Effective radiation shielding is imperative to safe operation of modern Medical Cyclotrons producinglarge activities of short-lived radioisotopes on a commercial basis. Like the containment shielding of Medical Linear Accelerators , the optimal shielding design of Medical Cyclotrons demands a careful balance between the radiological, economical and often the sociopolitical factors. One is required to optimize the cost of radiation protection and the cost of radiological health detriment . The cost of radiation protection depends explicitly on the nature of the ionising radiation field produced by the cyclotron, its operational condition, the cost of
shielding material, the level of dose reduction, the projected net revenue from the from the sale of the radioisotopes, and the depreciation rate of the cyclotron facility. The mathematical methods of accelerator shielding optimisation  within the guideline of ALARA  have been reported by various investigators.

The important radioisotopes produced by Medical Cyclotrons for present day diagnostic nuclear
medicine include 201Tl (T1/2= 73.06 h) and67Ga (T1/2= 78.26 h). These radioisotopes are generated by bombarding the thick copper substrates electroplated with enriched parent target materials with 30 MeV protons at ~ 400A beam current. The target bombardments result in the production of intense fields of high-energy neutrons and gamma rays. Therefore, in order to avoid the radio-activation of the cyclotron, the ancillaries and radiation exposure to cyclotron workers and members of the public, the high performance target irradiation stations of modern negative ion Medical Cyclotrons  are housed in separate target vaults made of high density concrete. Thus, the efficient shielding of the target vaults plays the most important role in the radiological safety of the commercial Medical Cyclotron facilities.

The conventional optimisation method for the functions of multiple variables, such as the cost benefit-
analysis of Medical Cyclotron shielding design is too complex and prone to serious pitfalls. Hence, a new
method based on the Genetic Algorithm (GA) was used to solve this problem. The GA is a mathematical technique that emulates the Darwinian Evolution paradigm, also known as the “Survival of the Fittest” strategy.

It is ideally suited to search for a global optimum in a large multi-dimensional solution space, havingdemonstrated strength compared to the classical analytical methods. This paper highlights the application of an interactive spreadsheet macro program for the optimised shielding thickness calculation of the target vault of a Medical Cyclotron. The present optimisation method is based on a Genetic Algorithm search engine and runs on a Pentium 300 MHz Personal Computer in the Windows 98 platform.

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Tungsten Heavy Alloy（WHA）helicopter counterweights, made of tungsten alloy from Chinatungsten Online, are used in many engineering applications, where high inertia forces and tungsten alloy helicopter counterweights are required under limited space conditions. Parts made of fine Tungsten based powder by the method of sintered are therefore used as tungsten heavy alloy helicopter counterweight and tungsten alloy aircrafts ballast, vibration damping elements and tungsten heavy alloy helicopter counterweights for various applications in the automotive industry, in aerospace and sports equipment.

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Tungsten alloy has so many properties, such as high density, small volume so it is widely used in aircraft and the best material to make tungsten alloy aircraft ballast and tungsten heavy alloy helicopter counterweight. We offer semi-finished and finished tungsten alloy aircraft ballast and tungsten heavy alloy helicopter counterweight according to customers' drawings. If you get any enquiry about the tungsten alloy aircraft ballast and tungsten heavy alloy helicopter counterweight, please feel free to contact us at sales@chinatungsten.com or call: 0086 592 512 9696, 0086 592 512 9595.

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Tungsten Alloys (WHAs) are the best choice when designers in aerospace and defense industries require a material which combines high density, good mechanical strength and which is easily machined. WHAs counterweights are incorporated into the pitch control system of many propeller designs as a fail-safe device such as tungsten ballast to ensure that overspeeding is prevented. WHAs materials are frequently make into tungsten ballast. Tungsten ballast plays a significant role to make sure the center of gravity is precisely located, during the progress of space flight, tungsten ballast ensure that correct orbit entry is achieved.

Tungsten ballast offered by us is qualified, we can provide all kinds of tungsten ballast as your requirements, tungsten ballast is our leader products.

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Designers can now enjoy high density, excellent mechanical strength and easy machining of the material. The same material is used in space flight and national military industry. The tungste heavy alloy is the best choice to be used as counterweight. Compared with lead,tungsten has smaller volume,so tungsten's resistance in the water is smaller than lead,which will make the yacht move ahead more quickly. Tungsten alloy yachts counterweights vary in size and shape.

The high density of the tungsten heavy alloy make contribution to reduce the physical size of the module, make it easier to control the distribution of the weight, enhance the flexibility of the control mechanism.When large mass has to be confined into very small space in the yacht,tungsten alloy yachts counterweights become the best choice.Tungsten alloy yachts counterweights are non-toxic and environmentally friendly. They successfully replace the toxic products such as lead.And tungsten alloy yachts counterweights can keep their shape unchanged for a long time.We can provide all kinds of tungsten alloy yachts counterweights according to your requirements.

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The hyperbaric heavy alloy is called"3H" :high density,high strength and high hardness,so one of its important usages is as the counterweight. Such as mechanical balance weight,fly ball;The weight used in the drilling industry;Horologe pendulum bob;Shorkproof cutter arbor;Coungterweight used in the voyage and sailboats counterweight; gyroscope、aircraft counterweight used in the space flight and aviation,etc.

Floating ships such as yachts need counterweight to maintain their stability in the water.The tungsten alloy yachts counterweights are non-toxic and comply with environmental standard.They have very high proportion(>18g/cm3), small volume, so it has the advantage of high wind resistance, quickly sinking,it is the best succedaneum for lead and it is active demanded in the developed country such as the Europe.

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Tungsten alloy is ideal for shielding against X rays and gamma radiation. The very high density of tungsten shielding (more than 60% denser than lead) allows a reduction in the physical size of shielding components, without compromising their rigidity or the effectiveness of the shielding characteristics.

Tungsten heavy alloy shielding is used in applications such as collimator, nuclear shielding, beam stop, PET syringe shield, vial shield, isotope container, FDG container, multi leaf collimator etc.

Positron emission tomography  is one of the nuclear medicine techniques available for diagnosis. Whilst X-rays provide information on the structure of the body, PET shows the chemical function of a particular organism.  As the
travels through the patient’s body it emits gamma radiation which is detected by a gamma camera, from which the chemical activity within cells and organs can be seen. Any abnormal chemical activity may be a sign that tumours are present.

Radiotherapy destroys cancer by directing beams of radiation directly onto the tumour. The beams of radiation require a very fine focus to avoid harming the surrounding healthy tissue. This focus is achieved by using a multi-leaf collimator, consisting of two rows of very thin tungsten alloy plates, which can be configured to exactly match the dimensions of the tumour.

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Tungsten alloy is used as collimator shielding in the following applications:

Geologging
　
Geologging is an exploration technique used mainly in the oil and gas industries. It is also known as wireline logging and borehole logging. A gamma ray source is lowered into a borehole and the radiation penetrates the rock strata. This data can then be analysed to determine whether deposits of gas or oil are present. tungsten alloy is used to shield the radioactive source and to act as a collimator for the gamma beam.

Pipe-line inspectionGamma
　
radiation is used to inspect welds and to detect cracks in pipelines. A gamma source is mounted on a remote-controlled wheeled trolley (sometimes called a "pig") and travels inside the length of the pipe. A WOLFMET tungsten collimator is used to direct the radiation onto the target, whilst the radioactive source is housed inside tungsten shielding.

Homeland Security and Border Control
　
The penetrating power of radiation has also been put to use in the fight against terrorism. The Homeland Security industry has designed scanners that use gamma radiation to detect objects in cargo containers or airline baggage.
　
The radioactive sources are very strong and require WOLFMET tungsten shielding to protect security staff and members of the public from the radiation. A tungsten collimator is also required to direct the gamma radiation onto its target.
 

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Tungsten alloy is used as Industrial radiography shielding in the following applications:

Industrial radiography uses gamma radiation to detect structural faults in materials such as metal and concrete. As with pipe-line inspection, the equipment uses tungsten shielding, coupled with a tungsten collimator.

Thickness, density and level gauging Radioactive sources are used in industrial processes to measure thickness, density or levels of materials during production e.g. paper, plastic film, steel sheet or surface coatings. The material passes between a radioactive source, which is housed in tungsten alloy, and a detector. The strength of the detector signal is used to measure the thickness, density or level of the material.

The penetrating power of radiation has also been put to use in the fight against terrorism. The Homeland Security industry has designed scanners that use gamma radiation to detect objects in cargo containers or airline baggage.

The radioactive sources are very strong and require WOLFMET tungsten shielding to protect security staff and members of the public from the radiation. A tungsten collimator is also required to direct the gamma radiation onto its target.

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Staff preparing and injecting radiopharmaceuticals in hospitals may receive significant radiation doses to their hands. These doses may be high enough to warrant that they be classified as radiation workers. The influence of local shielding on finger doses has been investigated. Staff preparing radioactive liquids in a radionuclide dispensary and drawing up and injecting radiopharmaceuticals in a nuclear medicine department have been studied.

The Tungsten Alloy Syringe Shield magnetically docks with the ChinaTungsten Dispensing Pig. Designed to accept 3cc, 5cc and 10cc B-D syringes, it places the needle inside the vial septum when engaged. The body of the shield is constructed of solid tungsten 2.1cm thick for maximum shielding. The external calibration rod allows the precise volume to be withdrawn without a leaded glass viewing port, where high exposure levels cannot be adequately shielded. The system allows the plunger to be pulled back with a pair of forceps, allowing you to keep your exposure as low as reasonably achievable.

Product Description

High strength tungsten carbide
    
The daily operation bumps will not affect the shape of the pot and protection ability
    
Solid tungsten walls 2.25cm thick
    
Weighs only 15.6lbs.
    
The "T" handle on the cap allows the unit to be easily lifted out of traditional "ammo can" delivery cases.
    
The threaded top provides easy access to the 3 or 5 or 10cc syringe.
    
The use of the thermos style handle reduces hand exposure by permitting to be carried to the imaging suite without holding container sidewalls.
    
Prior to injection, the base unscrews, allowing the centre portion to be used as a syringe shield.
   

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