{"id":21931,"date":"2020-07-22T11:37:49","date_gmt":"2020-07-22T11:37:49","guid":{"rendered":"https:\/\/www.radiation-dosimetry.org\/o-que-e-radiacao-ionizante-definicao\/"},"modified":"2020-07-22T11:37:49","modified_gmt":"2020-07-22T11:37:49","slug":"o-que-e-radiacao-ionizante-definicao","status":"publish","type":"post","link":"https:\/\/www.radiation-dosimetry.org\/pt-br\/o-que-e-radiacao-ionizante-definicao\/","title":{"rendered":"O que \u00e9 radia\u00e7\u00e3o ionizante &#8211; Defini\u00e7\u00e3o"},"content":{"rendered":"<div class=\"su-quote su-quote-style-default\">\n<div class=\"su-quote-inner su-u-clearfix su-u-trim\">Radia\u00e7\u00e3o ionizante \u00e9 qualquer radia\u00e7\u00e3o (part\u00edculas ou ondas eletromagn\u00e9ticas) que transporta energia suficiente para derrubar el\u00e9trons de \u00e1tomos ou mol\u00e9culas, ionizando-os.\u00a0Dosimetria de Radia\u00e7\u00e3o<\/div>\n<\/div>\n<div class=\"su-divider su-divider-style-dotted\"><\/div>\n<div class=\"lgc-column lgc-grid-parent lgc-grid-100 lgc-tablet-grid-100 lgc-mobile-grid-100 lgc-equal-heights lgc-first lgc-last\">\n<div class=\"inside-grid-column\">\n<figure id=\"attachment_24861\" class=\"wp-caption alignright\" aria-describedby=\"caption-attachment-24861\"><a href=\"https:\/\/www.radiation-dosimetry.org\/wp-content\/uploads\/2019\/12\/ionizing-radiation-hazard-symbol-1.png\"><img loading=\"lazy\" class=\"size-full wp-image-24861 lazy-loaded\" src=\"https:\/\/www.radiation-dosimetry.org\/wp-content\/uploads\/2019\/12\/ionizing-radiation-hazard-symbol-1.png\" alt=\"radia\u00e7\u00e3o ionizante - s\u00edmbolo de perigo\" width=\"220\" height=\"192\" data-lazy-type=\"image\" data-src=\"https:\/\/www.radiation-dosimetry.org\/wp-content\/uploads\/2019\/12\/ionizing-radiation-hazard-symbol-1.png\" \/><\/a><figcaption id=\"caption-attachment-24861\" class=\"wp-caption-text\">radia\u00e7\u00e3o ionizante &#8211; s\u00edmbolo de perigo<\/figcaption><\/figure>\n<p><strong>Radia\u00e7\u00e3o ionizante<\/strong>\u00a0\u00e9 qualquer radia\u00e7\u00e3o (\u00a0<span class=\"ILfuVd\">part\u00edculas ou ondas eletromagn\u00e9ticas<\/span>\u00a0) que transporta energia suficiente para derrubar el\u00e9trons de \u00e1tomos ou mol\u00e9culas, ionizando-os.\u00a0Para radia\u00e7\u00e3o ionizante, a energia cin\u00e9tica das part\u00edculas (\u00a0<strong>f\u00f3tons, el\u00e9trons, etc.<\/strong>\u00a0)\u00a0<strong>\u00e9 suficiente e a part\u00edcula pode ionizar<\/strong>\u00a0(formar \u00edons pela perda de el\u00e9trons) atingir \u00e1tomos para formar \u00edons.<\/p>\n<p>O limite entre a radia\u00e7\u00e3o ionizante e a n\u00e3o ionizante n\u00e3o \u00e9 claramente definido, uma vez que diferentes mol\u00e9culas e \u00e1tomos ionizam em energias diferentes.\u00a0Isso \u00e9 t\u00edpico para ondas eletromagn\u00e9ticas.\u00a0Entre as ondas eletromagn\u00e9ticas pertencem, em ordem crescente de freq\u00fc\u00eancia (energia) e comprimento de onda decrescente: ondas de r\u00e1dio, microondas, radia\u00e7\u00e3o infravermelha, luz vis\u00edvel, radia\u00e7\u00e3o ultravioleta, raios X e raios gama.\u00a0<a title=\"Raios gama \/ radia\u00e7\u00e3o gama\" href=\"https:\/\/www.nuclear-power.com\/nuclear-power\/reactor-physics\/atomic-nuclear-physics\/fundamental-particles\/photon\/gamma-ray\/\">Raios gama<\/a>\u00a0,\u00a0<a title=\"Gamma Rays \/ Gamma Radiation\" href=\"https:\/\/www.nuclear-power.com\/nuclear-power\/reactor-physics\/atomic-nuclear-physics\/fundamental-particles\/photon\/gamma-ray\/\">raios\u00a0<\/a><a href=\"https:\/\/www.nuclear-power.com\/nuclear-power\/reactor-physics\/atomic-nuclear-physics\/radiation\/x-rays-roentgen-radiation\/\">X<\/a>\u00a0e a parte ultravioleta mais alta do espectro s\u00e3o ionizantes, enquanto os raios ultravioleta mais baixos, luz vis\u00edvel (incluindo luz laser), infravermelho, microondas e ondas de r\u00e1dio s\u00e3o considerados radia\u00e7\u00e3o n\u00e3o ionizante.<\/p>\n<p>Todos\u00a0\u00a0<a href=\"https:\/\/www.nuclear-power.com\/nuclear-engineering\/radiation-protection\/biological-effects\/\"><strong>os efeitos de danos biol\u00f3gicos<\/strong><\/a>\u00a0\u00a0come\u00e7am com a conseq\u00fc\u00eancia das intera\u00e7\u00f5es de radia\u00e7\u00e3o com os\u00a0\u00a0<a href=\"https:\/\/www.nuclear-power.com\/nuclear-power\/reactor-physics\/atomic-nuclear-physics\/atom-properties-of-atoms\/\">\u00e1tomos que<\/a>\u00a0\u00a0formam as c\u00e9lulas.\u00a0Todos os seres vivos s\u00e3o compostos de uma ou mais c\u00e9lulas.\u00a0Cada parte do seu corpo consiste em c\u00e9lulas ou foi constru\u00edda por elas.\u00a0Embora tendamos a pensar nos efeitos biol\u00f3gicos em termos do efeito da radia\u00e7\u00e3o nas c\u00e9lulas vivas, na realidade, a\u00a0\u00a0<a href=\"https:\/\/www.nuclear-power.com\/nuclear-power\/reactor-physics\/atomic-nuclear-physics\/radiation\/\">radia\u00e7\u00e3o ionizante<\/a>\u00a0, por defini\u00e7\u00e3o, interage apenas com os \u00e1tomos por um processo chamado ioniza\u00e7\u00e3o.<\/p>\n<p>O perigo de radia\u00e7\u00e3o ionizante reside no fato de que a radia\u00e7\u00e3o \u00e9 invis\u00edvel e n\u00e3o diretamente detect\u00e1vel pelos sentidos humanos.\u00a0As pessoas n\u00e3o podem ver nem sentir radia\u00e7\u00e3o, mas ela deposita energia nas mol\u00e9culas do corpo.\u00a0A energia \u00e9 transferida em pequenas quantidades para cada intera\u00e7\u00e3o entre a radia\u00e7\u00e3o e uma mol\u00e9cula e geralmente existem muitas dessas intera\u00e7\u00f5es.<\/p>\n<h2><span id=\"Forms_of_ionizing_radiation\">Formas de radia\u00e7\u00e3o ionizante<\/span><\/h2>\n<p><strong><a href=\"https:\/\/www.radiation-dosimetry.org\/pt-br\/shielding_radiation-dosimetrie-des-rayonnements\/#main\" rel=\"attachment wp-att-726\"><img loading=\"lazy\" class=\"alignright wp-image-15336 lazy-loaded\" src=\"http:\/\/www.radiation-dosimetry.org\/wp-content\/uploads\/2019\/12\/shielding_radiation-558x1024.gif\" sizes=\"(max-width: 426px) 100vw, 426px\" srcset=\"http:\/\/www.radiation-dosimetry.org\/wp-content\/uploads\/2019\/12\/shielding_radiation-558x1024.gif 558w, https:\/\/www.radiation-dosimetry.org\/wp-content\/uploads\/2019\/12\/shielding_radiation-164x300.gif 164w, https:\/\/www.radiation-dosimetry.org\/wp-content\/uploads\/2019\/12\/shielding_radiation-768x1408.gif 768w\" alt=\"Blindagem de radia\u00e7\u00e3o ionizante\" width=\"426\" height=\"782\" data-lazy-type=\"image\" data-src=\"http:\/\/www.radiation-dosimetry.org\/wp-content\/uploads\/2019\/12\/shielding_radiation-558x1024.gif\" data-srcset=\"\" \/><\/a>A radia\u00e7\u00e3o ionizante<\/strong>\u00a0\u00e9 categorizada pela natureza das part\u00edculas ou ondas eletromagn\u00e9ticas que criam o efeito ionizante.\u00a0Essas\u00a0<strong>part\u00edculas \/ ondas<\/strong>\u00a0t\u00eam diferentes mecanismos de ioniza\u00e7\u00e3o e podem ser agrupadas como:<\/p>\n<ul>\n<li><strong>Ionizante direto<\/strong>\u00a0.\u00a0Part\u00edculas carregadas (\u00a0<strong>n\u00facleos at\u00f4micos, el\u00e9trons, p\u00f3sitrons, pr\u00f3tons, m\u00faons etc.<\/strong>\u00a0) podem ionizar \u00e1tomos diretamente por intera\u00e7\u00e3o fundamental atrav\u00e9s da for\u00e7a de Coulomb, se transportarem energia cin\u00e9tica suficiente.\u00a0Essas part\u00edculas devem estar se movendo em velocidades relativ\u00edsticas para alcan\u00e7ar a energia cin\u00e9tica necess\u00e1ria.\u00a0Mesmo os f\u00f3tons (raios gama e raios X) podem ionizar \u00e1tomos diretamente (apesar de serem eletricamente neutros) atrav\u00e9s do efeito Fotoel\u00e9trico e do efeito Compton, mas a ioniza\u00e7\u00e3o secund\u00e1ria (indireta) \u00e9 muito mais significativa.\n<ul>\n<li><a title=\"Radia\u00e7\u00e3o alfa\" href=\"https:\/\/www.radiation-dosimetry.org\/pt-br\/o-que-e-radiacao-alfa-definicao\/\"><strong>Radia\u00e7\u00e3o alfa<\/strong><\/a>\u00a0.\u00a0A radia\u00e7\u00e3o alfa consiste em<a title=\"Alpha Particle\" href=\"https:\/\/www.nuclear-power.com\/nuclear-power\/reactor-physics\/atomic-nuclear-physics\/fundamental-particles\/alpha-particle\/\">\u00a0part\u00edculas alfa<\/a>\u00a0em alta energia \/ velocidade.\u00a0A produ\u00e7\u00e3o de part\u00edculas alfa \u00e9 denominada decaimento alfa.\u00a0As part\u00edculas alfa consistem em dois pr\u00f3tons e dois n\u00eautrons unidos em uma part\u00edcula id\u00eantica a um n\u00facleo de h\u00e9lio.\u00a0As part\u00edculas alfa s\u00e3o relativamente grandes e carregam uma carga positiva dupla.\u00a0Eles n\u00e3o s\u00e3o muito penetrantes e um peda\u00e7o de papel pode det\u00ea-los.\u00a0Eles viajam apenas alguns cent\u00edmetros, mas depositam todas as suas energias ao longo de seus caminhos curtos.<\/li>\n<li><a title=\"Radia\u00e7\u00e3o Beta\" href=\"https:\/\/www.radiation-dosimetry.org\/pt-br\/o-que-e-radiacao-beta-definicao\/\"><strong>Radia\u00e7\u00e3o beta<\/strong><\/a>\u00a0.\u00a0A radia\u00e7\u00e3o beta consiste em el\u00e9trons livres ou p\u00f3sitrons em velocidades relativ\u00edsticas.\u00a0<a title=\"Part\u00edcula Beta\" href=\"https:\/\/www.nuclear-power.com\/nuclear-power\/reactor-physics\/atomic-nuclear-physics\/fundamental-particles\/beta-particle\/\">As part\u00edculas beta<\/a>\u00a0(el\u00e9trons) s\u00e3o muito menores que as part\u00edculas alfa.\u00a0Eles carregam uma \u00fanica carga negativa.\u00a0Eles s\u00e3o mais penetrantes que as part\u00edculas alfa, mas o metal fino de alum\u00ednio pode det\u00ea-las.\u00a0Eles podem percorrer v\u00e1rios metros, mas depositam menos energia em qualquer ponto do caminho do que as part\u00edculas alfa.<\/li>\n<\/ul>\n<\/li>\n<li><strong>Ionizando indiretamente<\/strong>\u00a0.\u00a0A radia\u00e7\u00e3o ionizante indireta \u00e9 part\u00edculas eletricamente neutras e, portanto, n\u00e3o interage fortemente com a mat\u00e9ria.\u00a0A maior parte dos efeitos de ioniza\u00e7\u00e3o \u00e9 devida a ioniza\u00e7\u00f5es secund\u00e1rias.\n<ul>\n<li><strong>Radia\u00e7\u00e3o de f\u00f3tons<\/strong>\u00a0(\u00a0<a title=\"Raios gama \/ radia\u00e7\u00e3o gama\" href=\"https:\/\/www.nuclear-power.com\/nuclear-power\/reactor-physics\/atomic-nuclear-physics\/fundamental-particles\/photon\/gamma-ray\/\">raios gama<\/a>\u00a0ou\u00a0<a title=\"Raios gama \/ radia\u00e7\u00e3o gama\" href=\"https:\/\/www.nuclear-power.com\/nuclear-power\/reactor-physics\/atomic-nuclear-physics\/fundamental-particles\/photon\/gamma-ray\/\">raios<\/a>\u00a0X).\u00a0A radia\u00e7\u00e3o de f\u00f3tons consiste em\u00a0<a title=\"F\u00f3ton - Part\u00edcula Fundamental\" href=\"https:\/\/www.nuclear-power.com\/nuclear-power\/reactor-physics\/atomic-nuclear-physics\/fundamental-particles\/photon\/\">f\u00f3tons<\/a>\u00a0de alta energia\u00a0.\u00a0Esses f\u00f3tons s\u00e3o part\u00edculas \/ ondas (Dualidade de Part\u00edculas de Onda) sem massa de repouso ou carga el\u00e9trica.\u00a0Eles podem viajar 10 metros ou mais no ar.\u00a0Esta \u00e9 uma longa dist\u00e2ncia em compara\u00e7\u00e3o com part\u00edculas alfa ou beta.\u00a0No entanto, os raios gama depositam menos energia ao longo de seus caminhos.\u00a0Chumbo, \u00e1gua e concreto impedem a radia\u00e7\u00e3o gama.\u00a0Os f\u00f3tons (raios gama e raios X) podem ionizar \u00e1tomos diretamente atrav\u00e9s do efeito Fotoel\u00e9trico e do efeito Compton, onde o el\u00e9tron relativamente energ\u00e9tico \u00e9 produzido.\u00a0O el\u00e9tron secund\u00e1rio continuar\u00e1 produzindo\u00a0<strong>m\u00faltiplos<\/strong>\u00a0eventos de\u00a0<strong>ioniza\u00e7\u00e3o<\/strong>\u00a0; portanto, a\u00a0<strong>ioniza\u00e7\u00e3o<\/strong>\u00a0secund\u00e1ria (indireta) \u00e9 muito mais significativa.<\/li>\n<li><strong>Radia\u00e7\u00e3o de n\u00eautrons<\/strong>\u00a0.\u00a0A radia\u00e7\u00e3o de\u00a0<a title=\"N\u00eautron gr\u00e1tis\" href=\"https:\/\/www.nuclear-power.com\/nuclear-power\/reactor-physics\/atomic-nuclear-physics\/fundamental-particles\/neutron\/free-neutron\/\" target=\"_blank\" rel=\"noopener noreferrer\">n\u00eautrons<\/a>\u00a0consiste em\u00a0<a title=\"N\u00eautron gr\u00e1tis\" href=\"https:\/\/www.nuclear-power.com\/nuclear-power\/reactor-physics\/atomic-nuclear-physics\/fundamental-particles\/neutron\/free-neutron\/\" target=\"_blank\" rel=\"noopener noreferrer\">n\u00eautrons livres<\/a>\u00a0em qualquer energia \/ velocidade.\u00a0<a title=\"N\u00eautron\" href=\"https:\/\/www.nuclear-power.com\/nuclear-power\/reactor-physics\/atomic-nuclear-physics\/fundamental-particles\/neutron\/\" target=\"_blank\" rel=\"noopener noreferrer\">Os n\u00eautrons<\/a>\u00a0podem ser emitidos por\u00a0<a title=\"Fic\u00e3o nuclear\" href=\"https:\/\/www.nuclear-power.com\/nuclear-power\/fission\/\" target=\"_blank\" rel=\"noopener noreferrer\">fiss\u00e3o nuclear<\/a>\u00a0ou pelo\u00a0<a title=\"Decaimento radioativo - Decaimento nuclear\" href=\"https:\/\/www.nuclear-power.com\/radioactive-decay\/\" target=\"_blank\" rel=\"noopener noreferrer\">decaimento<\/a>\u00a0de alguns \u00e1tomos radioativos.\u00a0Os n\u00eautrons t\u00eam carga el\u00e9trica nula e n\u00e3o podem causar ioniza\u00e7\u00e3o diretamente.\u00a0Os n\u00eautrons ionizam a mat\u00e9ria\u00a0<strong>apenas indiretamente<\/strong>\u00a0.\u00a0Por exemplo, quando n\u00eautrons atingem os n\u00facleos de hidrog\u00eanio, ocorre radia\u00e7\u00e3o de pr\u00f3tons (pr\u00f3tons r\u00e1pidos).\u00a0Os n\u00eautrons podem variar de part\u00edculas de alta velocidade e alta energia a part\u00edculas de baixa velocidade e baixa energia (chamados n\u00eautrons t\u00e9rmicos).\u00a0Os n\u00eautrons podem viajar centenas de p\u00e9s no ar sem nenhuma intera\u00e7\u00e3o.<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<div class=\"lgc-column lgc-grid-parent lgc-grid-100 lgc-tablet-grid-100 lgc-mobile-grid-100 lgc-equal-heights  lgc-first lgc-last\">\n<div class=\"inside-grid-column\">\n<h2><span>Radia\u00e7\u00e3o High-LET e Low-LET<\/span><\/h2>\n<figure id=\"attachment_25310\" class=\"wp-caption alignright\" aria-describedby=\"caption-attachment-25310\"><a href=\"http:\/\/www.radiation-dosimetry.org\/wp-content\/uploads\/2019\/12\/Radiation-weighting-factors-current-ICRP.png\"><img loading=\"lazy\" class=\"wp-image-25310 lazy-loaded\" src=\"http:\/\/www.radiation-dosimetry.org\/wp-content\/uploads\/2019\/12\/Radiation-weighting-factors-current-ICRP.png\" alt=\"Fatores de pondera\u00e7\u00e3o por radia\u00e7\u00e3o - corrente - ICRP\" width=\"503\" height=\"266\" data-lazy-type=\"image\" data-src=\"http:\/\/www.radiation-dosimetry.org\/wp-content\/uploads\/2019\/12\/Radiation-weighting-factors-current-ICRP.png\" \/><\/a><figcaption id=\"caption-attachment-25310\" class=\"wp-caption-text\"><span>Fonte: ICRP Publ.\u00a0103: As recomenda\u00e7\u00f5es de 2007 da Comiss\u00e3o Internacional de Prote\u00e7\u00e3o Radiol\u00f3gica<\/span><\/figcaption><\/figure>\n<p><span>Como foi escrito, cada tipo de radia\u00e7\u00e3o\u00a0<\/span><a href=\"https:\/\/www.nuclear-power.com\/nuclear-power\/reactor-physics\/interaction-radiation-matter\/\"><strong><span>interage com a mat\u00e9ria de uma maneira diferente<\/span><\/strong><\/a><span>\u00a0.\u00a0Por exemplo, part\u00edculas carregadas com altas energias podem ionizar diretamente \u00e1tomos.\u00a0<\/span><a href=\"https:\/\/www.nuclear-power.com\/nuclear-power\/reactor-physics\/atomic-nuclear-physics\/fundamental-particles\/alpha-particle\/\"><span>As part\u00edculas alfa<\/span><\/a><span>\u00a0s\u00e3o bastante maci\u00e7as e carregam uma carga positiva dupla, de modo que tendem a percorrer apenas uma curta dist\u00e2ncia e n\u00e3o penetram muito no tecido, se \u00e9 que o fazem.\u00a0No entanto, as part\u00edculas alfa depositam sua energia em um volume menor (possivelmente apenas algumas c\u00e9lulas se entrarem no corpo) e causam mais danos a essas poucas c\u00e9lulas.<\/span><\/p>\n<p><a href=\"https:\/\/www.nuclear-power.com\/nuclear-power\/reactor-physics\/atomic-nuclear-physics\/fundamental-particles\/beta-particle\/\"><span>As part\u00edculas beta<\/span><\/a><span>\u00a0(el\u00e9trons) s\u00e3o muito menores que as part\u00edculas alfa.\u00a0Eles carregam uma \u00fanica carga negativa.\u00a0Eles s\u00e3o mais penetrantes que as part\u00edculas alfa.\u00a0Eles podem viajar v\u00e1rios metros, mas depositam menos energia em qualquer ponto do caminho do que as part\u00edculas alfa.\u00a0Isso significa que as part\u00edculas beta tendem a danificar mais c\u00e9lulas, mas com menos danos a cada uma.\u00a0Por outro lado, part\u00edculas eletricamente neutras interagem apenas indiretamente, mas tamb\u00e9m podem transferir parte ou todas as suas energias para o assunto.<\/span><\/p>\n<p><span>Certamente simplificaria as coisas se\u00a0<\/span><strong><span>os efeitos biol\u00f3gicos<\/span><\/strong><span>\u00a0da radia\u00e7\u00e3o fossem diretamente proporcionais \u00e0\u00a0<\/span><a href=\"https:\/\/www.radiation-dosimetry.org\/pt-br\/o-que-e-dose-absorvida-formula-equacao-definicao\/\"><span>dose absorvida<\/span><\/a><span>\u00a0.\u00a0Infelizmente,\u00a0<\/span><strong><span>os efeitos biol\u00f3gicos<\/span><\/strong><span>\u00a0dependem tamb\u00e9m da maneira como a dose absorvida \u00e9 distribu\u00edda ao longo do caminho da radia\u00e7\u00e3o.\u00a0Estudos mostraram que a radia\u00e7\u00e3o alfa e n\u00eautron causa maior dano biol\u00f3gico para uma dada deposi\u00e7\u00e3o de energia por kg de tecido do que a radia\u00e7\u00e3o gama.\u00a0Foi descoberto que os efeitos biol\u00f3gicos de qualquer radia\u00e7\u00e3o\u00a0<\/span><strong><span>aumentam<\/span><\/strong><span>\u00a0com a\u00a0<\/span><strong><span>transfer\u00eancia linear de energia<\/span><\/strong><span>\u00a0(LET).\u00a0Em resumo, o dano biol\u00f3gico da\u00a0<\/span><strong><span>radia\u00e7\u00e3o<\/span><\/strong><span>\u00a0de\u00a0<strong>alta LET<\/strong>\u00a0(\u00a0<\/span><a href=\"https:\/\/www.nuclear-power.com\/nuclear-power\/reactor-physics\/atomic-nuclear-physics\/fundamental-particles\/alpha-particle\/\"><span>part\u00edculas alfa<\/span><\/a><span>\u00a0,\u00a0<\/span><a href=\"https:\/\/www.nuclear-power.com\/nuclear-power\/reactor-physics\/atomic-nuclear-physics\/fundamental-particles\/what-is-proton-properties-of-proton\/\"><span>pr\u00f3tons<\/span><\/a><span>\u00a0ou\u00a0<\/span><a href=\"https:\/\/www.nuclear-power.com\/nuclear-power\/reactor-physics\/atomic-nuclear-physics\/fundamental-particles\/neutron\/\"><span>n\u00eautrons<\/span><\/a><span>) \u00e9 muito maior do que o da\u00a0<\/span><strong><span>radia\u00e7\u00e3o<\/span><\/strong><span>\u00a0de\u00a0<strong>baixa LET<\/strong>\u00a0(\u00a0<\/span><a href=\"https:\/\/www.nuclear-power.com\/nuclear-power\/reactor-physics\/atomic-nuclear-physics\/fundamental-particles\/photon\/gamma-ray\/\"><span>raios gama<\/span><\/a><span>\u00a0).\u00a0Isso ocorre porque o tecido vivo pode reparar mais facilmente os danos causados \u200b\u200bpela radia\u00e7\u00e3o que se espalha por uma \u00e1rea grande do que aquela que est\u00e1 concentrada em uma \u00e1rea pequena.\u00a0Obviamente, em n\u00edveis muito altos de exposi\u00e7\u00e3o, os raios gama ainda podem causar muitos danos aos tecidos.<\/span><\/p>\n<p><span>Como mais danos biol\u00f3gicos s\u00e3o causados \u200b\u200bpela mesma dose f\u00edsica (ou seja, a mesma energia depositada por unidade de massa de tecido), um\u00a0<\/span><a href=\"https:\/\/www.radiation-dosimetry.org\/pt-br\/o-que-e-gray-unidade-de-dose-de-radiacao-definicao\/\"><span>cinza<\/span><\/a><span>\u00a0de radia\u00e7\u00e3o alfa ou n\u00eautron \u00e9 mais prejudicial do que um cinza de radia\u00e7\u00e3o gama.\u00a0Esse fato de que radia\u00e7\u00f5es de diferentes tipos (e energias) produzem efeitos biol\u00f3gicos diferentes para a mesma dose absorvida \u00e9 descrito em termos de fatores conhecidos como\u00a0<\/span><strong><span>efetividade biol\u00f3gica relativa<\/span><\/strong><span>\u00a0(RBE) e\u00a0<\/span><a href=\"https:\/\/www.nuclear-power.com\/nuclear-engineering\/radiation-protection\/equivalent-dose\/radiation-weighting-factor\/\"><strong><span>fator de pondera\u00e7\u00e3o de radia\u00e7\u00e3o<\/span><\/strong><\/a><span>\u00a0(wR).<\/span><\/p>\n<p><span>O\u00a0<\/span><strong><span>fator de pondera\u00e7\u00e3o da radia\u00e7\u00e3o<\/span><\/strong><span>\u00a0\u00e9 um fator adimensional usado para determinar a dose equivalente da dose absorvida m\u00e9dia sobre um tecido ou \u00f3rg\u00e3o e baseia-se no tipo de radia\u00e7\u00e3o absorvida.\u00a0A dose ponderada resultante foi designada como a dose equivalente de \u00f3rg\u00e3o ou tecido:<\/span><\/p>\n<p><a href=\"http:\/\/www.radiation-dosimetry.org\/wp-content\/uploads\/2019\/12\/equivalent-dose-equation-definition.png\"><img loading=\"lazy\" class=\"aligncenter size-full wp-image-25373 lazy-loaded\" src=\"http:\/\/www.radiation-dosimetry.org\/wp-content\/uploads\/2019\/12\/equivalent-dose-equation-definition.png\" alt=\"dose equivalente - equa\u00e7\u00e3o - defini\u00e7\u00e3o\" width=\"444\" height=\"159\" data-lazy-type=\"image\" data-src=\"http:\/\/www.radiation-dosimetry.org\/wp-content\/uploads\/2019\/12\/equivalent-dose-equation-definition.png\" \/><\/a><\/p>\n<p><a href=\"https:\/\/www.radiation-dosimetry.org\/wp-content\/uploads\/2019\/12\/equivalent-dose-definition-min.png\"><img loading=\"lazy\" class=\"alignright size-medium wp-image-25395 lazy-loaded\" src=\"https:\/\/www.radiation-dosimetry.org\/wp-content\/uploads\/2019\/12\/equivalent-dose-definition-min-300x267.png\" alt=\"dose equivalente - defini\u00e7\u00e3o\" width=\"300\" height=\"267\" data-lazy-type=\"image\" data-src=\"https:\/\/www.radiation-dosimetry.org\/wp-content\/uploads\/2019\/12\/equivalent-dose-definition-min-300x267.png\" \/><\/a><span>Uma dose equivalente de\u00a0<\/span><strong><span>um Sievert<\/span><\/strong><span>\u00a0representa a quantidade de dose de radia\u00e7\u00e3o equivalente, em termos de\u00a0<\/span><strong><span>dano biol\u00f3gico<\/span><\/strong><span>\u00a0especificado\u00a0, a\u00a0<\/span><a href=\"https:\/\/www.radiation-dosimetry.org\/pt-br\/o-que-e-gray-unidade-de-dose-de-radiacao-definicao\/\"><strong><span>um cinza<\/span><\/strong><\/a><span>\u00a0de\u00a0<\/span><a href=\"https:\/\/www.nuclear-power.com\/nuclear-power\/reactor-physics\/atomic-nuclear-physics\/radiation\/x-rays-roentgen-radiation\/\"><span>raios X<\/span><\/a><span>\u00a0ou\u00a0<\/span><a href=\"https:\/\/www.nuclear-power.com\/nuclear-power\/reactor-physics\/atomic-nuclear-physics\/fundamental-particles\/photon\/gamma-ray\/\"><span>raios gama<\/span><\/a><span>\u00a0.\u00a0<\/span><strong><span>Dose equivalente<\/span><\/strong><span>\u00a0\u00e9 uma\u00a0<\/span><strong><span>quantidade n\u00e3o-f\u00edsica<\/span><\/strong><span>\u00a0(w\u00a0<\/span><sub><span>R<\/span><\/sub><span>\u00a0\u00e9 derivado de consequ\u00eancias biol\u00f3gicas da radia\u00e7\u00e3o ionizante) amplamente usados na dosimetria medido por dos\u00edmetros.\u00a0Dose equivalente \u00e9 designada pelo ICRP como uma \u201cquantidade limitadora\u201d;\u00a0especificar limites de exposi\u00e7\u00e3o para garantir que &#8220;a ocorr\u00eancia de efeitos estoc\u00e1sticos \u00e0 sa\u00fade seja mantida abaixo de n\u00edveis inaceit\u00e1veis \u200b\u200be que as rea\u00e7\u00f5es teciduais sejam evitadas&#8221;.<\/span><\/p>\n<h2><span>Energia de ioniza\u00e7\u00e3o<\/span><\/h2>\n<p><strong><span>Energia de ioniza\u00e7\u00e3o<\/span><\/strong><span>\u00a0, tamb\u00e9m chamada\u00a0<\/span><strong><span>potencial de ioniza\u00e7\u00e3o<\/span><\/strong><span>\u00a0, \u00e9 a energia necess\u00e1ria para\u00a0<\/span><strong><span>remover um el\u00e9tron<\/span><\/strong><span>\u00a0do \u00e1tomo neutro.<\/span><\/p>\n<p><strong><span>X + energia \u2192 X\u00a0<\/span><sup><span>+<\/span><\/sup><span>\u00a0+ e\u00a0<\/span><sup><span>&#8211;<\/span><\/sup><\/strong><\/p>\n<p><span>onde X \u00e9 qualquer \u00e1tomo ou mol\u00e9cula capaz de ser ionizada, X\u00a0<\/span><sup><span>+<\/span><\/sup><span>\u00a0\u00e9 aquele \u00e1tomo ou mol\u00e9cula com um el\u00e9tron removido (\u00edon positivo) e e\u00a0<\/span><sup><span>&#8211;<\/span><\/sup><span>\u00a0\u00e9 o el\u00e9tron removido.<\/span><\/p>\n<p><span>Um \u00e1tomo de nitrog\u00eanio, por exemplo, requer a seguinte energia de ioniza\u00e7\u00e3o para remover o el\u00e9tron mais externo.<\/span><\/p>\n<p><strong><span>N + IE \u2192 N\u00a0<\/span><sup><span>+<\/span><\/sup><span>\u00a0+ e\u00a0<\/span><sup><span>&#8211;<\/span><\/sup><span>\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0IE = 14,5 eV<\/span><\/strong><\/p>\n<p><span>A energia de ioniza\u00e7\u00e3o associada \u00e0 remo\u00e7\u00e3o do primeiro el\u00e9tron \u00e9 mais comumente usada.\u00a0O\u00a0<\/span><em><span>n<\/span><\/em><span>\u00a0de energia de ioniza\u00e7\u00e3o th refere-se \u00e0 quantidade de energia necess\u00e1ria para remover um electr\u00e3o a partir das esp\u00e9cies com uma taxa de (\u00a0<\/span><em><span>n<\/span><\/em><span>\u00a0-1).<\/span><\/p>\n<p><span>1a energia de ioniza\u00e7\u00e3o<\/span><\/p>\n<p><span>X \u2192 X\u00a0<\/span><sup><span>+<\/span><\/sup><span>\u00a0+ e\u00a0<\/span><sup><span>&#8211;<\/span><\/sup><\/p>\n<p><span>2a energia de ioniza\u00e7\u00e3o<\/span><\/p>\n<p><span>X\u00a0<\/span><sup><span>+<\/span><\/sup><span>\u00a0\u2192 X\u00a0<\/span><sup><span>2+<\/span><\/sup><span>\u00a0+ e\u00a0<\/span><sup><span>&#8211;<\/span><\/sup><\/p>\n<p><span>3a energia de ioniza\u00e7\u00e3o<\/span><\/p>\n<p><span>X\u00a0<\/span><sup><span>2+<\/span><\/sup><span>\u00a0\u2192 X\u00a0<\/span><sup><span>3+<\/span><\/sup><span>\u00a0+ e\u00a0<\/span><sup><span>&#8211;<\/span><\/sup><\/p>\n<h2><span>Energia de ioniza\u00e7\u00e3o para diferentes elementos<\/span><\/h2>\n<p><span>Existe uma energia de ioniza\u00e7\u00e3o para cada el\u00e9tron sucessivo removido.\u00a0Os el\u00e9trons que circundam o n\u00facleo se movem em \u00f3rbitas bastante bem definidas.\u00a0Alguns desses el\u00e9trons est\u00e3o mais fortemente ligados ao \u00e1tomo do que outros.\u00a0Por exemplo, apenas 7,38 eV s\u00e3o necess\u00e1rios para remover o el\u00e9tron mais externo de um \u00e1tomo de chumbo, enquanto 88.000 eV s\u00e3o necess\u00e1rios para remover o el\u00e9tron mais interno.\u00a0Ajuda a entender a reatividade de elementos (especialmente metais, que perdem el\u00e9trons).<\/span><\/p>\n<p><span>Em geral, a energia de ioniza\u00e7\u00e3o aumenta subindo um grupo e movendo da esquerda para a direita ao longo de um per\u00edodo.\u00a0Al\u00e9m disso:<\/span><\/p>\n<ul>\n<li><strong><span>A energia de ioniza\u00e7\u00e3o<\/span><\/strong><span>\u00a0\u00e9 mais baixa para os metais alcalinos que possuem um \u00fanico el\u00e9tron fora de uma concha fechada.<\/span><\/li>\n<li><strong><span>A energia de ioniza\u00e7\u00e3o<\/span><\/strong><span>\u00a0aumenta em uma linha no m\u00e1ximo peri\u00f3dico para os gases nobres que fecharam as conchas<\/span><\/li>\n<\/ul>\n<p><span>Por exemplo, o s\u00f3dio requer apenas 496 kJ \/ mol ou 5,14 eV \/ \u00e1tomo para ioniz\u00e1-lo.\u00a0Por outro lado, o neon, o g\u00e1s nobre, imediatamente anterior \u00e0 tabela peri\u00f3dica, requer 2081 kJ \/ mol ou 21,56 eV \/ \u00e1tomo.<\/span><\/p>\n<figure id=\"attachment_16766\" class=\"wp-caption aligncenter\" aria-describedby=\"caption-attachment-16766\"><a href=\"https:\/\/www.radiation-dosimetry.org\/wp-content\/uploads\/2019\/12\/Ionization-energy-first-min.png\"><img loading=\"lazy\" class=\"size-full wp-image-16766 lazy-loaded\" src=\"https:\/\/www.radiation-dosimetry.org\/wp-content\/uploads\/2019\/12\/Ionization-energy-first-min.png\" alt=\"Energia de ioniza\u00e7\u00e3o\" width=\"1139\" height=\"432\" data-lazy-type=\"image\" data-src=\"https:\/\/www.radiation-dosimetry.org\/wp-content\/uploads\/2019\/12\/Ionization-energy-first-min.png\" \/><\/a><figcaption id=\"caption-attachment-16766\" class=\"wp-caption-text\"><span>Fonte: wikipedia.org Licen\u00e7a: CC BY-SA 3.0<\/span><\/figcaption><\/figure>\n<\/div>\n<\/div>\n<div class=\"lgc-column lgc-grid-parent lgc-grid-100 lgc-tablet-grid-100 lgc-mobile-grid-100 lgc-equal-heights  lgc-first lgc-last\">\n<div class=\"inside-grid-column\">\n<div class=\"su-spoiler su-spoiler-style-default su-spoiler-icon-arrow\" data-anchor=\"References\">\n<div class=\"su-spoiler-title\" tabindex=\"0\" role=\"button\"><\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<p>&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;&#8230;.<\/p>\n<p>Este artigo \u00e9 baseado na tradu\u00e7\u00e3o autom\u00e1tica do artigo original em ingl\u00eas. Para mais informa\u00e7\u00f5es, consulte o artigo em ingl\u00eas. Voc\u00ea pode nos ajudar. Se voc\u00ea deseja corrigir a tradu\u00e7\u00e3o, envie-a para: translations@nuclear-power.com ou preencha o formul\u00e1rio de tradu\u00e7\u00e3o on-line. Agradecemos sua ajuda, atualizaremos a tradu\u00e7\u00e3o o mais r\u00e1pido poss\u00edvel. Obrigado.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Radia\u00e7\u00e3o ionizante \u00e9 qualquer radia\u00e7\u00e3o (part\u00edculas ou ondas eletromagn\u00e9ticas) que transporta energia suficiente para derrubar el\u00e9trons de \u00e1tomos ou mol\u00e9culas, ionizando-os.\u00a0Dosimetria de Radia\u00e7\u00e3o radia\u00e7\u00e3o ionizante &#8211; s\u00edmbolo de perigo Radia\u00e7\u00e3o ionizante\u00a0\u00e9 qualquer radia\u00e7\u00e3o (\u00a0part\u00edculas ou ondas eletromagn\u00e9ticas\u00a0) que transporta energia suficiente para derrubar el\u00e9trons de \u00e1tomos ou mol\u00e9culas, ionizando-os.\u00a0Para radia\u00e7\u00e3o ionizante, a energia cin\u00e9tica das &#8230; <a title=\"O que \u00e9 radia\u00e7\u00e3o ionizante &#8211; Defini\u00e7\u00e3o\" class=\"read-more\" href=\"https:\/\/www.radiation-dosimetry.org\/pt-br\/o-que-e-radiacao-ionizante-definicao\/\" aria-label=\"More on O que \u00e9 radia\u00e7\u00e3o ionizante &#8211; Defini\u00e7\u00e3o\">Ler mais<\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":[],"categories":[51],"tags":[],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v15.4 - https:\/\/yoast.com\/wordpress\/plugins\/seo\/ -->\n<title>O que \u00e9 radia\u00e7\u00e3o ionizante - Defini\u00e7\u00e3o<\/title>\n<meta name=\"description\" content=\"Radia\u00e7\u00e3o ionizante \u00e9 qualquer radia\u00e7\u00e3o (part\u00edculas ou ondas eletromagn\u00e9ticas) que transporta energia suficiente para derrubar el\u00e9trons de \u00e1tomos ou mol\u00e9culas, ionizando-os. 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