus, and then exposed. - for a mandibular tori, the receptor must be placed between the tori and the tongue, not on the tori, and then exposed.

Identify the parts of the processing tank: insert tanks, master tank, and lid.

- insert tanks: 2 removable 1 gallon insert tanks to hold the developer and mixer solutions - master tank: suspends both insert tanks and is filled with circulating water

Discuss the difference between radiation and radioactivity.

- radiation: the emission and propagation of energy through space or a substances in the form of waves or particles - radioactivity: the process by which certain unstable atoms or elements undergo spontaneous disintegration or decay, in effort to attain a more balanced nuclear state

Differentiate between radiolucent and radiopaque areas on a dental image.

- radiolucent: portion of the image that is dark or black - radiopaque: portion of the image that is white or light

Describe the difference between short-scale contrast and longscale contrast.

- short scale: image that shows only two densities, areas of black and areas of white - long scale: image that has many densities, or shades of grey

state the three principles of the paralleling technique

- the receptor is placed in the mouth parallel to the long axis of the tooth being radiographed - the central ray of the xray beam is directed perpendicular to the receptor and the long axis of the tooth - a beam alignment device must be used to keep the receptor parallel with the long axis of the tooth.

list the uses of dental images

- to detect lesions, diseases, and conditions of the teeth surrounding structures that cannot be identified clinically - to confirm or calssify suspected disease - to localize lesions or foreign objects - to provide information during dental procedures - to evaluate growth and development

Discuss miscellaneous requirements necessary in the darkroom.

- workspace must include adequate counter area. must be clean work area - storage place must have room for supplies - controlled humidity level

Describe the effect that the kilovoltage has on the quality of the x-ray beam and identify the range of kilovoltage required for dental imaging.

-quality: increasing kilovoltage results in higher energy xray beam with increased penatrating ability - range: 60-70 kV

Discuss room lighting and safelighting.

-room lighting: required for procedures not associated with the act of processing films - safelighting; special type of lighting used to provide illumination in the darkroom. Doesn't damage film

List and discuss the five steps of manual film processing.

1. development 2. rinsing 3. fixing 4. washing 5. drying

Describe radiation exposure in digital imaging.

50-80% less than others

identify the types of extraoral film available.

screen film: film that requires the use of a screen for exposure nonscreen: doesn't require a screen

Howard Riley Raper

Established the first college course in radiography for dental students

W. J. Morton

First dental radiograph in the United States (Skull)

Frank Van Woert

First to use film in intraoral radiography

Otto Walkhoff

Made the first dental radiograph

Describe the collimator used in dental x-ray machines and state the recommended diameter of the useful beam at the patient's skin.

Rectangular collimator restricts area of exposure to just larger than the detector size and thereby reduces unnecessary patient exposure.

Discuss the risk versus benefit of dental images.

When dental images are properly prescribed and exposed, the benefit of disease detection far outweighs the risk of damage from x-radiation

Describe how milliamperage influences the quantity of the x-ray beam and identify the range of milliamperage required for dental imaging.

a hiher milliamperage setting increases the temp of the cathode fillament and more xrays produced

Describe the infection control procedures that are necessary for digital imaging.

add barriers during use, then remove and disinfect

describe a portable x ray unit and how operator exposure is limited during use

allow for exposures outside the dental office limited by the use of a lead acrylic disc shield that surrounds the PID and minimizes back scatter from the patient

Define and discuss the dose-response curve and radiation injury.

can be used to correlate the "response," or damage, of tissues with the "dose," or amount, of radiation received.When dose and damage are plotted on a graph, a linear, nonthreshold relationship is seen. A linear relationship indicates that the response of the tissues is directly proportional to the dose.

Describe how milliamperage affects the density of the image and how exposure time and milliamperage are related.

decrease in milliamperage decreases overall density and produces a lighter image. milliamperage increased, exposure time decreased

List the two visual characteristics of the radiographic image.

density and contrast

William H Rollins

developed first dental x-ray unit

List the four basic ingredients of the developer solution.

developing agent, preservative, accelerator, restrainer

describe the purpose and use of dental xray receptor holders

device used to hold and align intraoral dental xray receptors in the mouth

Discuss operator protection in terms of adequate distance, shielding, and avoidance of the useful beam.

distance: The dental radiographer must never hold a receptor in place for a patient, must never hold or stabilize the x-ray tubehead. shielding: Protective barriers that absorb the primary beam can be incorporated into the office design, thus protecting the operator from primary and scatter radiation. Whenever possible, the dental radiographer should stand behind a protective barrier

Discuss the regulation of dental xray machines at the federal, state, and local levels

federal: regulates the manufacture and installation of dental xray equipment state and local: regulate how dental xray equipment is used and dictates code of use

Identify the structure of the atom

nucleus: composed of particels known as protons and nuetrons

List the factors that influence distortion.

object receptor alignment and xray beam angulation

Describe duplicating film.

one that is identical to the original xray film

describe extraoral film and its packaging

placed outside the mouth during xray exposure packing is not enclosed in moisture proof packaging

List and discuss the four procedural steps for automatic film processing.

prepare darkroom, prepare films, insert films, process and retrieve films

Describe the rationale for infection control.

prevent the transmission of diseases

Describe in detail the basics of patient protection before x-ray exposure.

proper prescribing of dental images and proper use of radiographic equipment can minimize the amount of radiation that a patient receives.

Discuss the primary function of the darkroom, as well as the location and size requirements necessary for the darkroom.

provides a completely dark environment for film to be handled and processed - location and use: determined by: volume of film, number of people in room, type of processing equipment used, space required for duplication film and storage

Describe the purpose

purpose: to generate images that can be used in the diagnosis and assessment of dental disease

List common sources of radiation exposure.

radon in the air; uranium, radium, and thorium in the earth; cosmic rays from outer space and the sun; radioactive potassium in food and water; and radioactive material found within the human body

discuss film speed

refers to the amount of radiation required to produce a radiograph of standard density. ranges from A (slowest) to F (fastest)

List the factors that influence magnification

target receptor difference, object receptor difference

Describe the process of ionization

the production of ions, or the processes of converting an atom into ions

Identify the equipment accessories needed for manual film processing.

thermometer, timer, film hangers

List six ways to protect the patient from excessive radiation during x-ray exposure.

thyroid collar, lead apron, image recpetors, beam alignment devices, exposure factor selection, proper technique

Discuss dental radiation and exposure risks.

thyroid, bone marrow, skin and eyes

describe why the radiographer should be familiar with dental xray film

to avoid film related errors

Identify the component parts of the dental xray machine

tube head, extension arm, control panel

identify the types and sizes of intraoral film available

types: periapical, bite wing, occlusal sizes: 0-4

Describe a stepwedge and explain its function.

used to demonstrate short scale contrast and long scale contrast

describe the purpose of beam alignment devices

used to help the dental radiographer position the PID in relation to the tooth and receptor

List the characteristics of electromagnetic radiation.

wave like energy through space or matter, can be ionizing or nonionizing

Explain how the half-value layer determines the penetrating quality of the x-ray beam.

when placed in the path of an xray beam, the thickness of a specified material reduces the intensity by half

Summarize the discovery of x-radiation

wilhelm conrad roetgen discovered on November 8, 1895

List and describe the equipment used in digital imaging.

xray machine, intraoral sensor or phosphate plate, computer, mouse, and keyboard