Is Doing An X Ray Safe

X-rays use invisible electromagnetic energy beams to produce images of internal tissues, bones, and organs on film or digital media. Standard x-rays are performed for many reasons, including diagnosing tumors or bone injuries.

X-rays are made by using external radiation to produce images of the body, its organs, and other internal structures for diagnostic purposes. X-rays pass through body structures onto specially-treated plates (similar to camera film) or digital media and a "negative" type picture is made (the more solid a structure is, the whiter it appears on the film).

When the body undergoes x-rays, different parts of the body allow varying amounts of the x-ray beams to pass through. The soft tissues in the body (such as blood, skin, fat, and muscle) allow most of the x-ray to pass through and appear dark gray on the film or digital media. A bone or a tumor, which is more dense than the soft tissues, allows few of the x-rays to pass through and appears white on the x-ray. At a break in a bone, the x-ray beam passes through the broken area and appears as a dark line in the white bone.

X-ray technology is used in other types of diagnostic procedures, such as arteriograms, computed tomography (CT) scans, and fluoroscopy.

When medical X-rays are being produced, a thin metallic sheet is placed between the emitter and the target, effectively filtering out the lower energy (soft) X-rays. This is often placed close to the window of the X-ray tube. The resultant X-ray is said to be hard. Soft X-rays overlap the range of extreme ultraviolet. The frequency of hard X-rays is higher than that of soft X-rays, and the wavelength is shorter.

Hard X-rays overlap the range of "long"-wavelength (lower energy) gamma rays, however the distinction between the two terms depends on the source of the radiation, not its wavelength; X-ray photons are generated by energetic electron processes, gamma rays by transitions within atomic nuclei.

Since antigen's discovery that X-rays can identify bony structures, X-rays have been developed for their use in medical imaging. Radiology is a specialized field of medicine. Radiographers employ radiography and other techniques for diagnostic imaging. Indeed, this is probably the most common use of X-ray technology.

X-rays are especially useful in the detection of pathology of the skeletal system, but are also useful for detecting some disease processes in soft tissue. Some notable examples are the very common chest X-ray, which can be used to identify lung diseases such as pneumonia, lung cancer or pulmonary edema, and the abdominal X-ray, which can detect ileus (blockage of the intestine), free air (from visceral perforations) and free fluid (in ascites).

In some cases, the use of X-rays is debatable, such as gallstones (which are rarely radiopaque) or kidney stones (which are often visible, but not always). Also, traditional plain X-rays pose very little use in the imaging of soft tissues such as the brain or muscle. Imaging alternatives for soft tissues are computed axial tomography (CAT or CT scanning), magnetic resonance imaging (MRI) or ultrasound. Since 2005, X-rays are listed as a carcinogen by the U.S. government.

Diagnostic x-rays are safe. But who hasnt wondered about them when undergoing a chest x-ray, mammogram, routine dental x-rays, or an x-ray for a broken bone?

The safety of routine X-rays has been called into question following the unexpected discovery that cells exposed to low doses avoid or delay repairing damaged DNA.

Puzzlingly, cells given higher doses of X-rays were faster and more efficient at patching up any damage. But the German researchers who made the discovery say it is not clear whether the sloppy repairs that follow low level exposure is a good or bad thing.

Kai Rothkamm and Markus Brich, at the University of Saarland in Homburg, acknowledge that unrepaired breaks in DNA could well lead to cells becoming cancerous. But it is equally possible, they say, that the failure to repair low-level DNA damage has evolved as a safety measure.

Other experts state that no scientific data indicate any danger. In fact, there is evidence that low doses may actually reduce the chance of cancer. The question about the amount of radiation you receive is difficult for x-ray technicians and doctors to answer because very few x-ray units have an instrument to measure the radiation to the patient.

You may have heard that even the smallest amount of radiation may cause cancer. Based on this unscientific assumption, the risk of causing a fatal cancer from a chest x-ray is 10 times greater than the risk of dying in a commercial airline flight. Or a CT scan of the kidneys has a greater risk of inducing a fatal cancer than a cigarette smoker has of dying from any cancer. These statements produce unnecessary worry. There is no data to show any risk from diagnostic x-rays.

Lastly, radiation during pregnancy may lead to birth defects. Always tell your radiologist or physician if you suspect you may be pregnant.

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Techniques for Hydrostatic test

Leaks in pressure yacht such as pipelines, plumbing, etc can be found with one of the most ordinary methods knows as hydrostatic test. In short it is utilized to test mechanisms for leaks by pressurizing them within with a liquid. This testing technique can be utilized or tested on piping, tanks, valves and containers with fused or fixed sections. This technique of testing should not be perplexed with the Hydrostatic Body Fat Test that utilizes the philosophy of resilience to analyze a person's body fat. Hydrostatic tests, as a supplementary recital authenticate fluid stress vessels. By utilizing this mean of test we can uphold protection standards and sturdiness of a vessel eventually. Recently manufactured portion are firstly competent by means of the hydrostatic test and repeatedly re-qualified at usual hiatus by the proof pressure test which is also known as modified hydrostatic test. With the help of Hydrostatic we can check gas cylinder or a boiler is checked for leaks or defect. This method is very vital as such containers can blow up if they fail when containing dense gas.
Normally the benefits of this test is that it helps to measure the pressure capacity, manually control the systems, is fully automatic, precise control, is fully instrumentation and data logging, has strain measurement system, temperature control, etc.
This method requires that a constituent be entirely filled with a liquid such as water. Pressure is gradually applied to the liquid until the required pressure is reached. This pressure is detained for the necessary time at which point the constituent is examined visually to establish leaks.
There are two types of hydrostatic measures that are included in the method:
Firstly the pressure drops method with compassion. This technique would never place leaks but can be used to determine entirety system leakage. It is important that the technique be familiar with that water additives can speed up the flow of water through leaks and make the test more responsive.
Secondly is the Visual examination. This practice can attain compassion. This extensive bound in compassion is accomplished by not only plummeting confrontation to the liquid flow through leaks but by also enhancing the visibility of leakage proposition.One of the more attractive proposals is that it is frequently more helpful to pulsation the pressure throughout a test than it is to clutch a steady pressure. This is particularly true when the organization being tested will not function at a stable pressure or it is being tested at pressures well over those predictable during standard use. The cause for this prerequisite is that little leaks are not forever still. Several enlarge under pressure, several indentures Severe over pressurization may in reality close some leaks overall.

Salt Spray Weathering

Salt spray testing under ASTM B117 conditions subjects the test samples to conditions that are actually more corrosive than usual “real world” exposure. This is because the test uses sodium chloride in de-ionized water and usually lacks the moderating effects of other dissolved salts such as those containing calcium and magnesium, which tend to be somewhat protective.

is the most popular form of testing for protective coatings. These tests have been used for more than 90 years as accelerated tests in order to determine the degree of protection afforded by both inorganic and organic coatings on a metallic substrate. The most widely used salt spray (fog) tests are described below.

The neutral salt spray (fog) test (ASTM B 117): is perhaps the most commonly used salt spray test in existence for testing inorganic and organic coatings, in particular where such tests are used for material or product specifications. The duration of the test can range from 8 to over 3000 hours, depending on the product. A 5% sodium chloride solution containing not more than 200 parts per million (ppm) total solids and with a pH range of 6.5 to 7.2 is used. The temperature of the salt spray chamber is controlled to maintain 35 + 1.1 or – 1.7Þ C (95 + 2 or -3Þ F) within the exposure zone of the closed chamber.

The acetic acid salt spray (fog) test (ASTM G 85, Annex A1): is also used for testing inorganic and organic coatings, but is particularly applicable to the study or testing of decorative chromium plating and cadmium plating on steel or zinc die castings, as well as for the evaluation of product quality. This test can be as short as 16 hours, although it normally ranges from 144 to 250 hours or more. Similar to the neutral salt spray test, a 5% sodium chloride solution is used, but the solution is adjusted to a pH range of 3.1 to 3.3 by the addition of acetic acid. The temperature of the salt spray chamber is controlled to the same temperature range as for neutral salt spray.

The copper accelerated acetic acid salt spray (fog), or CASS test (ASTM B 368): is primarily used for the rapid testing of chromium plating on steel and zinc die castings. It is also useful in the testing of anodized, chromated, or phosphated aluminum. The duration of this test ranges from 6 to 720 hours. A 5% sodium chloride solution is used, with one gram of copper (II) chloride dihydrate added to each 3.8 liters of salt solution. The solution is then adjusted to a pH range of 3.1 to 3.3 by adding acetic acid. The temperature of the salt spray chamber is controlled to the same temperature range as for neutral salt spray and for acetic acid salt spray.

Basic Principles of Ultrasonic Testing

Ultrasonic Testing (UT) uses high frequency sound energy to conduct examinations and make measurements. Ultrasonic inspection can be used for flaw detection/evaluation, dimensional measurements, material characterization, and more. To illustrate the general inspection principle, a typical pulse/echo inspection configuration as illustrated below will be used.

A typical UT inspection system consists of several functional units, such as the pulser/receiver, transducer, and display devices. A pulser/receiver is an electronic device that can produce high voltage electrical pulses. Driven by the pulser, the transducer generates high frequency ultrasonic energy. The sound energy is introduced and propagates through the materials in the form of waves. When there is a discontinuity (such as a crack) in the wave path, part of the energy will be reflected back from the flaw surface. The reflected wave signal is transformed into an electrical signal by the transducer and is displayed on a screen. In the applet below, the reflected signal strength is displayed versus the time from signal generation to when a echo was received. Signal travel time can be directly related to the distance that the signal traveled. From the signal, information about the reflector location, size, orientation and other features can sometimes be gained.

Ultrasonic Inspection is a very useful and versatile NDT method. Some of the advantages of ultrasonic inspection that are often cited include:

• It is sensitive to both surface and subsurface discontinuities.
• The depth of penetration for flaw detection or measurement is superior to other NDT methods.
• Only single-sided access is needed when the pulse-echo technique is used.
• It is highly accurate in determining reflector position and estimating size and shape.
• Minimal part preparation is required.
• Electronic equipment provides instantaneous results.
• Detailed images can be produced with automated systems.
• It has other uses, such as thickness measurement, in addition to flaw detection.

As with all NDT methods, ultrasonic inspection also has its limitations, which include:

• Surface must be accessible to transmit ultrasound.
• Skill and training is more extensive than with some other methods.
• It normally requires a coupling medium to promote the transfer of sound energy into the test specimen.
• Materials that are rough, irregular in shape, very small, exceptionally thin or not homogeneous are difficult to inspect.
• Cast iron and other coarse grained materials are difficult to inspect due to low sound transmission and high signal noise.
• Linear defects oriented parallel to the sound beam may go undetected.
• Reference standards are required for both equipment calibration and the characterization of flaws.

The above introduction provides a simplified introduction to the NDT method of ultrasonic testing. However, to effectively perform an inspection using ultrasonics, much more about the method needs to be known. The following pages present information on the science involved in ultrasonic inspection, the equipment that is commonly used, some of the measurement techniques used, as well as other information.

Leak Testing

Leak testing equipment is used to measure the escape of liquids, vacuum or gases from sealed components or systems. Some configurations require a separate leak detector or sensor as an input. Such types of leak testing equipment are often equipped with various other components such as pumps, calibrators, gauges and cases. Output options include analog voltage, analog current, frequency or modulated frequency, and switch or alarm signal. Some leak testing equipment includes an analog front panel with potentiometers, dials, and switches. Other features a digital front panel that is set up with a keypad or menus. Leak testing equipment with a serial interface, a parallel interface, and/or integral application software is also available.

Leak test method is an important specification to consider when choosing leak testing equipment. Methods include bubble testing, colorimetric development, electronic gas detection, mass flow, mass spectrometry, and hydrogen leak detection. Bubble testing is used for applications which do not require high sensitivity. A pressurized test object is submerged in a water tank so that the emergence of bubbles indicates a leak. Colorimetric development uses a chemical developer which reacts with the leaking fluid, causing a visible color change to occur at the place of leakage. Leak testing equipment that uses electronic gas detection pressurizes the test object with a tracer gas so that a sniffer probe can be used to find the leak. Mass flow devices direct the leakage across a heating element. The temperature change produces an output voltage proportional to mass flow. Mass spectrometers are used with helium leak detection. Leak testing equipment that is designed to detect hydrogen leaks is also available.

Leak testing equipment may use test methods such as pressure differential (decay) and ultrasonic leak detection. A pressure decay test involves the initial inflation of the test object and the establishment of a reference pressure. After a designated amount of time, the pressure is measured again and the initial and final measurements are compared. The change in pressure can be used to calculate the leak rate given the internal volume of the device. Ultrasonic leak detection (sonic flow, choked flow) involves the turbulent flow of a fluid across a pressure boundary to create acoustic waves. These waves are transmitted through the medium of the fluid itself, through the containment structure, or through the air surrounding the containment structure. Leak testing equipment that uses other test methods is also available.

Positive Material Identification

ABC Testing was incorporated in December 1982 by Carleton A. Richardson. Since then the company’s number one commitment has been customer service. The company is certified as ASNT SNT TC 1A, level III in Ultrasonic, Radiography, Magnetic Particle, Liquid Penetrant and Visual Testing.

ABC Testing provides inspectors certified by the NYDOT in ultrasonic testing. This testing can be used to identify defects such as cracks, laminations, shrinkage cavities, gas holes, slag inclusions, incomplete fusion, incomplete penetration and lack of bond in a wide variety of materials. Radiographic testing is used when volumetric inspections are necessary to insure part reliability and a permanent record gets stored on film.

Magnetic particle helps detect surface flaws that would not be visible otherwise on ferrous materials. Liquid penetrant, on the other hand, helps detect surface flaws on non-magnetic materials that would not be seen visually. Visual testing is a cost effective examination used to check weld size and appearance. The company also offers various destructive tests to aid in welding procedure qualifications. It has several AWS Certified Welding Inspectors on its staff. They use Bend Testing, Tensile Testing and Charpy Impact Testing to test ductility, strength and material resistance, respectively. Destructive tests also include Hardness Testing which is used to verify whether heat treatment was done properly and Salt Spray Testing which helps in determining corrosion resistance.
Positive Material Identification is another technique that is used to give immediate results about the alloy in question with minimum surface penetration. It uses X-ray fluorescence to identify ferrous and non-ferrous materials without having to cut the sample out for analysis. Eddy current is normally used to check chiller system tubing for detecting defects, sorting materials, testing thickness and conductivity.


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Pressure Testing

ABC Testing Incorporated is certified as ASNT SNT TC 1A, level III in Ultrasonic, Radiography, Magnetic Particle, Liquid Penetrant. and Visual.

We have several AWS Certified Welding Inspectors on staff. We can provide inspectors certified by the NYDOT in ultrasonic testing. We are also certified by ABS to perform ship hull thickness surveys. We are Veriforce certified for inspection of gas pipelines.

For more details visit www.abcndt.com