X-ray Principles & Physics
Laboratory
Russell L. Wilson , CRT, RT(R)
Properties of X-ray
• X-rays travel in a straight line and diverge
from their point of origin.
• X-ray photons have many different
energies.
• X-rays are highly penetrating.
• X-rays are invisible.
• X-rays travel at the speed of light.
Properties of X-ray
• X-rays produce scatter radiation when
they enter-act with matter.
• X-rays affect radiographic and
photographic film.
• X-rays cause fluorescence of some
materials.
• X-rays cause biologic damage.
Properties of X-ray
• X-rays respond according to the inverse
square law.
X-ray Protection
• Because x-rays cause biologic damage,
the operator of the machine and the
patient must be protected from the
radiation.
• Lead is used to absorb radiation.
X-ray Hazards
• In the early days of
radiography, the
patient often was
burned by the
radiation.
• With proper operation
of equipment, x-rays
are relatively safe
today.
X-ray Injuries Still Occur
• These are serial
photographs on a
patient that had
multiple long
fluoroscopic
examination.
• Last image is after
skin graphs.
Patient Radiation Protection
• Later in the quarter, we will covers
methods used to keep the exposure to the
patient as low as possible.
• Keeping the exposure low is the
responsibility of the operator of the x-ray
machine.
X-ray Hazards
• With early x-ray
machine, there was a
real possibility of
electrocution.
• Today with proper
safety precautions,
radiography is very
safe for the operator.
X-ray Hazards
• X-ray was also very
hazardous for the
operator in those
early years.
• X-ray operators would
use their hands to
make sure the
machine was working
.
X-ray Hazards
• It was not uncommon
for both the operator
and patient to receive
burns.
• Today, with proper
precautions, x-ray is
safe for the operator.
The X-ray Room
• The radiographic
equipment consists
of:
– The Tube Stand,
Tube & Collimator
– Grid Holder or
Bucky
– Controls in the
Control Booth.
The X-ray Room
• The wall of the
x-ray room and
door are
shielded with
lead to protect
the operator and
staff.
Operator X-ray Protection
• The Door to the
X-ray Room
contains lead.
• It must be closed
during
exposures.
Operator X-ray Protection
• The wall of the
control booth is
leaded. Stand
completely
behind the wall
during
exposures.
Operator X-ray Protection
• Observe the
patient or
experiment
through the lead
glass window.
No peeking
around the wall!
X-ray Tube
• X-rays are
produced inside
the x-ray tube.
• Many properties
of light and x-ray
are the same.
Modern X-ray Tube
• This is a modern
rotating anode
general
• radiographic x-ray
tube.
• The leaded glass
holds the vacuum in
the tube.
• Anode rotated to cool
tube.
X-ray Collimator
• Using light in the
collimator, lead
shutters are
moved to restrict
the area of
exposure.
X-ray Collimator
• Collimation is our
best tool for
reducing
radiation
exposure to the
patient.
Observations
• 1. Did the light field match the x-ray
beam? Yes
• 2. What principle did this demonstrate?
X-ray s travel in a straight line line and
diverge from the point of origin. X-rays
have similar properties to light.
Observations
• 3. Did the intensity of the fluorescence of
the screen change when the kVp was
increased? Yes
• 4. Would this indicate that the intensity of
the beam changed? Yes
• 5. During the exposure could you see
inside the phantom? Yes
Observations
• 6. What property of x-ray did this
demonstrate? X-rays are highly
penetrating.
• 7.After the tone from the control
terminated, did the screen continue to
fluoresce? No
• 8.If the screen did not fluoresce, was there
any radiation coming from the tube after
the tone stopped? No
Observations
• 9. Did you hear any noise coming from the
tube after the tone stopped? Yes the rotor
continued to rotate.
• 10. What did you see on the film that was
sitting near the phantom? A blurry image.
• 11. What principle did this demonstrate?
X-rays produce scatter radiation.
Scatter radiation is not divergent.
The End
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