(4) The resistive values of the preceding examples were approximate. Their
exact value would depend on many other factors such as area of contact, callous
formation, moisture of the hands, etc. The point you should remember is that a given
voltage may be harmless under certain conditions and kill under slightly different
(5) It has been determined that the amount of current determines the
severity of an electrical shock, and that for a given voltage, the current can be
decreased by increasing the resistance. Therefore, the voltage required to produce a
given amount of current depends on the resistance of the conducting pathway. For
example, a patient undergoing heart catheterization could be accidentally electrocuted
by 10 volts or less because catheters and wires bypass the skin resistance.
Proper grounding of equipment is the most effective way of reducing electrical
hazards. Proper grounding of portable electrical equipment can be achieved with
polarized three-prong plugs. Otherwise, portable equipment must be grounded in some
other way. Permanently installed equipment, such as the x-ray table, tube stand,
fluoroscopic apparatus, etc., are all connected to a common ground. The purpose of
the common ground is to ensure that there is no difference in potential between the
chassis of the various pieces of equipment.
a. Polarized plugs ensure proper grounding by the use of three prongs. The
third prong connects the casing of the equipment to ground, thus preventing the
possibility of a potential difference between the equipment and ground. Unfortunately,
removing the ground connector to fit the three-prong plug to a two-prong outlet too often
voids the safety features of the three-prong plug.
b. Another common blunder is to use an adapter to connect the three-prong plug
to a two-prong outlet without using the ground wire. If, for some reason, a three-prong
plug must be connected to a two-prong outlet, the ground wire of the adapter should be
connected to the center screw of the cover plate.
COMMON DANGER AREA
In order to function safely, the x-ray specialist must know some common danger
areas within an x-ray department and how he can contribute to preventing electrical
shock to himself, the patient, and to fellow workers.
a. Equipment should be inspected daily for frayed wires and loose connections.
If discrepancies are found, they are reported to the department supervisor immediately
so that he can initiate actions to have the equipment repaired.