Transcript El Camino College

RAD TECH A
WEEK 2
RADIOGRAPHIC
EQUIPMENT
Fall 2007
Radiographic Room
OBJECTIVES
• IDENTIFY GENERIC COMPONENTS
OF THE RADIOGRAPHIC
EQUIPTMENT
• DESCRIBE VARIOUS PLANES OF
X-RAY TUBE AND TABLE
MOVEMENT
• DISCUSS CONTRAST & DENSITY
“ EXPOSURE FACTORS”
X-RAY TUBE
• MADE OF PYREX GLASS TO
WITHSTAND HIGH HEAT LOAD
• IS GAS EVACUATED
– (so electrons won’t collide with the air
molecules in the tube)
XRAY TUBE HOUSING
• MADE OF LEAD AND STEEL
• TO ABOSRB ANY STRAY RADIATION
• TO PREVENT X-RAY PHOTONS TO
LEAK FROM THE TUBE
TUBE HOUSING
MADE OF LEAD & STEEL
THE X-RAY TUBE
• Glass encased in a
sturdy lead and steel
housing
• Primary components
ANODE (+)
&
CATHODE (-)
\
X-Ray Machine
• Purpose:
– provide a specific current (mA) & voltage
(kV) to the x-ray tube
– convert electrical energy to electromagnetic
energy (x rays) in a controlled manner
• control the energy of the x-ray photons
• control the number of photons
kVp
& mAs
Early X-ray Tube
THE X-RAY TUBE
• The X-Ray tube is
the single most
important component
of the radiographic
system. It is the part
that produces the Xrays
How Are X-rays Made?
• X-rays are produced
when electrons strike
a metal target.
• The electrons are
released from the
heated filament and
accelerated by a high
voltage towards the
metal target.
• The X-rays are
produced when the
electrons collide with
the atoms (electrons)
of the metal target.
X-ray PHOTONS
• Electromagnetic waves
• Shorter wavelength and
higher energy than
normal light.
• Wave-particle duality
– Photons can be described
both as waves and
particles.
The Electromagnetic Spectrum
• X-rays have wavelengths much shorter than
visible light, but longer than high energy gamma
rays
MEASURED IN ANGSTROM 0.1 – 0.5 FOR X-RAYS
PRODUCTION OF X RAYS
Requirements:
– a source of fast moving electrons
– must be a sudden stop of the electrons’
motion
– in stopping the electron motion, kinetic
energy (KE) is converted to EMS energies
• Infrared (heat), light & x-ray energies
How “X-rays” are created
• Power is sent to x-ray tube via cables
• mA (milliamperage) is sent to filament on
cathode side.
• Filament heats up – electrons “boil off
– Thermionic emission
• Negative charge
How “X-rays” are created
• Positive voltage (kVp) is applied to ANODE
• Negative electrons = attracted across the tube to
the positive ANODE.
• Electrons “slam into” anode – suddenly
stopped.
• X-RAY PHOTONS ARE CREATED
How “X-rays” are created
• Electron beam is focused from the cathode
to the anode target by the focusing cup
• Electrons interact with the electrons on the
tungsten atoms of target material
• PHOTONS sent through the window PORT –
towards the patient
How “X-rays” are created
SEE:
MAN MADE RADIATION (PG.93)
TO PRODUCE X-RAYS
YOU NEED:
• A SOURCE OF ELECTRONS
• A FORCE TO MOVE THEM QUICKLY
• SOMETHING TO STOP THEM SUDDENLY
X-ray Production
e- e- etarget
e-
e- e- e- e- e- e- e- e- e- e- e- e- e- eeee-eee- e- e- e-e- e- e- e- e- e- e- e- e-e- e- e- e-
anode
electrons
• Electrons move at high speed (KE)
• Collide with target on anode
• KE of electrons converted to x rays & heat
Focusing Cup
focuses stream of electrons
• HIGH VOLTAGE
TO ANODE –
ATTRACTS –
ELECTRONS
FROM CATHODE
• CURRENT TO
STATOR CAUSES
ROTATION OF
ANODE
Anodes - Target
Rotating Anodes
• 2” to 5” disk (focal track)
Cu
W
Molybdenum or
Graphite base
•Common target material is Tungsten
X-ray Tube Anode




Tungsten anode disk
Stator and rotor make up
the induction motor
Rotation speeds
 Low: 3,000 – 3,600
rpm
 High: 9,000 – 10,000
rpm
Molybdenum stem (poor
heat conductor) connects
rotor with anode to
reduce heat transfer to
rotor bearings
Focal
track area
(spreads heat out
over larger area than
stationary anode
configuration)
Rotating Anode
TABLE OR UPRIGHT
BUCKY TRAY
The ‘BUCKY’
• The bucky is the
device in the table or
chest board that
holds the film
cassette. The
‘bucky’ is like a
drawer that opens
and closes to insert
and remove the film
cassette.
Tables
• Tilting rooms are designed for both
diagnostic and fluoroscopic work
– Tilting models usually tilt to 90 degrees in
one direction and 15 – 30 degrees in the
other direction
– Tilting models include ancillary equipment;
footboard, shoulder support, handgrips,
compression bands
Tube Supports
• Designed to help technologists with
various tube locations for creative imaging.
• Tube suspension systems are available in
5 versions:
– ceiling mounted, floor-to-ceiling, floor, mobile
and c-arm.
Tube
Movement
•
•
•
•
•
•
Longitudinal
Transverse
Vertical
Angling or Rolling
Rotating
Telescoping
Radiographic
grid & bucky tray
COLLIMATOR
• ATTACHES
DIRECTLY BELOW
THE X-RAY TUBE
• SERVES AS A X-RAY
BEAM LIMITING
DEVISE
• CONTROLS THE
SIZE AND SHAPE
OF X-RAY FIELD
Cone collimator
• ALWAYS KEEP
THE
COLLIMATED
AREA
SMALLER
THAN THE
SIZE OF THE
CASSETTE
RADIOGRAPH
• PERMANENT RECORD MADE USING
RADIATION
– RADIO-
RADIATION (usually x rays)
– GRAPH
PERMANENT RECORD
UNEXPOSED FILM PLACED IN A
CASSETTE
CASSETTE or FILM HOLDER
• The CASSETTE is
used to hold the film
during examinations.
It consist of front and
back intensifying
screens, and has a
lead (Pb) backing.
The cassette is light
tight
CONTROL CONSOLE
• GIVES THE
TECHNOLOGIST
CONTROL OF THE
X-RAY MACHINE
• TECHNIQUE
SELECTION
• Located OUTSIDE of
the Radiographic
Room
The Control Console
• The control console is
device that allows the
technologist to set
technical factors (mAs
& kVp) and to make
an exposure.
• Only a legally
licensed individual is
authorized to
energize the console.
“Technique”
kVp , mAs (mA x s)
• What is set at the control panel
• How the “image” is created on the
“film” or Image receptor (digital)
• kVp controls the “ENERGY” of the beam
• The Higher kVp – more penetrating
• Ranges is 50 -110 in Diagnostic x-ray
“Technique”
kVp , mAs (mA x s)
• mA- is the current in combination with the
time – determines HOW LONG the beam
will stay on
• Controls the density on the film/image
IMAGE CREATION
• ATOMS
• INTERACTION WITH “MATTER”
• ATOMIC NUMBER
Barium has a higher z#
more asorbtion of photons
Why you see what you see
• The films or images have different levels
of density – different shades of gray
• X-rays show different features of the body
in various shades of gray.
• The gray is darkest in those areas that do
not absorb X-rays well – and allow it to
pass through
• the images are lighter in dense areas (like
bones) that absorb more of the X-rays.
FLUOROSCOPY
IMAGES IN MOTION
FLUOROSCOPY
must wear shielding
while x-ray beam is on
REMOTE ROOM
&
OLD CONVENTIONAL FLUORO
MOBILE / PORTABLE UNITS
When patients cannot go the
the Radiology Deparment
The equipment is taken to their
room for imaging
What is in the Darkroom?
Safe Light
• 15 Watts
• Red filter
• Must be 3-6 feet
from counter top or
feed tray of
processor
• Used to be amber
or orange filter
Darkroom
CR
processor
• What does a digital
processor look like?
Other x-ray stuff….
• Positioning phantoms
• Pixie
Other x-ray stuff….
• Positioning sponges
• Lead markers
• Gurney
X-ray Tube Construction
A
C
B
D
E
Radiographic Equipment
G
F
X-ray Tube Construction
A. Glass housing (envelope)
B. Molybdenum neck of the anode
C. Stators /Electromagnets
D.Tungsten anode (focal spot)
E. Window or port for beam exit
F. Filament (cathode)
G. Focusing cup