EFFECTS OF RADIATION radiation biology ppt

Effects of radiation

1. HUMAN RESPONSE TO IONIZING RADIATION The effects of x-rays on humans are the result of interactions at atomic levels

2. HUMAN RADIATION RESPONSE

3. NOTE At nearly every stage in the sequence, it is possible to repair radiation damage and recover Observable human radiation injury results from change at the molecular level

4. HUMAN RADIATION RESPONSE DETERMINISTIC EFFECT Early or nonstochastic effect of radiation Radiation response occurs within minutes or days after radiation exposure The response increases in severity with increasing dose STOCHASTIC EFFECT Late effect of radiation Radiation response not observed for months or years after radiation exposure The incidence of the radiation response increases with increasing doses

5. EARLY EFFECT/ IMMEDIATE  if the radiation response occurs within minutes or days after the radiation exposures it is classified as an immediate/early effect. LATE EFFECT/ DELAYED  if the human injury is not observable for many months/years it is termed a delayed/late effect of radiation.

6. EARLY EFFECTS OF RADIATION ON HUMANS 1. ACUTE RADIATION SYNDROME Hematologic syndrome Gastrointestinal syndrome CNS syndrome 2. LOCAL TISSUE DAMAGE Skin Gonads Extremities 3. HEMATOLOGIC DEPRESSION 4. CYTOGENIC DAMAGE

7. LATE EFFECTS OF RADIATION ON HUMANS 1. LEUKEMIA 2. OTHER MALIGNANT DISEASE Bone cancer Lung cancer Breast cancer 3. LOCAL TISSUE DAMAGE Skin Gonads Eyes 4. LIFE SPAN SHORTENING 5. GENETICALLY SIGNIFICANT DOSE

8. EFFECTS OF FETAL IRRADIATION Prenatal death Neonatal death Congenital malformation Childhood malignancy Diminished growth and development

9. EARLY EFFECTS OF RADIATION

10. Early Effect of radiation exposure After an exposure to a massive dose of radiation (100 to 5000rad) there can be a response in humans within a few days to a few weeks  

11. Acute Radiation Lethality/ Syndrome  The sequent of events after high-level radiation syndrome that leads to death within a few days or weeks.  Death is of course the most devastating human response to radiation exposure  

12. Sequence of event/ three lethal syndrome: Hematologic death Gastrointestinal (GI) death Central nervous system (CNS) death/ Neuromuscular death  

13. There are three other stages of Acute Radiation Lethality Prodromal Latent manifest

14. A. Prodomal syndrome Consists of acute clinical symptoms that occur within hours of the exposure and continue for up to a day Immediate radiation sickness

15. B. Latent period During which time the subject is free of visible effects No sign of radiation sickness The latent period is sometimes mistakenly thought to indicate the early recovery from a moderate radiation dose.

16. C. Manifest illness stage Have a visible clinical signs and symptoms Classified into 3 principal groups: Hematologic Gastrointestinal Neuromuscular

17. Hemopoietic Syndrome Hemopoietic Syndrome appears at about 200 rads Characterized by depression or ablation of the bone marrow May be accompanied by nausea, vomiting, fatigue, and increased temperature Death occurs within 1-2 months unless medical treatment is successful 17

18. 1. Hematologic Syndrome 200 to 1000 rads Prodromal stage  the subject initially experiences mild symptoms in a matter of few hours and may persist for several days Latent stage  extend as long as 4 weeks Manifest stage  vomiting, mild diarrhea, malaise, lethargy, fever, reduction in numbers of WBC, RBC and platelets Mean survival time  10 to 60 days Cause of death  generalized infection, electrolyte imbalance and dehydration.

19. Gastrointestinal Syndrome Occurs at a whole body dose of 1000 rads or greater Characterized by the destruction of the intestinal epithelium and complete destruction of the bone marrow Accompanied by severe nausea, vomiting, and diarrhea soon after exposure Death occurs within a few weeks 19

20. 2. Gastrointestinal (GI) syndrome 1000 to 5000 rad Prodromal stage  vomiting and diarrhea occurs within hours of exposure and persist for hours to as long as a day Latent stage  3 to 5 days no symptoms are present Manifest stage  nausea, vomiting, diarrhea, anorexia, lethargy, Mean survival time  4 to 6 days Cause of death  severe damage to cell lining of the intestines; electrolytic imbalance and infection.

21. Central Nervous System Syndrome Occurs at whole body doses of 2000 rads or more Damages the central nervous system as well as all other organs and systems Unconsciousness occurs within minutes Death follows in a matter of a few hours to a few days 21

22. 3. Central nervous system (CNS) Syndrome >5000 rad Prodromal stage  onset of severe nausea, vomiting, extremely nervous, confused, burning sensation, lose vision, loss of consciousness within first hour. Latent stage  12 hours, the earlier symptoms subside or disappear Manifest stage  disoriented, loses muscle coordination, difficulty in breathing, convulsive seizures, loss of equilibrium, ataxia, lethargy, lapses into a coma, dies. Mean survival time  0 to 3 days Cause of death  elevated fluid content of the brain, increase intracranial pressure, vasculitis , and meningitis.

23. LD 50/30 Lethal dose Is the dose of radiation to the whole body that will result in death within 30 days to 50% of the subjects so irradiated. The LD 50/30 for human is estimated to be approximately 300rad With clinical support humans can tolerate much higher doses, the maximum is reported to be 800 rad

24. Local Tissue Damage Only part of the body is irradiated The manner in which local tissues response depends on their intrinsic radiosensitivity and the kinetics of cell proliferation and maturation Example of local tissue damage: Skin Gonads Bone marrow

25. Effects on Skin 300 to 1000 rad The basal cells are the stem cells that mature as they slowly migrate to the surface of the epidermis. Damage to these cells result in the earliest manifestation of radiation injury to the skin. Non linear, threshold dose response relationship

26. A. Effects on Skin 1. Erythema ( sunburnlike reddening of the skin) Erythema was perhaps the first observed biologic response to radiation exposure. 2. Desquamation (ulceration and denudation of the skin) Moist desquamation (clinical tolerance) Dry desquamation 3. Epilatiion (baldness, alopecia)

27. B. Effects on Gonads 10 rad The germ cells are produced by both ovaries and testes Female: Oogonia  primordial follicle  mature follicle( oocytes )*  corpus luteum  ovum Male : Spermatogonia *  spermatocytes  spermatid  sperm *most radiosensitive  

28. A. Ovaries 10 rad  delay or suppression of menstruation 200 rad  temporary sterility 500 rad  permanent sterility 25-50 rad  genetic mutations

29. A. Ovaries On the basis of those data, women should abstain from procreation for a period of several months after ovarian doses in excess of 10 rad. To minimize the possibility of genetic mutations in offspring.

30. B. Testes 10 rad  reduction in number of the spermatozoa (minimal aspermia ) 200 rad  temporary sterility 500 rad  permanent sterility

31. B. Testes After testicular irradiation of doses approximately 10 rad , the male should refrain from procreation for 2 to 4 months until all cells in the spermatogonia and postspermtogonial stage at the time irradiation have matured and disappeared.

32. Cytogenetic effects Cytogenetics  is the study of the genetics cells, in particular, cell chromosomes Chromosomes damage takes on the following deletion: Chromatid deletion (breakage of chromatid ) Ring chromosomes aberration Reciprocal translocation

33. Summary Biological effects of concern, in the occupational setting, do not appear for several years after radiation exposure, if effects appear at all. The probability of these effects increases with dose In any individual case, it can never be determined with 100% confidence that radiation was the cause 33