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EARLY NONSTOCHASTIC EFFECTS/LATE STOCHASTIC EFFECTS

EARLY NONSTOCHASTIC EFFECTS/LATE STOCHASTIC EFFECTS. Sherer Chapter 6, Reference: Bushong, Chapter 36 and 37 . Review of Dose response curves. Threshold Non threshold Linear quadratic non threshold curve Non linear (s-shaped or sigmoid) . Early, Nonstochastic Effects:.

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EARLY NONSTOCHASTIC EFFECTS/LATE STOCHASTIC EFFECTS

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  1. EARLY NONSTOCHASTIC EFFECTS/LATE STOCHASTIC EFFECTS Sherer Chapter 6, Reference: Bushong, Chapter 36 and 37

  2. Review of Dose response curves • Threshold • Non threshold • Linear quadratic non threshold curve • Non linear (s-shaped or sigmoid)

  3. Early, Nonstochastic Effects: • Soon after Rad. Exposure • minutes • hours • days • weeks • “x-ray burns”

  4. ACUTE RADIATION SYNDROMES • Total body exposure • acute exposure in a matter of minutes • 100’s or 1000’s of rads

  5. 200-1000 rads 1000-10,000 rads 10,000 + Survive a few weeks 3-4 days few minutes RADIATION AND MAMMALS

  6. FOUR STAGESTOTAL BODY IRRADIATION 1) PRODROMAL (NVD SYNDROME) 2)LATENT 3) MANIFEST ILLNESS 4) RECOVERY OR DEATH

  7. 1)Prodromal • Initial • can occur as low as 100 rads • within minutes with exposure to 1000 rads • nausea, vomiting, diarrhea (NVD)

  8. 2) Latent period • Weeks in low dose • Hours in high dose • pt appears symptom free • lethal effects or recovery is beginning

  9. A) Hematologic Gastrointestinal Cardiovascular Cerebrovascular/ CNS Bone Marrow 3) Manifest Illness

  10. AKA: bone marrow or hemotopoietic syndrome Rad exposure-low Stages: Prodromal (NVD) Latent Mitotic stem cells are sterilized pancytopenia-diminished supply of blood cells Death due to dehydration, electrolyte imbalance infection A) HEMATOLOGIC

  11. B) GI syndrome • 600 rads(6 gy)-1000 rads (10 gy) • prodromal - one day • latent 3-5 days-deterioration of the lining of the GI tract has begun • manifest of illness • death ( dehydration, anorexia ) 3-4 days • cannot prevent progression of syndrome

  12. CARDIOVASCULAR • Not a syndrome • Decreased BP • Increased pulse rate • Acute myocardial insufficiency

  13. C) Cerebrovascular/CNS • 5000 RADS • Prodromal (nausea and vomiting) • latent period 6-12 hours • Death occurs within hours- to several days • GI and Hemopoietic syndrome occurring simultaneously

  14. L/D • LD 50/30 (Sherer), LD 50/60 (Bushong) • used in animals • humans tend to survive longer (Chernobyl) • see curve (figure 36-1) on page 519 of Bushong or LD curve on page 120 Sherer

  15. REPAIR? • Can occur with sublethal doses but dependent on cell or organ’s potential for recovery. • 10% of radiation induced damage - irreparable

  16. LOCAL TISSUE DAMAGE • High doses • atrophy of organ • Skin-many x-ray pioneers suffered x-ray burns to skin

  17. Skin layers • Subcutaneous • middle layer • outer layer (epidermis) • accessory structures • sensory • hair • sebaceous • sweat

  18. Erythema • 100-300 rad - mild within 1-2 days • Q:Dose Response curve? • A: Non-linear, threshold • Hair loss –epilation • Q:Dose Response curve? • A: For high dose - Non-linear, threshold • low dose – linear, threshold • severe necrosis rare

  19. Late somatic effects Months or years after whole or partial ARS OR Low doses sustained over a couple of years

  20. WHAT ARE THE THREE MAJOR TYPES OF LATE SOMATIC EFFECTS?

  21. RISK ESTIMATES • Low doses (below 10 rem) effect must be estimated • Risk still exists –controversial concept • Absolute risk –specific # of excess cancers will result due to exposure • Relative risk - # of excess cancers will increase as the natural incidence of cancer increases in the population with age

  22. Carcinogenesis • Distinguishing radiation induced cancer from low doses difficult. Why? • Epidemiologic studies from high doses are used. Examples include: • Radium watch dial painters • Uranium miners • Early Radiation workers • Infants treated with radiation for enlarged thymus • Children of Marshall Island • Japanese atomic bomb survivors • Evacuees from Chernobyl

  23. Radium dial workers Uranium miners Early Medical radiation workers Infants treated for enlarged thymus Children of Marshall Islands Japanese atomic bomb survivors Chernobyl Thyroid Leukemia Breast cancer Bone cancer Skin cancer Lung cancer Match the pathology (can use more than once)

  24. EXTREMITIES • Amputations • radiodermatitis • shoe fluoroscopy • nuc med. techs

  25. LIFE SPAN SHORTENING • CATARCTOGENESIS • GENETIC EFFECTS

  26. American RT’s • Ongoing study of 146,000 RT’s • Higher risk of dying? • Higher risk of dying from leukemia? • Higher risk of dying from breast cancer? • When did these risks become less?

  27. GONADS • Highly sensitive • can pass on effects to future generations • animal studies/radiotherapy patients, radiation accident victims, convicts • oogonia • spermatogonia

  28. TESTES • 10 rad effect? • 200-250 rads effect? • 500-600 rads effect?

  29. OVARIES • 10 rad effect? • more sensitive in fetus /small children why? • 200 rad effect? • 500-625 rads compare this range with males why the difference?

  30. A) study of the genetics of cells B) a new type of karaoke machine C) a chromosome map D) a chromosome aberration Cytogenetic Not!!! Correct answer. Used for cytogenetic analysis Structural damage A karyotype is

  31. To Be continued • See power point entitled Chapter 8

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