radiation
DESCRIPTION
Radiation. Prepared by: Timothy John D. Matoy. Radiation. Radiation is energy that comes from a source and travels through some material or through space. Energy emitted and transferred through space. The transfer of energy. 2 types of radiation. Non-ionizing radiation Ionizing radiation. - PowerPoint PPT PresentationTRANSCRIPT
Radiation
Prepared by: Timothy John D. Matoy
Radiation is energy that comes from a source and travels through some material or through space.
Energy emitted and transferred through space.
The transfer of energy.
Radiation
Non-ionizing radiationIonizing radiation
2 types of radiation
Capable of removing an electron from an atom
Ionizing Radiation
Natural Environmental Radiation
Man-made Radiation
2 Sources of Ionizing Radiation
Annual dose of approximately 300 millirem (mrem) (3 millisievert [mSv])
Cosmic rays, terrestrial radiation, internally deposited radionuclides
Natural Environmental Radiation
Approximately 60 mrem (0.6 mSv) annually
Medical imaging, nuclear power generation, research application, industrial sources, consumer items
Man-made Radiation
Diagnostic x-rays constitute the largest man-made source of ionizing radiation (39 mrem/year) (0.39 mSv/yr)
Man-made Radiation
Particulate radiationElectromagnetic radiation
Two Types of Ionizing Radiation
Particle radiation is the radiation of energy by means of fast-moving subatomic particles.
Particulate radiation
Alpha ParticlesBeta Particles
Particulate radiation
Alpha particles are high energy, large subatomic structures of protons and neutrons.
They can travel only a short distance and are stopped by a piece of paper or skin.
Alpha Particles
Beta particles are fast moving electrons. They are a fraction of the size of alpha particles, but can travel farther and are more penetrating.
Beta Particles
This kind of radiation is pure energy with no mass and is like vibrating or pulsating waves of electrical and magnetic energy. Electromagnetic waves are produced by a vibrating electric charge and as such, they consist of both an electric and a magnetic component.
Electromagnetic Radiation
Gamma raysX-rays
Electromagnetic Radiation
Quantities and Units
The inverse square law can be applied to distances greater than seven times the longest dimension of the source
Inverse Square Law
Inverse Square Law
Where:
I1 = Intensity at distance 1 I2 = Intensity at distance 2
d1 = distance 1 d2 = distance 2
Inverse Square Law
The intensity of light from a reading lamp is 100 millilumens (mlm), I2, at a distance of 1 m, d2. What is the intensity, I1, of this light at 3 m?
Sample Problem
For a given technique, the x-ray intensity at 1 m is 450 mR. What is the intensity at the edge of the control booth, at a distance of 3 m, if the useful beam is directed at the booth?
Sample problem
For a given technique, the x-ray intensity at 2 m is 170 mR. What is the intensity at a distance of 1 m?
Practice problem
A temporary chest radiographic imaging system is to be set up in a large hall. The technique used results in an exposure of 25 mR at 180 cm. The area behind the chest stand in which the exposure intensity exceeds 1 mR is to be cordoned off. How far from the x-ray tube will this area be extend?
A temporary chest radiographic imaging system is to be set up in a large hall. The technique used results in an exposure of 15 mR at 230 cm. The area behind the chest stand in which the exposure intensity exceeds 1 mR is to be cordoned off. How far from the x-ray tube will this area be extend?