Radiation dose of personal dosimeter and its difference from dosimeter
Also referred to as the dose. The amount of ionizing radiation (dose) is a problem in radiation medicine and human radiation protection. International units (SI) are also used in the amount of radiation. According to the recommendations of the International Radiation Unit Measurement Committee (1962), the Japanese measurement method has been substantially revised in 1966. If the biological effect is the target, the number and distribution of ions and excitation molecules generated by the interaction between radiation and biomolecules are more important than the condition of the radiation spectrum. Therefore, the following various units are used.
Overview of radiation dose
(1) Exposure dose: The amount of irradiation describes the amount of ionizing ability of X-rays and gamma rays in the air. It is defined as producing 1 electrostatic unit of electricity in 1 cubic centimeter of air (1.293 milligrams of air) under standard conditions. The amount of irradiation X is the quotient obtained by dividing dQ by dm, where the value of dQ is the total charge of ions generated when all electrons (negative electrons and positrons) released by photons are completely blocked in the air in mass dm of air. Absolute quantity, ie: X = dQ / dm. Unit: Coulomb · kg ^ -1 (C / kg);
The definition of Roentgen is: in 1R X or γ-ray irradiation, the secondary electrons generated in the air at 0.001293g (corresponding to the mass of 1cm^-3 dry air at 0°C and 760mm Hg atmospheric pressure) A positive or negative ion with a charge of 1 electrostatic unit. The amount of exposure is only for air, only for X or gamma rays.
(2) absorbed dose: The so-called absorbed dose refers to the average energy of receiving ionizing radiation per unit mass of matter. Defined as the quotient obtained by dividing dε by dm, where dε is the average energy of the irradiated substance of mass dm given by ionizing radiation. That is, the SI unit of D=dε/dm absorbed dose is Joule·kg-1 (J·kg^-1), and the SI unit name is gray [gray], symbol Gy. The special unit name that is temporarily used with SI is Rad, and the symbol is rad. 1Gy=1J·kg^-1=100rad, or 1rad=10^-2 J·kg-1=10^-2Gy. It is the amount that describes the energy of ionizing radiation. When ionizing radiation interacts with a substance, some or all of its energy can be deposited in the illuminated medium. Its unit is rad, which is equivalent to 1 gram of material receiving 1 × 10 ^ -5 joules of energy. The currently used unit is Gy, which is equivalent to 1 kilogram of material receiving 1 joule of energy. 1Gy = 100rad. Unlike the case of exposure, the absorbed dose is an amount of radiation suitable for any type of ionizing radiation and any type of radiation dose type of illuminated material. It must be noted that when applying this metric, specify the specific substance to be involved, such as air, muscle or other specific materials.
(3) Absobed dose rate: the absorbed dose per unit time (such as rad/min);
(4) Exposure dose rate (exposure ra-te): refers to the exposure dose per unit time;
(5) Equivalent dose: An absorbed dose multiplied by an appropriate correction coefficient is referred to as an equivalent dose, and is represented by the symbol H. Equivalent doses are limited to applications in protection. The equivalent dose H at a point in the tissue is the product of D, Q, and N; the equivalent dose is the amount of ionizing radiation that reflects the biological effects of various rays or particles that are absorbed. It is not only related to the absorbed dose, but also related to the type and energy of the radiation. The equivalent dose is based on the absorbed dose and introduces a weighting factor (wR) related to the type of radiation and energy: H(T,R)=wR?D In the formula (T, R), D(T, R) is called the organ dose and is the average absorbed dose of radiation R produced in the tissue or organ T. International system: Sv (Swarth), 1Sv = 1J? kg^-1. Old dedicated unit: rem (rem), 1Sv = 100rem;
(6) Effective dose equivalent: The effective dose equivalent is the average dose equivalent received by various organs or tissues of the human body when the whole body is subjected to non-uniform irradiation when the radiation effect of human tissues or organs is considered as a random effect. The sum of the products of the corresponding weighting factors.
Folding and editing the basic knowledge of this personal dosimeter
It is mainly used to monitor the electronic equivalent of dose equivalent rate and dose equivalent of X-ray and γ-ray irradiation to human body.
Folding and editing the difference between the dosimeter and the dosimeter
1. The personal dosimeter and the personal dose alarm are the same instruments; they are just different in name. They generally measure cumulative doses and dose rates; the pictures are as follows:
2, personal dosimeter: is different from the personal dosimeter and personal dose alarm device; generally only used to measure the cumulative dose; and are all using a thermoluminescent dosimeter; the state regulations only have the qualifications issued by the Ministry of Health Institutions can provide data reading services for personal dosimeters
Example of a personal dosimeter
The personal dosimeter is a smart pocket instrument. The personal dose alarm device is made with the latest powerful single-chip technology. Mainly used to monitor X-rays and gamma rays. Within the measurement range, various threshold alarm values ​​can be arbitrarily set, and sound and light alarms are generated to prompt the staff to pay attention to safety. The personal dosimeter has a large memory and can store data for about one week. The main technology of the instrument conforms to national standards and international standards. It is a wearable pocket instrument with strong function, small size and low power consumption in domestic similar instruments. It is widely used in medical, nuclear military, nuclear submarines, nuclear power plants, industrial non-destructive testing, isotope applications and hospital cobalt treatment, occupational disease protection, radiation dose measurement of residents around nuclear power plants.
main feature:
â—Two functions: X/γ dose rate around the place (μSv/h), personal cumulative dose (μSv)
◠The alarm threshold is continuously adjustable. Generally, it is set to 2.5μSv per day, not exceeding 50 mSv per year, and 2000 hours per year.
The aim is to meet the needs of highly radioactive workers and reduce working hours.
â— The data storage capacity is large, with 1500 hours of data storage capacity.
â—The threshold is continuously adjustable, with threshold alarm function such as cumulative dose, dose rate, blocking, timeout, etc.
â—Automatically record various data, power off or replace battery data without losing
â— Displayable, cumulative dose, dose rate, working time, time and size of maximum dose rate, cumulative dose threshold, dose rate threshold, etc.
â—High sensitivity, also respond to the environmental background, small size, simple operation, strong anti-electromagnetic interference
Product details:
SDM2000 Personal Dose Alarm This personal dose alarm monitors the cumulative personal dose equivalent and personal dose equivalent rate caused by X and γ radiation. The dose equivalent and dose equivalent rate values ​​can be read by the LCD directly by button switching. Measurement data, working time, etc. can be stored in the dosimeter and lost without loss, and can be transmitted to the reader and the central computer by infrared communication. The personal dose alarm device can preset the dose and dose rate alarm thresholds, and can emit sound and light alarms when the threshold is exceeded. The dosimeter has two modes of operation, which can work in conjunction with the reader and the computer, or stand alone.
Use of personal dosimeter
Widely used in nuclear power plants, nuclear submarines, irradiation stations, customs, isotope applications, industrial X, γ nondestructive testing, radiology, cobalt source treatment, gamma irradiation, radiological laboratories, environmental monitoring of nuclear facilities, etc. Personal safety monitoring and radiological tips
principle
Personal dosimeter An instrument used to measure the amount of radiation received by a worker exposed to nuclear radiation during operation. Commonly used are personal dose pens, film dosimeters and thermoluminescent dosimeters. The dose pen is a sensitive pen-shaped electroscope that, after charging, has a maximum deflection of the metal-coated quartz wire. When exposed to radiation, the gas in the electroscope is ionized, so that the deflection angle of the quartz wire is reduced. The dose can be read directly by the scale of the roentgen scale, which is convenient to use, but the environmental humidity has a great influence.
Personal dose alarm instrument intelligent pocket instrument. It is made with the latest powerful single-chip technology. Mainly used to monitor X-rays and gamma rays. Within the measurement range, various threshold alarm values ​​can be arbitrarily set, and sound and light alarms are generated to prompt the staff to pay attention to safety. The instrument has a large memory and can store data for about one week. Measurements made using personal dosimeters worn by the staff member, or measurements of the type and activity of radionuclides in the body or excreta, and interpretation of the measurements.
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