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HOW
DOES THE PHARAOH FUNCTION ?
Due
to the many curves around the head and neck, the diaphragms
alwayslet through unabsorbed radiation, which overloads the
image and deteriorate subtraction. Shaping the beam especially
during ratation is almost impossible. Instead, the PHARAOH,
as a bolus, shapes the anatomy into cylinders allowing regular
coning without halation.
The COLLAR of the PHARAOH and its BONNET permit views of the
aortic arch,the carotid and the vertebral arteries without
halation, even during rotation.The LARGE MASK reshapes the
forehead without completely covering the eyes .
The SMALL MASK “LOUP” reshapes less but is more acceptable.
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WHY
THE PIVOTING SHIELDS ?
During
ROTATING examinations, they automatically adjust the width
of the field between the
PA (16 cm) and the LATERAL (22 cm). In addition, they shield
around the forehead and into the orbits in profile and oblique
views.
What are the ADVANTAGES of combining a MASK
and the PIVOTING SHIELDS ?
By
superposing their margins, they reduce the possibility of
letting through
unfiltered radiation at the margin of the skull, allowing
inclusion of the most peripheral arterial and venous trees
of the brain, even during rotation.
IS THE SMALL MASK SUFFICIENT ?
Yes,
in many situations. In addition, the EYE MASK ("L0UP" in French),
is more
acceptable to patients than the large one.
WHEN IS THE LARGE MASK PREFERRED TO THE SMALL
ONE ?
In
some cases where the small mask fits poorly and when no risks
of halation are acceptable.
WHAT OTHER IMPORTANT ROLE HAVE THE MASKS ?
They
insure powerful immobilization of the head, so important during
rotating examinations.
HOW CAN THE MASKS BE MADE MORE ACCEPTABLE TO
PATIENTS ?
It
must be realized that masks are only needed at the very end
of an
examination and only for a few minutes during visualization
of the middle and anterior cerebral arteries. When patients
are well informed and when they try on the mask(s) beforehand,
they will usually cooperate.
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HALATION
? MOTION ?
