What is Radiation? - Ab.ust.hk

Sources of Radiation affect human
Occupational:
less than 0.3%
Manmade:
18%
Natural
Background:
82%
Sources of Radiation
Man-made Radiation
The 4 major sources of man-made radiation
exposure are:
1. Medical Radiation (医疗辐射 医疗辐射 医疗辐射) 医疗辐射
2. Radioactive Fall out (核爆扩散 核爆扩散 核爆扩散) 核爆扩散
3. Industrial Applications (工业应用 工业应用 工业应用) 工业应用
4. Consumer Products (消费产品 消费产品 消费产品) 消费产品
Biological Effects (生物效应 生物效应 )
Deterministic Effects (确定性效应
确定性效应
确定性效应):
确定性效应
• generally a threshold dose level exist.
• effect shown out when receive dose greater
threshold level.
e.g. : eye receive radioactive dose of 1 Sv, cataract
(白內障 白內障 白內障) 白內障 occurs.
Stochastic Effects (随机性效应
随机性效应 ):
• generally without a threshold dose level.
• higher the dose, higher risk of the effect.
e.g.: cancer induction.
Sources of Radiation
Natural Background - radiation received from:
1. Cosmic Rays (宇宙射线)
2. Terrestrial Radiation (陸地輻射)
3. Food
4. Radon (氡氣)
Background is generally the main source of
radiation exposure to a population
Radiation Hazard
External Hazard (外照射危害):
Neutrons > Gamma/X > Beta > Alpha
Internal Hazard (內照射危害):
Alpha > Beta > Gamma/X
(intakes of neutron sources are rare.)
Radiation Damage on Cells
• Each organ of the human body is made
up of specialized cells.
• Ionizing radiation can potentially affect
the normal functioning of these cells.
• Radiation can damage or kill cells.
Some damages are repaired. Improper
repairs may cause potential health
effects.