7️⃣ Radiation Flashcards
(10 cards)
What daily-life radiation exposures exist?
Constant low levels from natural radioisotopes, and small amounts in consumer products (e.g., radioactive watch dials).
Distinguish ionizing vs non-ionizing radiation.
Ionizing (X-rays, gamma, α/β particles) displaces electrons, damaging DNA; non-ionizing (UV, IR, microwave, sound) moves atoms without ionization.
How does UV radiation damage DNA and what cancers result?
UVB/UVA induce pyrimidine dimers and ROS → mutations in DNA repair → squamous/basal cell carcinoma, melanoma.
Compare UVA, UVB, and UVC.
UVA (320–400 nm): deep dermal penetration, ROS; UVB (280–320 nm): epidermal stem cells, pyrimidine dimers; UVC (200–280 nm): very mutagenic but ozone-filtered.
Define Curie, Gray, and Sievert.
Curie (Ci): disintegrations/sec; Gray (Gy): energy absorbed/kg tissue; Sievert (Sv): biological effect dose (weighted by radiation type).
What factors determine radiation’s biological effect?
Dose, dose rate, exposed area size, cell proliferation rate (high in bone marrow, GI, gonads), tissue radiosensitivity.
Describe cellular effects of ionizing radiation.
Cytoplasmic swelling, mitochondrial/ER degeneration, membrane breaks; water radiolysis → ROS → DNA strand breaks, rearrangements, point mutations; early (hrs–wks) and late (mos–yrs) changes.
What are acute whole-body radiation syndromes?
Hematopoietic (neutrophil/platelet nadir ~2 wks), GI (vomiting, diarrhea, bleeding, infection ~1–3 wks), CNS (confusion, seizures, death 14–36 hrs at high doses).
How is radiation used therapeutically?
Focused fractional doses (<70 Gy) to tumors with shielding of adjacent normal tissues.
What are delayed effects of ionizing radiation?
Carcinogenesis (myeloid leukemia peak 5–7 yrs; breast/thyroid latency longer), vascular injury (endothelial necrosis, fibrosis, thrombosis, telangiectasia), parenchymal atrophy/fibrosis.
