4

Metal filters, usually aluminum or copper, are inserted
into the x-ray tube housing so that low-energy x-rays
are absorbed before they reach the patient. These x-rays
have little diagnostic value.

restricts the useful x-ray beam to that part
of the body to be imaged and thereby spares adjacent tissue from unnecessary radiation exposure. also reduces scatter radiation and
thus improves image contrast.

reduce exposure of the patient to x-rays
by more than 95% compared with examinations conducted without radiographic _

Lead-impregnated material is used to make aprons and
gloves worn by radiologists and radiologic technologists
during fluoroscopy and some radiographic procedures.

should be used with all persons of childbearing
age when the gonads are in or near the useful x-ray
beam and when use of such shielding will not interfere
with the diagnostic value of the examination.

lead lined and is equipped with a leaded-glass window. Under
normal circumstances, personnel remain behind the
it during x-ray examination.

3 measurable basic quantities in physics

One meter is now defined as the
distance traveled by light in

was originally defined to be the mass of
1000 cm3 of water at 4° Celsius (°C)

units of weight

is based on the vibration of
atoms of cesium.

Every measurement has two parts:

a segment of physics that deals with objects
at rest (statics) and objects in motion (dynamics

motion of an object can be described with the use
of two terms:

is a measure of how fast something
is moving or, more precisely, the rate of change of its
position with time

velocity of light is constant and is
symbolized by

The rate of change of velocity with time

first law - A body will remain
at rest or will continue to move with constant
velocity in a straight line unless acted on by an
external force.

The property of
matter that acts to resist a change in its state of motion
is called

second law - The force (F) that
acts on an object is equal to the mass (m) of the
object multiplied by the acceleration (a)
produced.

third law - For every
action, there is an equal and opposite reaction.

it is newton's word for force