<***N style="FONT-SIZE: 14pt; COLOR: #333333; FONT-FAMILY: 仿宋_GB2312; mso-font-kerning: 0pt; mso-hansi-font-family: 宋体; mso-bidi-font-family: 宋体">(射线辐射防护知识)***N><***N lang=EN-US style="COLOR: #333333; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体; mso-bidi-font-size: 10.5pt"> ***N><***N><***N style="FONT-SIZE: 9pt; COLOR: #333333; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">
<***N style="FONT-SIZE: 9pt; COLOR: #333333; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">[上接<***N style="FONT-SIZE: 14pt; COLOR: #333333; FONT-FAMILY: 仿宋_GB2312; mso-font-kerning: 0pt; mso-hansi-font-family: 宋体; mso-bidi-font-family: 宋体">关注:射线辐射对人体的危害!(1)]***N>***N>
***N><***N style="FONT-SIZE: 9pt; COLOR: #333333; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">***N>七、半衰期是长还是短,哪一个正确***N><***N lang=EN-US style="COLOR: #333333; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体; mso-bidi-font-size: 10.5pt">
<***N style="FONT-SIZE: 9pt; COLOR: #333333; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">射线的危害主要来自射线到达身体时对人体的损害。这些射线主要来自核放射元素的衰减,其半衰期从几个月到几十年不等,一块很小的放射材料都能轻易的放射出强烈的射线,这些材料虽然有衰减过程但是它具有漫长而稳定的衰减周期,从而长期的放射出射线,材料的半衰期是指材料衰减一半所需要的时间,如天然铀<***N lang=EN-US>238***N>的半衰期为<***N lang=EN-US>T0.5=45***N>亿年,对于短半衰期的核素会在很短的时间内放射出高密度射线,直到衰变到环境的射线水平。有些辐射污染是由于放射性材料污染到衣服,鞋子,皮肤上造成的辐射危害,这些污染也会蔓延到家中和其它的地方。向这种情况,会有很长的半衰期,所以造成的危害更严重。***N><***N lang=EN-US style="FONT-SIZE: 9pt; COLOR: #333333; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">
<***N style="COLOR: #333333; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体; mso-bidi-font-size: 10.5pt">八、普遍的放射性核素<***N lang=EN-US>
<***N style="FONT-SIZE: 9pt; COLOR: #333333; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">表<***N lang=EN-US>5***N>列举了常见的几种核素的**步衰变情况及其半衰期和释放出来的射线粒子类型。***N><***N lang=EN-US style="FONT-SIZE: 9pt; COLOR: #333333; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">
<***N style="FONT-SIZE: 9pt; COLOR: #333333; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">表<***N lang=EN-US>5***N>:常见核元素***N><***N lang=EN-US style="FONT-SIZE: 9pt; COLOR: #333333; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">
<***N style="FONT-SIZE: 9pt; COLOR: #333333; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">放射性元素<***N lang=EN-US> |
<***N style="FONT-SIZE: 9pt; COLOR: #333333; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">衰变<***N lang=EN-US> <***N style="FONT-SIZE: 9pt; COLOR: #333333; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">模式<***N lang=EN-US> |
<***N style="FONT-SIZE: 9pt; COLOR: #333333; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">半衰期<***N lang=EN-US>t1/2 |
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<***N style="FONT-SIZE: 9pt; COLOR: #333333; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">未精炼的<***N lang=EN-US>Pu***N>中的同位素<***N lang=EN-US> |
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<***N lang=EN-US style="FONT-SIZE: 9pt; COLOR: #333333; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">6***N><***N style="FONT-SIZE: 9pt; COLOR: #333333; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">小时<***N lang=EN-US> |
<***N style="FONT-SIZE: 9pt; COLOR: #333333; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">医学成像<***N lang=EN-US> |
<***N lang=EN-US style="FONT-SIZE: 9pt; COLOR: #333333; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">
<***N style="COLOR: #333333; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体; mso-bidi-font-size: 10.5pt">九、外照射防护三要素***N><***N style="COLOR: #333333; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体; mso-bidi-font-size: 10.5pt">:<***N lang=EN-US>
<***N lang=EN-US style="FONT-SIZE: 9pt; COLOR: #333333; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体"> ***N><***N style="FONT-SIZE: 9pt; COLOR: #333333; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">时间:累积剂量与受照时间成正比。措施:充分准备,减少受照时间<***N lang=EN-US>
<***N lang=EN-US style="FONT-SIZE: 9pt; COLOR: #333333; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体"> ***N><***N style="FONT-SIZE: 9pt; COLOR: #333333; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">距离:剂量率与距离的平方成反比(点源)。措施:远距离操作;任何源不能直接用手操作;注意<***N lang=EN-US>β***N>射线防护。<***N lang=EN-US>
<***N lang=EN-US style="FONT-SIZE: 9pt; COLOR: #333333; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体"> ***N><***N style="FONT-SIZE: 9pt; COLOR: #333333; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">屏蔽:措施:设置屏蔽体。屏蔽材料和厚度的选择:辐射源的类型、射线能量、活度;在进行屏蔽防护时,应考虑屏蔽设计、屏蔽方式及屏蔽材料等问题。***N><***N lang=EN-US style="FONT-SIZE: 9pt; COLOR: #333333; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">
<***N style="COLOR: #333333; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体; mso-bidi-font-size: 10.5pt">十、内照射防护的基本方法***N><***N lang=EN-US style="COLOR: #333333; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体; mso-bidi-font-size: 10.5pt">
<***N style="FONT-SIZE: 9pt; COLOR: #333333; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">内照射防护的基本原则是制定各种规章制度,采取各种有效措施,阻断放射性物质进入人体的各种途径,在**化原则的范围内,使摄入量减少到尽可能低的水平。<***N lang=EN-US>
<***N style="FONT-SIZE: 9pt; COLOR: #333333; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">放射性物质进入人体内的途径有三种,即放射性核素经由(<***N lang=EN-US>1***N>)食入、(<***N lang=EN-US>2***N>)吸入、(<***N lang=EN-US>3***N>)皮肤(完好的或伤口)进入体内,从而造成放射性核素的体内污染。下图概括了放射性核素进入人体内的途径及其在体内的代谢过程。***N><***N lang=EN-US style="FONT-SIZE: 9pt; COLOR: #333333; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">
<***N style="COLOR: #333333; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体; mso-bidi-font-size: 10.5pt">十一、核污染物监测及防护***N><***N lang=EN-US style="COLOR: #333333; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体; mso-bidi-font-size: 10.5pt">
<***N style="FONT-SIZE: 9pt; COLOR: #333333; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">核射线到达检测器和其它物体表面时不会造成该物体的污染。射线通过检测器时被检测器捕获,从而激发检测器对射线强度做出响应。暴露在射线中的物体不会变成放射性物质,除非受到中子射线的照射,该物质可能会变成放射性物质。因为中子射线能被稳定的原子核捕获成为放射性同位素。出现这种情况时,检测器的表面材料转变为放射性同位素,检测器本身就成为了一个放射源,令人放心的是,一般情况下不会有中子射线存在的可能。***N><***N lang=EN-US style="FONT-SIZE: 9pt; COLOR: #333333; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">
<***N style="COLOR: #333333; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体; mso-bidi-font-size: 10.5pt">十二、剂量率 ***N><***N lang=EN-US style="COLOR: #333333; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体; mso-bidi-font-size: 10.5pt">
<***N style="FONT-SIZE: 9pt; COLOR: #333333; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">剂量率即单位时间内的吸收剂量。一般说来,总剂量相同时,剂量率越高,生物效应越大。但当剂量率达到一定值时,生物效应与剂量率之间失去比例关系。在极小的剂量率条件下,当机体损伤与其修复相平衡时,机体可长期接受照射而不出现损伤。小剂量长期照射,当累积剂量很大时,便可产生慢性放射损伤。<***N lang=EN-US>
<***N style="FONT-SIZE: 9pt; COLOR: red; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">人体各组织对射线的敏感性大致有以下顺序:(如下) ***N><***N lang=EN-US style="FONT-SIZE: 9pt; COLOR: #333333; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">
<***N style="COLOR: red; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体; mso-bidi-font-size: 10.5pt">十三、高度敏感组织 ***N><***N lang=EN-US style="COLOR: red; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体; mso-bidi-font-size: 10.5pt">
<***N style="FONT-SIZE: 9pt; COLOR: #333333; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">淋巴组织 胸腺<***N lang=EN-US>(***N>**组织<***N lang=EN-US>)
<***N style="FONT-SIZE: 9pt; COLOR: #333333; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">胃肠上皮,尤其是**隐窝上皮细胞; 性腺 ***N><***N lang=EN-US style="FONT-SIZE: 9pt; COLOR: #333333; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">
<***N style="COLOR: red; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体; mso-bidi-font-size: 10.5pt">十四、中度敏感组织 ***N><***N lang=EN-US style="COLOR: red; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体; mso-bidi-font-size: 10.5pt">
<***N style="FONT-SIZE: 9pt; COLOR: #333333; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">*、肝、肺组织的上皮细胞。 <***N lang=EN-US>
<***N style="FONT-SIZE: 9pt; COLOR: #333333; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">人体组织结构和器官形态不同,厚度也不一致。其厚与薄的部分,或分界明确,或逐渐移行。厚的部分,吸收<***N lang=EN-US>X***N>线多,透过的<***N lang=EN-US>X***N>线少,薄的部分则相反。人体各部位细胞对<***N lang=EN-US>X***N>射的反应程度不一,其中以性腺*为敏感。辐射能够引起生殖细胞遗传物质的变化,形成遗传效应。这种变化表现为基因突变和染色体畸变。近年来,对辐射的遗传效应有了一些新的认识,认为在小剂量范围内对遗传方面的影响不大。***N><***N lang=EN-US style="FONT-SIZE: 9pt; COLOR: #333333; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">
<***N lang=EN-US style="COLOR: #333333; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体; mso-bidi-font-size: 10.5pt"> ***N><***N style="COLOR: #333333; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体; mso-bidi-font-size: 10.5pt">十五、如何防护<***N lang=EN-US>X***N>线<***N lang=EN-US> ***N>***N><***N lang=EN-US style="COLOR: #333333; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体; mso-bidi-font-size: 10.5pt">
<***N lang=EN-US style="FONT-SIZE: 9pt; COLOR: #333333; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体"> X***N><***N style="FONT-SIZE: 9pt; COLOR: #333333; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">线穿透人体将产生一定的生物效应。若接触的<***N lang=EN-US>X***N>线量过多,超过容许曝射量,就可能产生放射反应,甚至产生一定程度的放射损害。但是,如<***N lang=EN-US>X***N>线曝射量在容许范围内,一般影响极小。人们不必因为辐射而拒绝必要的<***N lang=EN-US>X***N>光和<***N lang=EN-US>CT***N>检查,更不必为此连医院的放射科的区域都不敢进。 <***N lang=EN-US>
<***N style="FONT-SIZE: 9pt; COLOR: #333333; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">技术方面:可以采取屏蔽防护和距离防护原则。屏蔽防护是指使用原子序数较高的物质,常用铅或含铅的物质,作为屏障以吸收不必要的<***N lang=EN-US>x***N>线。距离防护是指利用<***N lang=EN-US>x***N>线曝射量与距离平方成反比这一原理,通过增加<***N lang=EN-US>x***N>线源与人体间距离以减少曝射量。<***N lang=EN-US>
<***N style="FONT-SIZE: 9pt; COLOR: #333333; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">从<***N lang=EN-US>x***N>线管到达人体的<***N lang=EN-US>x***N>线,有原发射线和继发射线两类,继发射线是原发射线照射穿透其他物质过程中发生的,其能量较原发射线小,便影响较大。通常采用<***N lang=EN-US>x***N>线管壳、遮光筒和光圈、滤过板、荧屏后铅玻璃、铅屏、铅橡皮围裙、铅手套以及墙壁等,进行屏蔽防护。增加人体与<***N lang=EN-US>x***N>线源的距离以进行中国医大一院放射线科主任徐荣天表示,放射线治疗中,如果受到射线照射过量,会造成人体部分机体细胞受到损害,受损细胞如果不能自我修复,就会残存于体内,人体在免疫力低下或促癌因素存在的情况下,就极有可能迅速复制,出现一个癌症病灶。放射检查次数做得越多,诱发癌症的概率越大。眼睛如果过多受到<***N lang=EN-US> X***N>光的辐射,还可能造成失明。<***N lang=EN-US>
<***N style="FONT-SIZE: 9pt; COLOR: red; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">放射线对人的造血系统影响特别大,尤其是身体发育未成熟的**。<***N lang=EN-US> X***N>线会杀死白细胞,直接导致白细胞数量降低,容易引起血液系统肿瘤,如白血病等。<***N lang=EN-US> ***N>***N><***N lang=EN-US style="FONT-SIZE: 9pt; COLOR: red; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">
<***N style="FONT-SIZE: 9pt; COLOR: red; FONT-FAMILY: 宋体; mso-font-kerning: 0pt; mso-bidi-font-family: 宋体">孕妇如果在怀孕期间进行<***N lang=EN-US> X***N>线照射,很容易导致畸形儿出现。一般怀孕<***N lang=EN-US>8***N>个月内的孕妇是不允许接受<***N lang=EN-US> X***N>线检查的。严格来讲,育龄妇女在孕前一年都不允许接受<***N lang=EN-US> X***N>线检查。未成年人也要尽量减少接受放射线检查。 距离防护,是简易的防护措施。***N>
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