Radyasyon Nasıl Çalışır?

"Radyasyon" kelimesini üç farklı kişiye söyleyin ve muhtemelen üç farklı tepki alacaksınız. Teyzeniz radyasyonun kanserini nasıl yok ettiğini size söyleyebilir. Komşunuz, gününün "ördek ve örtün" prosedürlerinden bahsedebilir. Ve çizgi roman sever arkadaşınız gama ışınlarının Bruce Banner'ı nasıl Hulk'a çevirdiğini açıklayacak. Radyasyon birçok biçimde gelir ve her zaman etrafımızdadır. Bazen tehlikelidir; bazen değil.

Radyasyon hem doğal hem de insan yapımıdır. Vücudumuz her gün doğal radyasyona maruz kalır - toprak ve yeraltı gazlarından güneşten ve uzaydan gelen kozmik radyasyona kadar. Ayrıca kendi icatlarımızdan kaynaklanan radyasyona da maruz kalıyoruz - tıbbi prosedürler, televizyonlar , cep telefonları ve mikrodalga fırınlar . Radyasyon mutlaka her zaman tehlikeli değildir. Gücüne, türüne ve maruz kalma süresine bağlıdır.

Çoğu insan size Marie Curie'nin kocası ve araştırma ortağı Pierre ile birlikte radyasyon keşfettiğini söyleyecektir. Ve bu doğru -- bir nevi. Curie aslında radyum elementini 1898'de keşfetti ve bu onu Nobel Ödülü'nün ilk kadın alıcısı yapacak bir başarıydı. Bununla birlikte, 1895'te üç yıl önce, Wilhelm Röntgen adlı bir bilim adamı ilk olarak X-ışınlarını ve radyoaktivite fenomenini keşfetti (daha sonra Curie tarafından Latince "ışın" kelimesine dayanan bir terim). Röntgen'in keşfinden kısa bir süre sonra, Henri Becquerel adlı bir Fransız bilim adamı, X-ışınlarının nereden geldiğini anlamaya çalıştı ve bu süreçte uranyumun güçlü bir "ışın" yaydığını keşfetti. Marie Curie, doktora araştırmasını Becquerel'in radyum keşfine yol açan bulgularına dayandırdı [kaynak:].

Radyasyon , dalgalar (elektromanyetik radyasyon) veya yüksek hızlı parçacıklar (partikül radyasyonu) şeklinde yayılan enerjidir. Parçacık radyasyonu , kararsız (veya radyoaktif) bir atom parçalandığında meydana gelir. Elektromanyetik (EM) radyasyon ise kütlesizdir ve dalgalar halinde hareket eder. EM radyasyonu çok düşük enerjiden çok yüksek enerjiye kadar değişebilir ve biz buna elektromanyetik spektrum diyoruz . EM spektrumunda iki tür radyasyon vardır - iyonlaştırıcı ve iyonlaştırıcı olmayan.

Biraz bunalmış hissediyor musun? Merak etmeyin, tüm bunları ilerleyen sayfalarda detaylı olarak anlatacağız.

Ne yazık ki, Marie Curie'ye tarih kitaplarımızda sonsuz yaşam veren şey, sonunda onu öldüren şeydi. 1890'ların sonlarında, hem Marie hem de kocası Pierre çeşitli rahatsızlıklardan muzdarip olmaya başladı. Marie birkaç katarakt geçirdi (şimdi radyasyonun bilinen bir yan etkisi) ve sonunda kemik iliğinde radyasyona bağlı anemiye yenik düştü.

1. Elektromanyetik Spektrum
2. İyonlaştırmayan radyasyon
3. İyonlaştırıcı radyasyon
4. Radyasyona Maruz Kalma
5. Radyasyona Maruz Kalırsanız Ne Yapmalısınız?

Elektromanyetik (EM) radyasyon , dalgalar halinde hareket eden bir foton akışıdır. Foton , tüm EM radyasyon formları için temel parçacıktır. Ama foton nedir? Bu, her zaman hareket halinde olan bir enerji demetidir - ışık demetidir. Aslında, bir fotonun taşıdığı enerji miktarı onun bazen bir dalga gibi bazen de bir parçacık gibi davranmasını sağlar. Bilim adamları buna dalga-parçacık ikiliği diyor . Düşük enerjili fotonlar ( radyo gibi) dalgalar gibi davranırken, yüksek enerjili fotonlar (X-ışınları gibi) daha çok parçacıklar gibi davranır. Fotonların nasıl çalıştığı hakkında daha fazla bilgiyi Floresan Lambalar Nasıl Çalışır bölümünde okuyabilirsiniz .

EM radyasyonu boş uzayda seyahat edebilir. Bu, onu, içinden geçmek için bir ortama ihtiyaç duyan ses gibi diğer dalga türlerinden ayırır. EM radyasyonun tüm biçimleri, radyasyonu en düşük enerji/en uzun dalga boyundan en yüksek enerji/en kısa dalga boyuna doğru sıralayan elektromanyetik spektrumda bulunur. Enerji ne kadar yüksekse, radyasyon o kadar güçlü ve dolayısıyla daha tehlikelidir. Bir radyo dalgası ile bir gama ışını arasındaki tek fark, fotonların [kaynak: NASA ] enerji seviyesidir. Aşağıda bir bakışta elektromanyetik spektrum görülmektedir.

Radyo : Radyo dalgaları elektromanyetik spektrumda en uzun dalga boyuna sahiptir (bir futbol sahası uzunluğunda). Gözümüze görünmezler. Radyolarımıza müzik, televizyonlarımıza ses ve görüntü , cep telefonlarımıza sinyal taşıyorlar. Cep telefonu dalgaları, radyo dalgalarından daha kısa, ancak mikrodalgalardan daha uzundur.

Mikrodalgalar : Ayrıca görünmez, yiyeceklerimizi hızlı bir şekilde ısıtmak için mikrodalgaları kullanırız. Telekomünikasyon uyduları , sesi telefon aracılığıyla iletmek için mikrodalgaları kullanır . Mikrodalga enerjisi pus, bulutlar veya dumandan geçebilir ve bu nedenle bilgi iletmek için kullanışlıdır. Hava durumu sunucunuzun haberlerde kullandığı Doppler radarı gibi bazı mikrodalgalar radar için kullanılır . Tüm evren zayıf kozmik mikrodalga arka plan radyasyonuna sahiptir - bilim adamlarının Büyük Patlama Teorisine bağladığı bir şey .

Kızılötesi : Kızılötesi, EM spektrumunun görünen ve görünmeyen kısımları arasında yer alır. Uzaktan kumandanız, kanalı değiştirmek için kızılötesi ışık kullanır. Her gün güneşin ısısı yoluyla kızılötesi radyasyonu hissederiz. Kızılötesi fotoğrafçılık, sıcaklık farklılıklarını tespit edebilir. Yılanlar aslında kızılötesi radyasyonu algılayabilirler, bu sayede zifiri karanlıkta sıcak kanlı avlarını bulabilirler.

Görünür : Elektromanyetik spektrumun görebildiğimiz tek kısmı budur. Spektrumun bu bandındaki farklı dalga boylarını gökkuşağının renkleri olarak görüyoruz. Örneğin güneş , görünür dalgaların doğal bir kaynağıdır. Bir cisme baktığımızda gözlerimiz ışığın yansıyan rengini görür ve diğer tüm renkler emilir.

Ultraviolet: Ultraviolet (UV) rays are what cause us to become sunburned. Humans can't see UV rays, but some insects can. Our atmosphere's ozone layer blocks most UV rays. However, as our ozone layer depletes due to use of chlorofluorocarbons (CFCs), UV levels are increasing. This can lead to health effects like skin cancer [source: EPA].

X-rays: X-rays are very high-energy light waves. We're most familiar with their use in a doctor's office, but X-rays also naturally occur in space. But don't worry, X-rays can't penetrate from outer space to the Earth's surface. Read more in How X-rays Work .

Gamma rays: Gamma rays have the most energy and shortest wavelength of the entire spectrum. Nuclear explosions and radioactive atoms generate these rays. Gamma rays can kill living cells , and medical professionals sometimes use them to destroy cancerous cells. In deep space, gamma ray bursts occur daily, but their origins are still a mystery.

Read on to find out the difference between non-ionizing and ionizing radiation.

X-ray Shoe Fitter

­We know today that overexposure to X-rays is dangerous, and X-ray technicians and patients alike must wear protective gear. However, from the 1930s to 1950s, shoe sales clerks actually used an X-ray machine for shoe fitting. Although there were no reported overexposure injuries to customers, employees weren't so lucky. One shoe model suffered enough complications from X-ray overexposure to require amputation of her entire leg [source: Frame].

Radiation is broken down into two types: non-ionizing and ionizing. On the electromagnetic (EM) spectrum, this break occurs between infrared and ultraviolet. Drilling down further, ionizing radiation comes in three main types: alpha particles, beta particles and gamma rays. We'll discuss these types of radiation in more detail later in this article.

Non-ionizing radiation is relatively low-energy radiation that doesn't have enough energy to ionize atoms or molecules. It's located at the low end of the electromagnetic spectrum. Non-ionizing radiation sources include power lines, microwaves , radio waves, infrared radiation, visible light and lasers . Although considered less dangerous than ionizing radiation, overexposure to non-ionizing radiation can cause health issues. Let's take a look at some examples of non-ionizing radiation and the safety issues surrounding them.

Extremely low frequency (ELF) radiation is the radiation produced by things like power lines or electrical wiring. There are health concerns associated with magnetic field exposures near power lines, and this issue is very controversial. Obviously, ELF radiation surrounds us every day, but hazardous exposure depends on the strength of the ELF at the source, as well as the distance and duration of exposure. Research on ELF radiation focuses on cancer and reproductive issues. There is no definitive link between ELF radiation and illness, but studies have shown some preliminary connections [source: WHO].

Radio frequency (RF) and microwave (MV) radiation come most commonly from radios, televisions , microwave ovens and cell phones . Both RF and MV waves can interfere with pacemakers, hearing aids and defibrillators, and people should take appropriate precautions. In recent years, concerns about cell phone radiation have made headlines. Although there is no proven link between cell phone usage and health issues, the potential is there. Again, it's all about exposure. Large amounts of RF exposure can heat tissue, which can damage skin or eyes and raise body temperature. Some experts recommend using a headset or hands-free device if you use your cell phone frequently and for long periods [source: FCC]. You can find out more about cell phones and radiation in our article How Cell Phone Radiation Works .

Our skin and eyes absorb infrared radiation (IR) as heat. Overexposure to IR can result in burns and pain. Ultraviolet (UV) radiation overexposure concerns us because there are no immediate symptoms. However, effects can develop quickly afterward in the form of a sunburn or worse. Overexposure to UV radiation can lead to skin cancer, cataracts and a compromised immune system [source: EPA]. Besides sunlight, UV sources include black lights and welding tools.

Lastly, lasers emit IR, visible and UV radiation. They can be quite dangerous to the eyes and skin. People who work with lasers should wear protective gear on the eyes, hands and arms.

Keep reading to learn about high-energy ionizing radiation.

Radium Girls

In the 1920s, a watch company used the newly discovered substance radium to make its watches glow in the dark. Thousands of girls went to work in the watch factory to do the painstaking painting by hand. To make a finer point on their brushes, the girls would lick them. Sometimes to break up the monotony, the girls would paint their teeth and lips and turn off the lights. Although managers regularly tested the girls for radioactivity, the women never received the results of these tests. In 1938, a worker named Catherine Donahue finally sued the company for the results of her test. She won a settlement of several thousand dollars but died that same year. Many others died over the years, but a link was never proven and the company never took responsibility [source: Irvine].

Similar to non-ionizing radiation, ionizing radiation is energy in the form of particles or waves. However, ionizing radiation is so high in energy it can break chemical bonds -- meaning it can charge (or ionize) an atom that interacts with it. At a lower energy, it may strip off a couple of electrons. At a higher energy, it can destroy the nucleus of an atom . This means that when ionizing radiation passes through the tissues of the body, it actually has enough energy to damage DNA . It's why gamma rays, for example, are good at killing cancer cells through radiation treatment.

Ionizing radiation is given off by radioactive material, very high-voltage equipment, nuclear reactions and stars. It's both natural and man-made. A natural source of ionizing radiation is radon, a radioactive material found underground. X-rays are a good example of man-made ionizing radiation.

The three types of ionizing radiation we're going to discuss here are alpha particles, beta particles and rays.

Particulate radiation involves fast-moving, small particles that have energy and mass. When an unstable atom disintegrates, it produces particulate radiation, including alpha and beta particles. For example, when radioactive elements like uranium, radium and polonium decay, they release radioactive alpha particles. These particles, made up of protons and neutrons, are large and can only travel a short distance -- in fact, they can be stopped with just a piece of paper or even your skin. However, inhalation or ingestion of alpha particles can be very dangerous. Once inside your body, alpha particles expose your tissues to radiation.

Beta particles, on the other hand, are fast-moving electrons. They can travel and penetrate more than alpha particles. Beta particles can be stopped or reduced by a layer of clothing or a substance like aluminum (so think twice the next time you laugh at the guy on the corner wearing a protective tinfoil hat!). However, some beta particles have enough energy to penetrate the skin and cause damage like burns. As with alpha particles, beta particles are quite hazardous if inhaled or ingested.

Gamma rays are a type of electromagnetic radiation, but they still emit ionizing radiation because of their high energy. Gamma rays often accompany alpha and beta particles. Unlike alpha and beta particles, they are extremely penetrating. In fact, several inches of lead or even a few feet of concrete are required to stop gamma rays. They are a radiation hazard for the entire body, meaning that although they will pass through you, your tissue will absorb some rays. Gamma rays occur naturally in minerals like potassium-40. Don't stop taking your vitamins just yet, though. The radioactive isotope of potassium occurs at an extremely low concentration, and potassium is necessary for good health [source: HPS].

X-rays are essentially the same as gamma rays, but their origin is different. Where gamma rays come from inside the nucleus of an atom, X-rays come from processes outside the nucleus. X-rays come from a change in the electron structure of an atom and are mostly machine-produced. They aren't quite as penetrating as gamma rays, and just a few millimeters of lead can stop them. That's why you wear a "lead apron" when receiving medical X-rays.

Overexposure to ionizing radiation can cause mutations in your genes, which causes birth defects, a raised risk of cancer, burns or radiation sickness [source: NLM].

Is this information freaking you out? Then let's get to radiation exposure on the next page.

­Your superheroes are radioactive!

Radiation exposure has always tickled the fancy of comic book writers. We imagine it's because radiation can alter DNA -- therefore opening up a world of possibilities for mutations and superpowers. Here is just a sampling of some comic book characters affected by radioactivity: Spider-Man, The Hulk, Radioactive Man (of course), Sun Boy, Sandman, Godzilla, Graviton, X-ray, Rampage, Doctor Phosphorous, Doctor Manhattan, Flux and Ion. There are dozens more, and who knows how many are living in the minds of tomorrow's comic book creators [source: Comic Vine]?

Radiation is everywhere. It's been part of our environment since the planet was born. Radiation exists in the atmosphere, the ground, the water and even within our own bodies. It's called natural background radiation, and it's perfectly safe.

Radiation affects your body by depositing energy in your tissues, which can cause cell damage. In some cases, this won't cause any effect. In others, the cell can become abnormal and later malignant. It depends on the strength and duration of the exposure. In the rare occurrence of a huge amount of radiation exposure in a short time, death can occur in a matter of days or hours. We call this acute exposure. Chronic exposure, on the other hand, is frequent exposure to low doses of radiation, over a long period. There can be a delay between initial exposure and consequent health effects. To date, the best information we have about health risk and radiation exposure comes from the survivors of the atomic bomb in Japan and people who work with radiation every day or receive radiation as medical treatment.

We measure amounts of radiation exposure in units called millirem (mrem). Higher readings are measured in mSv, which you can multiply by 100 to get mrem. In the United States, people receive an average annual dose of about 360 mrem. More than 80 percent of this dose comes from natural background radiation [source: DOE]. However, outside considerations greatly affect the average dose. Where and how you live affects the amount of radiation exposure you receive. For example, people who live in the Pacific Northwest part of the United States typically only receive about 240 mrem from natural and man-made sources. However, people in the Northeast receive up to 1700 mrem per year, mostly due to radon that is natural to rocks and soil. Is 1700 mrem safe? Take a look at the sidebar to see.

So what do you do if you're exposed? Find out on the next page.

­Radiation Exposure Dosage Chart:

This chart lists ionizing radiation only. Of all the types of non-ionizing radiation, only ultraviolet rays are cancer-causing agents.

• 10,000 mSv (1,000,000 mrem) as a short-term and whole-body dose would cause immediate illness and subsequent death within a few weeks.
• 1,000 to 10,000 mSv (100,000 to 1,000,000 mrem) in a short-term dose would cause severe radiation sickness with increasing likelihood of fatality.
• 1,000 mSv (100,000 mrem) in a short-term dose will cause immediate radiation sickness in a person of average physical attributes, but would be unlikely to cause death.
• Short-term doses greater than 1000 mSv (100,000 mrem) over a long period create a definite risk to develop cancer in the future.
• At doses above 100 mSv (10,000 mrem), the probability of cancer (rather than the severity of illness) increases with dose.
• 50 mSv (5,000 mrem) is thought to be the lowest dose at which cancer may occur in adults. It is also the highest dose allowed by regulation in any one year of occupational exposure.
• 20 mSv/yr (2,000 mrem) averaged over five years is the limit for radiological personnel such as employees in the nuclear industry, uranium or mineral sands miners and hospital workers (who are all closely monitored).
• 10-12 mSv (1,000-1,200 mrem) in one dose is the equivalent of a full body CT scan.
• 3 mSv/yr (300 mrem) is the typical background radiation from natural sources in North America, including an average of almost 2 mSv/yr from radon in air.
• 2 mSv/yr (200 mrem) is the typical background radiation from natural sources, including an average of 0.7 mSv/yr from radon in air. This is close to the minimum dose received by all humans anywhere on Earth .
• 0.3-0.6 mSv/yr (30-60 mrem) is a typical range of dose rates from artificial sources of radiation, mostly medical. It includes bone density scans, dental X-rays , chest X-rays, and bone X-rays.
• 0.01-.03 mSv (1-3 mrem) is typical radiation from a single coast-to-coast airplane flight. However, high-mileage frequent flying (100,000 to 450,000 miles per year) can range from 1 to 6 mSv (100-600 mrem) per year.

[sources: World Nuclear Association and Health.com]

Many movies and books use threats from radiation, such as nuclear accidents and bombs, as fodder for thrill and chills. But what's real and what's not? It's probably safe to say that zombies won't rise up and take over the planet. We think. But radiation poisoning and sickness can and does happen. Radiation can leak into the environment in several ways -- a nuclear power plant accident, an atomic bomb explosion, accidental release from a medical or industrial device, nuclear weapons testing, or terrorism (like a dirty bomb). When we talk about radiation exposure here, we're mostly talking about the very rare occurrence of a large-scale release of radiation.

Every community has a radiation disaster plan in place. Your local officials should be trained in preparedness and will provide instructions should such an emergency occur. During a radiation emergency, the Centers for Disease Control and Prevention (CDC) may recommend you stay inside your home rather than evacuate. This is because the walls of your home can actually block some of the harmful radiation. The safest room in the house is the one with the least windows, possibly your basement or bathroom.

If you work around radiation and radioactive materials, there are mandates on the amount of radiation to which you can be exposed. Depending on the industry in which you work, there are also precautions like safety gear, masks, gloves and lead-lined aprons.

In the event of a radiation emergency, the first thing to figure out is if you are contaminated. If you have radioactive materials on or inside your body, you're contaminated. Contamination can quickly spread -- you'll shed external contaminants as you move about and release bodily fluids. The CDC recommends the following steps to limit contamination:

[source: CDC]

If you're exposed to radiation, medical personnel can evaluate you for radiation sickness or poisoning through symptom checks, blood tests, or a Geiger counter, which can locate radioactive particles. Depending on the severity of exposure, there are different types of medical treatment. Decontamination is the first step, and that may be all you need. Blood tests may be recommended every year or so to check for late-developing symptoms.

There are also pills you can take to reduce symptoms of exposure. You may have heard of people taking potassium iodide tablets in a nuclear emergency. These tablets prevent radioactive iodine from concentrating in your thyroid. It's important to understand that potassium iodide offers no protection from direct radiation exposure or other airborne radioactive particles. Prussian blue is a type of dye that will bind to radioactive elements like cesium and thallium. It will speed up your body's elimination of radioactive particles, reducing the amount of radiation your cells might absorb. Diethylenetriamine pentaacetic acid (DTPA) binds to the metal in radioactive elements like plutonium, americium and curium. The radioactive particles pass out of the body in urine, again reducing the amount of radiation absorbed.

For more information about radiation, expose yourself to the links on the next pa­ge.

Radiation Can Be Good For You

Before you lock yourself down in your fallout shelter, remember that some radiation is actually beneficial to your health. Ultraviolet (UV) radiation, for example, is essential for the body to stimulate production of Vitamin D. Yes, a little bit of sunlight is actually good for you. But don't throw out your sunblock just yet. Experts say that as little as five to 15 minutes a day, three times a week, is more than enough to keep your levels high.

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