Radiography Test #1

Front 1

*Ionizing radiation is...

Back 1

harmful and produces biologic changes in living tissue

Front 2

Radiation Biology

Back 2

the study of the effects of ionizing radiation on living tissue

Front 3

Ionization Radiation

Back 3

Produces biologic changes in living tissues.
Energy or xray photon strikes nucleus and ejects an electron.

Front 4

*A free Radical is...

Back 4

simply an atom with one or more unpaired electrons in its orbit

Front 5

*Free Radical Formation results in

Back 5

hydrogen and hydroxyl free radicals (toxin)

Front 6

To achieve stability, free radicals do 1 of 3 things:

Back 6

Recombine w/o causing changes in the molecule.
Combine w/ other free radicals & cause change.
Combine w/ ordinary molecules to form a toxin.

Front 7

Characteristics of a free Radical:

Back 7

Uncharged Molecule
Unpaired electron
Highly Reactive and Unstable
Combines with molecules to form toxins

Front 8

*Cell damage results when ionizing radiation directly hits critical areas within the cell (DNA)

Back 8

The Direct Theory

Front 9

*X-ray photons are absorbed within the cell and cause the formation of toxins which in turn damage the cell (via free radicals)

Back 9

The Indirect Theory

Front 10

The chance of free radical formation and indirect injury is great because cells are composed of...

Back 10

70-80% water

Front 11

*Dose-Response Curve is used to

Back 11

correlate the "response" or damage of tissues with the dose or amount of radiation received.

Front 12

Linear Relationship

Back 12

The response of the tissues-damage-is directly proportional to the dose.

Front 13

Nonthreshold Relationship:

Back 13

A threshold dose level for damage doesn't exist-it's not as if you need a certain dose for damage to occur. (A response can be seen at any dose)

-There is no absolute SAFE amount of radiation exposure.

Front 14

*Radiation Injury sequence, repair and accumulation:

Back 14

varying amounts of time are required for changes to cellular tissue to appear.

Front 15

The time that elapses between exposure to ionizing radiation and the appearance of observable clinical signs.

(The more radiation received and the faster the dose rate, the shorter the latent period.)

Back 15

*Latent Period (Sunburn=Red)

Front 16

Follows the latent period when cells show damage.

Back 16

*Period of Injury (Blisters)

Front 17

*Recovery Period:

Back 17

Depending on a number of factors, cells can repair the damage caused by radiation (if allowed time to repair).

Front 18

The effects of radiation exposure are additive and damage that remains un-repaired accumulates in the tissue

Back 18

*Cumulative Effects

Front 19

What are the determining factors of Radiation Injury?*

Back 19

Total dose, dose rate, amount of tissue irradiated, cell sensitivity, age.

Front 20

Total Dose:

Back 20

Quantity of radiation received. (Large quantities of Radiation=More damage)

Front 21

Dose Rate:

Back 21

Dose/Time; more damage takes place with high dose rates because a rapid delivery of radiation doesn't allow time for the cellular damage to be repaired.

Front 22

Amount of tissue irradiated:

Back 22

Extensive radiation injury occurs when large areas of the body are exposed because of the damage that occurs to the blood-forming tissues.

Front 23

Cell Sensitivity:

Back 23

Rapidly dividing, young cells are more adversely affected

Front 24

Age:

Back 24

Children are MORE susceptible to radiation than adults

Front 25

Stochastic Effects:

Back 25

occur as a direct function of dose.
The probability of occurrence increases with increasing absorbed dose. EX. Cancer and mutations (No dose threshold)

Front 26

non-Stochastic effects (Deterministic):

Back 26

Somatic effects that have a threshold and increase in severity with increasing absorbed dose. EX. Sunburn, hair loss, cataracts, decreased fertility.

Front 27

*Short Term Radiation Effects:

Back 27

Seen in Minutes, days, or weeks
ARS (Acute Radiation Syndrome): includes nausea, vomiting, diarrhea, hair loss, hemorrhage (Nuclear Radiation)

Front 28

*Long Term Effects:

Back 28

Genetic, seen after years, decades or generations
Linked to induction of cancer, birth abnormalities or genetic defects, deformations.

Front 29

All the cells in the body EXCEPT the reproductive cells.
Cells changes are NOT transmitted to future generations--> healthy offspring

Back 29

Somatic Cells *

Front 30

NOT seen in the person irradiated, but are passed on to future generations.

Back 30

Genetic Cells (aka. reproductive cells: ova, sperm)

Front 31

Can Genetic Damage be repaired?

Back 31

NO

Front 32

T or F: Cancer cells rapidly divide and are less differentiated. *

Back 32

TRUE: that's why radiation therapy can be successful in the treatment of cancer.

Front 33

Define Critical Organ:

Back 33

Organ that if damaged diminishes the quality of a person's life

Front 34

*Critical organs exposed during dental radiographs:

Back 34

Skin, Thyroid, Lens of the eye, Bone Marrow

Front 35

*Radiation Measurements

Back 35

units are used to define 3 quantities of radiation: Exposure, Dose, Dose Equivalent.

Front 36

Traditional/Standard system of measurement:

Back 36

-Roentgen (R)
-Radiation Absorbed Dose (rad)

-Roentgen Equivalent in man (rem)

Front 37

International System of Measurement:

Back 37

Coulombs/kilogram (C/kg)- electrical charge.
Gray (Gy)
Sievert (Sv)

Front 38

Both ____ and _____ are measured in 1 cc/Kg of air

Back 38

Roentgen & Coulomb

Front 39

*Gray (Gy):

Back 39

1 Gy= 100 rads (Radiation absorbed Dose)

Front 40

*Sievert:

Back 40

1 Sv= 100 REM's OR
1 rem=.01 Sv

Front 41

Background Radiation

Back 41

Form of radiation that is all around us (enviornment)
-in the US. average dose of BR per year is *150-300 mrads

-Sea level is less than the U.S average

Front 42

*likelihood of adverse effects or death resulting from exposure to a hazard

Back 42

Risk

Front 43

Risk of dental radiography inducing a fatal cancer in approx. is ...

Back 43

3/1,000,000

Front 44

*Thyroid Gland est. dose of ____mrad is necessary to produce cancer.

Back 44

600mrad

Front 45

Skin: ____mrads
Eyes: _____mrads

Back 45

Skin: 250 mrads, 500 dental films in 14 days

Eyes: 60 mrads, so low the scientists no longer consider the lens of the eye a critical organ.

Front 46

Collimation: use of rectangular instead of round reduces radiation by...

Back 46

60-70%

Front 47

T or F: The benefit of disease detection DOESN'T outweigh the risk of damage of radiation.

Back 47

FALSE. The benefit of disease detection outweighs the risk of radiation.

Front 48

Q: The Latent period in radiation biology is the time between:

A) Exposure of film and developing
B) Subsequent doses of radiation
C) Cell rest and cell mitosis
D) Exposure to x-radiation and clinical symptoms
E) None of the above

Back 48

D) Exposure to x-radiation and clinical symptoms

Front 49

Whats the difference between Direct and Indirect?

Back 49

Direct: Cell damage results when ionizing radiation directly hits critical areas within the cell (DNA)

Indirect: X-ray photons are absorbed within the cell and cause the formation of toxins which in turn damage the cell (via free radicals)

Front 50

Which of the follow are incorrect:
A) X-radiation is not harmful to living tissues
B) Dental Radiographs benefit the patient

C) In dental radiography, the benefit of disease detection outweighs the risk of damage of radiation
D) Radiography should only be prescribed when the benefit outweighs the risk
E) Biologic damages results from x-ray exposure

Back 50

A) X-radiation is not harmful to living tissues

Front 51

First important step in limiting the amount of x-radiation exposure

Back 51

Prescribing Dental Radiographs

Front 52

FMS (18 films) with lead apron recieves ___REM to the uterus
Background radiation in 9 mo. receives ___ REM to uterus

Back 52

FMS: 1mREM to uterus
Background radiation: 225mREM to uterus

Front 53

Provided by the glass window of the x-ray tube, the insulating oil, and the tubehead seal.

Back 53

Inherent filtration

Front 54

*Al disks placed in the path of the x-ray between the collimator and the tubehead seal; used to filter out the longer wavelength, low energy x-rays.

Back 54

Added Filtrations

Front 55

T or F: inherent filtration alone does not meet standards. You need ALL layers.

Back 55

TRUE

Front 56

collimation:

Back 56

Used to restrict the size and shape of the X-ray beam, reducing patient exposure.

Front 57

*Which Position-Indicating Device (Rectangular or Conical) is more effective?

Back 57

Rectangular is more effective than round at reducing patient exposure; disadvantage is that it's easier to "cone"-cut.

-Reduces x-radiation exposure by 60-70%

Front 58

What is the difference of collimation and filtration of the x-ray beam?

Back 58

Collimation focuses the beam, and filtration takes away wavelengths.

Front 59

T or F: The thyroid collar IS recommended for use with extraoral films

Back 59

FALSE: it is NOT recommended for use with extraoral films.

Front 60

What is the single most effective method in reducing a pt's exposure to x-radiation?

Back 60

Fast Film*

Front 61

E speed and F speed are the fastest intraoral film available, compared to the D speed film, it requires only ___ the exposure time.

Back 61

Half*

Front 62

Dental Radiography must stand at least how many feet away from the tubehead?

Back 62

6 feet*

Front 63

Any radiation with the exception of the primary beam that is emitted from the dental tubehead

Back 63

Leakage radiation

Front 64

Radiation Control for Health and Safety Act: enacted in ____ to standardize the performance of x-ray equipment.

Back 64

1968*

Front 65

Consumer-Patient Radiation Health and Safety Act: enacted in _____ and addressed the certification of persons using radiographic equipment.

Back 65

1981*

Front 66

Occupationally exposed (work in a nuclear plant or constantly around radiation) person:

Back 66

5.0 rem/yr*

Front 67

Nonoccupationally exposed (we are considered nonoccupational) persons:

Back 67

.01 rem/year*

Front 68

Maximum Accumulated Dose (MAD)* is determined by...

Back 68

worker's age (minimum age requirement is 18)

Front 69

what does ALARA stand for?

Back 69

"As Low As Reasonable Achievable"