224 Lesson 2: Somatic Effects

Somatic

Relating to internal organs

Mitosis

Nuclear cell division, daughter cells with same # chromosomes, most radiosensitive

Meiosis

Germ cell division, daughter cells with half # of chromosomes

Interphase

Period of cell cycle between cell divisions, least radiosensitive

Target theory

Premise that radiation hits to critical molecules can be lethal to cell

Direct effect

Radiation hits to DNA in nucleus

Indirect effect

Radiation hits to water in cell cytoplasm, radiolysis

Stochastic

Linear, non threshold effects that increase in probability, not severity, within population with increasing dose

Deterministic effects

Nonlinear, threshold effects; increase in severity within individual with increased dose; occurrence is predictable

Early effects of radiation

Hours, days, weeks; usually somatic and deterministic; erythema, epilation, ARS, etc.

Late effects of radiation

Months to years; usually stochastic (except for cataracts); life span shortening, cancer, cataracts

Acute radiation syndrome (ARS)

Hematological, GI, CNS symptoms seen in sudden exposure of >1Gy absorbed dose, severity increases with dose

Hematological syndrome

1Gy, ARS that causes damage to bone marrow and immune system

GI syndrome

6Gy, ARS that damages intestinal mucosae and nutrition/hydration deficits

CNS syndrome

50Gy, ARS that damages nervous system

Carcinogenesis

Normal cells become cancer cells