RAD TECH A WEEK 2

RADIOGRAPHIC EQUIPMENT

Spring 2009

RADIOGRAPHIC EQUIPMENT

RTA Week 2

Ch. 8 & 9 - pg (110 & 111)

Radiographic Room

OBJECTIVES• IDENTIFY GENERIC

COMPONENTS OF THE RADIOGRAPHIC EQUIPTMENT

• DESCRIBE VARIOUS PLANES OF X-RAY TUBE AND TABLE MOVEMENT

A look inside the body

• X-rays are a form of electromagnetic energy. X-rays have high enough energy to penetrate the human body leaving different densities on the image below

• Dependant on the Z# of the material

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

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 X-rays

THE X-RAY TUBE

• GLASS ENCASED IN STURDY STEEL HOUSING

• PRIMARY COMPONENTS

ANODE +

&

CATHODE --

How “X-rays” are createdSEE: MAN MADE RADIATION (PG.93)

TO PRODUCE X-RAYS

YOU NEED:

• A SOUCE OF ELECTONS

• A FORCE TO MOVE THEM QUICKLY

• SOMETHING TO STOP THEM SUDDENLY

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 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.

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”

• Negative charge

Cathode

• Filament – Dual-filament

• Focusing cup

Tungsten

• Filaments are usually made of tungsten

• Tungsten provides higher thermionic emission than other metals

• Tungsten has a very high melting point

Filament

• When current (mA) is applied to the coil of wire electron are ejected

• The outer-shell electrons of the filament atom are “boiled off”.

– This is known as thermionic emission

Focusing cup

• The filament is embedded in a metal cup that has a negative charge

• Boiled off e- tend to spread out due to electrostatic repulsion. The focusing cup confines the e- cloud to a small area

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

Mechanical support for the target

Anodes - Target

Cu

W

•Common target material is Tungsten• Electrons interact with W – photons created

Molybdenum or Graphite base

Rotating Anodes• 2” to 5” disk (focal track)• Induction motor

• Speed 3000 to 10000 rpm

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X-ray Production

• electrons move at high speed (kV)

• collide with target on anode

• kV of electrons converted to x rays & heat

electronsanode

target

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

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TUBE HOUSINGMADE OF LEAD & STEEL

XRAY TUBE HOUSING

• MADE OF LEAD AND STEEL

• TO ABOSRB ANY STRAY RADIATION

• TO PREVENT X-RAY PHOTONS TO LEAK FROM THE TUBE

Early X-ray Tube

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)

Radiographic Equipment

X-ray Tube Construction

GF

ED

C

A

B

X-ray Tube Construction

A. GLASS HOUSING (ENVELOPE)

B. MOLYBDENUM NECK OF ANODE

C. STATORS /ELECTROMAGNETS

D.TUNGSTEN ANODE (FOCAL SPOT)

E. WINDOW OR PORT FOR BEAM EXIT

F. FILAMENT (CATHODE)

G. FOCUSING CUP

X-RAY TABLE

Radiographic tables

Are designed to support the patient during a radiographic exam

Comfort is not the primary concern Foam pads should be used if the

patient will be required to be on the table for longer than 10 minutes

Tabletop

Must be uniformly radiolucent to easily permit x-ray to pass through.

Carbon fiber is used because it is strong and very little x-ray photons are absorbed.

Usually tabletops are flat however some are curved

Tabletop

Most tabletops are floating, some are motor-driven

The brakes can be released usually by the technologist hand or foot

The brakes are electromagnetic Floating table tops save significant

amounts of time and strain on the technologist

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

FLUOROSCOPYIMAGES IN MOTION

REMOTE ROOM &

OLD CONVENTIONAL FLUORO

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

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.

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 (film)

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

Why you see what you see

• The films or images have different levels of denisty – 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.

IMAGES

• DENSITY = THE AMOUNT OF BLACKENING “DARKNESS” ON THE RADIOGRAPH - mAs controlled

• CONTRAST – THE DIFFERENCES BETWEEN THE BLACKS TO THE WHITES - kVp controlled

+ 30% + 50 % mas

kVp Changes

What is in the Darkroom?

Analog processor

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

Computerized Radiography CR processor

• What a digital processor looks like

• No darkroom required

CHEST X-RAY IS THE

MOST COMMONLY

PERFORMED

PROCEDUREAnalog or Digital

Other x-ray stuff….

• Positioning phantoms • Pixie

Other x-ray stuff….

• Positioning sponges

• Lead markers

• Gurney

RTA LAB 1 : EQUIPMENT

• Next week…..

• TOUR OF THE IONIZING LAB HERE ON CAMPUS.

• COMPLETE IN CLASS WORKSHEET FOR TERMINOLOGY