physics radiation

1. Radiation protection

2. Internal and external hazards of radiation
 Internal exposure to ionizing radiation occurs when a radionuclide is inhaled,
ingested or otherwise enters into the bloodstream (e.g. injection, wounds).
Internal exposure stops when the radionuclide is eliminated from the body,
either spontaneously (e.g. through excreta) or as a result of a treatment.
 External contamination may occur when airborne radioactive material (dust,
liquid, aerosols) is deposited on skin or clothes. This type of radioactive
material can often be removed from the body by simply washing.
 Exposure to ionizing radiation can also result from external irradiation (e.g.
medical radiation exposure to X-rays). External irradiation stops when the
radiation source is shielded or when the person moves outside the radiation
field

3.  Radiation damage to tissue and/or organs depends on
the dose of radiation received, or the absorbed dose
which is expressed in a unit called the gray (Gy).
 The potential damage from an absorbed dose depends
on the type of radiation and the sensitivity of different
tissues and organs.

4.  External exposure occurs when all or part of the body
is exposed to a penetrating radiation field from an
external source. During exposure this radiation can be
absorbed by the body or it can pass completely through,
similar to a chest x-ray
 All ionizing radiation sources produce an external
radiation field

5.  Internal
The other type of radiation injury involves contamination with radioactive
material. Contamination means that radioactive material in the form of gases,
liquids, or solids are released into the environment and contaminate people
externally (such as on the skin), internally (such as by ingestion), or both.
 Contamination by radioactive material can lead to incorporation of radioactive
material into the body. This can be the result of uptake of radioactive material by
body cells, tissues, and target organs such as bone, liver, thyroid, or kidney. In
general, radioactive materials are distributed throughout the body based upon
their chemical properties. For example, radioiodine, such as 125I, is concentrated
in the thyroid gland of the body, just as non-radioactive iodine does.
 All radioisotopes are potentially hazardous if inhaled or ingested. This includes
low energy isotopes such as 3H and 14C

9. External radiation hazards
 External hazard arise when radiation from a source external to the body
penetrates the body and cause hazard .
 Exposures can be from gamma or X rays ,neutrons,alpha particles or beta
particles.
 Most beta particles don’t normally penetrate beyond the skin,but when
sufficiently intense ,can cause skin and eye damage.
 Very energetic beta particles such as those emitted by P32 can penetrate several
mm into the skin.
 X rays gamma rays along with neutron radiation are very penetrating and are
of primary importance .

10.  The effects of acute radiation exposure ,diminished
RBC count may occur at a dose of approximately
100rads of acute whole body radiation.
 The LD50 for humans lethal dose where 50% of
exposed population may die from a one time exposure
of the whole body is about 500 rads

11. Internal radiation hazards
 Radioactive material may be internally deposited in the body when an uptake
occurs through one of the three routes
 Inhalation
 Ingestion
 Skin contact.
 These exposure can occur when radioactive material is airborne,is inhaled and
absorbed by the lungs and deposited in the body
 Present in contaminated food,drink or other consumeable items and is ingested
and absorbed or enters through cuts or cracks.

12.  Low energy beta,gamma and alphas can cause internal radiation exposures.
 Alpha particles create a high concentration of ions along their path can cause
severe damage to internal organs and tissues when they are inhaled, ingested
or are present on the skin.
 Internal exposures are not limited to the intake of large amounts at one
time(acute exposure)
 Chronic exposure may arise from the accumulation of small amounts of
radioactive materials over a long period of time.
 Iodine will accumulate in thyroid gland and deposited within 24 hours.

13.  Calcium ,strontium,radium and plutonium accumulate in
bones.
 Significant long term exposure to radioisotopes,chronic
disease such as leukemia and osteosarcoma can occur.
 Rule of thumb used to assist in biological risk
assessment for radiation.it states that most mature cells
are radioresistant,all immature cells are radiosensitive.

14. Main principle to control external hazard

15. Main principle to control external hazard

21. How the people are protected from radiations?
 There are four ways by which people are protected from
radiations?
1. Limiting exposure
2. Distance
3. Shielding
4. Containment