Week 1 Review

Week 2: Radiographic Equipment

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Game PlanIdentify generic components of the radiographic equipment

Describe various planes of x-ray tube and table movement

Discuss contrast and density Exposure Factors

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Generic Components of Radiographic SystemX-ray Tube

Collimator Assembly

Radiographic Table

Control Console

Tube support

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Radiographic Room

X-ray Tube Housing

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X-RAY Tube Housing

• Lead and steel

• Absorbs stray radiation

• Prevents x-ray photons from leaking from tube

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X-RAY Tube

• Made with Pyrex glass– Withstands HIGH

heat loads

• Gas Evacuated– so electrons won’t

collide with the air molecules in the tube

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Early X-RAY Tube

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The X-RAY Tube

• Lead and steel housing

• Pyrex glass encased in a housing

• Primary components

ANODE (+)

&

CATHODE (-)

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X-RAY Tube

• Most important component

of the radiographic system

• Produces the X-rays

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X-Ray Machine

• Purpose:– provide a specific current (mA) & voltage

(kVp) to the x-ray tube• kVp controls the energy of the x-ray

photons• mA controls the number of x-ray photons

– convert electrical energy to electromagnetic energy (x- ray photons)

TO PRODUCE X-RAYS YOU NEED

A SOURCE OF ELECTRONS

A FORCE TO MOVE THEM QUICKLY

SOMETHING TO STOP THEM SUDDENLY

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Source of Electrons

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Cathode

• Filament– Thoriated

tungsten

• Focusing cup (beam focus)

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Process of x-ray production on Cathode side (-)

• mA (milliamperage) is sent to filament– Via cables

• Filament heats up – electrons “boil off” (thermionic

emission)– focusing cup focuses electron

beam toward anode

• Electrons have negative charge

A force to move them quickly.Something to stop them suddenly

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Process of x-ray production on Anode side (+)

• Positive voltage (kVp) is applied

• Causes electrons to accelerate towards anode– Laws of attraction

• Electrons “slam into” target of anode – suddenly stopped.

• X-RAY PHOTONS ARE CREATED

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• High voltage to anode attracts electrons from cathode

• Current to stator causes rotation of anode

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Anodes - Target

Cu

W

•Common target (focal track)material is Tungsten

Molybdenum or Graphite base

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

Rotation speeds Low: 3,000 – 3,600 rpm High: 9,000 – 10,000 rpm

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X-ray Tube Anode

Stator and rotor make up the induction motor

Molybdenum stem connects rotor with anode reduces heat transfer to

rotor and bearings

Focal track area (spreads heat out over larger area than stationary anode configuration)

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Rotating Anode

Molybdenum stem and base usedbecause it is a poor heat conductor

Tungsten can withstand high heat loads

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How Are X-rays Made?

• Source of electrons

move at high speed (KE)

• Collide with target or focal track) on anode

• KE of electrons converted to x rays & heat

– 99% heat

– 1% x-ray photons

Collimator Knobs

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Collimator

• Attaches directly below the x-ray tube

• Serves as a beam limiting device

• Controls size and shape of the x-ray field

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Collimator Knobs

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Cone collimator

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Radiographic Table

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Tables• Tilting tables – diagnostic and

fluoroscopic work– 90 degrees in one

direction – 15 – 30 degrees in

the other direction– ancillary

equipment:• footboard,

shoulder support, handgrips, compression bands

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http://www.youtube.com/user/ARCOMAMED?blend=1&ob=5#p/a/u/2/C9fTjmQrfj8

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TABLE OR UPRIGHT BUCKY TRAY

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The ‘bucky’ is like a drawer

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Image Receptors and Bucky tray

Film

Image ReceptorsCassette Based

1) Film /screen (FS)

2) Computed Radiography (CR)

Cassette-less

1)Digital Radiography (DR)

Indirect CaptureDirect Capture

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Film Screen

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Darkroom for Film Screen Image receptors

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What is in the Darkroom?

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Safe Light

• 7-15 Watts

• Red filter

• Must be 3-6 feet from counter top or feed tray of processor

• Used to be amber or orange filter

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FILM SCREEN PROCESSOR

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CR- PSP plate

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CR Reader for Computed Radiography image receptors

Multiloader

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Digital Radiography: Direct Capture

Amorphous selenium

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Digital Radiography: Indirect Capture

Amorphous silicon

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• The bucky tray can be found:– In the table

or chest board

• Holds the cassettes– CR– Film

Screen

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60Bucky tray

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Bucky Tray

Image receptor is held in bucky

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FLUOROSCOPY: Images in motion

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REMOTE ROOM

Conventional Room

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FLUOROSCOPYmust wear shielding

while x-ray beam is on

Lead apron Lead Curtain

Tube SupportsDesigned to help technologists with various

tube locations for creative imaging.

Tube suspension systems are available in 5 versions

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Floor mounted & Overhead Suspension

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Floor to Wall or Ceiling

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Table Suspension

Telescoping Tube

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Tube Movement

• Longitudinal

• Transverse

• Vertical

• Angling or Rolling

• Rotating

• Telescoping

CONTROL CONSOLEGives the

technologist control of the xray machine

Technique selection

Located OUTSIDE of the Radiographic Room

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kVp & mAs

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The Control Console

• Set technical factors (mAs & kVp)

• Make an exposure

• Only a legally licensed individual is authorized to energize the console

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“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

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“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

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Ancillary EquipmentGrids

View boxes and viewing computers

Darkroom

Processors and Readers

Misc Equipment

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Grids• Body parts

10cm & more

• Lead strips parallel to centerline

• Absorbs scatter– Improves

detail

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Scatter adds a “foggy appearance

Makes image more gray

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Other x-ray equipment

• Positioning phantoms • Pixie

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Other x-ray equipement• Positioning sponges• Lead markers

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Positioning sponges

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Lead Shields

Gonad shields

Lead wrap arounds

Lead aprons

Lead Gloves and Glasses

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Are x-ray machines prisoner to one room???

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Mobile X-RAY equipment

• Portables– Take machine to

patient

– Still images

• C-arm– Used in

interventional procedures

– Used in surgery

– Dynamic images

– Fluoroscopy

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PORTABLE UNITS

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Trauma wrist done portable- using positioning devices

Lead apron

sponge

TAPE

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When patients cannot go the Radiology Department

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Review

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X-ray Tube Construction

GF

ED

C

A

B

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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

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TUBE HOUSING

What is it made of?

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Is this rotating or stationary anode?

What is required to produce x-rays?

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What is required to produce x-rays?

Requirements:

– a source of fast moving electrons

– sudden stop of the electrons’ motion (KE)

– kinetic energy (KE) is converted to EMS energies

• Heat

• x-ray photons