to-end with their adjacent edges overlapping) or by the use of a special 36-inch cassette
adjusted underneath the part. When full-length coverage is required, it may be
necessary to increase the normal SID to accommodate the area of interest to the
exposing x-ray beam. To equalize the exposure between the thinner region of the leg
and the thicker region of the thigh, the x-ray tube should be positioned with the cathode
end toward the thigh. The use of a compensating filter should also be considered.
(b) The patient is assisted onto the x-ray table, and the lower extremity
under consideration is adjusted to the AP position. A 14- x 17-inch cassette is placed
beneath the extremity and centered to the region to be examined if nongrid technique is
used. With grid technique, the cassette is placed in a Bucky tray and the part or area
under consideration is aligned to the midline of the x-ray table.
(a) After the administration of local anesthesia, the examiner inserts
the catheter into the lumen of the common femoral artery just distal to the inguinal
(b) An automatic injector is loaded with 60 cc of the contrast solution.
The examiner gives the "Ready," signal and then rapidly injects the contrast solution. At
the same time, the examiner (or an assistant) applies manual or mechanical pressure
on the femoral artery proximal to the injection site.
(c) Additional exposures are made according to the examiner's
instructions; for example, lateral or oblique. When it is undesirable to change the
position of the patient, it may be necessary to use an extra machine, such as a mobile
unit, for the lateral projections with the use of a horizontal CR.
(4) Radiographic exposure factors. The kVp is usually increased 10 percent
over other exposures of the same part and the mA adjusted to hold density constant.
(1) Preparation. Patient preparation and administration of sensitivity test
have been covered earlier. Digital subtraction is used to demonstrate any part of the
(a) As soon as the patient is received at the x-ray clinic, the specialist
will ascertain from the examiner the area(s) of the extremity to be examined.