MAJOR COMPONENTS OF X-RAY

GENERATING UNITS

Prepared by:-

EN KAMARUL AMIN BIN ABDULLAH

XRAY HISTORY

Wilhelm Conrad Röntgen - First X-ray

On 8 Nov, 1895, Wilhelm Conrad Röntgen (accidentally) discoveredan image cast from his cathode ray generator, projected far beyondthe possible range of the cathode rays (now known as an electronbeam). Further investigation showed that the rays were generated atthe point of contact of the cathode ray beam on the interior of thevacuum tube, that they were not deflected by magnetic fields, andthey penetrated many kinds of matter.

A week after his discovery, Rontgen took an X-ray photograph ofhis wife's hand which clearly revealed her wedding ring and herbones. The photograph electrified the general public and arousedgreat scientific interest in the new form of radiation. Röntgen namedthe new form of radiation X-radiation (X standing for "Unknown").Hence the term X-rays (also referred as Röntgen rays, though thisterm is unusual outside of Germany).

CONTENTS

1.0 X-RAY TUBE

2.0 CONTROL PANEL (OPERATION CONSOLE)

3.0 X-RAY COUCH

4.0 TUBE STAND

5.0 BUCKY

OBJECTIVES

Describe what x-ray tube is.

Identify the parameter selectors on control panel and

their functions.

Discuss the characteristics of x-ray couch.

Describe the types of tube stand.

Describe briefly the principle of Bucky.

METHODOLOGY OF PRODUCING A

RADIOGRAPH

Patient positioned in relation to exam being undertaken.

Radiographic equipment (i.e. X-ray tube) positioned.

Exposure set on control panel.

Instructions given to patient.

Radiographer stands behind lead glass screen.

Exposure undertaken.

Cassette processed.

Radiograph reviewed.

Figure A: The X-ray Room

1.0 X-RAY TUBE

Attached to a tube support.

Produces X-rays (& Heat).

Operated at high voltage (40 - 150 kVp).

Insulation required.

Oil used to cool X-ray tube during exposures.

Oil also acts as an insulator.

X-ray tube lead lined.

Incorporate safety interlocks.

Light Beam Diaphragm.

Integrated Collimation.

Equipment Earthed (Shockproof).

Figure 1.1: The x-ray tube.

Figure 1.2: The x-ray tube with diagram.

X-ray tube encased

within LEAD lined

case.

2.0 CONTROL PANEL (OPERATION

CONSOLE)

THREE primary control

a) kVp – quality

b) mA

c) Time

Auxiliary control (anatomical programs @ AEC control)

quantity

Figure 2.1: The picture shows the control panel used at UiTM

PJ.

mA

selector

Exposure

Switch

Anatomical

Part

Selector

Main

Power

AEC

Bucky

Selector

Focal Spot

Selector

kVp

Selector

Timer

Selector

Figure 2.2: Control Panel

(Somasundaram, 2009)

Figure 2.3: Control Panel

(Medilux, 2010)

2.1 kV, mA and Timer(s) selectors

kVp(KiloVoltagePeak)

The energy (the penetrating power) of the x-ray beam is

controlled by the voltage adjustment.

It is labelled in keV (thousand electron volts) and

sometimes the level is referred to as kVp (kilovoltage

potential).

The higher the voltage setting, the more energetic will be

the beam of x-ray.

It plays major part in affecting contrast of image.

mA (MiliAmperage)

The second control of the output of the x-ray tube is

called the mA (milliamperage) control.

This control determines how much current is allowed to

flow through the filament which is the cathode side of the

tube.

The effect of the mA circuit is quite linear.

It is more concerned in density aspect of the image.

Timer (s)

Control length of time machine produces x rays

This is usually denoted as an "S" (exposure time in

seconds) and is combined with the mA control.

e.g using 10 milliampere seconds you could use a 10 mA

current with a 1.0 second exposure or a 20 mA current

for a 0.5 second exposure or any combination of the two

which would result in the number 10.

Both of these factors and their combination affect the

film in a linear way.

2.2 AEC (Automatic Exposure Chamber)

Variable densities exist within

subjects.

AEC’s monitor the beam

of X-rays transmitted from the

patient.

Production of X-ray radiation can

be measured.

Located under patient but above

cassette.

Minimizes inaccurate exposures.

Figure 2.4: Automatic Exposure

Chamber – Ionization Chamber.

Exposure terminates once a sufficient quantity of radiation has been received to produce a radiographic image of required density.

Permit accurate exposures

Usually three AED’s incorporated in table tops and vertical chest stands.

Markings usually on surface of table/chest stand.

Individual chambers may be selected – depending on the exam being performed.

Figure 2.5: The position of the chambers.

3.0 X-ray Couch

Figure 3.1: The picture shows the x-ray

table/couch available at UiTM PJ.

3.1 Characteristics of X-ray Couch

Strong enough to support large patients.

Low attenuation materials (Carbon Fibre).

Rise and fall facilities.

“Kick” buttons.

Integrated “Bucky” tray

Insulated.

Easy to clean – Cross infection

Pressure switches.

Figure 3.2: X-ray Couch

4.0 TUBE STAND

Figure 4.1: Ceiling Mounted X-ray

Tube

Figure 4.2: Floor Mounted X-

ray Tube

4.1 Ceiling Mounted

Advantages

Flexibility

Ease of use and Durable

Safety features/interlocks

Specifications of modern X-ray tube

Integral features

Wide range of movements

Disadvantages

Expensive

Interlock – too sensitive

4.2 Floor Mounted

Advantages

Inexpensive.

Can be used with

upright Bucky.

Require less space.

Disadvantages

Less flexible.

Not user friendly

for complicated

cases.

5.0 BUCKY

Figure 5.1: Table Bucky Figure 5.2: Erect Bucky

• It actually acts as cassette holder.

Characteristics of Bucky

Integrated within table top.

Lock mechanism ensures cassette is secure.

Grid mechanism incorporated within cassette tray.

Grid reduces scatter radiation from certain examinations

– Abdomen

– Pelvis

– Hips

Important that X-ray

tube and cassette tray

are aligned

Set distance between X-

ray tube and Cassette

tray

Oscillating movement

ensures scatter is

absorbed before reaching

filmFigure 5.3: The x-ray tube and bucky.

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