Nature of Radiation 2

Isotopes 2

Atoms that have the same atomic number different atomic mass number

Isotopes

contain the same number of protons but varying number of neutrons

Radioactivity

the spontaneous emission of particles and energy to become stable

Radionuclides

The nuclei going through radioactivity decay

Radioisotopes - affect nuclear stability

The most important factor in nuclear stability is the number of neutrons

Radioactive decay can result in

alpha emission, beta emission, positron emission, and gamma rays

Alpha particles

consist of 2 protons and 2 neutrons, atomic mass of 4 (Helium)

Beta decay

occurs more frequently than alpha emission

in order to emit an alpha particle

a nucleus must be extremely unstable to emit an alpha particle, loses 2 units of positive charge, only heavy radioisotopes are capable of alpha emission

what is capable of alpha emission?

radioisotopes

where is an electron created?

from the nucleus of an atom

during beta emission

An electron created in the nucleus is ejected from the nucleus with

considerable kinetic energy, results in loss of small quantity of mass and one unit of negative electric charge from the nucleus of the atom, simultaneously, a neutron undergoes conversion to a proton

Positron decay

a proton transforms into a neutron producing a positron (e+)

Gamma rays

no mass, no charge, travel at the speed of light

Gamma rays are emitted…

from the nucleus of a radioisotope, usually associated with alpha or beta emission

α

alpha symbol

β

beta symbol

γ

gamma ray symbol

alpha particles approximately

ionizes 40,000 atoms/cm of travel through air (energy is lost quickly)

Beta particles

beta particle range is linear compared to alpha particles (can travel 10-100cm of air, 1-2cm of soft tissue)

kVp range of diagnostic xrays

30-150 kVp

Radioactive Half life

time required for a quantity of radioactivity to be reduced to one-half its original value

Why does half-life matter?

has an exact parallel in x-ray terminology

Radioactive half life

the time required for a quantity of radioactivity to be reduced to one half its original size