Effects of Radiation

Effects of radiation
Signs and symptoms of radiation
Infected period of radiation
Dosage
Calculation of dosage
Units and SI units used
Diseases caused by radiation
Radioresistant

1. Topik 3 ( Biologi Radiasi )

2. 1. EFFECTS OF RADIATION

3. RADIATION EFFECTS Can be divided into high doses and low doses High doses of radiation over a short periods of time, producing acute or short term effects ( eg : CT scan) Low doses: low exposure doses over a long period of time producing chronic effects (example of chest x-ray or orthodontic radiographs)

4. High doses radiation tend to kill cells, it causes immediate problems to any body organ These are several effects of high doses radiation: Skin burn Hair loss Sterility cataracts HIGH DOSE

5. Skin burn Hair loss

6. Low doses radiation damage the cells and spread out over long periods of time Effects of exposure to low doses of radiation: Genetic: (suffer by offspring) Somatic (cancer) In utero (suffer by a developing embryo is seen after birth) LOW DOSE

7. 2. Effects of Whole-Body Irradiation

8. Acute Radiation Syndrome When the whole body is exposed to low or moderate doses of radiation, characteristic changes (acute radiation syndrome) develop Acute Radiation Syndromes include Hematopoietic Syndrome Gastrointestinal Syndrome Cardiovascular and Central Nervous System Syndrome

9. Acute Radiation Syndrome A collection of signs and symptoms experienced by persons after acute whole-body exposure to radiation. Information comes from : animal experiments human exposures (medical radiotherapy, atom bomb blasts, and radiation accidents) Individually, the clinical symptoms are not unique to radiation exposure, but taken as a whole, the pattern constitutes a distinct entity.

10. White, S. and Pharoah , M. (2009).  Oral radiology . 1st ed. St. Louis, Mo.: Mosby/Elsevier.

11. 1. Prodomal Period Within the first minutes to hours after exposure to whole-body irradiation of about 1.5 Gy , symptoms characteristic of gastrointestinal tract disturbances may occur. Individual may develop anorexia, nausea, vomiting, diarrhea , weakness, and fatigue. Cause is not clear but probably involves the autonomic nervous system. Severity & time of onset may be significant prognostic value as they are dose-related H igher dose , more rapid the onset & greater the severity of symptoms.

12. 2. Latent Period Occurs after prodromal period where no signs or symptoms of radiation sickness occur. The extent of the latent period is also dose-related E xtends from hours or days at supralethal exposures (> approximately 5 Gy ) to a few weeks at sublethal exposures (< 2 Gy ). Symptoms follow the latent period when individuals are exposed in the lethal range (approximately 2 to 5 Gy ) or supralethal range

13. Hematopoietic Syndrome Whole-body exposures of 2 to 7 Gy cause injury to the hematopoietic stem cells of the bone marrow and spleen . B one marrow is a highly radiosensitive tissue due to the high mitotic activity of these cells & the presence of many differentiating cells. D oses in this range cause a rapid and profound fall in the numbers of circulating granulocytes , platelets , and finally erythrocytes

14. Hematopoietic Syndrome Mature circulating granulocytes, platelets, and erythrocytes themselves are very radioresistant H owever, since they are nonreplicating cells, p aucity in the peripheral blood after irradiation reflects the radiosensitivity of their precursors Rate of fall in the circulating levels of a cell depends on the life span of that cell in the peripheral blood Granulocytes, short lives in circulation, fall off in a matter of days, R ed blood cells, long lives in circulation, fall off only slowly

15. White, S. and Pharoah , M. (2009).  Oral radiology . 1st ed. St. Louis, Mo.: Mosby/Elsevier. The shorter the life span of a cell, the faster the rate the cells fall off

16. Hematopoietic Syndrome Clinical signs of the hematopoietic syndrome include infection (in part from the lymphopenia and granulocytopenia ), hemorrhage (from the thrombocytopenia),and anemia (from the erythrocyte depletion). Individuals may survive exposure in this range if the bone marrow and spleen recover before the patient dies of one or more clinical complications. Death results from the hematopoietic syndrome, usually occurs 10 to 30 days after irradiation.

17. Gastrointestinal Syndrome Whole-body exposures in the range of 7 to 15 Gy cause extensive damage to the gastrointestinal system. Such exposure causes injury to rapidly proliferating basal epithelial cells of the intestinal villi and leads to a loss of the epithelial layer of the intestinal mucosa . Turnover time for cells lining the small intestine is normally 3 to 5 days.

18. Gastrointestinal Syndrome Because of the denuded mucosal surface, plasma and electrolytes are lost therefore efficient intestinal absorption cannot occur. Ulceration also occurs, with hemorrhaging of the intestines . All these changes are responsible for the diarrhea , dehydration , and loss of weight . Endogenous intestinal bacteria readily invade the denuded surface, producing septicemia . Death occurs before the full effect of the radiation on hematopoietic systems can be evidenced

19. Gastrointestinal Syndrome The combined effects on these stem cell systems cause death within 2 weeks from a combination of factors that include : fluid and electrolyte 'loss' infection possibly nutritional impairment.

20. Cardiovascular and CNS Syndrome Exposures in excess of 50 Gy usually cause death in 1 to 2 days . The few human beings who have been exposed at this level showed collapse of the circulatory system with a precipitous fall in blood pressure in the hours preceding death . Autopsy revealed necrosis of cardiac muscle Victims also may show intermittent stupor , incoordination , disorientation , and convulsions suggestive of extensive damage to the nervous system.

21. Cardiovascular and CNS Syndrome Syndrome is irreversible, and the clinical course may run from only a few minutes to about 48 hours before death occurs. C ardiovascular and central nervous system syndromes have such a rapid course I rradiated individual dies before the effects of damage to the bone marrow and gastrointestinal system can develop

22. Cardiovascular and CNS Syndrome Antibiotics are indicated when infection threatens or the granulocyte count falls. Fluid and electrolyte replacement is used as necessary. Whole blood transfusions are used to treat anemia , and platelets may be administered to arrest thrombocytopenia

23. Syndromes Whole Body Exposure ( Gy ) Length of Time to Death Signs & Symptoms Site of Injury Length of Time to Recover to Survive Hemapoietic Syndrome 2 - 7 10 – 30 Days Infection, Hemorrhage, Anemia Hematopoietic stem cells of the bone marrow and spleen Before 10 – 30 days Gastrointestinal Syndrome 7 - 15 Within 14 Days Diarrhea, Dehydration, Lose of weight Basal epithelial cells of the intestinal villi 3 – 5 days Circulatory & CNS Syndrome 50 Few minutes to 48 hours Stupor, Incoordianation , Disorientation, Convusions Cardiac muscle, Nervous system Confirmed death

24. 3. Disease Caused By Radiation

25. Radiation sickness is illness and symptoms resulting from excessive exposure to ionizing radiation. results when humans (or other animals) are exposed to very large doses of ionizing radiation.

26. Cancer Carcinogenesis is the actual formation of a cancer, whereby normal cells are transformed into cancer cells. Radiation causes cancer by modifying DNA. Radiation induced gene mutation. Radiator acts as initiator (it induces change in the cells so that it no longer undergoes terminal differentiation) and also promoter ( stimulating cells to multiply ).

27. Thyroid Cancer is a disease that a person gets when abnormal cells begin to grow in the thyroid gland. The incidence of thyroid carcinomas that arise from the follicular epithelium increases in human beings after exposure. Only about 10% of individuals with such cancers die from their disease.

28. Susceptibility to radiation-induced thyroid cancer is greater early in childhood than at any time later in life, and children are more susceptible than adults. Females are 2 to 3 times more susceptible than males to radiogenic and spontaneous thyroid cancers.

29. E sophageal Cancer Esophageal cancer is malignancy of the esophagus. . Esophageal cancer usually begins in the cells that line the inside of the esophagus . Esophageal tumors usually lead to difficulty swallowing, pain and other symptoms.

30. Brain and Nervous System Cancers are the second most common type of childhood cancer. A brain tumor is a collection (or mass) of abnormal cells in the brain. Patients exposed to diagnostic x-ray examinations in utero and to therapeutic doses in childhood or as adults (average midbrain dose of about 1 Gy) show excess numbers of malignant and benign brain tumors .

31. Salivary Gland Cancer is a rare form of cancer that begins in the salivary glands. can begin in any of the salivary glands in your mouth, neck or throat. The incidence is increased in patients treated with irradiation for diseases of the head and neck, Japanese atomic bomb survivors, and persons exposed to diagnostic x radiation.

32. the risk being highest in persons receiving full-mouth examinations before the age of 20 years. Only individuals who received an estimated cumulative parotid dose of 500mGy or more showed a significant correlation between dental radiography and salivary gland tumors .

33. Leukaemia the most common cancer The incidence of leukaemia rises after exposure of the bone marrow to radiation. Leukaemia's appear sooner than solid tumors because of the higher rate of cell division and differentiation of hematopoietic stem cells compared with the other tissues. Persons younger than 20 years are more at risk than adults.

34. Mental Retardation a condition diagnosed before age 18 that includes below-average intellectual function and a lack of skills necessary for daily living. Studies of individuals exposed in utero have shown that the developing human brain is radiosensitive.

35. An estimated 4% chance of mental retardation per 100mSv exists at 8 to 15 weeks of gestational age, with less risk occurring from exposure at other gestational ages. During this period, rapid production of neurons and migration of these immature neurons to the cerebral cortex occur.

36. Cataract A cataract is a clouding of the lens in the eye that affects vision. The most common symptoms of a cataract are: - Cloudy or blurry vision. - Poor night vision. - Double vision or multiple images in one eye. (This symptom may clear as the cataract gets larger.) - Frequent prescription changes in your eyeglasses or contact lenses.

37. The threshold for induction of cataracts ranges from about 2 Gy when the dose is received in a single exposure to more than 5 Gy when the dose is received in multiple exposures over a period of weeks. Most affected individuals are unaware of their presence.

38. 4. Biological Effects on Radiation

39. Biological effects of ionizing radiation divided into 2 major categories: A) Deterministic effects: the effects in which the severity of response is proportional to the dose. These effects, usually cell killing, occur in all people when the dose is large enough. A dose threshold below which the response is not seen. B) Stochastic effects: the effects in which is the probability of the occurrence of a change, rather than its severity. It is either all-or-none : a person either has or does not have the condition.

40. Changes in biological molecules 1) N ucleic Acid T he damage to the deoxyribonucleic acid (DNA) molecule is the primary mechanism for radiation-induced cell death, mutation, and carcinogenesis. Radiation produces a number of different types of alterations in DNA, including the following: breakage of one or both DNA strands, cross-linking of DNA strands within the helix, to other DNA strands, or to proteins, change or loss of a base, disruption of hydrogen bonds between DNA strands.

41. The most important types of damage are single- and double-strand breakage. Most single-strand breakage is of little biologic consequence as the broken stand is repaired using the intact second strand as a template. However , misrepair of a strand can result in a mutation and consequent biologic effect. Double-strand breakage occurs when both strands of a DNA molecule are damaged at the same location or within a few base pairs. In this instance repair is greatly complicated by the lack of an intact template strand and misrepair is common . Double-strand breakage is believed to be responsible for most cell killing and carcinogenesis as well as mutation.

42. 2) Cells A) Cells are undamaged by the dose Ionization may form chemically active substances which in some cases alter the structure of the cells. These alterations may be the same as those changes that occur naturally in the cell and may have no negative effect. B) Cells are damaged, repair the damage and operate normally Some ionizing events produce substances not normally found in the cell. These can lead to a breakdown of the cell structure and its components. Cells can repair the damage if it is limited. Even damage to the chromosomes is usually repaired. Many thousands of chromosome aberrations (changes) occur constantly in our bodies. We have effective mechanisms to repair these changes.

43. C) Cells are damaged, repair the damage and operate abnormally If a damaged cell needs to perform a function before it has had time to repair itself, it will either be unable to perform the repair function or perform the function incorrectly or incompletely. The result may be cells that cannot perform their normal functions or that now are damaging to other cells. These altered cells may be unable to reproduce themselves or may reproduce at an uncontrolled rate. Such cells can be the underlying causes of cancers. D) Cells die as a result of the damage If a cell is extensively damaged by radiation, or damaged in such a way that reproduction is affected, the cell may die. Radiation damage to cells may depend on how sensitive the cells are to radiation.

44. 3) Tissues Generally , the radiation sensitivity of a tissue is: proportional to the rate of proliferation of its cells inversely proportional to the degree of cell differentiation This also means that a developing embryo is most sensitive to radiation during the early stages of differentiation, and an embryo/fetus is more sensitive to radiation exposure in the first trimester than in later trimesters Blood-forming organs Reproductive organs Skin Bone and teeth Muscle Nervous system Sensit-iv ity

45. 4) Organs Organ Relative Radio sensitivity Chief Mechanism of Parenchymal Hypoplasia Lymphoid organs; bone marrow; testes and ovaries; small intestines High Destruction of parenchymal cells, especially the vegetative of differentiating cells Skin; cornea & lens of eyes; gastrointestinal organs; cavity; esophagus ; stomach; rectum Fairly High Destruction of vegetable and differentiating cells of the stratified epithelium Growing cartilage; the vasculature; growing bones Medium Destruction of proliferating chondroblasts or osteoblasts; damage to the endothelism; destruction of connective tissue cells & chondroblasts or osteoblasts Mature cartilage or bone; lungs; kidneys; liver; pancreas; adrenal gland; pituitary gland Fairly Low Hypoplasia secondary damage to the fine vasculature and connective tissue elements

46. 5. RADIOSENSITIVITY AND CELL TYPE

47. The most radiosensitive cells are those that (1) have a high mitotic rate (2) undergo many future mitoses (3) are most primitive in differentiation. Mammalian cells may be divided into five categories of radiosensitivity on the basis of histologic observations of early cell death. Oral Radiology Principle and Interpretation (Fifth Edition), White Pharoah

48. Sources: Oral Radiology Principle and Interpretation (Fifth Edition), White Pharoah

49. Sources: Oral Radiology Principle and Interpretation (Fifth Edition), White Pharoah

50. Sources: Oral Radiology Principle and Interpretation (Fifth Edition), White Pharoah

51. 6. Differences of radiosensitivity of tissues

52. Radiosensitivity the level of harm which radiation can cause to certain types of cells in the body 3 levels: high Intermediate low radiosensitive

53. High Radiosensitivity organs, cells or structures are highly susceptible to the harmful effects of radiation 1. Lymphoid organs 2. Bone marrow 3. WBC 4. Testes 5. Ovaries 6. intestines 7. relatively HIGH : skin & organs with epithelial cell lining (cornea, oral cavity, esophagus , rectum, bladder, vagina, uterine cervix, ureters)

54. Intermediate Radiosensitivity This organs, cells or structures are moderately susceptible to the harmful effects of radiation neither severely affected nor completely unaffected show moderate signs of radiation injury

55. Intermediate Radiosensitivity 1. Optic lens 2. Stomach 3. Growing cartilage 4. Kidneys 5. Fine vasculature 6. Growing bone 7. Liver 8. Salivary glands 9. Thyroid gland

56. Low Radiosensitivity This organs, cells or structures are resistant to damage from radiation and are not affected by the harmful effects of radiation 1. Mature cartilage 2. Mature bones 3. RBC 4. Respiratory organs 5. Kidneys 6. Liver 7. pancreas 8. Thyroid 9. Adrenal gland 10. Pituitary glands 11. Muscle 12. Brain 13. Spinal cord

57. Radio R esistance

58. What is R adioresistance ? Radioresistance is the relative resistance to ionizing radiation Applicable to cells , tissues, organs, or organisms to the injurious effects of ionizing radiation Examples of highly radioresistant cells are fibrocytes , chondrocytes, myocytes and nerve cells.

59. Induced radioresistance 2 ways either protecting against a subsequent exposure to radiation that may be substantially larger than the initial 'conditioning' dose. or by influencing the response to single doses so that small acute radiation exposures.

60. 7. Classification of biological effect due to radiation

61. 3 CATEGORY OF EFFECT SOMATIC DETERMINISTIC EFFECT SOMATIC STOCHASTIC EFFECT GENETIC STOCHASTIC EFFECT

62. CLASSIFICATION OF EFFECT

63. 1. Somatic deterministic effect Definitely result from high dose of radiation Eg : skin reddening , cataract formation Severity of effect = dose received Below threshold = no effect

64. 2. SOMATIC STOCHASTIC EFFECT Development is random, depends on probability  no threshold dose Eg : Leukemia , tumors May induced when exposed to any dose of radiation Every exposure have possibility of stochastic effect

65. 3. GENETIC STOCHASTIC EFFECT Mutation result from sudden change in gene / chromosome Caused by external factor : radiation Radiation to reproductive organ No threshold dose

66. Effect on unborn child Major problem : a. congenital abnormality / death (high dose) b. mental retardation (low dose)

67. Harmful effect important in dental radiology Size of dose is small Below threshold = x cause Somatic deterministic effect Dental radiology x involve radiation to reproductive organ = x cause Genetic stochastic effect Most concern = somatic stochastic effect

68. Topik 4 ( Dosimetri )

69. 1. Definition of Dosimetry

70. Dosimetry : Determining the quantity of radiation exposure or dose Dose : used to describe the amount of energy absorbed per unit mass at a site of interest Exposure : a measure of radiation based on its ability to produce ionization in air under standard conditions of temperature and pressure (STP)

71. Radiation dosimetry is the calculation and assessment of the ionizing radiation dose received by the human body due to both external irradiation and the ingestion or inhalation of radioactive materials Internal dose is calculated from a variety of physiological techniques, whilst external dose is measured with adosimeteror inferred from other radiological protection instruments Dosimetry is used extensively forradiation protectionand is routinely applied to occupational radiation workers, where a radiation dose is expected, but regulatory levels must not be exceeded

72. 2. Types of Units for Measuring Quantities of Radiation

73. 1. Exposure A measure of radiation quantity, the capacity of radiation to ionize air SI unit : KERMA (kinetic  energy released per unit  mass) KERMA: the sum of the initial kinetic energies of all the charged particles liberated by uncharged ionizing radiation (neutrons and photons) in a sample of matter, divided by the mass of the sample.

74. 2.Radioactivity The measurement of radioactivity (A) describes the decay rate of a sample of radioactive material. SI unit: becquerel ( Bq ) The traditional unit is the curie (Ci)

75. 3. Calculation of Dose Radiation / Dosimetry

76. Radiation-absorbed Dose (D) measure of the amount of energy absorbed from the radiation beam per unit mass of tissue SI unit: Gray, ( Gy ) measured in joules/kg Subunit: milligray , ( mGy ) (x 10 3 ) original unit: rad conversion : 1 Gray = 100 rads

77. Equivalent Dose (H) measure which allows the different radiobiological effectiveness (RBE) of different types of radiation to be taken into account radiation weighting factor WR represents the biological effects of different radiations common unit allowing comparisons to be made between one type of radiation and another

78. Equivalent dose (H) = radiation-absorbed dose (D) X radiation weighting factor (WR) SI unit : Sievert ( Sv ) subunits : millisievert ( mSv ) (x 10 3 ) original unit : rem conversion : 1 Sievert =100 rems

79. Effective Dose (E) allows doses from different investigations of different parts of the body to be compared, by converting all doses to an equivalent whole body dose some parts of the body are more sensitive to radiation than others -> tissue weighting factor (W τ)

80. Effective dose (E) = equivalent dose (H) X tissue weighting factor (W τ) SI unit : Sievert ( Sv ) subunit : millisievert ( mSv )

81. Collective Dose used when considering the total effective dose to a population Collective dose = effective dose (E) x population SI unit : man- sievert (man- Sv )

82. Dose Rate measure of the dose per unit time E.g : dose/hour Convenient and measurable SI unit : microsievert /hour

83. 4. Typical dose s encountered in the x-ray machine By : Nur Hamimi 160110142017

84. 1) The average annual dose for radiation sources from x-ray machine is 54 millirem /year (Adapted from NCRP Report No. 94. Exposure of the Population in the United States and Canada from Natural Background Radiation. National Council on Radiation Protection and Measurements, Bethesda, MD, 1987.) 2)Dose limit values ​​with upper limit should not be exceeded. Because of radiation, a person would experience significant adverse or become ill. Therefore, upper limit is used as a reference so that any unnecessary exposure should be avoided and acceptance should be sought as low-dose.

85. Value to the general public dose limit - 5 mSv per year. For pregnant women - 10 mSv during pregnancy. 3) In local irradiation on specific parts of the body, the average dose in each organ or tissue affected by patient should not be > 50 mSv The maximum annual dose recommended for health care operators - 50 mSv . Lifetime maximum allowable - 10 mSv multiplied by the person's age in years .

86. 4)Medical uses of radiation are by far the largest source of man-made exposure of the public; the global yearly average dose -   0.3 mSv . 5)The National Radiological Protection Board (NRPB) and the Royal College of Radiologists' document Guidelines on Radiological Standards for Primary Dental Care, published in 1994, provides examples of typical effective doses for a range of dental examinations using different equipment and image receptors .

87. Thank you 