WEEK 8 RADIATION BIOLOGY Spring 2012

2 THE EARLY YEARS

3

4

Biological Response to Ionizing Radiation (Slide 5) 1.Can causes ___________changes 2.Technologists should have an understanding of: 1.Cellular biology 2.How radiation ___________with cells in order to protect oneself and the patient. 5

Early Effects of Radiaton (slide 6) 1 _____________ 2 _____________ 3 _____________ 4 _____________ 5 _____________

Late Effects of Radiaton 1 _______________ 2 _______________ 3 _______________ 4 _______________ 5 _______________ 7

8 FIG. 9–7 Graph indicates no-threshold versus threshold response to radiation. Elsevier items and derived items © 2007, 2003 by Saunders, an imprint of Elsevier Inc. Linear Response to radiation: 1.Assumes _______ is safe 2.Diagnostic radiation: __________________ 3.____ dose over ___period of time 4.Early Radiology Exposure 5. ________________ Amount needed to see affect

EFFECTS OF RADIATION 1.Late effects: A. _______________ Individual exposed B. ________________ effects Future generations 9

10 Somatic Cells (SLIDE 29) 1.Perform all the __________________. 2.Possess ___ of every gene on two different chromosomes. 3.Divide through the process of ____________

11 Germ Cells (SLIDE 30) 1.______________ cells of an organism. 2._____________ the number of chromosomes as the somatic cells. 3.Reproduce through the process of ________

SOMATIC & GENETIC STOCHASTIC VS NON STOCHASTIC A) ______________EFFECTS 1.Genetic damage 2. Leukemia 3.Cancer 4.Diagnostic radiology BB) _______________Dose 1.Skin erythema 2.Catracts 3.Sterility 4.Malignancies 12

Cell Structure 1.Biologic response to ionizing radiation depends on cell structure 2.Comprised of: – Nucleus – Cytoplasm – Chromosomes (made up of genes) 13

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 14

Cell Type Examples 1.______________________ 1. Skin cells 2. Small intestine cells, 3. Germ cells 2.________________________: 1.Specialized in structure and function, 2.Do not undergo repeated mitosis 1. Nerve, muscle & brain cells 15

Radiosensitivity of Cells 1.Bergonie & Tribondeau (1906) – method of classifying a cell’s response to radiation according to sensitivity. 2.Cells are most sensitive during active division (primitive in structure & function). 16

17 The Law of Bergonie & Tribondeau Cells that are most sensitive to radiation are: _________________

RADIOSENSITIVITY OF CELLS 1.Mitotic activity 2.Specific characterisitics of the cell (primative) – Structure – Function 18

19 Cellular Response to Radiation 1._________before mitosis 2._______________ mitosis 3.Failure to divide at __________ mitotic rate

Cell Sensitivity Radiosensitive Cells Radioinsensitive Cells

21 Example of cell sensitivity

Direct Hit and Indirect Hit

23 Cellular Absorption Direct vs. Indirect Hit Direct Hit Theory: 1.When radiation interacts with _____ 2.Break in the bases or phosphate bonds 3.Can _____or ____ the cell Indirect Hit Theory: 1.Occurs when ____molecules are ionized 2.Produces chemical changes – 1.Can _____ or _______cell 3.__________ of cellular damage is from indirect hit

TARGET THEORY 1.Photons hit master molecule DNA 1. cell dies 2.Doesn’t hit nucleus – 1.Passes through 2.No essential damage 3.Hormoresis 1.repair that can occur when below 5 rads of expsoure 24

25

26

Cell bombarded with photons What damage will they cause? 27

Radiolysis poison water theory 1.H 2 O molecules - 2.Ejection of electron = free radical 3.H2 0 2 = hydrogen peroxide 28

HOH + recombine to H 2 O 29

Radiation Exposure and Cancer What are some of the causes of cancer? 30

31

32

Acute Radiation Syndrome Full body exposure given within minutes

34

35 Total Body Response to Radiaiton _____________________________– full body exposure given in a few minutes. 3 stages of response: 1. ______________: NVD stage (nausea, vomiting, diarrhea) 2. ______________: Feels well while undergoing biological changes 3. ______________: Full effects felt, leads to recovery or death

36 3 Radiation Syndromes (SLIDE 49) 1._______________________: results in infection, hemorrhage & anemia 2._______________________: results in diarrhea, nausea & vomiting, fever 3.________________________: results in convulsions, coma, & eventual death from increased intracranial pressure. CNS least sensitive in ADULTS – MOST sensitive in the FETUS

Late Effects of Radiation 1.Somatic Effects: develop in the individual who is exposed – Most common: Cataract formation & Carcinogenesis 2.Genetic Effects: develop in _____________ as a result of damage to germ cells. 37

Instances of Acute Radiation Exposure 1) Nagasaki and Hiroshima 2) Chernobyl 38

39

Cherynobyl - immediately Shortly after the blast – 20 R in less than 1 minute – clean up crew – fireman – 600,000 “liquidators” exposed A pilot saw a village where the dosimeter, the reading had gone off the scale – 500 roentgen per hour: – 'Above 500, the equipment - and human beings - aren't supposed to work. – he had flown in 1,500 roentgen an hour of expoure 40

Exposure in soil & water 1.11,000 mrem- current background in red zones 2.12 mrem is your average background radiation. 3. This is a thousand times greater than the normal background level of radiation 4.Approximately 15-20% of babies are born healthy. 41

Cherynobyl Fall out 42

43

44 This is Julia, who is four years old and her brain is not within her skull, it’s actually a separate entity onto the back of her head INCREASE IN BIRTH DEFECTS, CNS & BRAIN INJURY 250x MORE

45

46 BELARUS. Minsk. Children’s Home No 1. This hospital receives many of the most deformed babies soon after birth. Nurse Alla Komarova hugs 3-year-old Yulya, whose brain is in a membrane in the back of his head. 250X more birth defects / Mental Illness / Turmors

Hiroshima Nagasaki 47

US Nuclear Tests 1945 –

Nevada Testing Sites 49