week 8 radiation biology spring 2012. 2 the early years
TRANSCRIPT
WEEK 8RADIATION BIOLOGY
Spring 2012
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THE EARLY YEARS
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Biological Response toIonizing 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.
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Early Effects of Radiaton (slide 6)
• 1 _____________• 2 _____________• 3 _____________• 4 _____________• 5 _____________
Late Effects of Radiaton
• 1 _______________• 2 _______________• 3 _______________• 4 _______________• 5 _______________
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8FIG. 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
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Somatic Cells (SLIDE 29)
1. Perform all the __________________.
2. Possess ___ of every gene on two different chromosomes.
3. Divide through the process of ____________
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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 & GENETICSTOCHASTIC VS NON STOCHASTIC
A) ______________EFFECTS1. Genetic damage2. Leukemia3. Cancer4. Diagnostic radiology
BB) _______________Dose1. Skin erythema2. Catracts3. Sterility4. Malignancies
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Cell Structure
1. Biologic response to ionizing radiation depends on cell structure
2. Comprised of:– Nucleus– Cytoplasm– Chromosomes (made up of genes)
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Basic Cell Structure
1. Two parts:1. Nucleus- contains
DNA2. Cytoplasm is 80%
water
2. DNA is at risk when a cell is exposed to ionizing radiation
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Cell Type Examples
1. ______________________ 1. Skin cells2. Small intestine cells,3. Germ cells
2. ________________________: 1. Specialized in structure and function, 2. Do not undergo repeated mitosis
1. Nerve, muscle & brain cells
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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).
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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
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Cellular Response to Radiation
1. _________before mitosis
2. _______________ mitosis
3. Failure to divide at __________ mitotic rate
Cell Sensitivity
Radiosensitive Cells123456
Radioinsensitive Cells123456
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Example of cell sensitivity
Direct Hit and Indirect Hit
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Cellular AbsorptionDirect 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 THEORY1. 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
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Cell bombarded with photonsWhat damage will they cause?
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Radiolysispoison water theory
1. H 2 O molecules -2. Ejection of electron = free
radical 3. H2 0 2 = hydrogen peroxide
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HOH+ recombine to H2O
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Radiation Exposure and Cancer
What are some of the causes of cancer?
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Acute Radiation Syndrome
Full body exposure given within minutes
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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 changes3. ______________: Full effects felt, leads to recovery or death
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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.
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Instances of Acute Radiation Exposure
1) Nagasaki and Hiroshima2) Chernobyl
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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
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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.
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Cherynobyl Fall out
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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
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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
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US Nuclear Tests 1945 – 1992
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Nevada Testing Sites
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