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oral radiology > Lecture 1 > Flashcards

Lecture 1 Flashcards

1
Q

dark areas on radiographs
white areas on radiographs

A

dark: (radiolucent) large caries or lesions will allow the x-rays to pass through very easily and appear dark/black

white: (radiopaque) structures that are very dense, like restorative metal, will not allow X-rays to pass through easily to strike silver halide crystals

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2
Q

who are the radiology historians, what are they known for (6)

A

Roentgen - 1895 - discovered x-rays while experimenting with a vacuum and cathode rays. Noticed a glow when the cathode rays struck cardboard. Termed the unknown rays “x-rays”.

Dr. Otto Walkoff - 1896-first prototype of a dental radiograph.

Dr C. Edmund Kells - 1896- may have taken first dental radiograph in the US, and promoted the use of radiography in dentistry. Early advocate for radiation safety and realized the importance of radiation safety.

Dr. William Herbert Rollins - 1901- radiation safety pioneer and wrote many articles about radiation safety protocols.

Williams Davis Coolidge - 1913- introduced the hot cathode tube; accurately controlled the amount of radiation exposure.

Howard Riley Raper - 1925- wrote first dental x-ray textbook, and credited for inventing bitewing radiograph technique. Also a safety pioneer.

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3
Q

radiation protection 5

A
  • Follow the ALARA principle – “As Low As Reasonably Achievable”
  • Use professional judgment
  • X-rays are prescribed and not dictated by insurance
  • Prescription is based on selection criteria
  • Using evidence-based selection criteria is the most important way to ensure patients receive the lowest dose of radiation!
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4
Q

why do we follow ALARA 3

A
  • ionizing radiation can affect biological tissues
  • no known safe dose of radiation exposure
  • any dose of radiation may harm the clinician/patient
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5
Q

radiation protection depends on: 2

A
  1. Technical ability of the operator
    - Communication with the patient during procedures
    - Education and knowledge of operation and safety
  2. Equipment Standards
    - X-ray beam collimation
    - X-ray beam filtration
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6
Q

Dental x-ray machines must be inspected for safety by law:

what do collimation and filtration do

A

Collimation within the tube head, (where x-rays are produced), controls the size and shape of the primary x-ray beam. Collimation is in place to reduce scatter radiation.

Filtration (which can be inherent or added) helps to absorb long X-ray wavelengths that are less penetrating and do not contribute to the diagnostic quality of an image. The filter is placed in the path of the primary beam and is made of aluminum

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7
Q

what are the equipment standards for radiation protection 5

A
  1. filter and collimation
  2. image receptor holders
  3. digital sensors/fast speed film
  4. long, rectangular PIDs
  5. lead aprons/thyroid collars (required during all exposures)
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8
Q

how do image receptors help reduce radiation

A
  • patient doesn’t have to hold a sensor or film in their mouth
  • ultimately assists the radiographer with aligning the beam to a precise area to expose
  • cuts down on retake of x-rays
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9
Q

what film should we be using?

which is the best, by how much

A
  • D, E, or F speed film
  • F-speed film reduces radiation exposure to a patient by 25% compared to E-speed film and 60% compared to D-speed film
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10
Q

how does the PID shape and size reduce radiation exposure?

A
  • long, rectangular PID
  • 16 inch PID is recommended due to the inverse square law; as the distance from the X-ray source increases, the intensity of the beam decreases
  • rectangular PID reduces the exposure size to the approximate size of the image receptor, so there are fewer tissues receiving scatter radiation.
  • however, very precise alignment is required to avoid retakes
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11
Q

how do lead aprons/thyroid collars lower radiation exposure

A

.- placed on the patient’s abdomen to protect scatter radiation from reaching reproductive/radiosensitive organs
- Lead aprons must be .25mm thick or be a lead equivalent.
- In many states, it is a law that patients wear lead vests (with good judgment it should also include a thyroid collar)

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12
Q

what are the basic part of an x-ray machine

A
  • digital sensor goes in the holder
  • folding extension arm
  • yoke that rotates 360 horizontally
  • dial for reading vertical angulation
  • open ended PID
  • control panel
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13
Q

Describe the x-ray filter (cont.)

A
  • placed in the path of the primary beam
  • removes long, soft x-rays that may increase radiation dose to a patient
  • any x-ray unit machine operating above 70 kVp must have an aluminum filer that is 2.5mm thick
  • Operating below 70 kVp must be 1.5mm thick.
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14
Q

describe the collimator (cont.)

A
  • tiny lead diaphragm placed within the path of the primary x-ray beam
  • inside the tube housing where x-rays are produced
  • allows a precise, narrow beam to reach the patient’s tissue
  • can be round or rectangular
  • federal law requires the collimator to restrict the primary beam to 2.75 inches at the skin entrance of the patient.
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15
Q

with the use of a collimator, the x-ray beam becomes more ______

when the source of the x-ray beam is closer to the patient, the beam becomes more _______

A

narrow

wide

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16
Q

how does ALARA help protect the operators from scatter radiation

A

time: reduce amount of time spent near radiation; make sure we are never in the operatory while x-rays are being taken; make sure we are never stabilizing the sensor, film, or Rinn holding device while x-rays are being taken

shielding: have a barrier between yourself and the x-ray beam

distance: if no shield is available, stay the proper distance away from the x-ray beam; inverse square law, as the distance from the source increases, intensity decreases

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17
Q

who is the only person allowed in the operatory while xrays are being taken

A

patients parent, legal guardian, or caregiver

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18
Q

types of Shielding and control panel info

A
  • Plaster
  • Cinderblock
  • Thick drywall (3 in)
  • Steel (3/16 in)
  • Lead (1mm)
  • control panel should be mounted on a barrier
  • at ODU, control panels are mounted on thick dry wall and are 6 feet away from the source of radiation
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19
Q

Describe an operators distance

A
  • if no barrier is present between you and the source of radiation you must stand 6 feet away and at a 45-degree angle from the source of radiation as it exits the patient
  • maximum scatter most likely occurs back in the direction of the tube head
  • we know this is the safest positioning because of the inverse square law
  • If a patient is supine (lying down) while you are taking an x-ray, you must stand at an angle of 135 to 180 degrees behind the patient’s head
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20
Q

Radiation dosimetry (general)

A
  • another protection method for radiographers
  • only used for radiographers, not patient safety
  • used to measure radiation on a radiographer
  • dosimeters are not required to be worn, just recommended
  • In Virginia, you are only required to wear a dosimeter when you are working with a handheld/portable x-ray device
  • sent to the company, then given back a report of your exposure levels compared to the maximum allowable levels
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21
Q

Film badge 4

A
  • sensitive enough to indicate low dose of exposure
  • clip-on attachment of ring or bracelet worn on the operator
  • “read” electronically for one month and then sent off for evaluation
  • light weight and durable, cost efficient, and easily used.
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22
Q

TLDs > thermoluminescent dosimeter

A
  • made of lithium fluoride crystals and are very accurate, reliable, and can be used for many years
  • measure absorbed energy from radiation.
  • In the ODU dental hygiene clinic, we have TLD dosimeters clipped above every control panel in each operatory located on the exposure panel and on a barrier
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23
Q

OSLs

A
  • (optically stimulated luminescence)
  • like TLDs but release energy during optical stimulation

-can only be used once compared to TLDs

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24
Q

DIS

A
  • Direct ion storage (DIS) dosimeters measure absorbed radiation and give real-time instant readouts of absorbed dose
  • requires an on-sight reading device or internet connection
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25
Q

what is the average dose of background radiation to the US population

what is the maximum permissible dose for occupationally exposed workers

A

3 mSv (300 mrem)/ year > approx. 1mrem/day

50 mSv (5rem) / year

26
Q

what are the radiation protection guidelines we must follow as an exposed worker

A
  • maximum permissible dose
  • the dose equivalent of ionizing radiation that is not expected to cause detectable body damage to the average person at any point in their lifetime
  • our maximum permissible dose of radiation should not exceed 50 mSv of 5 rem per year.
27
Q

which agencies are responsible for radiation protection

A
  • International Commission on Radiological Protection (ICRP)
  • National Council on Radiation Protection & Measurements (NCRP)
  • Virginia Dept. of Health
  • Virginia Board of Dentistry
28
Q

facts about the agencies

A
  • ICRP and NCRP do not make laws governing the use of ionizing radiation
  • regulatory agencies use their recommendations to formulate laws and legislation controlling the use of radiation.

At the state level, the Virginia Department of Health and the Virginia Board of Dentistry make laws and policies regarding the use of ionizing radiation

  • they determine safety and inspection of equipment, who can expose or use radiation, etc.
29
Q

dental radiation safety certification

A

In the state of Virginia, one way you may be certified to take dental X-rays is by taking an accredited course and completing/passing the course with a 77%

  • we will satisfy this requirement and will be certified to take dental X-rays upon the completion of both DNTH 304 and 309
  • certificate will be received at the end of the spring semester upon passing 309
30
Q

other ways to get the dental radiation safety certification

A
  • Satisfactory completion of a course and examination of an accredited school
  • Completed a Radiation course and passed an exam given by the Dental Assisting National Board (DANB)
  • Certification by American Society of Radiological Technicians
31
Q

why do we expose dental radiographic images? bullet points

A

Disease

Growth and development > pediatric/adolescence

Missing teeth

Orthodontia

Wisdom teeth

Pathology

Trauma/ impacted teeth

Documentation

Education

32
Q

what is the ultimate goal when exposing radiopgraphs

A

to get the highest quality diagnostic image while maintaining the lowest radiation exposure risk to our patients

33
Q

types of dental radiographic projections

A

bitewing

periapical (PA)

occlusal

extra oral
*panoramic
*cephalometric

34
Q

describe bitewings

A
  • typically prescribed to examine for interproximal caries
  • takes an image of the crowns of the teeth in both arches at one time.
  • Typically, we take 4, two on each side of the mouth to examine the interproximal molar and premolar region
35
Q

describe periapical images

A
  • takes an image of the tooth or teeth from the crown all the way to the apex
  • taken on only one arch at a time
  • Peri-apical means “around the apex” or around the root
  • taken if there is an unexplained problem or if there is pathology suspected at the root of the tooth, like an abscess.
36
Q

describe panoramics

A
  • take a large image of both arches and the surrounding jaw, sinuses, and facial structures
  • commonly taken to examine growth and development
  • used in orthodontic evaluations
37
Q

what will we use in lab to create radiographs

A

digital sensors in lab

only use digital image receptors when exposing radiographs on clinic patients

CMOS

38
Q

Direct sensors:

A
  1. Pixels (digital equivalent of silver halide crystals) arranged in a matrix on a silicon surface act as “wells” into which radiation is deposited creating latent image
  2. Sensor technology is based on either CCD or CMOS-APS; both work equally well at converting x-rays into electronic signals sent to computer that processes data and presents image on monitor
  3. Connects to a computer via USB cord or wirelessly
  4. Sensors are slightly thicker
  5. Available in dimensions similar to intraoral film sizes for recording various types of intraoral projections
  6. Requires plastic barrier protection for infection control prior to placing intraorally
39
Q

digital sensors are made up of ____. explain

A
  • Digital sensors are made up of pixels where electrons produced by x-rays are deposited
  • A pixel is the digital equivalent of a silver halide crystal.
40
Q

indirect digital image receptors (psp)

A
  1. Phosphor-coated plate that absorbs and stores x-ray energy until later released as light when stimulated with laser scanner device connected to a computer that processes data and presents image on the monitor.
  2. Not connected directly to the computer so multiple plates are usually required to obtain a series of radiographs
  3. Must be protected from bright light after exposure to radiation and prior to the scanning process to avoid erasure
  4. Must be erased by exposure to bright light prior to reuse
  5. Dimensions and slight flexibility approximate a film packet
  6. Requires plastic barrier protection for infection control prior to placing intraorally
41
Q

what is the correct terminology when using film vs digital sensors

A
  • Using film to “take a radiograph”
  • “acquiring an image” when using a digital sensor
42
Q

film and digital image holders

A
  • Used to hold film and image receptors and guide X-rays to patient tissues
  • Rinn kits, bite tabs, sticky tabs
43
Q

Explain the features of digital image receptor holders/positioners. 12

A
  • Quality features
    1. Simple construction with minimal parts to assemble
  1. May be labeled or have color-coded parts to aid in correct assembly
  2. Available with instruction manual for learning assembly and use
  3. Ability to hold image receptor securely in place while maneuvering around oral cavity.
  4. Versatility to image all areas of oral cavity
  5. Lightweight construction to facilitate ability to tolerate placement intraorally.
  6. Biting surface made of soft plastic or polystyrene material will provide secure surface upon which patient can bite and stabilize image receptor during procedure
  7. Reusable following sterilization or may be disposable
  8. External aiming device with positioning ring or rectangle to aid in alignment
  9. Assist with determining correct angulation when instrument is assembled correctly
    * aids in alining PID over image receptor
    * eliminates need for precise patient head positioning
    * standardization of subsequent radiographs may be achieved
  10. May be modified for use with either paralleling or bisecting technique
  11. May be adapted to accommodate special conditions
44
Q

limitations to digital image receptors/positioners

A
  • Possible limitations
    1. Multiple parts require time and skill for correct assembly
  1. Multiple parts may possibly increase the occurrence of incorrect assembly leading to radiographic image errors
  2. Metal and/or thick plastic construction may be difficult for radiographers to place and for patient to tolerate
  3. Strict adherence to infection control protocols is required for sterilization of reusable positioners
  4. Disposable positioners add to waste stream and have recurring costs to replace supplies
45
Q

describe Rinn kits

A
  • utilize bite blocks that attach to an extension arm with an external aiming ring
  • different bite blocks for different types of X-ray projections
  • help with the ALARA principle by providing a more precise guide for where radiation should be directed
46
Q

describe bite tabs

A
  • typically used with film and are used with a free hand method as they only provide a place for the patient to bite and then the PID is centered around that bite tab
47
Q

describe sticky tabs

A
  • used in the same manner as bite tabs
  • can be used with a rinn kit
  • typically used for digital sensors
48
Q

describe stable holders

A

used with film and are used to take periapical images using a free hand method

49
Q

care of image receptors

A
  • Digital sensors are incredibly expensive, but they save money in the long run as you do not have to buy additional supplies
  • Sensors should be neatly hung with no twisting of the cord.
  • Always pull the sensor USB out at the part closest to the plug
  • Sensors and sensor parts do age
  • phosphor plates have a shelf life and need to be replaced after a certain amount of exposures
  • all varies by manufacturer
50
Q

What are the items on a control panel/exposure button 4

A
  • Power line (ON/OFF)
  • Milliamperage (mA) selector
  • controls amount of radiation generated
  • directly proportional to image density
  • Kilovolt (kV) selector
  • controls the penetrating power of theXx-ray beam
  • directly proportional to image density
  • inversely proportional to image contrast
  • Exposure time (impulses or seconds)
  • controls length of time exposure at a set mA and kV
    conditions
  • directly proportional to image density.
  • Exposure button
  • exposure switch must be engaged for duration of timer setting or exposure will terminate
  • audible sound (beep) and indicator light will activate for duration of exposure indicating that radiation is being emitted
51
Q

What are the functions of the extension arm and tube head support?

A
  1. allow the tube head to be moved into various positions
  2. yoke attached to extension arm allows tube head to be moved 360 degrees in vertical (up and down) and horizontal (side to side)
52
Q

What are the functions of the tube head?

A
  1. houses vacuum tube where x-rays are generated
  2. provides protection and insulation to vacuum tube
  3. is lead-lined to prevent stray radiation from escaping
53
Q

What are the functions of the position indicating device (PID)?

A
  1. extends from tube head
  2. used to direct x-rays toward structures to be imaged
  3. round cylinder or rectangular shaped
    * collimates (restricts) x-ray toward structures to be imaged
    * rectangular shaped PID reduces amount of radiation reaching patient by approximately 70% over round cylinder PID
  4. available in various lengths: 8 inch, 12 inch, and 16 inch
    * long PID may be recessed into tube head, giving appearance of being shorter
    * long PID projects less divergent x-ray beam, resulting in less patient radiation exposure.
54
Q

What are characteristics of radiographic film?

A
  1. Film packet contents
    * film- one or two films per packet
    * outer moisture-proof plastic or paper wrap
    * light-tight black paper
    * lead foil to absorb scatter radiation
  2. Film emulsion contents
    * silver halide crystals- light and x-ray sensitive component
    * gelatin- suspends and evenly disperses silver halide crystals
  3. Film speed
    * D speed- slowest dental x-ray film currently available; requires greater amount of radiation exposure
    * E speed- requires one-half amount of radiation exposure as D speed film, but replaced by F speed
    * F speed- fastest; requiring the least amount of radiation exposure
  4. Film is available in a variety of sizes to accommodate various needs
55
Q

What intraoral dental x-ray machine component is used to aim and direct the x-ray beam toward an image receptor?

A

PID

56
Q

Where is the ON/OFF switch of an intraoral dental x-ray machine located?

A

control panel

57
Q

What are exposure variable settings for a dental x-ray machine?

A
  • Milliamperage
  • Kilovoltage
  • Impulse/exposure time
58
Q

What are functions of the dental x-ray machine tube head?

A
  • Houses the vacuum tube where x-rays are generated
  • Provides protection and insulation to the vacuum tube
  • Is lead lined to prevent stray radiation from escaping
59
Q

What are the components of an intraoral film packet?

A
  • Lead foil
  • Moisture-proof wrap
  • Light-tight black paper
60
Q

When assembled correctly, an image receptor will aid in what __?

A
  • Alining the PID over the image receptor
  • Determining correct angles when a patient is in a supine position
  • Standardizing subsequent radiographs
61
Q

What uses indirect digital imaging technology

A

PSP plate

oral radiology (7 decks)

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