b. Standing Clear of the Primary Beam. Because of the difficulty involved in
positioning and immobilizing certain patients, you may be tempted to expedite an
examination by holding the patient or film holder with one hand while making the
exposure with the other. Do not engage in this practice! Use personnel who are not
occupationally exposed to radiation to assist you in holding the patient and film holder in
order to keep yourself clear of the primary beam. These assistants must wear lead
aprons and gloves and stay out of the primary beam.
c. Using the Inverse Square Law. Always stand as far as possible from the
tube and patient when making an exposure. By doing this, you will be taking advantage
of the inverse square law. For example, if you stand 6 feet from the tube, your
exposure would be about 25 percent of the amount you would receive standing 3 feet
from the tube.
d. Using Beam Restricting Devices. If the portable unit is equipped with a
collimating device, use it to restrict the primary beam to the size of the film. If no
collimator is available, use a cone, cylinder, or diaphragm to reduce the primary beam
to the film size. Restricting the primary beam is a protective aid. First, it reduces the
amount of SR (secondary radiation and scatter radiation) by reducing the exposed
areas that produce secondary radiation. In addition, it will reduce the primary radiation
exposure to the patient. Radiographic detail will also be enhanced because of the
reduction of film fog due to SR.
e. Wearing Protective Devices. The x-ray specialist should wear a lead apron
when making the exposure. When worn properly, the apron will shield a major portion
of the body from radiation. Ensure that personnel assisting you in holding the patient or
film holder are also protected with lead aprons and gloves. As mentioned before, use
only personnel not occupationally exposed to ionizing radiation. All others in the area
not essential to the examination should be asked to leave until after the examination is
f. Wearing the Film Badge. The importance of the film badge greatly
increases when the x-ray specialist is using portable equipment, because the radiation
hazard is increased. Be sure to wear it properly. The whole body film badge is worn
beneath the lead apron on the outside of the basic clothing and below the shoulder and
above the hips.
g. Rotating Personnel. When practical, it is advisable to rotate personnel
operating portable equipment so that no one x-ray specialist operates the unit
permanently or for extended periods. This policy is particularly important when a
number of portable equipment examinations are performed day after day.