Directional Dose Equivalent – H’(d,Ω)
The directional dose equivalent is an operational quantity for area monitoring of weakly penetrating radiation. The directional dose equivalent, H’(d,Ω), is the operational quantity for determination of equivalent dose to skin, lens of the eye, etc., also for beta radiation and low-energy photons.
According to the ICRP, the directional dose equivalent is defined as:
ICRP Publication 103:
“The dose equivalent at a point in a radiation field that would be produced by the corresponding expanded field in the ICRU sphere at a depth, d, on a radius in a specified direction, Ω. ”
The directional dose equivalent is given the symbol H’ (0.07,Ω) or, in rare cases, H'(3,Ω). The SI unit of H’ (d,Ω) is the sievert (Sv). Unit of sievert was named after the Swedish scientist Rolf Sievert, who did a lot of the early work on dosimetry in radiation therapy. For all types of external radiation, the operational quantities for area monitoring are defined on the basis of a dose equivalent value at a point in a simple phantom, the ICRU sphere, which is a sphere of tissue-equivalent material (30 cm in diameter, ICRU (soft) tissue with density: 1 g/cm3 , and mass composition: 76.2% oxygen, 11.1% carbon, 10.1% hydrogen, and 2.6% nitrogen).
As was written, operational quantities are measurable unlike an effective dose, and instruments for radiation monitoring are calibrated in terms of these quantities. In monitoring, the values of these operational quantities are taken as a sufficiently precise assessment of effective dose and skin dose, respectively, in particular, if their values are below the protection limits. Numerical links between operational quantities and effective dose is represented by conservative conversion coefficients, which are defined for a reference person.
See also: Dose Limits
Dose limits are split into two groups, the public, and occupationally exposed workers. According to ICRP, occupational exposure refers to all exposure incurred by workers in the course of their work, with the exception of
- excluded exposures and exposures from exempt activities involving radiation or exempt sources
- any medical exposure
- the normal local natural background radiation.
The following table summarizes dose limits for occupationally exposed workers and for the public:
According to the recommendation of the ICRP in its statement on tissue reactions of 21. April 2011, the equivalent dose limit for the lens of the eye for occupational exposure in planned exposure situations was reduced from 150 mSv/year to 20 mSv/year, averaged over defined periods of 5 years, with no annual dose in a single year exceeding 50 mSv.
Limits on effective dose are for the sum of the relevant effective doses from external exposure in the specified time period and the committed effective dose from intakes of radionuclides in the same period. For adults, the committed effective dose is computed for a 50-year period after intake, whereas for children it is computed for the period up to age 70 years. The effective whole-body dose limit of 20 mSv is an average value over five years. The real limit is 100 mSv in 5 years, with not more than 50 mSv in any one year.
Occupational Exposure – Effective Dose
In most situations of occupational exposure the effective dose, E, can be derived from operational quantities using the following formula:
The committed dose is a dose quantity that measures the stochastic health risk due to an intake of radioactive material into the human body.
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Directional Dose Equivalent  H(d,Ω) Directional dozi sawa ni kiasi cha uendeshaji kwa ajili ya eneo la ufuatiliaji wa mionzi dhaifu penetrating. "Dose sawa ya mwelekeo (DEE) ni kiasi cha kazi cha kuamua ""dose sawa"" kwa ngozi, lensi ya jicho, na kadhalika, pia kwa mionzi ya beta na fotoni za nishati ya chini." ICRP (Directional Dose Equivalent) ni kiwango cha kipimo cha kipimo cha kipimo cha kipimo cha kipimo cha kipimo cha kipimo cha kipimo cha kipimo cha kipimo cha kipimo cha kipimo cha kipimo cha kipimo cha kipimo cha kipimo cha kipimo cha kipimo cha kipimo cha kipimo cha kipimo cha kipimo cha kipimo cha kipimo cha kipimo cha kipimo cha kipimo cha kipimo. <unk> Directional dozi sawa ni kupewa ishara H <unk> (0.07,Ω) au, katika kesi nadra, H '(3,Ω). Kitengo cha SI cha H<unk> (d,Ω) ni sievert (Sv). Kiwango cha Sievert ni jina la kisayansi wa Sweden Rolf Sievert, ambaye alifanya kazi ya kwanza ya dosimetry katika tiba ya mionzi. Kwa aina zote za mnururisho wa nje, kiasi cha uendeshaji kwa ajili ya ufuatiliaji wa eneo hufafanuliwa kwa msingi wa thamani ya dozi sawa katika sehemu ya phantom rahisi, ICRU (sphere ya tishu sawa) - 30 cm kipenyo, ICRU (soft) tishu na wiani wa 1 gcm3 na muundo wa wingi wa nitrojeni: 76.2% oksijeni, 11.1% kaboni, 10.1% na 2.6% hidrojeni. Kama ilivyoandikwa, kiasi cha uendeshaji ni kipimo tofauti na kipimo cha ufanisi, na vyombo vya ufuatiliaji wa mionzi ni calibrated katika suala la kiasi hiki. Katika ufuatiliaji, maadili ya kiasi hiki cha kazi huchukuliwa kama tathmini sahihi ya kutosha ya kipimo cha ufanisi na kipimo cha ngozi, hasa ikiwa maadili yao ni chini ya mipaka ya ulinzi. Uhusiano wa tarakimu kati ya kiasi cha uendeshaji na kipimo cha ufanisi ni kuwakilishwa na coefficients uongofu kihafidhina, ambayo ni maalum kwa mtu rejea. Angalia pia: Mipaka ya kipimo Mipaka ya kipimo imegawanywa katika vikundi viwili, umma, na wafanyakazi walioathiriwa na kazi. ICRP inazungumzia athari za kazi kwa kazi zote zinazohusika na kazi, isipokuwa athari za kazi zilizofutwa na athari za shughuli zilizofutwa zinazohusisha mnururisho au vyanzo vilivyofutwa, athari za matibabu, na athari za kawaida za asili za asili. "Tabla ifuatayo ina muhtasari wa mipaka ya kipimo kwa wafanyakazi walioathiriwa kazi na kwa umma: ""Kulingana na mapendekezo ya ICRP katika taarifa yake juu ya athari za tishu za 21." Mipaka ya kipimo cha kipekee cha mtihani wa macho kwa ajili ya mfiduo wa kazi katika hali za mfiduo uliopangwa ilipunguzwa kutoka 150 mSv kwa mwaka hadi 20 mSv kwa mwaka, kwa wastani katika vipindi maalum vya miaka mitano, bila kipimo cha kila mwaka katika mwaka mmoja. Kiwango cha kipimo cha ufanisi ni jumla ya kipimo cha ufanisi kutoka kwa mfiduo wa nje katika kipindi maalum cha muda na kipimo cha ufanisi cha ahadi kutoka kwa uingizaji wa radionuclides katika kipindi hicho. Kwa watu wazima, kipimo cha ufanisi cha kujitolea kinahesabiwa kwa kipindi cha miaka 50 baada ya ulaji, wakati kwa watoto kinahesabiwa kwa kipindi hadi umri wa miaka 70. Kiwango cha juu cha athari ya mwili wote wa 20 mSv ni wastani wa miaka mitano. Kiwango cha juu cha kiwango cha 100 mSv ni miaka 5 na sio zaidi ya 50 mSv kwa mwaka mmoja. "Kwenye hali nyingi za mfiduo wa kazi, kipimo cha ufanisi, E, kinaweza kupatikana kutoka kwa kiasi cha kazi kwa kutumia formula ifuatayo: ""Dose ya kujitolea"" ni kiasi cha kipimo ambacho hupima hatari ya afya ya stochastic kutokana na uingizaji wa nyenzo za mnururisho katika mwili wa binadamu." Tunatumaini, makala hii, Directional Dose Equivalent  H(d,Ω), inakusaidia. Kama ni hivyo, kutupa kama katika sidebar. Kusudi kuu la tovuti hii ni kusaidia umma kujifunza baadhi ya habari ya kuvutia na muhimu kuhusu mionzi na dosimeters.