CT真正的辐射量有多少？人对医疗辐射的接受程度到底是怎样的

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                    <p style="">当身体不适时，医生经常要求我们做一些X射线的检查，目前，虽然人们对辐射有一些了解，但大多数人并不是很清楚做一次检查的辐射剂量。</p><p style=""><br  /></p><p style="">射线辐射量参考值： &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp;<br  /></p><ul class=" list-paddingleft-2" style=""><li><p style="margin-top: 5px; margin-bottom: 5px;">胸透一次大约1.1mSv &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;<br  /></p></li><li><p style="margin-top: 5px; margin-bottom: 5px;">胸片一次剂量0.2mSv &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;<br  /></p></li><li><p style="margin-top: 5px; margin-bottom: 5px;">头颅CT 2mSv &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;<br  /></p></li><li><p style="margin-top: 5px; margin-bottom: 5px;">胸部CT 8mSv &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;<br  /></p></li><li><p style="margin-top: 5px; margin-bottom: 5px;">腹部CT 10mSv &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;<br  /></p></li><li><p style="margin-top: 5px; margin-bottom: 5px;">骨盆CT 10mSv</p></li><li><p style="margin-top: 5px; margin-bottom: 5px;">公众年剂量限值1mSv</p></li><li><p style="margin-top: 5px; margin-bottom: 5px;">乘坐飞机20小时的剂量0.1mSv</p></li><li><p style="margin-top: 5px; margin-bottom: 5px;">每天吸20支烟年0.5-2mSv</p></li><li><p style="margin-top: 5px; margin-bottom: 5px;">地铁安检乘客每年可能接受剂量&lt;0.01mSv</p></li></ul><p style="">辐射照射有随机性效应和确定性效应，只有确定性效应有阈值，严重程度取决于剂量多少，随机性效应发生的概率与剂量有关，严重程度和剂量无关。也就是说单次照射即使受照的剂量大，也不一定导出问题，具有随机性。 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp;<br  /></p><ul class=" list-paddingleft-2" style=""><li><p style="margin-top: 5px; margin-bottom: 5px;">＜0.25Gy【1】：不明显和不易觉察的病变可恢复的机能变化 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;<br  /></p></li><li><p style="margin-top: 5px; margin-bottom: 5px;">0.25Gy以上可能产生不同机能变化</p></li><li><p style="margin-top: 5px; margin-bottom: 5px;">Gy和mSv是不同的剂量单位，具体的解释见描述【1】<em>，</em>大概说来差1000量级</p></li></ul><p style="">人体不同组织或器官对辐射的敏感度是不同的,射线对人体作用时，有三种生化指标可能会发生变化 &nbsp;白血球、血小板、染色体。 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp;<br  />单次照射剂量的确定性症状，单位Gy &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp;<br  />（1）皮肤： &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp;<br  /></p><ul class=" list-paddingleft-2" style=""><li><p style="margin-top: 5px; margin-bottom: 5px;">红斑（X、γ）5～8 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;<br  /></p></li><li><p style="margin-top: 5px; margin-bottom: 5px;">暂时性脱发3～5 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;<br  /></p></li><li><p style="margin-top: 5px; margin-bottom: 5px;">永久性脱毛7</p></li></ul><p style="">（2）造血：2-3 受照者50％死亡 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp;<br  />（3）眼睛： &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp;<br  /></p><ul class=" list-paddingleft-2" style=""><li><p style="margin-top: 5px; margin-bottom: 5px;">晶体混浊（X射线）2 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;<br  /></p></li><li><p style="margin-top: 5px; margin-bottom: 5px;">白内障（100％）7.5 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;<br  /></p></li><li><p style="margin-top: 5px; margin-bottom: 5px;">白内障（随访35年）5</p></li></ul><p style="">（4）睾丸： &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp;<br  /></p><ul class=" list-paddingleft-2" style=""><li><p style="margin-top: 5px; margin-bottom: 5px;">暂时性不育0.15 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;<br  /></p></li><li><p style="margin-top: 5px; margin-bottom: 5px;">永久性不育3</p></li></ul><p style="">（4）卵巢：2.5-6不育 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;<br  /><br  />因此，在做影像检查时，如果可能的话，可以优先考虑无辐射的MRI，但是很多诊断MRI是不解决问题的，一般是先拍X片，必要再局部做切片CT。 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp;<br  />另外，针对儿童和孕妇的诊疗有区别于普通成人的标准。 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp;<br  />-------------------------------------------------------------------------------------------------- &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp;<br  />【1】单位换算： &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp;<br  /></p><ul class=" list-paddingleft-2" style=""><li><p style="margin-top: 5px; margin-bottom: 5px;">吸收剂量：1Gy（戈瑞）=1J（焦耳）/kg，每1千克受照物质吸收1焦耳核辐射能时，其核辐射剂量称为1戈瑞。</p></li><li><p style="margin-top: 5px; margin-bottom: 5px;">当量剂量：1Sv(希沃特)=吸收剂量×权重系数，通常用于辐射防护中,X射线我们通常把权重系数设为1，通常我们说有效剂量是指对全身器官的当量剂量取的平均值。</p></li></ul><p style="">补充： &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;<br  />1、在整理这份资料时，查到的拍X光胸片的剂量说法不一，因此特别咨询了专家，专家给的答复如下：辐射剂量是个概数，不同的资料来源可能会不一样，关键是要注明出处。 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;<br  /><br  />2、以下数据引自 联合国原子辐射效应科学委员会 UNSCEAR, 2008，供大家有大致范围概念。 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;<br  />--------------------------------------------------------------------------------------------------------- &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp;<br  />&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 每次检查平均有效剂量（mSv） &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp;<br  />检查部位 &nbsp; &nbsp; &nbsp;|1970-1979 &nbsp; &nbsp;|1980-1990 &nbsp; &nbsp;|1991-1996 &nbsp; &nbsp;|1997-2007 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;<br  />--------------------------------------------------------------------------------------------------------- &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;<br  />胸部X光摄影| &nbsp; &nbsp;0.25 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;| &nbsp; &nbsp;0.14 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; | &nbsp; &nbsp;0.14 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; | &nbsp; &nbsp;0.07 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;<br  />胸部X光透视| &nbsp; &nbsp;0.72 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;| &nbsp; &nbsp;0.98 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; | &nbsp; &nbsp;1.1 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; | &nbsp; &nbsp; 2.1 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;<br  />四肢和关节 &nbsp;| &nbsp; &nbsp;0.02 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; | &nbsp; &nbsp;0.06 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; | &nbsp; &nbsp;0.06 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; | &nbsp; &nbsp; 0.05 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;<br  />盆骨和臀部 &nbsp;| &nbsp; &nbsp;2.2 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; | &nbsp; &nbsp;1.7 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; | &nbsp; &nbsp;1.8 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; | &nbsp; &nbsp;1.1 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;<br  />头部 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;| &nbsp; &nbsp;2.1 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; | &nbsp; &nbsp;1.2 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; | &nbsp; &nbsp;0.83 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; | &nbsp; &nbsp; 0.08 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;<br  />乳腺摄影 &nbsp; &nbsp; &nbsp;| &nbsp; &nbsp;1.8 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; | &nbsp; &nbsp;1 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;| &nbsp; &nbsp;0.51 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; | &nbsp; &nbsp; 0.26 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;<br  />腹部 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;| &nbsp; 1.9 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;| &nbsp; 1.1 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; | &nbsp; &nbsp;0.53 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; | &nbsp; &nbsp; 0.82 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;<br  />CT &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; | &nbsp; &nbsp;1.3 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; | &nbsp; &nbsp;4.3 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;| &nbsp; &nbsp;8.8 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; | &nbsp; &nbsp; 7.4</p><p style=""><br  /></p><p style=""><strong>不同档次的CT，因为探测器技术差异所需辐射剂量也是不同的。</strong><br  />比如GE最高端的Revolution CT 所需辐射剂量下降82%；<br  /><img src="http://mmbiz.qpic.cn/mmbiz/A1DicCH9Vl6PTBIAj56ecyvBRFic9bQiajHzYia9x7KwRSp1Fv0iaAWWCartrKR7ENa1OejpowHCr5EFEuwc5CHtE2w/0?wx_fmt=png" style="box-sizing: border-box; background-color: rgb(255, 255, 255);" class="" data-type="png" data-ratio="0.5953237410071942" data-w=""  /></p><p><span style="font-size: 12px;"><br  />链接：http://www.zhihu.com/question/19604523/answer/13241429<br  />来源：知乎</span></p>