Module 4

Question 1

Describe the possible cell injury from x-rays

Answer 1

Radiation Carcinogenesis
Ionization
Free radical formation

Question 2

Define ionization

Answer 2

Process by which an electrically stable/neutral atom or molecule gains or loses electrons and acquires a positive/negative charge; unstable

Question 3

What effect does ionization have on possible cell injury?

Answer 3

When x-rays pass through living tissues, ionization of certain chemicals, especially water in the cells, can result in biological effects

Question 4

Define free radical formation

Answer 4

An uncharged (neutral) atom or molecule that exists with a single electron in its outer shell that is highly unstable and reactive

Question 5

What effect does free radical formation have on possible cell injury?

Answer 5

Free radicals can recombine without causing changes
Free radicals can combine with other free radicals
Free radicals can combine with other molecules to form toxins

Question 6

What are the two theories of radiation injury?

Answer 6

Direct theory and indirect theory

Question 7

Define direct theory

Answer 7

Cell damage occurs when ionizing radiation directly hits critical areas within the cell like the DNA

Question 8

Define indirect theory

Answer 8

X-ray photons are absorbed within the cell and the formation free radicals produce toxins which damage the cell

Question 9

Define dose-response curve

Answer 9

It’s the correlation of the amount/dose of radiation received with the response of the tissue

Question 10

What are the 3 types of dose-response curve?

Answer 10

Linear curve, non-threshold linear curve, and threshold curve

Question 11

Explain the linear curve

Answer 11

Response of the tissue is proportional to the dose

Question 12

Explain the non-threshold linear curve

Answer 12

No matter how small the dose, some damage occurs

Question 13

Explain the threshold curve

Answer 13

Below a certain dose/level, no response is seen

Question 14

What factors influence or determine radiation injury?

Answer 14

Total dose
Dose rate
Amount of tissue irradiated
Cell sensitivity
Age

Question 15

Define total dose

Answer 15

Quantity of radiation received or absorbed; more damage occurs with larger tissue absorption

Question 16

Define dose rate

Answer 16

Rate at which exposure to radiation occurs and absorption takes place. More radiation damage takes place with high dose rate because there is rapid delivery without time for cell repair

Question 17

Describe amount of tissue irradiated

Answer 17

Total body exposure is of greater concern than localized areas of the body

Question 18

Define cell sensitivity

Answer 18

More damage occurs in rapidly dividing cells and younger cells

Question 19

Describe how age influences radiation injury

Answer 19

Children are more susceptible to radiation damage than adults

Question 20

Describe the short-term effects of radiation exposure

Answer 20

Effects associated with large amounts of radiation seen within minutes, days, weeks

Question 21

Describe the long-term effects of radiation exposure

Answer 21

Associated with small amounts of radiation absorbed repeatedly over time seen within years or exposure

Question 22

Describe the genetic effects of radiation exposure

Answer 22

Effects not seen in the person irradiated, but in future generations

Question 23

Describe the somatic effects of radiation exposure

Answer 23

Seen in the person irradiated; examples = burns, cancer, or leukemia

Question 24

Describe the effects of radiation on cells, tissues, and organs

Answer 24

The Law of Bergoine and Tribondeau

Question 25

What is the Law of Bergoine and Tribondeau?

Answer 25

States that the radiosensitivity of cells is directly proportional to their reproductive activity (mature cells are least affected), inversely proportional to their degree of differentiation (younger tissue/cells are more radiosensitive), and directly proportional to their metabolic activity (radiosensitivity increases with metabolic activity)

Question 26

What are the critical tissues and organs that are exposed to radiation in the head/neck area?

Answer 26

Skin
Thyroid
Lens of the eye
Bone marrow

Question 27

List the cells in descending order of sensitivity that are effected by radiation

Answer 27

WBC
RBC
Immature reproductive cells
Epithelial cells
Endothelial cells
Connective tissue cells
Bone cells
Nerve cells
Brain cells
Muscle cells

Question 28

What are the units used in the traditional system?

Answer 28

Roentgen (R)
Radiation absorbed dose (RAD)
Roentgen equivalent in man (REM)

Question 29

What are the units used in the SI system?

Answer 29

Coulombs/kilogram (C/kg)
Gray (Gy)
Sievert (Sv)

Question 30

Name some common sources of radiation exposure?

Answer 30

Background

Medical/Dental

Question 31

Give an example of background radiation

Answer 31

Always present in the environment, cosmic (from stars), and terrestrial (from earth/air)

Question 32

Give an example of human made radiation

Answer 32

luminous wristwatches, TV’s, and fallout from atomic weapons

Question 33

Give an example of medical/dental radiation

Answer 33

x-rays; accounts for most radiation exposure

Question 34

How can we discuss the risks of radiation with our patients?

Answer 34

Compare the radiation to other risks
Find something the patient can relate to
Let them know the risk is less than many other everyday activities
We need to educate the patient so they understand the importance vs the risk

Question 35

What do we do to reduce radiation?

Answer 35

Film speed (F speed)
Digital x-rays (reduce by 50%)
Collimation (rectangular)
Technique (long PID)
Exposure (use higher kVp)