(2) Patient protection. It is the responsibility of the x-ray technician to use
all available protective measures to reduce exposure to the patient. Only those
radiographs requested by the dental officer will be taken. Be sure that a good quality
x-ray is produced each time a request is made. Wrong exposures, improper exposures,
and faulty processing techniques must be avoided. These mistakes result in retakes
and unnecessary patient exposure. Also, the lead apron must be used for every
Lead aprons are stored flat or hung unfolded. Do not fold or bend lead aprons
These safety devices significantly reduce patient exposure.
(3) ALARA. ALARA stands for "as low as reasonably achievable." It refers
to taking every reasonable effort to maintain exposures to radiation as far below
prevailing dose limits as practical.
1-11. X-RAY BEAM QUANTITY AND QUALITY
The quality of the x-ray beam is controlled by the voltage while the milliamperes
control the quantity. An increase in the voltage and milliamperes reduces exposure
time for the patient.
a. X-ray Beam Quality. The quality of the x-ray beam is controlled by the
amount of voltage. Voltage provides contrast to the film. The desired contrast appears
as various shades of gray, black, and white in the x-ray negative (radiograph).
Increased voltage provides less contrast (or more shades of gray). However, the beam
has more penetrating power. Decreased voltage, on the other hand, provides more
contrast (fewer shades of gray and more black and white shades). However, there is
less penetrating power in the low voltage exposure. The technique most commonly
used to expose periapical and bite-wing X-rays is a 75 kilovolt peak and 15
b. X-ray Beam Quantity. The x-ray beam quantity is controlled by the
milliamperes. The more x-rays (photons) in the x-ray beam, the more dense (dark) the
x-ray negative (radiograph) becomes. By increasing the milliamperes, we increase the
number of available electrons at the cathode filament. When electrical current (voltage)
is applied to the x-ray tube, the electrons cross the gap. When they impact on the
anode (tungsten target), a greater number of x-rays (photons) are also produced. The
more x-rays that are available to penetrate an object, the more dense (dark) is the x-ray