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<section><section powered-by="gulangu"><section><p><img src="image/20201019/e56a9ea0c109c2680b32c2a64482ef39_1.gif" /></p></section></section><section powered-by="gulangu"><section><section><p>照射量</p></section> <p><img src="image/20201019/1845a9dc9cd36569f291c3d21a604c62_2.png" /></p> <section></section></section></section><section powered-by="gulangu"><section><section><p> 照射量是用来描述传递给患者的辐射总量，单位为伦琴（R）。1伦琴就是指在1kg空气中产生的2.58*10-4（库仑）静电荷所需要的X线或者γ射线的能量。<br /></p><p> 伦琴表达照射量只用于能量低于3MeV的X线或γ射线辐射，不适合粒子辐射或能量高于3MeV的光子。只适用于描述射线对空气的照射，并不准确表达患者对辐射的吸收。</p></section></section></section><section powered-by="gulangu"><section><section><p>吸收剂量</p></section> <p><img src="image/20201019/1845a9dc9cd36569f291c3d21a604c62_2.png" /></p> <section></section></section></section><section powered-by="gulangu"><section><section><p> 吸收剂量是描述组织吸收的射线能量，单位为戈瑞（Gy）。1戈瑞（Gy）就是指1kg物质（人体组织）吸收1焦耳能量时的辐射量。</p><p> 吸收剂量D：质量为m（kg）的物质在辐射中吸收的能量E（J）时，其吸收剂量为</p><p> D=E/m （Gy）<span> </span></p></section></section></section><section powered-by="gulangu"><section><section><p>剂量当量</p></section> <p><img src="image/20201019/1845a9dc9cd36569f291c3d21a604c62_2.png" /></p> <section></section></section></section><section powered-by="gulangu"><section><section><p> 吸收剂量并不总是与生物效应呈正相关关系，组织的生物效应还应考虑被吸收的能量在组织中的分布情况。</p><p> 要更精确地表达吸收剂量与生物效应的关系，需要给吸收剂量再乘以一个因子，即品质因子（quality factor,QF）,并提出剂量当量（dose equivalent,DE<span>） 的概念。</span></p><p><span> DE=D*QF</span></p><p><span> DE的单位：希沃特（Sv），D:戈瑞（Gy），QF无量纲</span></p><p><span> DE常用于辐射防护的定量计算。</span></p></section></section></section><section powered-by="gulangu"><section><section><p>当量剂量</p></section> <p><img src="image/20201019/1845a9dc9cd36569f291c3d21a604c62_2.png" /></p> <section></section></section></section><section powered-by="gulangu"><section><section><p> 综合以人类为对象的研究结果，专家们对QF进行了适当的调整，确定了辐射权重因子Wr（radiation weighting factor）的值，并提出了当量剂量ED（equivalent dose）的概念。</p><p> ED=D*Wr</p><p> 当辐射有多个种类和能量时，在一个组织或器官的当量剂量就是各个辐射所致的当量剂量的和。</p></section></section></section><section powered-by="gulangu"><section><section><p>有效剂量</p></section> <p><img src="image/20201019/1845a9dc9cd36569f291c3d21a604c62_2.png" /></p> <section></section></section></section><section powered-by="gulangu"><section><section><p> ED给出了不同辐射条件下人体发生生物效应的定量描述，但人体不同组织或器官对辐射的敏感性和给人体造成的危害是不同的。</p><p> 因此又提出组织权重因子Wt（tissue weighting factor） 对上述的ED进行进一步修正。由Wr和Wt两个因子修正后的吸收剂量成为有效剂量（effective dose，ED）</p><p> ED=D*Wr*Wt</p><p> ED（有效剂量）考虑了人体具体组织器官承受辐射的能力和危险系数，能更准确的反映不同类型的辐射对人体造成的危害。</p></section></section></section><section powered-by="gulangu"><section><section> <section powered-by="gulangu"><section><section><p>欢</p></section></section></section> </section><section> <section powered-by="gulangu"><section><section><p>迎</p></section></section></section> </section><section> <section powered-by="gulangu"><section><section><p>关</p></section></section></section> </section><section> <section powered-by="gulangu"><section><section><p>注</p></section></section></section> </section></section></section><section powered-by="gulangu"><section><section><p><br /></p></section></section></section><section powered-by="gulangu"><section><section> <section powered-by="gulangu"><section><p><img src="image/20201019/00843a9321383fd0ae8b6d247af6abe2_7.jpg" /></p></section></section> </section><section> <section powered-by="gulangu"><section><section> </section></section></section> </section><section> <section powered-by="gulangu"><section><section><p>关注我们</p><p>一起涨姿势！</p></section></section></section> </section></section></section></section>
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发表于 2020-10-19 13:33:16