Radioactive Material:

Radioactive Material:
When these excess neutron do not upset the balance of the nucleus. Then this new isotope is said to be “ Stable”
When these excess neutrons do upset the balance of the nucleus this isotope is unstable and will disintegrated or decay in to a more stable form.

Unstable Atoms are said to be radioactive.

Some radioactive isotopes are found in nature such as radium and uranium.

Identification of Elements:

Identification of Elements:
Atomic Number or Z number is the number of protons in the nucleus of the atom and is used for identifying basic elements. Therefore an atom of beryllium with 4 protons would have a “Z” number of 4.
Basic elements may also be identified by their weight.
Mass number or “A” number is combination of protons and Neutrons. ( Heavy Parts of the Atom)
Each atom is then assigned a number equal to the total number of protons and neutrons in the nucleus. As shown below the beryllium atom has a “Z” number of 4 and an “A” number of 9.

Structure of Atom:

Structure of Atom:
All Atoms are composed of three basic particles.
1. Proton : Has a positive charge and is relatively heavy.
2. Neutron : About the same size and weight as the proton but has no electrical charge.
3. Electron : Very light particle about 1/1840 of the weight of a proton it has a negative charge.
The number of the particle determines the kind of atoms it is.
There are over 100 different kind of atoms know and they are called elements and given a name oxygen, copper and lead and some common element.
Element or combinations of elements ( Molecules) from all the things we see every day living.
For example there are billions of atoms in the tips of a pencil with over 99.99 % of each atoms being empty space.
A very simple atom is that of the element Helium.

Radiography Sensitivity:

Radiography Sensitivity:
Sensitivity of radiography is a function of the “ Contrast “ and the “ Definition “ of the radiography. Contrast is the comparison between film densities for different areas of the radiography .
Sensitivity of radio graph is a function of the “ Contrast “ and the “ Definition “ of the radiography. Contrast is the comparison between film densities for different areas of the radiography

Properties Of X-Ray & Gamma Rays

Properties Of X-Ray & Gamma Rays:
The formation of an image on the film depends upon the amount of radiation received by different section of the film. As below. A discontinuity such as a void represents a thickness difference in the specimen and will appear as a dark spot on the developed film.

Properties of X-Rays and Gamma Rays.

Properties of X-Rays and Gamma Rays.

  • They are not detected by human senses (cannot be seen, heard, felt, etc.).
  • They travel in straight lines at the speed of light.
  • Their paths cannot be changed by electrical or magnetic fields.
  • They can be diffracted to a small degree at interfaces between two different materials.
  • They pass through matter until they have a chance encounter with an atomic particle.
  • Their degree of penetration depends on their energy and the matter they are traveling through.
  • They have enough energy to ionize matter and can damage or destroy living cells.