week 8 radiation biology spring 2012. 2 the early years

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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