{"id":18034,"date":"2020-06-25T03:34:37","date_gmt":"2020-06-25T03:34:37","guid":{"rendered":"https:\/\/www.radiation-dosimetry.org\/o-que-e-roentgen-unidade-de-exposicao-definicao\/"},"modified":"2020-07-23T09:57:12","modified_gmt":"2020-07-23T09:57:12","slug":"o-que-e-roentgen-unidade-de-exposicao-definicao","status":"publish","type":"post","link":"https:\/\/www.radiation-dosimetry.org\/pt-br\/o-que-e-roentgen-unidade-de-exposicao-definicao\/","title":{"rendered":"O que \u00e9 Roentgen &#8211; Unidade de exposi\u00e7\u00e3o &#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\">O roentgen, abreviado R, \u00e9 a unidade de exposi\u00e7\u00e3o \u00e0 radia\u00e7\u00e3o.\u00a0Um roentgen corresponde a 2,58E-4 coulomb por kg de \u00edons gerados no ar e uma exposi\u00e7\u00e3o de um coulomb por quilograma \u00e9 equivalente a 3876 roentgens.\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<p><strong>A exposi\u00e7\u00e3o \u00e0 radia\u00e7\u00e3o<\/strong>\u00a0\u00e9 uma medida da ioniza\u00e7\u00e3o do\u00a0<strong>ar<\/strong>\u00a0devido \u00e0 radia\u00e7\u00e3o ionizante dos\u00a0<strong>f\u00f3tons<\/strong>\u00a0de\u00a0<strong>alta energia<\/strong>\u00a0(raios X e raios gama).\u00a0<strong>A exposi\u00e7\u00e3o \u00e0 radia\u00e7\u00e3o<\/strong>\u00a0\u00e9 definida como a\u00a0<strong>soma das cargas el\u00e9tricas<\/strong>\u00a0(\u2206q) em todos os \u00edons de um sinal produzido\u00a0<strong>no ar<\/strong>\u00a0quando todos os el\u00e9trons, liberados pelos f\u00f3tons em um volume de ar cuja massa \u00e9 \u2206m, s\u00e3o completamente parados no ar.<\/p>\n<p><a href=\"http:\/\/www.radiation-dosimetry.org\/wp-content\/uploads\/2019\/12\/radiation-exposure-definition.png\"><img loading=\"lazy\" class=\"aligncenter size-full wp-image-25336 lazy-loaded\" src=\"http:\/\/www.radiation-dosimetry.org\/wp-content\/uploads\/2019\/12\/radiation-exposure-definition.png\" alt=\"exposi\u00e7\u00e3o \u00e0 radia\u00e7\u00e3o - defini\u00e7\u00e3o\" width=\"165\" height=\"76\" data-lazy-type=\"image\" data-src=\"http:\/\/www.radiation-dosimetry.org\/wp-content\/uploads\/2019\/12\/radiation-exposure-definition.png\" \/><\/a><\/p>\n<p><strong>A exposi\u00e7\u00e3o \u00e0 radia\u00e7\u00e3o<\/strong>\u00a0\u00e9 dado o s\u00edmbolo\u00a0<strong>X<\/strong>\u00a0.\u00a0A unidade SI de exposi\u00e7\u00e3o \u00e0 radia\u00e7\u00e3o \u00e9 o coulomb por quilograma (C \/ kg), mas, na pr\u00e1tica, o\u00a0<strong>roentgen<\/strong>\u00a0\u00e9 usado.<\/p>\n<h2>Roentgen &#8211; Unidade de Exposi\u00e7\u00e3o \u00e0 Radia\u00e7\u00e3o<\/h2>\n<p>O\u00a0<strong>roentgen\u00a0<\/strong>\u00a0, abreviado\u00a0<strong>R<\/strong>\u00a0, \u00e9 a unidade de exposi\u00e7\u00e3o \u00e0 radia\u00e7\u00e3o.\u00a0Na defini\u00e7\u00e3o original,\u00a0<strong>1 R<\/strong>\u00a0significa a quantidade de\u00a0<a href=\"https:\/\/www.nuclear-power.com\/nuclear-power\/reactor-physics\/atomic-nuclear-physics\/radiation\/x-rays-roentgen-radiation\/\">raios X<\/a>\u00a0ou\u00a0<a href=\"https:\/\/www.nuclear-power.com\/nuclear-power\/reactor-physics\/atomic-nuclear-physics\/fundamental-particles\/photon\/gamma-ray\/\">radia\u00e7\u00e3o \u03b3<\/a>\u00a0necess\u00e1ria para liberar cargas positivas e negativas de uma unidade de carga eletrost\u00e1tica (esu) em 1 cm\u00b3 de ar seco \u00e0 temperatura e press\u00e3o padr\u00e3o (STP).\u00a0Observe que, 1 esu 33 3,33364 \u00d7 10\u00a0<sup>\u221210<\/sup>\u00a0C. Como resultado,\u00a0<strong>um roentgen<\/strong>\u00a0corresponde a\u00a0<strong>2,58 x 10\u00a0<sup>-4<\/sup>\u00a0coulomb por kg<\/strong>\u00a0de \u00edons gerados no ar e uma exposi\u00e7\u00e3o de um coulomb por quilograma \u00e9 equivalente a 3876 roentgens.<\/p>\n<p><a href=\"http:\/\/www.radiation-dosimetry.org\/wp-content\/uploads\/2019\/12\/roentgen-unit-of-exposure-definition.png\"><img loading=\"lazy\" class=\"aligncenter size-full wp-image-25337 lazy-loaded\" src=\"http:\/\/www.radiation-dosimetry.org\/wp-content\/uploads\/2019\/12\/roentgen-unit-of-exposure-definition.png\" alt=\"roentgen - unidade de exposi\u00e7\u00e3o - defini\u00e7\u00e3o\" width=\"238\" height=\"133\" data-lazy-type=\"image\" data-src=\"http:\/\/www.radiation-dosimetry.org\/wp-content\/uploads\/2019\/12\/roentgen-unit-of-exposure-definition.png\" \/><\/a><\/p>\n<p>As exposi\u00e7\u00f5es \u00e0 radia\u00e7\u00e3o medidas na ind\u00fastria (exceto medicina nuclear) geralmente t\u00eam doses compar\u00e1veis \u200b\u200ba um roentgen e os seguintes m\u00faltiplos s\u00e3o frequentemente usados:<\/p>\n<p><strong>1 mR (milli roentgen) = 1E-3 R<\/strong><\/p>\n<p><strong>1 kR (quilo roentgen) = 1E3 R<\/strong><\/p>\n<p>O c\u00e1lculo da\u00a0<a href=\"https:\/\/www.radiation-dosimetry.org\/pt-br\/o-que-e-dose-absorvida-formula-equacao-definicao\/\">dose de radia\u00e7\u00e3o<\/a>\u00a0(em Gy) a partir de uma\u00a0<strong>exposi\u00e7\u00e3o \u00e0 radia\u00e7\u00e3o<\/strong>\u00a0de 1 R depende da energia dos raios X ou \u03b3 e da composi\u00e7\u00e3o do material irradiado.\u00a0Por exemplo, se o tecido mole for exposto a raios y de 1 R, a dose de radia\u00e7\u00e3o ser\u00e1 de aproximadamente 9,3 miligray (mGy).<\/p>\n<h3>Convers\u00e3o: Exposi\u00e7\u00e3o a Dose Absorvida<\/h3>\n<p><a href=\"https:\/\/www.radiation-dosimetry.org\/pt-br\/o-que-e-dose-absorvida-formula-equacao-definicao\/\"><span>A dose<\/span><\/a><span>\u00a0\u00e9 definida como a quantidade de energia depositada pela radia\u00e7\u00e3o ionizante em uma subst\u00e2ncia.\u00a0Para um dado campo de radia\u00e7\u00e3o, a dose absorvida depender\u00e1 do tipo de mat\u00e9ria que absorve a radia\u00e7\u00e3o.\u00a0Embora seja conhecido um grande n\u00famero de poss\u00edveis intera\u00e7\u00f5es, existem tr\u00eas\u00a0<\/span><a href=\"https:\/\/www.nuclear-power.com\/nuclear-power\/reactor-physics\/interaction-radiation-matter\/interaction-gamma-radiation-matter\/\"><span>mecanismos<\/span><\/a><span>\u00a0principais de\u00a0<a href=\"https:\/\/www.nuclear-power.com\/nuclear-power\/reactor-physics\/interaction-radiation-matter\/interaction-gamma-radiation-matter\/\">intera\u00e7\u00e3o dos raios gama com a mat\u00e9ria<\/a>\u00a0.<\/span><\/p>\n<ul>\n<li><a href=\"https:\/\/www.nuclear-power.com\/nuclear-power\/reactor-physics\/interaction-radiation-matter\/interaction-gamma-radiation-matter\/photoelectric-effect\/\"><strong><span>Efeito fotoel\u00e9trico<\/span><\/strong><\/a><\/li>\n<li><a href=\"https:\/\/www.nuclear-power.com\/nuclear-power\/reactor-physics\/interaction-radiation-matter\/interaction-gamma-radiation-matter\/compton-scattering\/\"><strong><span>Efeito Compton<\/span><\/strong><\/a><\/li>\n<li><a href=\"https:\/\/www.nuclear-power.com\/nuclear-power\/reactor-physics\/interaction-radiation-matter\/interaction-gamma-radiation-matter\/pair-production\/\"><strong><span>Produ\u00e7\u00e3o de pares<\/span><\/strong><\/a><\/li>\n<\/ul>\n<p><span>Por exemplo, para uma exposi\u00e7\u00e3o de\u00a0<\/span><strong><span>1 roentgen<\/span><\/strong><span>\u00a0por raios gama com uma energia de\u00a0<\/span><strong><span>1 MeV<\/span><\/strong><span>\u00a0, a dose no ar ser\u00e1 de\u00a0<\/span><strong><span>0,876 rad<\/span><\/strong><span>\u00a0.\u00a0Isso pode ser determinado usando a\u00a0<\/span><a href=\"https:\/\/www.periodic-table.org\/ionization-energy-of-chemical-elements\/\"><span>energia<\/span><\/a><span>\u00a0de\u00a0<a href=\"https:\/\/www.periodic-table.org\/ionization-energy-of-chemical-elements\/\">ioniza\u00e7\u00e3o<\/a>\u00a0do ar seco a 20 \u00b0 C e 101,325 kPa de press\u00e3o, que \u00e9 33,97 J \/ C.\u00a0Portanto, uma exposi\u00e7\u00e3o de\u00a0<\/span><strong><span>2,58 \u00d7\u00a0<\/span><sup><span>10-4<\/span><\/sup><span>\u00a0C \/ kg<\/span><\/strong><span>\u00a0(1 roentgen) depositaria uma dose absorvida de\u00a0<\/span><strong><span>8,76 \u00d7\u00a0<\/span><sup><span>10-3<\/span><\/sup><span>\u00a0J \/ kg<\/span><\/strong><span>\u00a0(0,876 rad) em ar seco nessas condi\u00e7\u00f5es.\u00a0Uma tabela que mostra a exposi\u00e7\u00e3o \u00e0 convers\u00e3o de dose para v\u00e1rios materiais para uma variedade de energias de raios gama pode ser encontrada na literatura.<\/span><\/p>\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<\/div>\n","protected":false},"excerpt":{"rendered":"<p>O roentgen, abreviado R, \u00e9 a unidade de exposi\u00e7\u00e3o \u00e0 radia\u00e7\u00e3o.\u00a0Um roentgen corresponde a 2,58E-4 coulomb por kg de \u00edons gerados no ar e uma exposi\u00e7\u00e3o de um coulomb por quilograma \u00e9 equivalente a 3876 roentgens.\u00a0Dosimetria de Radia\u00e7\u00e3o A exposi\u00e7\u00e3o \u00e0 radia\u00e7\u00e3o\u00a0\u00e9 uma medida da ioniza\u00e7\u00e3o do\u00a0ar\u00a0devido \u00e0 radia\u00e7\u00e3o ionizante dos\u00a0f\u00f3tons\u00a0de\u00a0alta energia\u00a0(raios X e raios &#8230; <a title=\"O que \u00e9 Roentgen &#8211; Unidade de exposi\u00e7\u00e3o &#8211; Defini\u00e7\u00e3o\" class=\"read-more\" href=\"https:\/\/www.radiation-dosimetry.org\/pt-br\/o-que-e-roentgen-unidade-de-exposicao-definicao\/\" aria-label=\"More on O que \u00e9 Roentgen &#8211; Unidade de exposi\u00e7\u00e3o &#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 Roentgen - Unidade de exposi\u00e7\u00e3o - Defini\u00e7\u00e3o<\/title>\n<meta name=\"description\" content=\"O roentgen, abreviado R, \u00e9 a unidade de exposi\u00e7\u00e3o \u00e0 radia\u00e7\u00e3o. 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