The average transmission is sensitive to the physical density of the multileaf collimator(MLC). Since in order to make it machinable the be pure tungsten with density of 19.3 g/cm3 will give erroneous results for the calculated transmission. Tungsten material is 90%–95% tungsten plus alloying elements and may vary in density within the range 17–18 g/cm3. In practice, short of dismantling tungsten alloy multi-leaf collimator the tungsten alloy density can be determined for a particular tungsten alloy multi-leaf collimator by matching the calculated direct transmission to the measured direct transmission. Thus, the density becomes the only free parameter in the calculation. To match the measured direct transmission of 1.48% required an assumed tungsten alloy multi-leaf collimator physical density of 17.7 g/cm3. With the density and transmission values for tungsten alloy multi-leaf collimator suggests that variations in the average material density, and consequently the transmission, could be significant among individual tungsten alloy multi-leaf collimators.

  Tungsten Alloy Manufacturer & Supplier: Chinatungsten Online- http://www.tungsten-alloy.com
  Tel.: 86 592 5129696; Fax: 86 592 5129797
  Email:  sales@chinatungsten.com
  Tungsten & Molybdenum Information Bank: http://i.chinatungsten.com
  Tungsten News & Tungsten Prices, 3G Version: http://3g.chinatungsten.com
  Molybdenum News & Molybdenum Price: http://news.molybdenum.com.cn

In order to target radiation precisely to the diseased tissue, it is necessary to use tungsten alloy multi-leaf collimators.

First of all, X-ray images are produced to determine the precise position and outline of the tumor.An electric motor moves each individual tungsten alloy leaf in the collimator to the correct position – with up to 120 tungsten alloy leaves being used to shape the outline of the tumor with millimeter accuracy. Then, the tumor is exposed to high energy radiation. During this process, the tumor is radiated by turning the gantry with tungsten alloy multi-leaf collimator 360°around the patient. To protect the surrounding healthy tissue, a highly precise tungsten alloy multi-leaf collimator is necessary. Thus, the more tungsten alloy leaves means the highly precise of multi-leaf collimator.

  Tungsten Alloy Manufacturer & Supplier: Chinatungsten Online- http://www.tungsten-alloy.com
  Tel.: 86 592 5129696; Fax: 86 592 5129797
  Email:  sales@chinatungsten.com
  Tungsten & Molybdenum Information Bank: http://i.chinatungsten.com
  Tungsten News & Tungsten Prices, 3G Version: http://3g.chinatungsten.com
  Molybdenum News & Molybdenum Price: http://news.molybdenum.com.cn
 

One of the complications in calculating the overall transmission of the leaf bank is in accurately accounting for the complex leaf shape. The individual tungsten alloy leaves have a projected nominal width of 1 cm at isocenter 100 cm" and a physical thickness of 6.13 cm at their thickest point. The tungsten alloy leaves of the multiLeaf collimator(MLC) are single focused, i.e., the sides are shaped to converge at the source but each tip is rounded in the vertical direction in order to present an approximately constant penumbra at the isocenter plane. The radius of curvature at the center of the tungsten alloy leaf profile is 8 cm. The remainder of the tip profile is defined by two lines, each being tangent to the circular arc and at an 11.3°angle to the vertical.

  Tungsten Alloy Manufacturer & Supplier: Chinatungsten Online- http://www.tungsten-alloy.com
  Tel.: 86 592 5129696; Fax: 86 592 5129797
  Email:  sales@chinatungsten.com
  Tungsten & Molybdenum Information Bank: http://i.chinatungsten.com
  Tungsten News & Tungsten Prices, 3G Version: http://3g.chinatungsten.com
  Molybdenum News & Molybdenum Price: http://news.molybdenum.com.cn

Process of tungsten carbide cutting tools abrasive wear in detail can be devided into the following steps: a surface layer bonded tungsten carbide cuttingtools with mobile; increase grain plastic strain;; plastic deformation fracture binder phase single grain; grain between fracture; grain pull out from the base.

Under different experimental conditions, the degree of tungsten carbide cutting tools abrasive wear appears different. For example, tungsten carbide cutting tools in a smaller case load is much less abrasive wear than that in the case of large pressure.



In the initial phase of tungsten carbide cutting tools abrasive wear, the binder phase material contacts the inner surface of a certain depth range of Co plastic deformation and micro-abrasion in the role of friction surface Co is out from between the WC grains. With the loss of Co binder phase, surface damage the integrity of  tungsten carbide cutting tools, WC skeleton becomes unstable, cracks between the WC grains, so that part of the particles start to pull out from the surface of the substrate. When the friction surface is extruded and Co and WC particles reach a certain number, abrasion enter a relatively balanced steady-state level. In this case, loss of WC particles begin to appear in the form of abrasive grains, laminated in the outside world, the formation of tungsten carbide cutting tools abrasive wear.

Tungsten Carbide Manufacturer & Supplier: Chinatungsten Online - http://www.tungsten-carbide.com.cn
Tel.: 86 592 5129696; Fax: 86 592 5129797; Email: sales@chinatungsten.com
Tungsten & Molybdenum Information Bank: http://i.chinatungsten.com
Tungsten News & Tungsten Prices, 3G Version: http://3g.chinatungsten.com
Molybdenum News & Molybdenum Price: http://news.molybdenum.com.cn