1. { Radiation Biology Cellular Level Cell Sensitivity Radiolysis of Water Direct Effect/Indirect Effect Target Theory Radiation Effect Early Effects Prodromal/Latent period/Manifest Illness Hematopoietic Syndrome GI Syndrome CNS Syndrome Local tissue damage Late Effects Local Tissue Effect Life Span shortening Radiation Protection Time Distance Shielding Shield Types ALARA 1

2. Radiation Biology Radiation Biology History 1895-Roentgen announces discovery of X-rays 1896-(4 months later) Reports of skin effects in x-ray researchers 1902-First cases of radiation induced skin cancer reported 1906-Pattern for differential radiosensitivity of tissues was discovered. 2

3. Largest sources of man-made radiation are medical and dental x- rays Largest sources of man-made radiation are medical and dental x- rays. 3

4. 4 THE EARLY YEARS

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6. Radiation Biology Radiation can cause biological changes Technologists should have an understanding of: Cellular biology How radiation interacts with cells in order to protect oneself and the patient. 6

7. Cellular Level 7

8. { Cellular Levels Radiation passes thru individual without any damage to cells No damage Radiation causes injury to cell but cell is able to repair damage Injury/damage Cells repair but incorrectly causing deformity Cells incorrectly repair Radiation causes cell to die Cells die 8

9. Cell Sensitivity Early Effect:  radiation response occurs within minutes/days after exposure  acute radiation syndrome  local tissue damage  Late Effect:  radiation response not observable for months or years  leukemia cataracts  other cancers  local tissue damage  Life span shortening  genetic damage 9

10. Cell Sensitivity 1. Stem cells are radiosensitive. 2. The younger the tissues and organs, the more radiosensitive 3. When level of metabolic activity is high, radiosensitivity is high 4. As proliferation rate for cells and growth rate for tissues increases, the radiosensitivity increases. Law of Bergonie and Tribondeau 10

11. Cell Sensitivity Radiosensitivity High LymphocytesSpermatogoniaErythroblasts Intestinal crypt cells Intermediate Endothelial cells osteoblastsspermatidsfibroblasts Low Muscle cellsNerve cellsChondrocytes 11

12. Linear Response to radiation: 1.Non-threshold Assumes no dose is safe 2.Threshold assumes Minimum dose needed to produce a response A dose response relationship is produced by extrapolating high dose experimental data to low doses. 12

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14. Cell Sensitivity Diagnostic radiology is almost exclusively concerned with the late of effects for radiation exposure. This assumes a linear non-threshold dose- response relationship. However, no dose is considered safe. 14

15. Basic Cell Structure 1. Two parts: 1. Nucleus- contains DNA 2. Cytoplasm is 80% water 2. DNA is at risk when a cell is exposed to ionizing radiation 15

16. Cell Structure Genetic: Reproductive Cells Somatic: All other cells, non- reproductive cells 16

17. Ionization radiation interacts with a water (H 2 O). Water dissociates into 2 ions. This process creates free radicals. These are uncharged molecules containing as single unpaired electron in outer shell. 17

18. Radiolysis of Water 1. H 2 O molecules - 2. Ejection of electron = free radical 3. H2 0 2 = hydrogen peroxide 18

19. HOH + recombine to H 2 O 19

20. Direct Effect Photon ionizes “master molecule” Master molecule is destroyed, cell dies, damaged Indirect Effect Photon ionized non-critical molecule Transfer energy to master molecule Most frequently water molecules 20

21. Let’s Play Jenga !! 21

22. Target theory suggests that a key molecule must be inactivated. The key molecule is assumed to be DNA. When interaction occurs between radiation and target molecule, it is When interaction occurs between radiation and target molecule, it is considered a “hit” considered a “hit” An indirect hit has a larger target area because of the mobility An indirect hit has a larger target area because of the mobility of the free radicals of the free radicals Radiation acts randomly. Radiation acts randomly. 22

23. B3…..miss……..A4…..hit…….You sunk my Battleship!!! 23

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25. ACUTE RADIATION SYNDROME 25 ◊ Three different levels of exposure effects: ◊ Hematologic syndrome ◊ GI syndrome ◊ CNS syndrome Acute Radiation Syndrome – full body exposure given in a few minutes.

26. Early Effects Each syndrome has 3 main sub-stages prodromal stage latent stage manifest illness cell death/repair 26

27. Total Body Response to Radiation  Acute Radiation Syndromes – full body exposure given in a few minutes.  3 stages of response: 1. Prodromal -NVD stage (nausea, vomiting, diarrhea) 2. Latent Period-Feels well while undergoing biological changes 3. Manifest Illness-Full effects felt, leads to recovery or death 27

28. 3 Radiation Syndromes 1. Hematologic : results in infection, hemorrhage & anemia 2. Gastrointestinal : results in diarrhea, nausea & vomiting, fever 3. Central Nervous System : results in convulsions, coma, & eventual death from increased intracranial pressure. CNS least sensitive in ADULTS – CNS least sensitive in ADULTS – MOST sensitive in the FETUS MOST sensitive in the FETUS 28

29. Cherynobyl Fall out 29

30. Exposure in soil & water For Chernobyl: o 11,000 mrem- current background in red zones o 12 mrem is your average background radiation. o This is a thousand times greater than the normal background level of radiation o Approximately 15-20% of babies are born healthy. 30

31. Late Effects ◊ Late Effects ◊ Local Tissue Effect ◊ Erythema ◊ Cataracts ◊ Life Span Shortening ◊ Cancers/Malignancies ◊ Genetic Effects 31

32. Late Effects of Radiation 1. 1. Somatic Effects: develop in the individual who is exposed   Most common:   Skin Damage, Cataract formation & Carcinogenesis 2. 2. Genetic Effects: develop in future generations as a result of damage to germ cells. 32

33. Fukushima, Japan 33 Fukushima 50 occupational exposure due to rescue work After reading this article, write your thoughts on the rescue workers in Japan. Include allowable exposures to workers, possible acute affects, their prognosis for long term health.

34.  Cardinal Principles of Radiation Protection TimeDistanceShielding  ALARA Radiation Protection 34

35. { Cardinal Principles of Radiation Protection Time Distance and Shielding 35

36. Cardinal Principles of Protection  Triad of Radiation Safety 1. Time 2. Distance 3. Shielding *Apply to the patient & Technologist 36

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38. Over Radiation to Skin Too much time under beam Skin burns from 30 min of beam on time 38

39. Acute Localized Radiation Effects The Table 2-2 provides examples of possible radiation effects to skin caused by typical fluoroscopy exposures. Note that patient and technique factors can substantially increase exposure rates, significantly reducing the time necessary for the subsequent effect. Table 2-2: Dose and Time to Initiate Localized Radiation Effects 39.7 of an hour isapproximately 42 miutes

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41. This is an actual arm tatoo. Now that’s dedication ! 41

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43. Shielding A lead protective shield is placed  Between the x-ray tube and the individuals exposed  Absorbs unnecessary radiation 43

44. TYPES OF SHIELDING 1. Contact 2. Shaped 3. Shadow 44

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48. Breast Shield Shadow shields 48

49. SHIELDING 1. TECHNOLOGIST. 25 mm LEAD  Lead apron  Gloves  Thyroid shield  Glasses 2. PATIENT –. 5 mm LEAD  Gondal Shielding 49

50. As Low As Reasonably Achievable 50

51. Primary Barriers 51

52. Stay out of primary beam 52

53. Image Wisely Image Wisely website 53

54. PROTECTING THE PATIENT RISK VS.REWARD 54

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