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Grid Construction: The
prime purpose of a grid being the absorption of stray radiation, lead
strips (the material which is most practical in the absorption of
x-rays) are its basic component. The strips -- five hundred or two
thousands or more of them -- are set on edge, properly angled to a mean
focal distance and separated by x-ray transparent interspacers. The
whole is bonded together into a single flat structure, suitably covered
for strength, durability and protection against moisture.
Significance of Grid Ratio: The ratio of a grid is
defined as the relation of the height of the lead strips to the distance
between them. Thus with interspacers 5 times as high as they are wide, a
grid is said to be 5:1 ratio, etc. Generally speaking, the higher the
ratio of a grid, the more scattered radiation is absorbed (see Diagram).
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As grid ratio increases, the necessity of having the
focused grid exactly centered and perfectly level under the x-ray tube
becomes more and more important. Also, it becomes more necessary to use
the grid as its focal distance from the tube, instead of being able to
use it through a range of distances. For example, the 40" focal
distance, 12:1 ratio grid must be used at 40" for satisfactory results,
and must be perfectly centered and leveled.
The 5:1 ratio focused grid, on the other hand, will give satisfactory
results over a wide range of focal distances, and need not to be as
accurately centered or leveled. Of course the 5:1 ratio linear grid will
not have nearly the effectiveness of secondary removal that the 12:1
has, but in some cases this may be willingly sacrificed to gain the
latitude and ease-of-use of the low ratio grid. However, a 5:1 crossed
grid will produce as good a secondary removal as 12:1 grid at low
kilo-voltages, while retaining the latitude of the 5:1 ratio.
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Simply call 888-459-9729 to request your pricing.
E-Mail your request to:
jzimaging@sbcglobal.net.
Fax your request to: Your purchase order or
Download our Quote Request form
(type right in the PDF
file or write in it), print it and then fax it to 440-942-1388
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