Читайте также:
|
Distinguish the physical, chemical and biological methods of dosimetry: ionization, luminescent, semiconductive, thermoluminiscent, neutron-activating, calorimetrical, photographic, chemical, biological and calculative|computation| (mathematical).
The ionization method of dosimetry is used with|by means of| an ionization chamber|cell| and based on estimating|appraisal| the environment ionization |Wednesday| degree through|from,because of| which|what| the radiation passes. Than greater power|capacity| of dose, the more so|nevertheless| arises up ions, the greater ionization current. Measuring the size|value| of ionization current get|receives| the picture of power|capacity| of dose of ionizing radiation. Scheme of structure|building| and principle the robots of ionization dosimeter are resulted|pointed| on fig|.1.1.
Fig.1.1 The structure scheme and principle of the ionization dosimeter work.
П1 и П2 — electrodes|; Б —battery; И-| radiation; O window| in an ionization chamber|cell|; Г galvanometer.
The scintillation method of dosimetry consists in measurings the intensity of the light|photic| flashes, which arise up in the materials with a luminescent property (potassium iodide, sodium, caesium or anthracene, stilbene | and others) during passing of x-rays or γ-rays through|from,because of| them. The structure|building| scheme of a luminescent dosimeter see |q.v.|fig|.1.2
Fig|. 1.2 The luminescent dosimeter structure scheme.
The semiconductive method of dosimetry – during radiation exposure in semiconductive detectors there arises up the current, after the magnitude|value| of which|what| it is possible to define the radiation dose power|capacity|, which effects on the detector.
The thermoscintilation (photoscintilation|, radioscintilation|) method is based on the ability|power| of crystalline люмінофорів| (lithium fluorid| activated by silver) to accumulate the absorbed radiation energy. In case of additional heating of crystals in a certain|definite| mode|regime| there occurs the thermoscintilation| "flash", the intensity of which|what| depends on the dose of radiation exposure, which люмінофор| has absorbed.
The neutron-activating method is the determination|definition| of the directed|pointed| radioactivity as a result of|because of,owing to| neutrons streams influence.
The photographic method of dosimetry is based on the ability|power| of radiation to cause the|calls| photolysis of haloid silver (see above), as a result of which there occurs its |its| partial recreation|reproduction,reproducing|. In the process of revealing in the places|seats| of radiation exposure the film darkens proportionally to the dose of radiation exposure.
The chemical method — is based on the ability|power| of ionizing radiations to cause|calls| in the compounds the dissociation of polyatomic molecules with the formation of new compounds. The transparency or colour of solutions changes, some part of the dissociation product sediments or turns into gas. The quantitative estimation|appraisal| of these changes|changing| allows defining the dose of radiation exposure, using the measuring system graduated| with applying of the standard radiant|spring,source|.
The calorimetrical (thermal) method of dosimetry — is based on measuring the amount|quantity| of heat, which is excreted in a detector at absorbing ionizing radiations (little used in medicine because of its|its| low sensitiveness).
The calculation|computation| (mathematical) method —supposes using tables and nomograms| for the calculating|computation| the personal absorbed doses at different|diverse| variants of irradiating a man.
The biological methods of dosimetry are based on evalvulationing biomaterials (the chromosomal analysis of lymphocytes | of the peripheral blood, the| marrow biopsy phantom, the electronic paramagnetic resonance of the teeth enamel extracted after medical indications|demonstrations|) and the account of radio reeffects of the organism. This method of dosimetry is used in clinical practice.
Дата добавления: 2015-09-11; просмотров: 84 | Поможем написать вашу работу | Нарушение авторских прав |