Placeholder Image

字幕列表 影片播放

已審核 字幕已審核
  • In 1895, a physicist named Wilhelm Roentgen

    1895 年,一位名叫威廉·倫琴的物理學家

  • was doing experiments with a cathode tube,

    用一支陰極射線管在做實驗

  • a glass container in which a beam of electrons lights up a fluorescent window.

    那是一個玻璃容器,裏面用一串電子束點亮一個螢光屏幕

  • He had wrapped cardboard around the tube

    他用硬紙板包覆整個管子

  • to keep the fluorescent light from escaping,

    以避免螢光逸出

  • when something peculiar happened.

    這時一件奇怪的事情發生了

  • Another screen outside the tube was glowing.

    在管子外面的另一個螢幕發亮了

  • In other words, invisible rays had passed through the cardboard.

    換句話說,有無形的射線穿透了硬紙板

  • Wilhelm had no idea what those rays were, so he called them X-rays,

    威廉不知道那射線是什麼,所以他就稱它為 X-射線

  • and his discovery eventually won him a Nobel Prize.

    而他的發現後來使他獲得了諾貝爾獎

  • Here's what we now know was happening.

    以下就是我們目前所了解它是怎麼發生的

  • When high energy electrons in the cathode tube hit a metal component,

    當在陰極射線管的高能量電子撞擊一個金屬物質時

  • they either got slowed down and released extra energy,

    它們不是減速釋放多餘的能量

  • or kicked off electrons from the atoms they hit,

    就是從被它們碰撞的原子撞出電子

  • which triggered a reshuffling that again released energy.

    這會引發重組而釋出能量

  • In both cases, the energy was emitted in the form of X-rays,

    這兩種情況,被釋放的能量轉為 X-射線

  • which is a type of electromagnetic radiation

    這是一種電磁波

  • with higher energy than visible light, and lower energy than Gamma rays.

    比可見光的能量高,而比伽馬射線能量低

  • X-rays are powerful enough to fly through many kinds of matter

    X-射線強到足以穿透許多物質

  • as if they are semi-transparent,

    就好像這些物質是半透明的一樣

  • and they're particularly useful for medical applications

    它們對於醫學應用特別有用

  • because they can make images of organs, like bones, without harming them,

    因為它們能使諸如骨頭的器官呈現影像,而不會傷害到它們

  • although they do have a small chance

    儘管如此,它們還是有微小機會

  • of causing mutations in reproductive organs, and tissues like the thyroid,

    造成生殖器官或如甲狀腺組織的突變

  • which is why lead aprons are often used to block them.

    這就是為什麼常用鉛衣來阻擋它們的原因

  • When X-rays interact with matter, they collide with electrons.

    當 X-射線與物質相互作用時,它們碰撞電子

  • Sometimes, the X-ray transfers all of its energy to the matter and gets absorbed.

    有時候,X-射線將其能量傳給物質而全部被吸收

  • Other times, it only transfers some of its energy,

    又有時候,它只是傳送部分能量

  • and the rest is scattered.

    而其餘的散射掉

  • The frequency of these outcomes

    這些結果發生的頻率

  • depends on how many electrons the X-rays are likely to hit.

    端視 X-射線可能撞擊電子數目的多寡而定

  • Collisions are more likely if a material is dense,

    假如物質是緻密的,碰撞的機率會比較高

  • or if it's made of elements with higher atomic numbers,

    或物質是由原子數較高的元素所構成

  • which means more electrons.

    意謂有較多的電子 (所以撞擊率也較高)

  • Bones are dense and full of calcium, which has a relatively high atomic number,

    骨頭是緻密且充滿鈣質,具有較高的原子序數

  • so they absorb X-rays pretty well.

    所以它們蠻能夠吸收 X-射線

  • Soft tissue, on the other hand, isn't as dense,

    相反的,軟組織不是那麼緻密

  • and contains mostly lower atomic number elements,

    大部分含有較低原子序數的元素

  • like carbon, hydrogen, and oxygen,

    如碳、氫及氧

  • so more of the X-rays penetrate tissues like lungs and muscles,

    所以比較多的 X-射線能穿透如肺及肌肉組織

  • darkening the film.

    使底片變得較黑

  • These 2-D pictures are only useful up to a point, though.

    不過這些 2D 影像的作用只能達到一定的程度

  • When X-rays travel through the body,

    當 X-射線穿過身體

  • they can interact with many atoms along the path.

    它們在行經途徑中與許多原子相互作用

  • What is recorded on the film reflects the sum of all those interactions.

    這些作用的總和最後反應在底片上

  • It's like trying to print 100 pages of a novel on a single sheet of paper.

    這就如同試著把 100 頁的小說印在一張紙上

  • To see what's really going on,

    為了能夠看到全貌

  • you would have to take X-ray views from many angles around the body

    你必須從身體的許多角度照 X 光片

  • and use them to construct an internal image.

    然後將他們組成一個身體內部的圖像

  • And that's something doctors do all the time in a procedure

    這就是醫生常做的的一種檢查

  • called a CT, Computed Tomography scan,

    稱為 CT ,電腦斷層掃描

  • another Nobel Prize winning invention.

    也是另一個獲得諾貝爾獎的發明

  • Think of CT like this.

    將 CT 想像成這樣子

  • With just one X-ray,

    只憑一張 X 光片,

  • you might be able to see the density change due to a solid tumor in a patient,

    你也許能夠看到因病人體內的腫瘤所導致的密度變化

  • but you wouldn't know how deep it is beneath the surface.

    可是你無法知道它在體表下有多深

  • However, if you take X-rays from multiple angles,

    然而,你若從多重角度照 X 光片,

  • you should be able to find the tumor's position and shape.

    就可以知道腫瘤的位置及形狀

  • A CT scanner works by sending a fan or cone of X-rays through a patient

    電腦斷層掃描是將一個扇形或錐狀 X-射線射出,穿過病人

  • to an array of detectors.

    到一個個排列好的影像接收器

  • The X-ray beam is rotated around the patient,

    X 光射線繞著病人旋轉

  • and often also moved down the patient's body,

    也常往病人下方移動

  • with the X-ray source tracing a spiral trajectory.

    讓 X-射線光源按照螺旋軌跡走

  • Spiral CT scans produce data that can be processed into cross sections

    螺旋電腦斷層掃描產生的數據,可以處理成橫斷面

  • detailed enough to spot anatomical features, tumors,

    精細到足以標記出解剖的特徵、腫瘤、

  • blood clots, and infections.

    血塊及感染

  • CT scans can even detect

    電腦斷層掃描甚至可以偵測出

  • heart disease and cavities in mummies buried thousands of years ago.

    數千年前埋葬的木乃伊的心臟疾病及蛀牙

  • So what began as Roentgen's happy accident has become a medical marvel.

    當初倫琴的巧妙意外如今已變成醫學奇蹟

  • Hospitals and clinics now conduct over 100 million scans each year worldwide

    現在每年,全世界的醫院和診所執行超過一億次的掃描

  • to treat diseases and save lives.

    來治療疾病及拯救性命

In 1895, a physicist named Wilhelm Roentgen

1895 年,一位名叫威廉·倫琴的物理學家

字幕與單字
已審核 字幕已審核

影片操作 你可以在這邊進行「影片」的調整,以及「字幕」的顯示

B1 中級 中文 美國腔 TED-Ed 射線 物質 斷層 能量 掃描

【TED-Ed】你了解X光嗎?告訴你X光是如何透視體表! (How X-rays see through your skin - Ge Wang)

  • 7000 653
    Ann 發佈於 2015 年 07 月 30 日
影片單字