RADIOBIOLOGY P1

“Radius”

radio Comes from the

Latin word

Ray

“Radius”

meaning

life

bio meaning

radiobiology

as low as reasonably achievable

alara

atomic level

high px dose

con of high mas

fog

con of high kvp

tube loading

con of high sid

quantum mottle

con of low mas

high px dose

con of low kvp

low spatial resolution

con of low sid

Ionization & Excitation

What process occurs when X-rays remove or excite electrons in atoms?

Deposition of Energy in Tissue

What happens when X-ray energy is absorbed by biological tissue?

Deterministic Effects

These occur only if radiation dose exceeds a certain level.

Stochastic Effects

These effects can occur at any dose, even very low ones.

Syndrome

– a group of symptoms which consistently

occur together, or a condition characterized by a set

of associated symptoms.

Severity increases as dose increases

What happens to severity as dose increases in deterministic effects

The chance or incidence of the effect

What increases with dose in stochastic effects

no

Does severity increase with dose in stochastic effects

Deterministic Effect

Occurs within days

after the radiation

exposure

Stochastic Effect

Not observed for

months or years

atomic composition

The character and degree of Radiation Interaction

depends on the___ of the body

atoms

The human body is composed of

molecular and tissue

composition

defines the nature

of the radiation response

Robert Hooke

In 1665, named the Cell, as

the biologic building block

1665

Robert Hooke In___, named the Cell, as

the biologic building block

Antonvan

Leeuwenhoek

In 1673, accurately described

a living cell through his

microscopic observations

1673

Antonvan

Leeuwenhoek In ___, accurately described

a living cell through his

microscopic observations,

Schneider & Swann

In 1838, showed conclusively

that in all plants and animals,

cells are the basic functional

units.

Deoxyribonucleic Acid

DNA

Watson and Crick

1953, Description of the molecular

structure of DNA as the genetic

substance of the cell

Human Genome Project

HGP

Positron Emission Tomography

PET

ingle Photon Emission Computed Tomography)

SPECT

❖Water

❖Protein

❖Lipids (fats)

❖Carbohydrates (sugars and starches)

❖Nucleic Acid

5 principal types of molecules found in the body:

macromolecules

❖Protein

❖Lipids

❖Carbohydrates

❖Nucleic Acid

Organic Molecules

❖Protein

❖Lipids

❖Carbohydrates

molecules that are Life supporting and

contains carbon

(DNA)

most critical and

radiosensitive target

molecule

❖Nucleic Acid

Rarest Molecule

❖Water

Most abundant & simplest molecule

❖Water

Plays an essential role in

delivering energy to

molecules-- Thereby

contributing to radiation

effects.

composition of water

Perspiration and Respiration

Water is lost through

Homeostasis

Relative constancy of the human body’s internal environment

Metabolism

set of chemical processes in your body's cells that

convert food and drink into energy

Catabolism

Breaking of Macromolecules to

Smaller units

Anabolism

Production of large molecules

from Small

Protein

Long-chain of macromolecules consisting of a linear sequence of Amino Acids

connected by peptide bonds

Protein

Long-chain of macromolecules consisting of a linear sequence of Amino Acids

connected by peptide bonds

Protein

Long-chain of macromolecules consisting of a linear sequence of ___

connected by ___

protein synthesis

the process by which cells make proteins

Twenty-two amino acids

How many amino acids are used in protein synthesis

At least two amino acids

What is the minimum number of amino acids needed to form a protein

Enzymes, hormones, antibodies

What are the three important functional roles of proteins in the body

Enzymes

Molecules necessary to allow continuation of biochemical

reactions.

❖ They do or do not directly enter into the reaction.

Hormones

Molecules that exercise regulatory control of some

bodily functions e.g., growth and development

Antibodies

Primary defense mechanism of the body against

infection and disease.

antigen

The precision of an antibody’s molecular configuration

varies on its design for attacking a particular type of

antigen

Invasive or infectious agent

1. Carbon

2. Hydrogen

3. Oxygen

Lipids Composed solely of:

1 Glycerol

3 Fatty Acid

Lipids Composed of 2 smaller molecules

Lipids

Present in all tissues of the body

❖ Structural components of cell membranes

❖ Concentrated just under the skin

❖ Acts as thermal insulator

❖ Serves as energy stores for body fuel

❖ Harder to extract them stored energy

❖ Excess storage may lead to OBESITY

Carbohydrates

Aside from Lipid, what

also serve as fuel for

the body by providing

energy stores?

Composed solely of:

1. Carbon

2. Hydrogen

3. Oxygen

Carbohydrates ❖ Composed solely of:

2:1

In a Carbohydrate, ___ ratio of

Hydrogen to Oxygen

Saccharides

Carbs is aka

In plants

Where is starch stored

In animals

Where is glycogen stored

glucose

DNA RNA

2 Principal Nucleic Acid Important to Human Metabolism

DNA

RNA

mRNA

❖ Copies the instructions from DNA

❖ It tells the factory (cell) what to make

tRNA

Brings the building blocks (amino acids)

to the factory

Deoxyribose (a sugar)

and Phosphate

DNA consists of a “backbone” composed of

alternating segments of:

1. Adenine

2. Guanine

3. Thymine

4. Cytosine

Attached to each Deoxyribose is one of four

different nitrogen-containing organic bases:

Nucleotides

– base sugar-phosphate combination

DOUBLE-HELIX

DNA exists as these 2 long chains attached

together in ladder fashion This ladder is then twisted

❖ Producing a ____

Adenine

2. Guanine

Purines

3. Thymine

4. Cytosine

Pyrimidines

Adenines bonded to Thymines

❖ Cytosines bonded to Guanines

Sequence of Base Bonding is limited to:

single

RNA is double or single helix?

Ribose

in RNA Sugar Component

is ___ instead

of Deoxyribose

uracil

WHAT replaces thymine as a base component in RNA

Nucleus, Cytoplasm

2 Major Structures of the Cell

DNA

principal

molecular component

of the Nucleus

Cytoplasm

Contains great quantities

of all molecular

components except DNA

Endoplasmic Reticulum

channel allowing nucleus to

communicate with the cytoplasm

Mitochondria

large bean-shaped structures

- site where Macromolecules are

digested to produce energy;

- engine of the cell

Ribosomes

Small, dot-like structures.

- Site of protein synthesis

- Scattered throughout the cytoplasm

or the endoplasmic reticulum.

❖ Lysosomes

Small, pea-like sacs

- Contain enzymes for digestion of

cellular fragments

- Helps control intracellular

contaminants

codon

Codon

is a set of three bases on mRNA

Ribosome

reads the mRNA one codon at a time

tRNA

It has an anticodon that matches the mRNA codon

anticodon

tRNA has an___ that matches the mRNA codon

stop codon

When a ___ is reached, the protein is finished

Genetic, Somatic

2 general types of cells inside the human body

Genetic

cell that Carry hereditary information

Somatic

All other body cells that make up

tissues and organs