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Digital flat panel x-ray detectors are an excellent example of how an established technology can enter into a new market. This is apparent in their use in medical imaging, where flat panel digital x-ray technology continues to show great promise in diagnostic and treatment capabilities.
Keeping this in mind, medical imaging has become the focus for flat panel digital applications and solutions, replacing traditional film radiography in hospitals and clinics as it improves efficiency, accuracy and productivity. For example, hospital technicians can position a patient, take an image and review it immediately. The technology takes only minutes to process information that with older technologies took hours or even days, delaying important and even life-saving treatments.
An X-ray tube is basically a vacuum tube that produces X-rays, which are used in X-ray machines. X-rays are part of the electromagnetic spectrum, an ionizing radiation with wavelengths shorter than ultraviolet light. X-ray tubes evolved from experimental Crookes tubes with which X-rays were first discovered in the late 19th century. The discovery of this controllable source of X-rays created the field of radiography: the imaging of opaque objects with radiation that penetrates. X-ray tubes are also used in airport luggage scanners, CAT scanners, X-ray crystallography and for industrial inspection.
As with any other type of vacuum tube, there is a cathode, which emits electrons into the vacuum and an anode to collect the electrons ─ creating a flow of electrical current, known as the beam, through the x-ray tube. A high voltage power source is connected across the cathode and the anode to accelerate the electrons. The X-ray spectrum depends on the anode material and the accelerating voltage.
In many applications, the current flow is able to be pulsed on for between approximately 1ms to 1s. This allows for consistent doses of x-rays, and taking snapshots of motion. Until the late 1980s, X-ray generators were merely high-voltage, AC to DC variable power supplies. In the late 1980s a different method of control emerged, which became known as high-speed switching. This followed the electronics technology of switching power supplies (also known as switch mode power supply), and allowed for: more accurate control of the X-ray unit, higher-quality results, and reduced exposure to X-ray.
Electrons from the cathode collide with the anode material, usually tungsten, molybdenum or copper, and accelerate other electrons, ions and nuclei within the anode material. About 1% of the energy generated is emitted/radiated, usually perpendicular to the path of the electron beam, as X-rays. The rest of the energy is released as heat. Over time, tungsten is deposited from the target onto the interior surface of thex-ray tube, including the glass surface. This slowly darkens the tube and was thought to degrade the quality of the X-ray beam, but research has suggested there is no effect on the quality. Eventually, the tungsten deposit becomes sufficiently conductive that at high enough voltages, arcing occurs. The arc jumps from the cathode to the tungsten deposit, and then to the anode. The arcing causes an effect called "crazing" on the interior glass of the X-ray window. As time goes on, the tube becomes unstable even at lower voltages, and must be replaced. At this point, the x-ray tube assembly (also called the "tube head") is removed from the X-ray system, and replaced with a new tube assembly. The old tube assembly is shipped to a company that reloads it with a new, replacement X-ray tube.
The range of photonic energies emitted by the system can be adjusted by changing the applied voltage, and installing aluminum filters of varying thicknesses. Aluminum filters are installed in the path of the X-ray beam to remove "soft" (non-penetrating) radiation. The numbers of emitted X-ray photons or doses are adjusted by controlling the current flow and exposure time.
In simple terms, the high voltage controls X-ray penetration, and thus the contrast of the image. The tube current and exposure time affect the dose and consequently, the darkness of the image.
Some x-ray examinations (such as: non-destructive testing and 3-D microtomography) need very high-resolution images and therefore require x-ray tubes that can generate very small focal spot sizes, typically below 50 µm in diameter. These tubes are called microfocus x-ray tubes.
There are two basic types of microfocus x-ray tubes: solid-anode x-ray tubes and metal-jet-anode x-ray tubes.
Solid-anode microfocus x-ray tubes are in principle very similar to the Coolidge tube, but with the important distinction that care has been taken to focus the electron beam into a very small spot on the anode. Many microfocus x-ray sources operate with focus spots in the range 5-20 µm, but in rare cases spots smaller than 1 µm may be produced.
The major drawback of solid-anode microfocus x-ray tubes is the very low power in which they operate. To avoid melting of the anode, the electron-beam power density must be below a maximum value. This value is somewhere in the range 0.4-0.8 W/µm depending on the anode material. This means that a solid-anode microfocus source with a 10 µm electron-beam focus can operate in the range 4-8 W.
In metal-jet-anode microfocus x-ray tubes, the solid metal anode is replaced with a jet of liquid metal, which acts as the electron-beam target. The advantage of the metal-jet anode is that the maximum electron-beam power density is significantly increased. Values in the range 3-6 W/µm have been reported for different anode materials (gallium and tin).[4][5] In the case with a 10 µm electron-beam focus a metal-jet-anode microfocus x-ray source may operate at 30-60 W.
The major benefit of the increased power density level for the metal-jet x-ray tube is the possibility to operate with a smaller focal spot to increase image resolution, and at the same time acquire the image faster, since the power is higher (15-30 W) than for solid-anode tubes with 10 µm focal spots.
MedWOW’s inventories feature X-Ray tubes from most of the major manufacturers including: Shimadzu, Varian, Dunlee, Fischer Imaging, GE Healthcare, Philips, Siemens, Picker and Raymed, with more being added all the time, so finding exactly what you need is efficient and simple for busy medical professionals. With dozens of types of x-ray tubes currently featured through MedWOW’s comprehensive online catalogue ─ finding and purchasing your next x-ray tube is trouble- free and as thousands of medical professionals use the MedWOW portal on a daily basis, the prices are always competitive.
Computed Radiography (CR), is a method of digitally capturing x-ray images for reading using computers and laser technology. Images are captured on imaging plates that offer flexible positioning because you can insert the imaging plates into any existing wall or table bucky, or wherever you currently use a film plate. When the image has been captured, the imaging plates are then inserted into the computed radiography (CR) reader, the image is read and stored electronically, and the imaging plate is erased and made available for the next usage. The stored computed radiography (CR) image is then available for viewing or distribution through a DICOM viewer or PACS.
Computed radiography (CR) technology uses a reusable phosphor imaging plate, which is scanned by a laser scanner after being exposed to X-ray. This technology is very similar to film in that the images need to be scanned (instead of developed like film) in order to retrieve the x-ray data. However, phosphor computed radiography (CR) plates can be erased and used over and over again to produce extremely high-definition images.
The main benefit of computed radiography (CR) systems over DR imaging systems is that the imaging plates themselves are extremely flat and flexible so they can fit into tight gaps, behind paneling and even wrapped around a target object. Computed radiography (CR) imaging plates are available in a range of different sizes at relatively low cost, so you can purchase several formats to cover a large number of different tasks.
The advantage of computed radiography (CR) systems over traditional x-ray film is that the digital image film can be used again and again so there are no regular consumable costs. X-ray images are much higher resolution and can be digitally enhanced to produce clear defined images. Images can also be stored digitally and will not fade over time. No chemicals or darkroom are needed.
Summary of the key benefits of computed radiography (CR)
Very high resolution forensic level imaging
Perfect for revealing complex electronics and circuitry
Extremely thin, flat, flexible imaging plates
Reuse image plates 1000+ times
Enhance and store images digitally
Range of image plate sizes up to 90 cm long
Mains/vehicle or battery powered image plate processor
Auto image plate erase (user selection)
Fast deployment at target area
No chemicals
No carousel or clips required in the imaging process
Complete system in a single transit case
Image plate processor can be used from inside transit case for all weather operation
The top marketplace for medical equipment, including computed radiography (CR) systems and other imaging equipment, MedWOW, has firmly established its place in the international market. MedWOW provides good-quality computed radiography (CR) image systems in a safe and secure trading environment. When purchasing or selling a computed radiography (CR), MedWOW has the market, the platform and the buyers. MedWOW has recently upgraded its medical equipment catalogue with various manufacturers, refurbished equipment and new and used computed radiography (CR) systems.
MedWOW represents a variety of makes and model leaders in computed radiography (CR) such as: Carestream Health, Fuji Medical Systems, Agfa, Air Techniques, CoRE labs, CR Medical, Fuji, Kodak, Konica Minolta, Orex and Radlink. These offerings include single and multi-plate systems to fit your volume and need.
Wilhelm Roentgen, is best known is best known for the discovery of "Roentgen Rays", now univerally known as x-rays. Around this time, in 1985, various scientists were investigating the movement of electrons through a glass apparatus known as a Crookes tube. Roentgen wanted to visually capture the action of the electrons, so he wrapped his Crookes tube in black photographic paper. When he ran his experiment, he noticed that a plate coated with a fluorescent material, which just happened to be lying nearby the tube, glowed. This was unexpected, because no visible light was being emitted from the wrapped tube. Upon further investigation, he found that indeed there was some kind of invisible light produced by this tube, and it could penetrate materials such as wood, aluminum, and even human skin.
As the field of radiography expanded, x-ray technology steadily improved. One of the major limitations of conventional x-rays was that they lacked depth; therefore many internal structures were superimposed on each other, making it difficult to read results. With the help of computers, scientists developed methods to solve this problem. One such method was computed tomography (CT), or computerized axial tomography (CAT). The first CT scanner was demonstrated in 1970 by Godfrey Hounsfield and Allen Cormack. Over the next 20 years, significant advances were made in CT scanner design, which have resulted in the high-quality imaging scanners used today, and still constantly improving.
A CT scanner x-ray tube is a special type of vacuum-sealed, electrical diode that was designed and developed to produce x-rays. The CT scanner x-ray tube is comprised of two electrodes: the cathode and anode. To generate x-rays, a filament in the cathode is charged with electricity from a high -voltage generator. This causes the filament to heat up and emit electrons. Using their natural attraction and a special focusing cup, the electrons travel directly toward the positively charged anode. X-rays are indiscriminately released when the electrons strike the anode. The anode, which can be rotating or not, then conducts the electricity back to the high-voltage generator to complete the circuit. To focus the x-rays into a beam, the CT scanner x-ray tube is contained inside a protective housing. This housing is lined with lead, except for a small window at the bottom. Functional x-rays are able to escape out this window, while the lead prevents the escape of stray radiation in other directions.
CT scanner x-ray tubes have gone through several generations of technological evolution. In the third generation, developers realized that if a pure rotational scanning motion could be used, rather than the slam-bang translational motion, then it would be possible to use higher power, rotating CT scanner x-ray tubes and therefore improve scan speeds in thicker, harder to penetrate body parts. A standard machine which most x-ray technicians are familiar with, uses a large fan beam, so that the patient is completely covered by the fan and the detector elements are aligned along the arc of a circle centered on the focus of the CT scanner x-ray tube. The CT scanner x-ray tube and detector array rotate as one through 360 degrees, different projections are attained during rotation by pulsing the x-ray source, and bow-tie shaped filters are chosen to suit the body or head shape by some manufacturers to avoid extreme variations in signal strength.
The fourth generation of CT scanners uses rotate-fixed ring geometry, where a ring of fixed detectors completely surrounds the patient. The x-ray tube rotates inside the detector ring through a full 360 degrees with a wide fan beam producing a single image.
A limiting factor in image acquisition used to be the CT scanner x-ray tube. The need for long, high intensity exposures and very stable output placed enormous demands on both the CT scanner x-ray tube and generator (power supply). Very high performance rotating anode CT scanner x-ray tubes were developed to keep up with demand for faster imaging, as were the regulated 150 kV switched mode power supplies to drive them. Current CT scanning systems have power ratings up to 100 kW.
The most popular, international marketplace for all types of medical equipment, featuring a large selection of CT scanner x-ray tubes, MedWOW, is an excellent place to find reliable and good-quality imaging equipment and parts. When purchasing or selling CT scanner x-ray tubes, MedWOW’s comprehensive portal attracts nearly 12,000 medical equipment professionals daily, making it easy to find what you seek. MedWOW has recently upgraded its imaging and CT scanner x-ray tubes section with additional manufacturers, including refurbished equipment and new and used CT scanner x-ray tubes. CT scanner x-ray tubes manufacturers represented on MedWOW include: Elscint, Esaote, GE Healthcare, Philips, Picker, Shimadzu, Siemens, Toshiba and more.
Digital, cutting-edge imaging technologies, such as 3-dimensional tomosynthesis, have already found to be significant in earlier identification and diagnosis of breast cancer. Unlike current mammography systems, which generate a two-dimensional (2-D) image, breast tomosynthesis produces a three-dimensional image. Additionally, it is anticipated that tomosynthesis will enhance new applications, in combination with ultrasound. Using current mammography technologies, usually two x-rays of each breast are taken from different angles: from top-to-bottom and from side-to-side. The breast is pulled away from the body, compressed, and held between two glass plates to make sure that the entire breast can be carefully observed. Standard mammography records the images on film, and digital mammography records the images on computer, which can then be read and interpreted by a radiologist. Breast cancer, which is denser than most healthy nearby breast tissue, appears as uneven white areas which are referred to as shadows.
Mammography is an excellent technology, but also has the following considerable limitations, which tomosynthesis technologies overcome:
Some women cannot tolerate the breast compression component and find it so uncomfortable that they avoid annual or indicated testing.
This necessary compression also causes overlapping of the breast tissue. Breast cancer can be hidden in the overlapping tissue and not show up on the mammogram.
Mammograms take only one picture, across the entire breast, in the two directions as described above. In this limited way, it is possible to miss cancerous areas or lesions that are too small to detect.
Digital tomosynthesis was developed to overcome these limitations. Tomosynthesis takes multiple x-ray pictures of each breast from many angles and the breast is positioned the same way it is in a conventional mammogram, but much less pressure is necessary. Tomosynthesis requires just enough pressure to keep the breast in a stable position during the procedure. The x-ray tube moves in an arc around the breast while 11 images are taken during a 7-second examination. Then the information is sent to a computer, where it is assembled to produce clear, highly focused 3-dimensional images throughout the breast. In this way, none of the tissue is missed as using tomosynthesis, there is no folding or “hiding” of potentially cancerous tissue.
Early results with digital tomosynthesis are promising and it is believed that this new imaging technique will make breast cancers easier to see in dense breast tissue and will make mammography screenings more comfortable.
In addition to mammography, tomosynthesis also gives better results than standard planar X-ray in the following applications:
The introduction of flat panel detectors to cardiovascular x-rays have been an important advance in increasing the speed of C-arm rotations and decreasing the time it takes for examinations. The flat panel detector converts the x-rays into signals which the computers use to produce an image.Cardiovascular X-ray Systems are particularly important in difficult or intricate procedures as they optimize the intervention and enhance the power of the entire cath lab, the examination room used to support catheterization for procedures with cardiovascular involvement.
Newer digital cardiovascular x-ray systems provide crystal-clear imaging of cardiac and vascular interventions with versatility in diagnostic imaging, providing lucid visualization of small details and objects for complex interventions. These state-of-the-art cardiovascular x-rays also have the benefit of giving much lower x-ray dosages than their predecessors, which minimizes X-ray dose for cardiac, vascular, and especially pediatric examinations. Now cardiologists can get twice the information with a single contrast injection, which is much safer and easier as it minimizes the dose of radiation to both patients and staff during x-ray examination.
These modern digital cardiovascular x-ray systems allow cardiologists to personalize their settings and conveniently control all movements and interventional tools in order to provide outstanding support for treating congenital heart disease and performing vascular examinations. One of the major advantages of this type of cardiovascular x-ray equipment is that treatment can also be carried out at the same time. Occlusion of the blood vessels can be opened by inflating a balloon catheter and if necessary, a stent can be placed to keep the vessel open.
Some of the most recent models offer navigation for cardiologists for structural heart procedures, utilizing real-time 2D x-ray images and 3D cardiac models from multiple modalities, such as vascular x-ray, CT and MR, and image stabilization features. 3D tools particularly support treatment strategies for coronary angiography procedures as3D x-ray techniques allow easier visualization of vessels and heart. In addition, 3D angiography delivers a lower patient radiation dose, using less contrast material, as well as being faster and therefore, increasing medical facility efficiency.
Thanks to the technology used in these innovative x-ray systems, interventional procedures, vascular, and cardiovascular applications are streamlined. Because it simplifies cath lab workflow, cardiologists can now completely and more accurately focus on a wider range of cardiac patients and help them deliver faster, more accurate diagnoses and treatment.
