RAD BIO

Question 1

Mechanisms of RAD Injury

Answer 1

ionization, free radical formation

Question 2

Free Radical

Answer 2

formed when x-ray photon ionized [breaks up] water; highly reactive and unstable uncharged atom (unpaired electron in outer shell); primary cause for cell damage

Question 3

Ionization

Answer 3

produced during photoelectric effect or compton scatter; dislodged electrons interact w/ other atoms causing chemical changes

Question 4

Direct Theory

Answer 4

photons strike critical cells directly (like DNA), infrequent

Question 5

Indirect Theory

Answer 5

cells absorb photons causing toxins OR photons absorbed by water in cell form free radicals > combine to form toxins; more frequent

Question 6

Dose-Response Curve types

Answer 6

Threshold, Linear, *Linear Non-threshold

Question 7

Linear Non-threshold

Answer 7

biologic damage occurs no matter how small the amount of radiation is received

Question 8

Stochastic Effects

Answer 8

occurrence increases w/ increasing dose; no threshold; ie. cancer/genetic mutations

Question 9

Nonstochastic Effects

Answer 9

requires large dose to cause issues, has threshold, severity increases w/ increasing dose; ie. erythemia/hair loss/decreased fertility

Question 10

Latent Period

Answer 10

time between exposure and effects; dependent on dose + amount of time

Question 11

Recovery Period

Answer 11

most damage to cells during radiation is repaired

Question 12

Cumulative Effects

Answer 12

repeated exposure compounds/accumulates

Question 13

Short Term Effects

Answer 13

associated with large doses in short time like minutes, days, weeks > ARS [acute radiation syndrome] ie. nausea/vomit/diarrhea *not applicable to dentistry

Question 14

Long Term Effects

Answer 14

small doses over long period of time like years, generations; ie. cancer, birth defects

Question 15

Somatic Effects

Answer 15

seen in the person irradiated

Question 16

Genetic Effects

Answer 16

seen in future generations

Question 17

Mitotic Activity

Answer 17

cells that divide more frequently are more radiosensitive

Question 18

Cell Differentiation

Answer 18

immature/not highly specialized are more radiosensitive

Question 19

Cell Metabolism

Answer 19

higher metabolism of cell > more radiosensitive

Question 20

Critical Organs in Dental Imaging

Answer 20

skin, thyroid (radioresistant) , eye, bone marrow (requires extremely high doses to cause damage)

Question 21

Roentgen

Answer 21

[R] measures radiation by amount of ionization in the AIR; no SI equivalent

Question 22

Radiation Absorbed Dose

Answer 22

[rad] amount of energy absorbed by tissue. SI equivalent is the gray [Gy]

Question 23

Roentgen Equivalent Man

Answer 23

[rem] SI equivalent is the sievert [Sv]

Question 24

Dental Radiography units

Answer 24

milirad [mrad], millisievert [mSv],