UNITIII MEDICAL IMAGING SYSTEM Instrumentation for diagnostics Xray

UNIT-III : MEDICAL IMAGING SYSTEM • Instrumentation for diagnostics X-ray : X- ray basics properties, X-ray machine , Special imaging technique. • Ultrasonic imaging system: Physics of Ultrasound, Biological effect of ultrasound. Ultrasonic A-scan, M-scan, B-scan, Realtime ultrasonic imaging systems.

X-RAY

William Roentgen discovered X-rays A bit of History in 1895 & determined they had the following properties 1. Travel in straight lines 2. Are exponentially absorbed in matter with the exponent proportional to the mass of the absorbing material 3. Darken photographic plates 4. Make shadows of absorbing material on photosensitive paper • Roentgen was awarded the Nobel Prize in 1901

The first x-ray photograph: Roentgen’s wife Bertha’s hand

X-RAY • X-rays are electromagnetic radiation. • X-ray machine sends individual x-ray particles through the body. • Capablity to penetrate matter coupled with differential absorption oserved in various material • The images are recorded on a computer or film. • Ability to produce luminenescence and its effect on photographic emulsions

X-RAY • • • Medical diagnosis region have wavelength 10 -10 m Speed of propogation 3 x 108 m/sec SHORT WAVELENGTH Extremly high energy Absorption depends on density of matter Xray produce secondary radiation in all matter which they pass.

X-RAY MACHINE

PARTS OF X-RAY MACHINE 1. 2. 3. 4. X-ray tube Transformer Tube stand Control panel

Block Diagram of X-ray equipment Main supply k. V control Filament CKT including m. A control k. V indication m. A indication High Tension source Exposure timing and switching X- Ray Tube

BLOCK DIAGRAM KV METER EXPOSURE SWITCH HIGH TENSION SUPPLY RECTIFIER m. A TIMER meter KV SELECTOR m. A CONTROL VOLTAGE COMPANSATOR VOLT METER FILAMENT SUPPLY AND TEPERATURE CONTROL X-RAY TUBE

1. X-RAY TUBE

X-ray Tube

How “X-rays” are created ? Power is sent to x-ray tube via cables m. A is sent to filament on cathode side. Filament heats up – electrons are produced Positive voltage (k. Vp) is applied to anode Negative electrons are attracted across the tube to the positive anode. § Electrons slow down and finally come to rest § Electron beam is focused from the cathode to the anode target by the focusing cup § § §

When the electrons from the cathode are accelerated at high voltage to the anode: • 99% of the energy is dissipated as heat (anode materials are selected to withstand the high temperatures they are able to withstand) • 1% is given off as x-rays

2. TRANSFORMER

3. CONTROL PANEL

WORKING

PRODUCTION OF X-RAY

BLOCK DIAGRAM KV METER EXPOSURE SWITCH HIGH TENSION SUPPLY RECTIFIER m. A TIMER meter KV SELECTOR m. A CONTROL VOLTAGE COMPANSATOR VOLT METER FILAMENT SUPPLY AND TEPERATURE CONTROL X-RAY TUBE

HISTORY • 1895 Discovery of X Rays- W. K. Roentgen • 1896 first time used in surgery • 1975 Diagnostic x-ray Machines • 1997 Digital x-ray introduced

TECHNOLOGY DEVELOPMENT