What Is a Radiation Dose?

Radiation dose abbreviated dose in the field of ionizing radiation

Definition of radiation dose

The concept of dose is related to the dose of a medicament, which refers to the amount of medicine a patient takes at one time. Later it also refers to the amount of medicine injected or otherwise given to a patient. But radiation is not a "medicine" in the general sense, and it is difficult to use the word "give". It depends on the "received" or "absorbed" radiant energy. So the so-called "dose" just borrows the word, which is very different from the original intention.

Radiation dose Even the interpretation of the term dose in the field of ionizing radiation is divided. On the one hand, many scientists think that this word cannot be regarded as a scientific term because he has no precise definition; on the other hand, he has to use this term that is not a term heavily, because without him, it is difficult to describe what we are facing. Topic. For this reason, one or more definitions of the word dose have to be given below.

First, there is a broad and narrow interpretation of the term dose.

In a broad sense, the term dose generally refers to the quantities related to the interaction of radiation and radiation with matter in the field of ionizing radiation, such as the absorbed dose, exposure, specific kinetic energy, and flux density.

The narrow understanding, and the only definition that can be defined for the term dose, is the absorbed dose. The term "dose" in radiobiology and radiotherapy often refers specifically to the water absobed dose.

The term dosimeter sometimes refers to an absorbed dosimeter, such as a chemical dosimeter (Frick dosimeter), but more often it refers to a broader dose. For example, the term unmodified dosimeter usually refers to a measuring instrument consisting of an ionization chamber and an electrometer (the electrical measurement unit of the dosimeter). Such instruments can measure the absorbed dose of water, the amount of exposure, the specific kinetic energy of air, etc. according to the scale.

Overview of radiation dose

Also referred to as dose. The amount of ionizing radiation (dose) is a problem in radiation medicine and human radiation protection. International units (SI) are also used in radiation doses. According to the recommendations of the International Radiation Unit Measurement Board (1962), Japan's metrology law has been significantly revised in 1966. If the biological effect is the target, the number and distribution of ions and excited molecules generated by the interaction between radiation and biomolecules are more important than the state of the radiation energy spectrum. Therefore, the following various units are used:

Ionizing radiation sign

Radiation dose

Exposure dose

The so-called irradiation amount describes the amount of X-rays and -rays ionizing ability in the air. It is defined as generating 1 electrostatic unit of electricity in 1 cubic centimeter of air (1.293 mg of air) under standard conditions. Exposure X is the quotient obtained by dividing dQ by dm, where the value of dQ is the total charge of the ions generated when all electrons (negative and positrons) released by photons are completely blocked in air with mass dm Absolute quantity, that is: X = dQ / dm. Unit: Coulomb · kg ^ -1 (C / kg);

Roentgen's definition is: under 1R X or -ray irradiation, the secondary electrons generated in the air at 0.001293g (equivalent to the mass of 1cm ^ -3 dry air at 0 ° C and 760mm Hg atmospheric pressure) in the air form The amount of charge is a positive ion or a negative ion of one electrostatic unit. The exposure is only for air, and only for X or gamma rays.

Radiation dose absorbed dose

Absorbed dose refers to the average energy of ionizing radiation received per unit mass of substance. It is defined as the quotient of d divided by dm, where d is the average energy given by ionizing radiation to a irradiated substance with mass dm. That is, the SI unit of the absorbed dose of D = d / dm is Joule · kg-1 (J · kg ^ -1), and the proper name of the SI unit is Gray [gray], symbol Gy. The name of the special unit 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 describes the amount of ionizing radiation energy. When ionizing radiation interacts with matter, part or all of its energy can be deposited in the illuminated medium. Its unit is rad, which is equivalent to receiving 1 × 10 ^ -5 joules of energy per gram of matter. 1Gy = 100rad. Unlike the case of exposure, the absorbed dose is the amount of radiation suitable for any type of ionizing radiation and any type of irradiated substance. It must be noted that when applying this measure, it is necessary to indicate the specific exposure substance, such as air, muscle or other specific materials.

Radiation dose

Radiation dose absorption rate

Absobed dose rate refers to the absorbed dose per unit time (such as rad / min);

Radiation dose

Exposure ra-te refers to the exposure dose per unit time;

Radiation dose equivalent dose

Equivalent dose

The absorbed dose multiplied by the appropriate correction factor is called the equivalent dose, and it is represented by the symbol H. The equivalent dose is limited to protective applications. 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 strength of biological effects caused by the absorption of various rays or particles. It is not only related to the absorbed dose, but also to the type and energy of the radiation. The equivalent dose is based on the absorbed dose and introduces a weight 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 it is the average absorbed dose of radiation R in the tissue or organ T. International units: Sv (Sievert), 1Sv = 1J? Kg ^ -1. Old dedicated unit: rem (Rem), 1Sv = 100rem;

Radiation dose effective equivalent

Effective dose equivalent refers to the average dose equivalent received by each organ or tissue of the human body and the corresponding machine weight factor when the whole body is subjected to non-uniform irradiation when the radiation effect occurring in human tissues or organs is a random effect. The sum of the products.

Radiation dose

Radiation	Radiation dose SI unit	SI unit proper name	Special unit
Exposure	Coulomb kg-1 (C · kg ^ -1)	Undecided	Roentgen (R) 1 Lun = 2.58 × 10 ^ -4 Coulomb · kg ^ -1 (1R = 2.58 × 10 ^ -4C · kg ^ -1)
Absorbed dose	Joule · kg ^ -1 J · kg ^ -1	Gy (Gy) 1 Gy = 1 Joule · kg ^ -1 = 100 Rad	Rad (rad) 1 rad = 10-2 joules · kg ^ -1 = 100 erg · g ^ -1
Equivalent dose	Joule · kg ^ -1 J · kg ^ -1	Sv (Sv) 1 Sv = 1 Joule · Kg ^ -1 = 10	Rem 1 rem = 10 ^ -2 joules · kg ^ -1 (1rem = 10-2J · kg ^ -1)
Radioactivity	Second ^ -1 (s ^ -1)	Becoller (Bq) 1 Becoller = 1 second -1 (1Bq = 1s ^ -1)	Curie (Ci) 1 Curie = 3.7 × 1010 · s ^ -1 (1Ci = 3.7 × 1010s ^ -1) personal

Personal dose limit

Overview of radiation dose

Individual dose limits are defined practices (referring to radiation-related occupational activities, such as the nuclear industry) and frequent and continuous exposures of the radiation protection authority (such as the International Commission on Radiological Protection ICRP, the highest authority of the country) to established practices (Eg public exposure associated with the source) a dose level established above which the consequences for individuals of an exposure are considered unacceptable.

The implementation of personal dose limits is only part of the protection system. The purpose is to take the economic and social factors into consideration to achieve the lowest possible dose. Therefore, the personal dose limit can be considered as an increase in the tolerable level

Personal dose of radiation

application	Dose limit
application	Occupational exposure	public
Effective dose (systemic), mSv · a ^ -1	20 (averaged within 5 years)	1
Annual equivalent dose, mSv · a ^ -1	150	15
Eye lens	500	50
skin	500
Brotherhood

ICRP 1990

ICRP 1990 Dose

Individual dose limits set out in the ICRP 1990 Recommendation

With regard to internal exposure, the individual's annual intake limit (ALI) for radionuclides is calculated on the basis of an effective dose of 20mSv.

From the Dictionary of Safety Engineering (Chemical Industry Press)

Radiation dose experiment software

MCNP Radiation dose MCNP

MCNP (Monte Carlo Neutron and Photo Transport Code):

Radiation dose A set of general MC calculation programs developed by Los Alamos National Laboratory to simulate the transport of neutrons, photons and electrons in matter. In its earlier version, it did not include the process of electron transport Simulation, only neutrons and photons are simulated, and newer versions (such as MCNP4A) introduced ETRAN and added simulation of electrons.

Geant4 Radiation dose Geant4

Geant4 is a Monte Carlo application software toolkit for accurately simulating the transport of particles through a medium. Among the many Monte Carlo simulation programs, compared with commercial software such as MCNP and EGS, the main advantage of Geant4 is that the original code is completely open, and users can improve and expand their programs according to actual needs.