📚 Ionising Radiation Hazards | 电离辐射的危害
Ionising radiation is a key topic in the Edexcel IGCSE Science specification (point 6.36), covering how high-energy particles or electromagnetic waves can remove electrons from atoms and cause damage to living tissue. Understanding the types of ionising radiation, their effects on the human body, radiation dose measurement and essential safety precautions is crucial for both the exam and real-world applications.
电离辐射是 Edexcel IGCSE 科学大纲（要点 6.36）中的一个关键主题，涉及高能粒子或电磁波如何使原子失去电子并对活组织造成损伤。理解电离辐射的类型、对人体的影响、辐射剂量的测量以及必要的安全防护措施，对考试和实际应用都至关重要。
1. What is Ionising Radiation? | 什么是电离辐射？
Ionising radiation is radiation that carries enough energy to knock electrons out of atoms or molecules, turning them into ions. When an atom loses an electron, it becomes a positively charged ion. The process is known as ionisation and can break chemical bonds, including those in DNA molecules.
电离辐射是指携带足够能量将电子从原子或分子中击出，使其变成离子的辐射。原子失去电子后会变成带正电的离子。这一过程称为电离，它可以破坏化学键，包括 DNA 分子中的化学键。
2. Types of Ionising Radiation | 电离辐射的类型
There are several types of ionising radiation relevant to the IGCSE syllabus. Alpha particles (α) are helium nuclei (²He²⁺), consisting of two protons and two neutrons. They have a strong ionising power but very low penetrating ability, being stopped by a sheet of paper or a few centimetres of air. Beta particles (β⁻) are fast-moving electrons emitted from unstable nuclei. They can penetrate further than alpha particles, passing through paper but being stopped by a few millimetres of aluminium. Gamma rays (γ) are high-frequency electromagnetic waves with no mass or charge. They are weakly ionising but highly penetrating, requiring thick lead or several metres of concrete to absorb them. X-rays are a form of ionising electromagnetic radiation similar to gamma rays but produced by different processes; they are widely used in medical imaging.
IGCSE 大纲中涉及几种电离辐射类型。α 粒子（α）是氦原子核（²He²⁺），由两个质子和两个中子组成。它们电离能力强，但穿透力很弱，一张纸或几厘米空气即可阻挡。β 粒子（β⁻）是从不稳定原子核中发射出的高速电子，穿透能力比 α 粒子强，能穿过纸张，但几毫米厚的铝板即可阻挡。γ 射线（γ）是高频电磁波，无质量也不带电。它们电离能力弱，但穿透力很强，需要厚铅板或数米混凝土才能吸收。X 射线也是一种电离电磁辐射，类似于 γ 射线但产生方式不同，被广泛用于医学成像。
3. Sources of Ionising Radiation | 电离辐射的来源
Ionising radiation comes from both natural and artificial sources. Natural background radiation includes cosmic rays from space, radon gas from rocks and soil, and radioactive isotopes in food and water. Artificial sources include medical procedures such as X-rays and CT scans, nuclear power generation, industrial radiography and fallout from nuclear weapons testing.
电离辐射有天然和人工两种来源。天然本底辐射包括来自太空的宇宙射线、来自岩石和土壤的氡气，以及食物和水中的放射性同位素。人工来源包括 X 射线和 CT 扫描等医疗程序、核能发电、工业射线照相以及核武器试验的沉降物。
4. How Radiation Damages Living Tissue | 辐射如何损伤活组织
Ionising radiation damages cells primarily by ionising water and other molecules, producing highly reactive free radicals. These free radicals can break DNA strands. If the DNA repair mechanisms fail, the damage may lead to cell death, malfunction or uncontrolled cell division. Rapidly dividing cells, such as those in bone marrow, skin and the gut lining, are especially vulnerable.
电离辐射主要通过电离水和其他分子产生高反应性的自由基来损伤细胞。这些自由基可以打断 DNA 链。如果 DNA 修复机制失效，损伤可能导致细胞死亡、功能失常或不受控制的细胞分裂。快速分裂的细胞，如骨髓、皮肤和肠道内壁的细胞，特别容易受到伤害。
5. Health Effects of Radiation Exposure | 辐射暴露的健康影响
Short-term exposure to high doses of ionising radiation can cause radiation sickness, with symptoms such as nausea, vomiting, hair loss and a lowered white blood cell count. Long-term effects include an increased risk of cancers, particularly leukaemia and thyroid cancer, as well as genetic mutations that can be passed on to future generations. The severity depends on the dose, the type of radiation and the part of the body exposed.
短期暴露于高剂量电离辐射可能引起辐射病，症状包括恶心、呕吐、脱发和白细胞数量下降。长期影响包括癌症风险增加，尤其是白血病和甲状腺癌，以及可能遗传给后代的基因突变。严重程度取决于剂量、辐射类型和受照身体部位。
6. Acute vs Chronic Exposure | 急性暴露与慢性暴露
Acute exposure refers to receiving a large radiation dose over a short period of time, which can overwhelm the body's repair systems and cause immediate damage. Chronic exposure involves long-term, low-level radiation doses, such as from natural background radiation or certain occupations. While the body can repair some low-level damage, chronic exposure still carries a cumulative risk of cancer.
急性暴露是指在短时间内接受大量辐射剂量，可能超出人体的修复能力并造成立即伤害。慢性暴露则是指长期低水平的辐射剂量，例如天然本底辐射或某些职业暴露。尽管人体可以修复部分低水平损伤，但慢性暴露仍具有累积的致癌风险。
7. Measuring Radiation Dose | 测量辐射剂量
In physics, the absorbed dose is measured in grays (Gy), where 1 Gy represents one joule of energy deposited per kilogram of tissue. For biological risk assessment, the equivalent dose is measured in sieverts (Sv). Because different types of radiation cause different amounts of biological damage, a radiation weighting factor is used: for alpha particles the factor is 20, meaning 1 Gy of alpha radiation gives 20 Sv equivalent dose. Doses are often given in millisieverts (mSv). The average annual background radiation dose for a person in the UK is about 2.7 mSv.
在物理学中，吸收剂量以戈瑞（Gy）为单位，1 Gy 表示每千克组织沉积了 1 焦耳的能量。为了评估生物风险，当量剂量以希沃特（Sv）为单位。由于不同类型的辐射造成的生物损伤不同，会使用辐射权重因子：α 粒子的因子为 20，意味着 1 Gy 的 α 辐射产生 20 Sv 的当量剂量。剂量通常以毫希沃特（mSv）表示。英国人均每年接受的天然本底辐射剂量约为 2.7 mSv。
8. Safety Precautions | 安全预防措施
There are three key principles for reducing exposure to ionising radiation: time, distance and shielding. Minimise the time spent near a radiation source. Increase the distance from the source, as intensity follows the inverse square law. Use appropriate shielding – alpha particles are stopped by paper, beta by aluminium, and gamma by lead or thick concrete. In laboratories, sources are handled with tongs and never pointed at people. Protective clothing and dosimeter badges are worn to monitor exposure.
减少电离辐射暴露的三个关键原则是：时间、距离和屏蔽。尽可能缩短在辐射源附近的时间。增加与辐射源的距离，因为强度遵循平方反比定律。使用适当的屏蔽——α 粒子可用纸阻挡，β 用铝，γ 用铅或厚混凝土。在实验室中，放射源用钳子操作，绝不指向人体。还要穿着防护服并佩戴剂量计以监测暴露量。
9. Uses of Ionising Radiation | 电离辐射的应用
Despite its dangers, ionising radiation has many beneficial uses. In medicine, gamma rays are used to sterilise surgical equipment and in radiotherapy to kill cancer cells. Radioactive tracers can diagnose thyroid problems or detect leaks in pipes. In industry, beta particles are used to monitor the thickness of paper or aluminium foil. Smoke detectors often contain a small alpha source (americium-241).
尽管电离辐射存在危险，它也有许多有益的用途。在医学上，γ 射线用于消毒手术器械和通过放射疗法杀死癌细胞。放射性示踪剂可用于诊断甲状腺问题或检测管道泄漏。在工业中，β 粒子用于监测纸张或铝箔的厚度。烟雾探测器通常含有一个小的 α 放射源（镅-241）。
10. Summary of Key Points | 关键点总结
Ionising radiation includes alpha, beta, gamma and X-rays. It ionises atoms and can damage DNA, leading to cell death or cancer. Alpha particles are the most ionising but least penetrating; gamma rays are the most penetrating. Radiation dose is measured in sieverts, and exposure is controlled through time, distance and shielding. While harmful, controlled use of ionising radiation is vital in medicine, industry and research.
电离辐射包括 α、β、γ 和 X 射线。它使原子电离并可能损伤 DNA，导致细胞死亡或癌症。α 粒子电离能力最强但穿透力最弱；γ 射线穿透力最强。辐射剂量以希沃特为单位，通过控制时间、距离和屏蔽来限制暴露。尽管有害，但在受控条件下使用电离辐射对医学、工业和研究至关重要。
Published by TutorHao | Science Revision Series | aleveler.com
更多咨询请联系16621398022（同微信）
或截图后用「扫一扫 → 相册」选择本图