Fluke Biomedical 57-411 - Manual (Page 10)

Nuclear Associates
Operators Manual
1-6
1.7 1” Wedge Filter (Model 57-431)
The 1" wedge filter is used to prevent "burn out" or overexposure where parts of the body vary in
thickness over a short distance. It is appropriate when radiographing the breast in a tangential direction
(for example, when locating radioactive therapy "seeds").
Two such filters, with their thin edges placed together or at a slight separation, form a trough whose
spacing is adjustable. This positioning is particularly useful for angiography of the limbs, where
overexposure would make details near peripheral edges of the limb difficult to see.
1.8 2” Wedge (Decubitus) Filter (Model 57-432)
This filter is ideal for preventing over-exposure to the upper portion of the colon during double contrast
(Barium and Air) studies when the patient is in the Lateral Decubitus Position. With the patient lying on
one side, the viscera tend to drop, so that the upper side of the body has less attenuation to x-rays. The
decubitus filter is placed on the holder rails horizontally, with its thicker (more attenuating) side up, so that
it attenuates approximately the upper half of the field of view. Placement is facilitated by using the
collimator light.
A pair of these filters, with their thin edges (low attenuating edges) together or nearly together, forms a
trough filter that may be used for angiography of the head and neck. This makes the peripheral regions of
the subject more easily visible. In an emergency, 2” wedge filters can also be used for angiography of the
limbs when 1” wedges are not available.
1.9 3” Wedge Filter (Model 57-433)
The first two-thirds of this filter may be considered as a thinner or less attenuating decubitus filter.
Therefore it is useful for the decubitus view on children or adults who are particularly thin or small.
When used in pairs (as a trough) the 3” wedges are particularly suited for most films of the abdominal
region. This makes the peripheral parts more visible than in a non-filtered view. An I.V.P. film will benefit
in the same way.
1.10 Long-Leg Filter (Model 57-435)
This filter is intended for use with ceiling-mount x-ray generators. It is used in radiographing the whole leg,
from the ankle up to and including the lower abdomen. Such films, used in orthopedics as well as in
angiography, would otherwise require dividing the view into several sections. Each section would be
exposed with a technique appropriate to the thickness of that section of the leg.
The filter is mounted at the bottom of the beam-defining cone so that the thickest part of the filter covers
the lowest part of the foot and leg. The thinnest part reaches approximately 3/5 of the way up,
approximately half way up the thigh. Ceiling-mounted generators do not have a collimator light, and the
size of the x-ray beam can be located with a fluorescent target (e.g., Nuclear Associates' Beam-Size
Ruler, Model 07-606). Since these x-ray generators are usually used only for long-leg radiography,
permanent mounting of the filter on the cone is practical, and either a long (36”) cassette or two 14” x 17"
cassettes may be used.