https___www.arpansa.gov.au_understanding-radiation_what-is-radiation_ionising-radiation_x-ray.xml
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Like all forms of ionising radiation, X-rays produce electrons and ions when they pass through materials. What are X-rays? An X-ray is a packet of electromagnetic energy (photon) that originate from the electron cloud of an atom. This is generally caused by energy changes in an electron, which moves from a higher energy level to a lower one, causing the excess energy to be released. X-rays are similar to gamma rays however the main difference is the way they are produced, X-rays are produced by electrons external to the nucleus. Traditionally X-rays had longer-wavelengths and lower energy than gamma rays but this is obsolete with modern X-ray production methods. What are the properties of X-rays? X-rays are a form of electromagnetic radiation similar to radio waves, microwaves, visible light and gamma rays. X-ray photons are highly energetic and have enough energy to break up molecules and hence damage living cells. When X-rays hit a material some are absorbed and others pass through. Generally, the higher the energy the more X-rays will pass through (Table 1). It is this penetrating power that allows us to take internal images of the human body or objects. X-rays cannot be steered by electric and magnetic fields like alphas, betas or other charged particles. Table 1 What are the health effects of exposure to X-rays? X-rays are highly penetrating and interact with matter through ionisation via three processes, photoelectric effect, Compton scattering or pair production. Due to their high penetration power the impact of X-rays can occur throughout a body, they are however less ionising than alpha particles. X-rays are considered an external hazard with regards to radiation protection. Similar to all exposure to ionising radiation high exposures can cause direct acute effects through immediate damage to cells. Low levels of exposure carry a stochastic health risk where the probability of cancer induction increases with increased exposure. What is the difference between gamma rays and X-rays? The key difference between gamma rays and X-rays is how they are produced. Gamma rays originate from the settling process of an excited nucleus of a radionuclide after it undergoes radioactive decay whereas X-rays are produced when electrons strike a target or when electrons rearrange within an atom. What are some common sources of X-rays? X-rays are commonly produced in X-ray tubes by accelerating electrons through a potential difference (a voltage drop) and directing them onto a target material (i.e. tungsten). The incoming electrons release X-rays as they slowdown in the target (braking radiation or bremsstrahlung). The X-ray photons produced in this manner range in energy from near zero up to the energy of the electrons. An incoming electron may also collide with an atom in the target, kicking out an electron and leaving a vacancy in one of the atom’s electron shells. Another electron may fill the vacancy and in so doing release an X-ray photon of a specific energy (a characteristic X-ray). The X-ray spectrum shown in the picture is a plot of the number of photons against the photon energy. A computed tomography (CT) scanner is a particular type of X-ray machine in which the X-ray tube produces a beam in the shape of a fan and moves around the patient in a circle. The X-rays are detected electronically and a computer uses the information to reconstruct an image of the region of the body exposed. X-rays can also be produced by a synchrotron. A synchrotron is a device that accelerates electrons in an evacuated ring (often several tens of metres in diameter), steering them with magnets. Manipulating the electron beam in a controlled way with the magnets can produce intense beams of X-rays. Synchrotron facilities are used for research purposes. What are some uses of X-rays? X-rays have a large range of uses for medical, industrial and research purposes. Diagnostic medical X-rays are the most likely way you will encounter X-rays. Data from the Health Insurance Commission shows that each year there are over 12 million Medicare claims for exams on X-ray machines and also over 2 million claims for computed tomography (CT) exams. Radiotherapy is another example of the medical use of X-rays to treat cancer. On average, each Australian receives an effective dose of about 1.7 mSv per year from medical procedures, including about 1.1 mSv from CT scans. This is similar to the dose everyone receives from background radiation that is and always has been in our environment. Industrial and research uses of X-rays include X-ray crystallography and fluoroscopy which are commonly used for the quality control of materials (i.e. metal quality) and investigating the properties of materials. Industrial radiography can use X-ray or gamma sources for analysis to look for cracks in buildings, structures or pressure vessels. X-rays are also used in security processes for baggage/container screening at airports and ports. The accelerating voltage and the target material used to produce X-rays vary depending on the particular application (Table 2). Table 2 How can my risk from X-ray exposure be minimised? As with all types of radiation the protection principles are time, distance and shielding . A diagnostic X-ray should be performed to provide information that helps medical staff treat a patient’s condition appropriately. In general, this information is much more important to a person’s health than the small estimated risk (typically less than 0.01%) of the chance of developing cancer from the procedure. As lead is a very good attenuator of X-rays (see Table 1), a garment impregnated with a small amount of lead can be used to cover sensitive parts of the body. Modern X-ray equipment has many features that if used properly can limit the area irradiated and the dose delivered to the minimum necessary for obtaining the diagnostic information. In some cases an alternative type of imaging (ultrasound or magnetic resonance imaging) may be able to provide the information sought and therefore may be used instead of an X-ray.
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एक्सरे किन गरिन्छ ? आजको आधुनिक युगमा रोग पत्ता लगाउन एक्सरे (रेडियोलोजीकल ) जाँच गर्न आवश्यक छ । एक्सरेबाट शरीरको भित्री अंगको जाँच गरेर रोग पत्ता लगाउन सजिलो भएको छ । छातीको एक्सरे गर्दा साँस तानेर एकछिन रोकेर राख्नुपर्छ, यसो गर्दा फोक्सो फुल्छ र एक्सरेमा छातीका अंगहरुको विवरण राम्रोसँग देखिन्छ। गर्भवती महिलाहरुमा एक्सरेको विकिरणले भ्रुणको विकास क्रममा असर गर्नसक्ने भएकोले अति आवश्यक अवस्थामा बाहेक अरु बेला यो जाँच गरिदैन । हुन त भ्रुणमा यसको असर देखिन आवश्यक विकिरणको मात्रा भन्दा साधारण एक्सरे जाँचहरुमा पर्ने विकिरण धेरै कम हुन्छ । यो पनि पढ्नुहोस् ग्याष्ट्रिकको कारण, लक्षण र उपचार स्वाइन फ्लू (Swine Flu) र यसको उपचार सास गनाउने समस्या र यसको उपचार महिनाबारी गडवड र यसको प्राकृतिक उपचार छातीको एक्सरे किन गरिन्छ ? सामान्यतया निम्न लक्षणहरुका लागि छातीको एक्सरे गरिन्छ । १. श्वास बढ्ने ज्वरो आउने भएमा, २. लगातार खोकी लाग्ने, छाती दुख्ने, खकारमा रगत देखिने भएमा, ३. छातीमा चोटपटक लागेमा ४. निमोनिया, दमको रोग (COPD), क्षयरोग, फोक्सोको क्यान्सर, हार्ट फेलर (Heart Failure) अर्थात मुटुले काम नगरेको अवस्था आदि विभिन्न रोगहरुमा छातीको एक्सरेले रोगको पहिचान र उपचारमा आवश्यक सहयोग पुर्याउँछ । छातीको एक्सरे गर्दा एक्सरॆ विकिरणको हानिकारक असर कति हुन्छ ? प्रत्येक पल्ट एक्सरे गर्दा न्यून मात्रामा एक्सरे विकिरण शरीरमा पार्ने गरिन्छ । यो करिब ०.१ mSv हुन्छ र यो हामीले प्राकृतिक रुपमा करिब १० दिनमा पाउने विकिरण बराबर हुन्छ । Like & Follow us on Facebook एक्सरे गर्दा ध्यान दिइने केहि कुराहरु १. एक्सरे गर्दा छाती घाटीमा लगाएका धातुका गहना सामानहरु फुकाल्नुपर्छ । यसले एक्सरे विकिरणलाई छेकेर एक्सरे राम्रो नआउन सक्छ । २. छातीको एक्सरे गर्दा साँस तानेर एकछिन रोकेर राख्नुपर्छ, यसो गर्दा फोक्सो फुल्छ र एक्सरेमा छातीका अंगहरुको विवरण राम्रोसँग देखिन्छ । *डा. राम बहादुर बोहरा नेपाल वैकल्पिक चिकित्सा विकास परिषद नवलपरासीको अध्यक्ष, बरिष्ट आयुर्वेद डाक्टर तथा साइन्स इन्फोटेकका सल्लाहकार हुनुहुन्छ ।