WEEK 8RADIATION BIOLOGY

Spring 2012

2

THE EARLY YEARS

3

4

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.

5

Early Effects of Radiaton (slide 6)

• 1 _____________• 2 _____________• 3 _____________• 4 _____________• 5 _____________

Late Effects of Radiaton

• 1 _______________• 2 _______________• 3 _______________• 4 _______________• 5 _______________

7

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

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 & GENETICSTOCHASTIC VS NON STOCHASTIC

A) ______________EFFECTS1. Genetic damage2. Leukemia3. Cancer4. Diagnostic radiology

BB) _______________Dose1. Skin erythema2. Catracts3. Sterility4. 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

DNA2. Cytoplasm is 80%

water

2. DNA is at risk when a cell is exposed to ionizing radiation

14

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

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 Cells123456

Radioinsensitive Cells123456

20

21

Example of cell sensitivity

Direct Hit and Indirect Hit

23

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

24

25

26

Cell bombarded with photonsWhat damage will they cause?

27

Radiolysispoison water theory

1. H 2 O molecules -2. Ejection of electron = free

radical 3. H2 0 2 = hydrogen peroxide

28

HOH+ recombine to H2O

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 changes3. ______________: 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 Hiroshima2) 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 – 1992

48

Nevada Testing Sites

49