Understanding Radiation Measuring Devices and Their Importance
Radiation Measuring Devices
For security reasons and due to ionizing radiation that cannot be detected by the body, it is essential to use equipment that can detect radiation whenever a person is exposed to ionizing radiation, such as:
- Radiation Detector Photographic Emulsion: This device is composed of a cellulose acetate film, to which silver atoms are added in photographic emulsions. The film is very thin, allowing it to change when in contact with radiation. It is then taken to a laboratory and compared with a clean film to check the degree of darkening, which indicates the amount of radiation that has been trapped by the film.
- Gaseous Ionization Detector: Based on the principle of collecting ions formed by the action of ionizing radiation on a particular gas, this device analyzes air or inert gases such as helium, argon, and krypton. These gases are enclosed in a metal cylinder that forms the cathode, with a wire in the center acting as the anode. When subjected to ionizing radiation, the gas in the tube is ionized, becoming an electrical conductor. The power transferred is measured in proportion to the amount of ionizing radiation present in the environment.
- Radiation Scintillation Detector: This detector identifies radiation through the flashes of light produced in certain crystals by the radiation they emit. These flashes are captured and converted into electrical impulses using a photomultiplier, which amplifies the signal and conducts the survey to determine the intensity of the radiation exposure.
- Thermoluminescence Detector: Some crystals emit light when heated after being exposed to ionizing radiation. These are known as thermoluminescent crystals, which are used to measure radiation doses. They are utilized as plates and rings that are analyzed in a laboratory to determine the cumulative radiation dose.
- Quartz Dosimeter Direct Reading Personal: This dosimeter allows the operator of radioactive equipment to read the dose they are exposed to in real-time. This feature enables the recording of daily absorbed doses, serving as a preventive strategy.
Relevant Figures: It is important to remember the effects caused by ionizing radiation when interacting with the area. There are three relevant quantities:
- Transferred Energy: Ionizing radiation (Linear Energy Transfer) is measured in Roentgen.
- Absorbed Power: For a natural material medium, it is measured in R: A: D.
- Energy Equivalent in Humans: This is measured by the effect it produces in living matter from the absorption of this energy, which causes biological damage, measured in REM.
Roentgen: This is the unit of radiometric measurement of exposure, indicating the total load of ions released from a given mass of dry air at normal pressure and temperature. It measures the amount of electric charges in the air; the more charged the air, the more ionized it is. (1 kg of air contains approximately 2.58 x 10-4 Coulombs or 0.000258 Coulombs of ion pairs.)
Rad: A unit of ionizing radiation absorbed by a material. 1 Rad = 100 ergs/g, 1 Rad = 0.01 Joule/kg.
Rem: A unit used to measure the danger of radiation, representing the biological effects of ionizing radiation. It quantifies the stochastic effects of ionizing radiation, where 1 Sv = 100 Rem.
Stochastic or Random Effects: These effects increase in occurrence with the dose received and exposure time. Statistically, there is no threshold dose for manifestation.
Features: Stochastic effects are uncommon and may manifest randomly in some individuals. Even with a high exposure dose, there is no established threshold dose based on symptoms and effects produced.
Stochastic Effects: The severity of injury increases with the radiation dose and occurs after a threshold dose. Characteristics include burns, and the biological damage caused by radiation on the human body is due to energy levels produced by the source and transferred to the human body. Low doses, less than 5 Rem per year, are quarterly and 1.25 Rem hourly doses of 2.5 mRem/hour. These can cause injuries and diseases such as leukemia, infertility, abnormal fetal development, eye cataracts, and damage to the respiratory and intestinal tracts. 1 to 6 Sv are considered high levels of whole-body radiation that can produce serious injury and death.
Radiation Protection Techniques:
- Distance: Radiation intensity decreases as the distance from the source increases, following the inverse square law.
- Time: The longer the exposure, the greater the chance of developing a disease or injury caused by the radioactive source. Dose intensity is directly proportional to exposure time.
- Shielding: To provide better radiation protection for operators of radiation-emitting equipment, materials of sufficient thickness are used to absorb radiation, thereby decreasing its intensity.
18,302 Radiation Standards Act:
- Ionizing Radiation: The propagation of energy, either corpuscular or electromagnetic, that interacts with matter to produce ionization.
- Radioactive Material: Any material that has a specific activity greater than 2 thousandths of a microcurie per gram.
- Radioactive Facility: Any facility that produces, processes, handles, stores, or uses radioactive materials or equipment that generates ionizing radiation.
- Nuclear Substance: These are nuclear fuels, except for natural and depleted uranium, that can produce energy through a self-supporting nuclear fission process outside a nuclear reactor.
- Radioactive Waste: Any radioactive substance or material contaminated by it, which is discarded after being used in medical, scientific, or agricultural applications.
- Dosimetry: The technique used to measure the dose absorbed by a person exposed to radiation over a period of time.
- Dosimetry History: A set of documents attesting to the doses received by a person exposed to ionizing radiation during their job performance.
Decree 133
Categories of Radioactive Facilities:
- Category 1: Facilities that operate particle accelerators, irradiation facilities, radiotoxicity laboratories, radiotherapy, industrial radiography, scintigraphy, and require authorization for construction, operation, and temporary or permanent closure.
- Category 2: Facilities with low radiotoxicity laboratories, x-rays for medical diagnosis and dental purposes, which require authorization for operation and temporary or permanent closure.
- Category 3: Enterprises that employ sealed sources for industrial use, such as pesómetros, densitometers, and flow meters, which require only an operating permit.
Decree Law No. 3 Radiation Protection:
Occupationally Exposed Person: An individual who works in radioactive facilities or operates equipment that generates ionizing radiation. They must wear a personal dosimeter designed to record and detect radiation, provided by the employer as necessary.
Dose Limits for Workers Exposed to Ionizing Radiation: Whole body, gonads, and bone marrow: 5 Rem per year; 30 Rem for the annual crystal; any other organ: 50 individual annual Rem.
Women of childbearing age should not be exposed to ionizing radiation, and if they are, the exposure should not exceed 1.25 Rem per quarter.
Children under 18 cannot be exposed to jobs where ionizing radiation is used.