(1) Standing behind a protective barrier. Always remain behind a protective
barrier when making an exposure. Control booths are designed so that the specialist
will not be exposed to any radiation that has scattered only once. In other words, the
radiation must scatter at least twice before it reaches you. Use the lead impregnated
glass window to observe the patient. Do not defeat the purpose of the control booth by
leaning out from behind the barrier to make the exposure.
(2) Using distance for protection. Distance is an effective means to reduce
exposure. Since radiation intensity decreases as the distance from the source
increases, exposure can be reduced by staying as far from the source as possible. This
rule is particularly important to remember when taking portable radiographs where
protective barriers are usually not available.
(3) Protection during fluoroscopy. During fluoroscopy, be sure to wear a
protective apron. When you are not needed to assist the radiologist, remain in the
4-35. PROTECTION FOR THE PATIENT
As previously mentioned, any radiation protection program must include patients.
There are several ways to reduce radiation exposure to the patient.
a. Avoid Repeat Films. A common cause of additional patient exposure is to
repeat films. When a film is repeated because of improper processing, positioning,
technique selection, or other technical reasons, the patient and you are both subjected
to twice the original exposure. Therefore, getting a diagnostic radiograph on the first
attempt helps considerably in avoiding damage.
b. Collimation. A major cause of excessive patient exposure is failure to
adequately restrict the primary beam. Always limit the primary beam to the- smallest
size necessary to include the part or parts being x-rayed. Primary radiation should not
cover any areas beyond the borders of the film. In other words, if you are using a 14" X
17" film, the beam should never be greater than 14" X 17." There are times when it is
advisable to restrict the primary beam to a size smaller than the size of the film. Some
examples are sinuses, spot films, and other examinations where a restricted beam will
not interfere with the diagnostic information. (An added "bonus" of restricting the
primary beam to the smallest practical size is the reduction of SR, and consequently
less fogging of the film).
c. Filtration. In most instances, soft or low energy x-rays that exit from the tube
serve no useful purpose in diagnostic radiology. They have little or no penetrating
power and consequently are absorbed by the patient1s skin. To protect the patient from
this type of radiation, filters must be added to the useful beam. According to U.S. Army
TB MED 521, total filtration in the useful beam shall not be less than 2.5 mm of
aluminum or its equivalent for voltages greater than 70 kVp. For voltages between 50
and 70 kVp, a minimum of 1.5 mm of aluminum or its equivalent is required. Below 50