Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Pediatric Dentistry Prepatory Boards > Radiography > Flashcards

Radiography Flashcards

1
Q

T/F

The YOUNGER the individual and the FASTER tissue grows, the HIGHER the potential RISK to develop a fatal CANCER from being exposed to ionizing radiation.

A

TRUE

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Radiation Dosimetry.

How are units measured?

A

MILLISEVERT (mSv)

A Millisevert is defined as the AVERAGE accumulated BACKGROUND radiation dose to an individual, exclusive of Radon.

1 mSv is the dose produced by exposure to 1 milligray of radiation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Radiographic contrast

A

RADIOGRAPHIC CONTRAST

Differences in densities between various regions on a radiograph.

A film that shows VERY LIGHT and very DARK areas has HIGH CONTRAST or a SHORT GRAY SCALE as there are few shades of gray from one extreme to the other.

A radiograph that has MANY SHADES of gray is referred to as one with LOW CONTRAST or LONG GRAY SCALE. [wide latitude]

  • The RATIO of transmitted radiation through different regions of THICKNESS or DENSITY.
  • As the density of the object increases so the kVp must be increased to compensate for penetrating power

⬆️ T and D requires ⬆️ kVp

-As the thickness and density of the anatomic structure increases, so does the RADIOPACITY.

⬆️T and D = ⬆️RO

EACH BODY PART contains a certain type of cellular composition which requires an x-ray beam with a certain kVp to penetrate it. That body part is said to have “SUBJECT CONTRAST”

Controlled by kVp “KONTRAST”

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

kVp

represents what 3 things?

A
  1. Penetrating Power
  2. Wave Length
  3. Gray Scale

kVp is the component that controls the QUALITY of the x-ray beam produced.
It is also what controls the CONTRAST or GRAY SCALE in the produced x-ray film.
The HIGHER the kVP, the LOWER the CONTRAST.

⬆️ kVp = ⬇️ contrast

⬆️ kVp = ⬆️ radiation scattering

⬆️ kVp = ⬆️ photon radiation

When the kV is set on the control console, the MAXIMUM kilovolt that will be achieved is the number you have selected. For example, if you set the kVp at “60”, the maximum kilovolt that will be produced is 60 kV, or 60,000 volts.

“KONTRAST”

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Radiographic Density

A

RADIOGRAPHIC DENSITY

  • the OVERALL amount / degree of DARKENING on a radiograph.

In routine radiography, the useful RANGE of density varies from 0.3 to 2.0 density.
The density below 0.3 is due to the density produced by the base and by some fog on the film (base plus fog).

-DENSITY is primarily determined by mA “mAD”

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Radiographic Latitude

A

RADIOGRAPHIC LATITUDE

the measure of the RANGE of EXPOSURES that may be recorded as a series of usefully DISTINGUISHABLE DENSITIES on a film.

The WIDER the latitude of a film, the GREATER the RANGE of object densities visualized. Films with wide latitude show relatively LOW CONTRAST [LONG GRAY SCALE], because many densities between totally black and totally clear are recorded.

⬆️ width lat = ⬆️ range densities

Such films are useful when both osseous and soft tissue must be viewed.

Influencing factors: kVp.

  • HIGH kVp will result in images with WIDE
    latitude.

⬆️ kVp = ⬆️ width lat

Different films have different latitudes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is the Compton Scattering and Effect?

A

COMPTON SCATTERING

is the SCATTERING of a PHOTON by a CHARGED particle, usually an ELECTRON.

***Photon leaves the X-ray unit and enters the patients body hitting an electron resulting in two things.

  1. It kicks the electron out of orbit (IONIZATION)
  2. The photon decreases its energy and changes direction, being SCATTERED off its original path.

Results: an IONIZED electron and a SCATTERED photon.

  • Ejected electron is ultimately absorbed by the PATIENTS body affecting RADIATION DOSE
  • Scattered photon may also be absorbed by the PATIENTS body or come out of the patient and go into the RADIOGRAPHERS body. (OCCUPATIONAL DOSE)

Scattering Photons DECREASE image ⬇️ QUALITY by DECREASING image ⬇️ contrast.

It results in a DECREASE in ⬇️ ENERGY (increase in wavelength) of the photon called the Compton EFFECT.

  • FORWARD scattering, towards receptor loses the LEAST amount of energy. (Has highest energy)
  • BACK scattering, towards the X-ray tube, lose the MOST energy. (Has lowest energy)

⬆️ THICKNESS affects scattering: “More Matter, More Scatter”.

⬆️ RECEPTOR SIZE also increases scattering photon reaching receptor.

⬆️ kVP causes more of the photons to be scattered towards the receptor.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

How does a Radiographer keep Radiation Scattering / Ionization to a minimum?

A
  1. Reduce kVp
  2. Use small field/receptors if possible
  3. Use Fast Film (F-Film)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

How dangerous are dental x-rays?

A

Dental x-rays are one of the lowest radiation dose studies performed.

A routine exam which includes 4 BITEWINGS is about 0.005 mSv

LESS THAN ONE DAY of natural background radiation.

It is also about the same amount of radiation exposure from a SHORT AIRPLANE FLIGHT (~1-2 hrs).

The American Dental Association recommends that patients who are not having problems have dental x-rays performed every TWO years.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What two areas are commonly exposed to radiation even if wearing a proper lead shield?

A
  1. EYES 👁

Your EYES are 4X more SENSITIVE to radiation than other parts of your body. Not too long ago, few doctors used leaded eyewear to protect against x-ray radiation. With the increase in occurrences of early onset CATARACTS lead glasses are now a staple in every procedure requiring the use of x-ray and fluoroscopy.

The ICRP has set an occupational equivalent dose limit of 20 mSv per year to the lens.

  1. HANDS🖐

While the hands are not particularly radiosensitive, they are often in the direct path of x-rays during procedures. Radiation reducing sterile gloves can reduce exposure

The ICRP has set an occupational equivalent dose limit of 500 mSv per year to the hands.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Patients under the age of 10 have how many more times the risk of developing a fatal cancer of developing a fatal cancer from radiation exposure?

A

< 10 years 3X

10-20 years 2X

Pediatric patients are at the greatest risk of developing cancer from radiation exposure.

Rapidly dividing or growing cells are at greater risk of damage from ionizing radiation.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

How does Radiation increase your chance for cancer?

A

When x-rays, or any IONIZATION radiation, pass through the body they cause ELECTRONS to be EJECTED from atoms, leaving behind positive ions. These POSITIVE IONS, or FREE RADICALS, can cause damage to DNA.

DNA can also be damaged directly by radiation.
If DNA is damaged, there are three possible outcomes:

  1. The cell dies (only occurs with very high doses).
  2. The cell repairs itself perfectly (most common result).
  3. The cell repairs itself with mistakes (rare).

The inaccurate repair of DNA is rare, but can cause a cell to act wildly or grow into a cancer. Oftentimes it takes decades for cancer to be detected following radiation exposure.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

If radiation can cause cancer, why is radiation used to treat cancer?

A

Radiation treatment DOSES are MUCH HIGHER than doses used for medical imaging.

High dose radiation causes CELL DEATH, specifically the cells which are growing the fastest including:

cancer cells
hair cells
gastrointestinal tract lining

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Do dental x-rays have an affect on a person who currently HAS cancer?

A

No.

Low dose radiation from medical imaging does not affect known cancer.

Low dose exposure increases the risk of developing new cancer decades after exposure.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Is there gender differences in risk to radiation?

A

In general, women are at slightly higher risk of developing cancer when compared to men exposed to the same dose of radiation.

Men and women also have different average risks for developing cancer.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Airplanes and Airport scanners.

Radiation risks?

A

Airlines:

A seven hour airplane trip exposes passengers to 0.02 mSv of radiation, which is a fraction of the exposure of a standard Chest x-ray (0.1 mSv). Domestic airline pilots are exposed to an additional 2.2 mSv per year, about the same dose as a brain CT.

Airport Scanners:

There are two types of whole body security scanners at airports which are very different than the baggage scanners.
—Millimeter Wave Scanners use RADIO WAVES which are not ionizing (i.e. do not induce cancer). —Backscatter Wave Scanners use very weak x-rays at a dose of less than 10 microrem per scan (0.0001 mSv)14.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Cell-Phone Radiation risk?

A

Research studies fail to prove a consistent link between cell phone use and brain cancer. Cell phones emit radiofrequency energy which is a form of non-ionizing radiation, unlike ionizing radiation used in x-rays and CT scans.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is the Government regulated amount of radiation exposure for health-care workers per year?

A

Radiation workers are limited to a total body dose of 50 mSv/yr (≈7 chest CTs) with averages ranging between 2-5 mSv/yr.

Pregnant workers are limited to 5 mSv during pregnancy (≈7 abdominal x-rays).

Workers are monitored closely with radiation badges that are collected monthly.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What phase of cell division is most radiosensitive?

What phase is least radiosensitive?

A

MOST SENSITIVE

M Phase (Mitosis) “m-m”

LEAST SENSITIVE

Cells are least sensitive when in the S phase, then the G1 phase, then the G2 phase.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

T/F

Tumor cells are always highly radiosensitive

A

FALSE

Tumor cells can be HYPOXIC and therefore LESS SENSITIVE to X-rays because most of their effects are mediated by the free radicals produced by ionizing oxygen.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What body cells are most Radiosensitive?

What are least Radiosensitive?

A

MOST SENSITIVE

most sensitive cells are those that are UNDIFFERENTIATED , well nourished, dividing quickly and highly ACTIVE METABOLICALLY.

  • Erythroblasts (RBC, lymphocytes) #1 sens
  • Spermatogonia, oocytes
  • Epidermal stem cells
  • Gastrointestinal stem cells

LEAST SENSITIVE

  • Nerve cells
  • Muscle Fibers
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is the most likely Secondary Cancer after treating a Primary Cancer with radiation?

A

Sarcomas

Usually 5-10 years later

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

mAs

A

mAs

a measure of radiation produced (MILLIAMPERAGE) over a set amount of time (SECONDS) via an x-ray tube. It directly influences the RADIOGRAPHIC DENSITY, when all other factors are CONSTANT.

Affects film density by governing the AMOUNT of X-ray photons which REACH the FILM emulsion.

Milliamp (1/1000 of an amp) times(x) TIME (in seconds) is what controls the QUANTITY or the AMOUNT of x-ray photons produced.

This is also what controls the BLACKENING or DENSITY on the x-ray film.
​
To CALCULATE the mAs, you multiply mA x s
mA = Milliamp s = seconds (usually in fractions of a sec.)

For example: mA = 200, s = 0.25
-​(200 x 0.25)​mAs = 50 mAs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What is the 15 rule in radiography?

A

15 RULE

changing the kVp by 15% has the same effect as doubling the mAs or reducing the mAs by 50%

INVERSE RELATIONSHIP

raise kVp 15% ⬆️⬇️ decrease mA 50%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

Increase of kVp vs Increase of mA

A

INCREASE kVp

Photons move faster, are stronger, get through pt easier

INCREASE mA

Greater amount of photons

27
Q

Optimum kVp?

A

is the minimum amount of kVp required to penetrate the patient

28
Q

T/F

No amount of mAs can compensate for a lack of adequate kVp.

A

True

29
Q

15% increase in kVp and 50% decrease in mAs can be done to?

A

REDUCE patient DOSE; for example if pregnant

Reduces dose by 2/3

30
Q

Tissue Opacity?

A

determined by the atomic number of the cells that make up the anatomy of interest.

31
Q

Radiograph filtration

A

Removes low energy x-ray, saves the patient dose.

32
Q

Absorbed Dose

A

ABSORBED DOSE

  • ENERGY absorbed from ionizing radiation per unit mass
  • SI unit is J/kg or Gray (Gy)
  • Conventional unit is RAD

1 Gray = 100 RAD
or
1 RAD = 10 mGy

33
Q

Equivalent Dose

A

EQUIVALENT DOSE

Converts Absorbed Dose to equivalent tissue damage for different types and energies of radiation.

In the SI system of units, the unit of measure is the sievert (Sv).

Common symbol: H

Equivalent dose HT is calculated using the mean absorbed dose deposited in body tissue or organ T, multiplied by the radiation weighting factor WR which is dependent on the type and energy of the radiation R.

HT is the equivalent dose in sieverts (Sv) absorbed by tissue T
DT,R is the absorbed dose in grays (Gy) in tissue T by radiation type R
WR is the radiation weighting factor defined by regulation

34
Q

Photon

A

PHOTON

Photons are called X-RAYS if they are produced by ELECTRON INTERACTIONS

An x-ray photon has a wavelength of 0.01 to 10 nanometers, with a frequency of 3×1016 Hz to 3×1019 Hz.

It possesses enough energy (100 eV to 100 keV) to disrupt molecular bonds and ionize atoms making it, by definition, ionizing radiation.

Some of the energy from the X-ray photon works to separate the electron from the atom, and the rest sends the electron flying through space. A LARGER ATOM is more likely to ABSORB an X-ray PHOTON in this way, because larger atoms have greater energy differences between orbitals.

The soft tissue in your body is composed of smaller atoms, and so does not absorb X-ray photons particularly well. The CALCIUM ATOMS that make up your BONES are much larger, so they are better at absorbing X-ray photons

35
Q

When should a child’s first Panorex be taken?

A

Transitional Dentition

After eruption of FIRST PERMANENT tooth

36
Q

A child who is in either a primary or mixed dentition who has NO history of CARIES and is at their recall exam. What is the recommended INTERVAL for POSTERIOR BITEWINGS?

A

12-24 months

37
Q

A child who is in either a primary or mixed dentition WITH history of CARIES and is at their recall exam. What is the recommended INTERVAL for POSTERIOR BITEWINGS?

A

6-12 months

38
Q

A child who is in PERMANENT dentition who has NO history of CARIES and is at their recall exam. What is the recommended INTERVAL for POSTERIOR BITEWINGS?

A

18-36 months

39
Q

A child who is in PERMANENT dentition WITH history of CARIES and is at their recall exam. What is the recommended INTERVAL for POSTERIOR BITEWINGS?

A

6-12 months

40
Q

Atomic number of Calcium?

A

CALCIUM

Atomic Number: 20

Number of Neutrons: 20

Number of Protons: 20

Number of Electrons: 20

Number of Energy Levels: 4

41
Q

Atomic Density relation to x-rays

A

ATOMIC DENSITY

Atomic density means the number of atoms per unit volume.

The more energy an X-ray photon has, the more material it penetrates. The depth of penetration is related to the density of the material, as well as to the energy of the photon. The denser the material, the fewer X-ray photons get through.

42
Q

How can Absorbed dose be lowered?

A

ABSORBED DOSE can be REDUCED while keeping the image receptor exposure constant by choosing

1 ⬆️ HIGHER kVp
2 ⬇️ LOWER mAs.

increase KVP decrease patient dose.
increase mAs increase patient dose.

As this reduction is achieved with higher energy photons, however, the tradeoff is lower image contrast.

43
Q

How is tube current affected if MA is increased from 200 to 400?

A

The # of electrons crossing from cathode to anode has doubled.

44
Q

When you decrease the the wavelength and increase the frequency what happens to the energy of the x ray photons?

A

INCREASES

⬆️ Frequency = ⬆️ energy

45
Q

What is Exposure Time?

A

Actual time electrons are allowed to cross from cathode to anode

length of potential difference is applied to the tube.

length of time of x ray are emitted from the tube, determines how long the filament is heated.

46
Q

how would ADDED FILTRATION affect the radiograph?

A
  1. QUALITY ⬆️ increase average

2. QUANTITY ⬇️ decrease average

47
Q

If you half the SID the radiographic DENSITY will be ______ times greater?

SID (source to image distance)

The patient dose will increase with ______ SIDs

A

4

Decrease
⬆️ Dose = ⬇️ SID

48
Q

Reducing KVP does what to the image?

A

as the kilovolts are reduced, the contrast of the image does increase and the dose to the skin also increases.

with the lower kilovolts exposures, the density differences are more abrupt.
as the kilovolts increases, you can see more subtle density steps.
The subtle steps are referred to as long scale contrast and the lower kilovolts steps are short scale which is the opposite.

⬇️ kVp = ⬆️ contrast ⬆️ short scale
⬆️ kVp = ⬇️ contrast ⬆️ long scale

Kilovolts peak is used to control contrast because of its ability to affect the DIFFERENTIAL ABSORPTION of different anatomical parts.

Using a KVP TOO LOW tends to INCREASE the ABSORPTION of the radiation and therefore
the differential absorption rate is increased.
- can be UNDERPENETRATED

if the KVP is TOO HIGH, the attenuation properties of the anatomy will be OVERWHELMED by the kilovolts peak and the part will appear excessively DARK

As the kilovolts peak is increased above the level it should be, the DIFFERENTIAL absorption rate DECREASES and the contrast becomes very low or dark.

49
Q

What is the order from longest to shortest wave lengths?

A

LONGEST

RADIO WAVES
 ⬇️
MICROWAVES
⬇️
THERMAL RADIATION 🔺〰️
⬇️
VISIBLE LIGHT 💡 🌈 
⬇️
ULTRAVIOLET RADIATION 🟣〰️
⬇️
XRAYS 
⬇️
GAMMA

SHORTEST

50
Q

Wavelength in Radiation

What controls?

A

When the kilovolts peak is high, this actually reduces exposure to the patient.

As the kilovolts peak increases, the wavelength of the photon also decreases and this is what actually reduces the exposure.

The wavelength of the x-ray photon is the mechanism of injury and as the wavelength becomes smaller, it becomes less damaging

51
Q

Analog Dental Film 🎞

A
  1. D Speed should NOT be used!!
  2. F Speed: Fast, uses similar exposure times to digital image receptors
  3. Rare Earth Screen Film (for Panormic and Cephalometric cases) reduces absorbed radiation dose significantly
52
Q

X-Ray Machines and KVP

A

INCREASING mA or exposure TIME increases radiation DOSE equally and vice versa.

  1. Wall Mounted
    • between 60-70 kVP
    • either fixed or adjustable mA / timer
  2. Handheld (Nomad)
    • 60 kVp
    • Lower mA
    • requires LONGER exposure time
  3. Cone Beam CT (CBCT)
    -produces a lot of scattered radiation
    -make sure field of view and area of
    interest coincide.
    USES:
    -impacted/supernumerary teeth
    -craniofacial anomalies
    -malocclusions/causes/TMJ
    -dento-alveolar trama
    -complex ortho treatment
53
Q

Should a Digital Image ever be erased?

A

NO!

The are a record of number of exposures

54
Q

Radiation Safety techniques

What Law is involved?

A

DISTANCE:

  • At least 6 FEET (2m) from TUBE HEAD
  • NEVER in the PRIMARY radiation beam

INVERSE SQUARE LAW:

-XRays diverge from their source and beams become less intense further away from the source.

(At 3 feet the intensity of the XRay beam is 1/9 of its initial energy)

55
Q

What is Attenuation?

A

ATTENUATION

the REDUCTION of the INTENSITY of an X-RAY beam as it traverses MATTER.

The reduction may be caused by ABSORPTION or by deflection (SCATTER) of photons from the beam and can be AFFECTED by different factors such as beam ENERGY and atomic NUMBER of the absorber.

56
Q

How is an X-Ray produced?

A

X-RAY PRODUCTION

ELECTRICITY
⬇️
PRODUCES HEAT (heated filament emits electrons by THERMONIC EMISSION)
⬇️
PRODUCES ELECTRONS (electrons are accelerated by high voltage)
⬇️
BECOMES X-RAY (x-rays produced when high speed electrons hit the metal target, TUNGSTEN 🎯 )

57
Q

Grey Values on X-rays

A

THICKER/MORE DENSE

GREY VALUES

RADIOPAQUE

Less Photons make it through to the receptor

RADIOLUCENT

More Photons make it through to the receptor.

Dental CARIES appear RADIOLUCENT do to MINERAL LOSS.

58
Q

What is the BUCCAL OBJECT RULE?

A

BUCCAL OBJECT RULE

SLOB = Same Lingual Opposite Buccal

⬅️✌️➡️

59
Q

How often should X-rays be taken on a child with primary or mixed dentition that has NO Caries or increased rate of Caries?

A

12-24 months

60
Q

How often should X-rays be taken on a child with primary or mixed dentition that HAS HAD Caries or increased rate of Caries?

A

6-12 months

61
Q

How often should X-rays be taken on an adolescent with permanent dentition that has NO Caries or increased rate of Caries?

A

Posterior Bitewings

18-36 month intervals

62
Q

To minimize their exposure, what position should the clinician assume during radiographic procedures?

A

45 DEGREES from the primary beam as it EXITS the patient.

Pediatric Dentistry Prepatory Boards (39 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions