WEEK 8
RADIATION BIOLOGY & PROTECTION Part 2

FINAL

Biological Response to
Ionizing Radiation

  1. Can cause ______changes
  2. Technologists should have an understanding of:
  3. Cellular biology
  4. How radiation ______with cells in order to protect oneself and the patient.

Early Effects of Radiaton

1

2

3

4

5

Late Effects of Radiaton

1

2

3

4

5

EFFECTS OF RADIATION

  1. Late effects:

A. ______effects

Individual exposed

B. ______effects

Future generations

Somatic Cells

  1. Perform all the ______
  2. Possess _____ of every gene on two different chromosomes
  3. Divide through the process of ______

Germ Cells

  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

B) ______Dose

  1. Skin erythema
  2. Catracts
  3. Sterility
  4. Malignancies

Cell Structure

  1. Biologic response to ionizing radiation depends on cell structure
  2. Comprised of:

Nucleus

Cytoplasm

Chromosomes (made up of genes)

Basic Cell Structure

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

Cell Type Examples

  1. ______:
  2. Skin cells
  3. Small intestine cells,
  4. Germ cells
  5. ______:
  6. Specialized in structure and function,
  7. Do not undergo repeated mitosis
  8. Nerve, muscle & brain cells

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).

The Law of
Bergonie & Tribondeaux

Cells that are most sensitive to radiation are:

  1. ______
  2. ______
  3. ______
  4. ______

RADIOSENSITIVITY OF CELLS

  1. Mitotic activity
  2. Specific characterisitics of the cell (primative)

Structure

Function

Cellular Response to Radiation

  1. ______before mitosis
  2. ______mitosis
  3. Failure to divide at ______mitotic rate

Cell Sensitivity

Radiosensitive Cells

1

2

3

4

5

6

Radioinsensitive Cells

1

2

3

4

5

6

Direct Hit and Indirect Hit

Cellular Absorption
Direct vs. Indirect Hit

______Theory:

  1. When radiation interacts with ____
  2. Break in the bases or phosphate bonds
  3. Can ______or ______the cell

______Theory:

  1. Occurs when ______molecules are ionized
  2. Produces chemical changes –
  3. Can ______or ______cell
  4. ______of cellular damage is from indirect hit

TARGET THEORY

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

Cell bombarded with photons
What damage will they cause?

Radiolysis
poison water theory

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

HOH+ recombine to H2O

Radiation Exposure
and Cancer

What are some of the causes of cancer?

Acute Radiation Syndrome

Full body exposure given within minutes

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

3 Radiation Syndromes

  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

  1. Genetic Effects: develop in future generations as a result of damage to germ cells.

Instances of Acute Radiation Exposure

1)

2)

3)

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

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.

Cherynobyl Fall out

Hiroshima
Nagasaki

US Nuclear Tests
1945 – 1992

Nevada Testing Sites

PROTECTING THE PATIENT

RISK

VS.

REWARD

ALARA

  1. AS LOW AS REASONABLY ACHIEVABLE
  2. The RADIOGRAPHER has the responsibility to:
  3. Obtain quality radiograph
  4. While minimizing the risk to the patient

Cardinal Principles of Protection

Triad of Radiation Safety

1. ______

2. ______

3. ______

*Apply to the patient & Technologist

NCR

  1. Time
  2. Distance
  3. Shielding
  4. Containment – for radioactivity

Time

  1. The exposure is to be kept as short as possible because the exposure is directly proportional to time.
  2. 20 mrem = 2min
  3. 10 mrem = 1min

Over Radiation to Skin
Too much time under beam

Shielding

  1. A lead protective shield is placed
  2. Between the x-ray tube and the individuals exposed
  3. Absorbs unnecessary radiation

Thickness of Lead Shielding

  1. LEAD APRONS MUST BE:
  2. ______mm of Pb or equivalent
  3. GONAD SHIELDS:
  4. ______mm of Pb or equivalent

Rules for Shielding

Must be shielded whenever the primary beam is within

______

of the reproductive organs

TYPES OF SHEILDING

  1. ______
  2. ______
  3. ______

Breast Shield
Shadow shields

SHEILDING

1. TECHNOLOGIST . 25 mm LEAD

•Lead apron

•Gloves

•Thyroid shield

•Glasses

2. PATIENT – . 5 mm LEAD

•GONAD SHEILDING

Primary Barriers

Stay out of primary beam

Proper shielding when holding
during an exposure (not a student)

Inverse Square Law

INVERSE SQAURE LAW FORMULA

Distance

Distance from the radiation source should be kept as great as possible

Physical Law:

- Inverse Square Law

Intensity is Spread Out

QUESTIONS ?