High Level Exposure To Portions Of The Body :
High Level Exposure to The Whole Body :
After reading all of the above subjects and you still don't know what is dangerous read this section.
PLAIN TALK ABOUT RADIATION.
First of all you should always be aware of the risks around you and minimize your exposure by utilizing good common sense. Now that I said that I would like to get into the subject of radiation and you.
There are two kinds of radiation that you should be aware of. One is the cosmic radiation and that's the one that comes from the outer space and we have no control over. The other is Earth sourced radiation and that can be divided into two categories. The first is radiation that is emitted from the Earth itself. It comes from all of the different oars and minerals in the ground. The second is man-made radiation. This Radiation the comes from power plants, medical facilities, industrial plants and of course our government experimenting with the weapons using depleted uranium. See: http://www.workers.org/du/
Cosmic radiation is a very low-level radiation and it is not dangerous to us. Radiation that can be dangerous is Alpha, Beta, Gamma and X-Rays generated on Earth. Now you ask, how much radiation is safe? The answer to this is not that easy and will require an example.
Alpha particles are of the lowest energy of radiation in fact putting a piece of paper between a source and a detector will stop almost all of the alpha particles. Also alpha particles will be stopped by your skin and they cannot enter your body in this matter so this means that they cannot cause damage, well this is not entirely true. If you have an alpha source that is in the form of a powder, like dust and this dust is ingested by putting it on food this dust could stay in your stomach or intestines and over a long period of time cause cancers. Yet the same dust applied to your skin would probably not harm you because it would be washed off. Also if the dust was airborne and you breathe it into your lungs it could stay there causing cancer. The same is true for Beta. Here is an excerpt from a web page on uranium:
(The alpha radiation of the 8 alpha emitting nuclides contained in the U-238 series (and to a lesser degree, of the 7 alpha emitters in the U-235 series) presents a radiation hazard on ingestion or inhalation of uranium ore (dust) and radon.)
To see more go to: http://www.antenna.nl/wise/uranium/rup.html#DUMETAL
If you have a Geiger counter that is capable of reading Alpha and Beta in the range of .05mR/Hr. you could probably find radiation in the dust in your house. If you are a camper or use lanterns that burn gas Be very careful when handling lantern mantles.
Some of them contain thorium a Beta source. Leave them in the plastic bag. There are health threats involved with breathing or ingesting beta sources. Once lodged inside your body, a beta emitter can remain there for extended periods of time, subjecting the cells surrounding the particles to continuous beta bombardment. One should take great care when replacing a lantern mantle and particularly should avoid breathing lantern mantle ash or getting it on food.
DEFINITIONS
NUCLEAR MEDICINE IMAGING
Nuclear medicine is the process of injecting radioactive material or breathing radioactive gases to visualize organ functions by using an external detector. There are many methods used to create images of the body. Some are Gamma Camera Imaging, Single Photon Emission Computed Tomography (SPECT) and Positron Emission Computed Tomography (PET).
DOSE
The quantity of ionizing radiation exposure is measured in terms of ionizations called roentgens but may also be measured in terms of energy absorbed called rads or rems. The range of measured dose is from thousands of units to one thousandth of a unit.
R = roentgen -The special unit of exposure, 2.58 x 10-4 Coulomb per kilogram of air under standard conditions. There is no special unit for exposure. The "International System of Units" (SI) developed a set of rules for units of measurements that will replace the radiation units defined here.
Rad -Unit of absorbed dose is the energy imparted to matter (such as tissue) by ionizing radiation per unit mass of irradiated material at the place of interest. For X or gamma rays, 1R of exposure will produce about I rad of absorbed dose in soft tissue.
Gy=(Gray) -The SI unit of absorbed dose I Rad=0.01 Gy
Rem- Roentgen equivalent man. A special unit of dose equivalent. The dose equivalent in rems is numerically equal to the absorbed dose in rads multiplied by a factor weighted for relative biological effect on the tissue being exposed, For routine protection calculations of exposure to X-Rays IR I rad @ I rem. Reported doses are sometimes in millirems. One millirem = one thousandth of a rem. Milli is abbreviated m in this text: millirem = rnRem.
Sv=(sievert) -The 51 unit dose equivalent I Rem=0.01 Sv
Acute Exposure- Radiation exposure of short duration.
Chronic Exposure -Radiation exposure of long duration either continuous or by repeated exposures.
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To get the hourly rates divide the yearly rates by 8760. ex: 200mR/Yr = 200/8760 = .023 mR/Hr.
Maximum natural radiation (Background) would be .035 mR/Hr.
All radiation exposure is of concern. When working around sources of radiation you should be aware of the possible risks. Allowable levels of personal exposure will vary depending on the situation.
Limits of total exposure for radiation workers have been established as shown in the table on this page, but in any radiation work the limits that are actually received should be As Low As Reasonably Achievable (ALARA).
The greatest radiation risks are from exposures which will produce symptoms in a short period of time. This kind of an exposure is on the order of hundreds of rem and will not be encountered from routine radiation sources. However, smaller repeated doses can accumulate and cause radiation induced injuries. Safe work habits are of concern to everyone.
The effects of radiation are influenced by many factors.
HIGH LEVEL ACUTE AND CHRONIC EXPOSURES TO LIMITED PORTIONS OF THE BODY
The portion of the body irradiated is an important exposure parameter. The larger the area exposed, other factors being equal, the greater the overall damage to the organism. Exposure of specific parts of the body is routinely used in the treatment of cancer and other serious illnesses. A beam of penetrating X-Rays or gamma rays can be focused on the tumor regardless of its location or depth. In such cases, a large dose can be directed at a very small part of the body and the risks are accepted for the total benefit of the patient.
Any exposure to a developing fetus at its most sensitive stage (up to 3 months) may be enough to produce malformations, and a dose as small as 20 rads to the thyroid region of infants has been related to later incidence of thyroid cancer. A lethal dose of radiation to some people could be from 200 to 500 rads of whole body exposure in a short time. However, short-time doses of 200 to 500 rads to limited portions of the body may result in temporary sterility, local inflammation, temporary loss of hair, depression of blood forming cells in bone marrow, etc. On the other hand, radiologists may give up to 6,000 rads in local areas for the treatment of cancer with only reversible short-term reactions and moderate late atrophic changes. Following treatment, other changes must be watched for, such as additional cancer, aseptic bone necrosis, radiation cataracts, etc.
DISTANCE
Distance is very effective and, in many cases, the most easily applied method of radiation protection. The inverse square law for reduction of radiation intensities which applies to most sources of x and gamma radiation shows that radiation intensity falls off very rapidly as the distance increases. For example, if you double the distance from the source of radiation you decrease the intensity of the radiation by a factor of four. Therefore, for greatest radiation safety, you should stay as far from the sources of radiation as possible while doing the necessary work.
SHIELDING
Any material placed between the source of radiation and the occupied area will absorb some of the radiation and thus reduce its intensity. The more material used, and the greater its density, the more radiation it will stop. Because of the statistical nature of radiation shielding, it is impossible to eliminate all transmitted radiation, but the radiation can be reduced to levels that are considered acceptable to work around.
Good shielding begins with properly designed enclosures for the radiation source so that no large amount of radiation comes out except through the desired exit window. Collimators must be provided to restrict the beam to the area of interest.
Good shielding is essential to reduce the occupational exposure of working personnel and minimize unnecessary patient exposure. Low occupational exposures can be maintained by rigorous attention to shielding design, and the use of accessory shields.
TIME
When working with radiation sources, the more time you are exposed to the source, the more radiation exposure you will receive. Radiation exposure should be controlled so that radiation is not being produced unless there is some useful application for its use. Since all radiation you receive is significant to you, always keep your exposure to a minimum by using radiation sources only when necessary.
CONTAMINATION CONTROL
When working with radioactive materials, there is always a possibility of source spillage or breakage and spread of radioactive contamination. When a source is broken or thought to be leaking, it should be isolated from all personnel and the Radiation Safety Officer notified immediately. The basic steps to follow in contamination control are:
1. Prevent loose radioactive material from getting on clothes or skin.
2. Guard against ingesting any radioactive material.
3. Contain loose radioactive material from spreading.
4. Have trained personnel clean up contamination and monitor personnel and area for radiation levels.