kVp, total filtration should be 0.5 mm of aluminum or its equivalent. This requirement
(0.5 mm) may be assumed to have been met if a conventional diagnostic tube is
employed since inherent filtration in conventional tubes is at least equivalent to 0.5 mm
of aluminum. If a beryllium window tube is employed, added filtration will be required.
d. High-kVp Technique. The absorbed radiation dose, and the biologically
significant dose to the patient, can be reduced by using the high-kVp technique.
Intelligent use of high-kVp technique produces excellent results, but the
x-ray specialist must be aware of its limitations. Obviously, when the maximum contrast
is required, as in mammography, high kVp cannot be used. In terms of radiation
protection, high kVp does not necessarily mean 100 to 150 kVp, but it should be
interpreted to mean the highest kVp that will produce a good quality radiograph of a
particular part.
e. Films and Screens. High-speed screens and films are available and their
use will certainly reduce the radiation exposure of the patient. Again, they must be
intelligently used. When the speed of a screen or film is increased, there is some loss
of detail. If the radiologist is willing to sacrifice some radiographic detail in order to
reduce exposure to the patient, by all means use high-speed screens and films. The
radiologist must make the decision, since he is the one who interprets the films.
f. Shielding. Appropriate and effective gonadal shielding should be utilized on
patients who have a reasonable reproductive potential when the gonads will be within
the useful beam or within 2 inches (5 cm) of the beam edge of an adjacent useful beam
despite proper beam limitation, unless such devices interfere with the conditions or
clinical objectives of the examination. Specific area gonad shielding should provide
attenuation of x-rays at least equivalent to that afforded by 0.25 mm of lead. In the case
of male patients, it is recommended that specific area testicular shielding be employed
for those examinations in which the pubic symphysis can be visualized on the film and
the clinical objectives will not be compromised by the use of specific area testicular
shielding. Specific area testicular shielding should always be used during those
examinations in which the testes usually are in the useful (primary) beam, such as
projections of the pelvis, hip, and upper femur. Specific area testicular shielding is also
warranted in projections of the abdomen, lumbar spine, and lumbosacral spine;
intravenous pylograms; and abdominal scout films for barium enemas and upper GI
series. In addition to the aforementioned instances in which shielding is indicated, when
children are being examined by x-ray, a special effort should be made to protect the
sternum, femurs, and the humeri, since most of the red blood cells are produced in the
marrow of these bones.
g. Pregnant Patients. The dangers of exposing pregnant women to ionizing
radiation, particularly during early pregnancy, have already been discussed. The
decision as to whether the diagnostic information to be gained outweighs the potential
radiation danger rests entirely with the patient's physician. In some cases such as
"prenatal" chest films and pelvimetry, diagnostic information may be considered
necessary. In other cases, it may be appropriate to delay the examination until later in
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