Dr Mohamed el Safwany, MD.

Radiation Wave length Frequency

Radio waves 3x106cm – 0.01cm 104-1012

Infrared 0.01-7000Aº 1012-1014

Visible light 7000Aº-4000Aº 1014-1015

UV 4000Aº-100Aº 1014-1016

X & gammaX & gamma 100Aº-10-4Aº 1016-1022

10-12cm

Types of electromagnetic wavesTypes of electromagnetic waves

X Rays are high-energy EM radiation and part of EM spectrum

X-Ray tube consists of:

Evacuated tube Cathode (tungsten) Focusing cup Copper anode block Tungsten target (high Z material)

› high melting point high melting point

› high thermal conductivity high thermal conductivity

› More efficient X-Ray productionMore efficient X-Ray production

X-Ray tube consists of:

Evacuated tube Cathode (tungsten) Focusing cup Copper anode block Tungsten target (high Z material)

› high melting point high melting point

› high thermal conductivity high thermal conductivity

› More efficient X-Ray productionMore efficient X-Ray production

Probing patient from different directions during 360rotations with x-ray beam of known intensity (I0) & measuring it after it has passed the pt (I).Attenuation depends thickness and density of tissues

• Image displays on computer or multiple films

New technologies are

• Helical CT &• Multiple slice / detector arrays

Computed Axial Tomography (CT)Computed Axial Tomography (CT)

Ultrasound machine transmits high-frequency sound into body using a probe.

Sound waves travel into body & hit a boundary between tissues (fluid & soft tissue).

Some waves reflected back to the probe and are detected by probe while some travel on further until they reach another boundary and then reflect back to the probe.

So image depends on transmission characteristics of the interfaces.

Image display on computer or films.

DR Azza HelalDR Azza Helal

160Us

260Us

Reflection

Reflection

Time between pulse Time between pulse emission and echo emission and echo return determines return determines depthdepth

12cm

20cm

Echo

Echo

Velocity =Distance/

Time

The Ultrasound Machine

A basic ultrasound machine has the following parts: 1.Transducer probe - probe that sends and receives the sound waves 2.Central processing unit (CPU) - computer that does all of the calculations and contains the electrical power supplies for itself and the transducer probe 3.Transducer pulse controls - changes the amplitude, frequency and duration of the pulses emitted from the transducer probe 4.Display - displays the image from the ultrasound data processed by the CPU 5.Keyboard/cursor - inputs data and takes measurements from the display 6.Disk storage device (hard, floppy, CD) - stores the acquired images 7.Printer - prints the image from the displayed data

•Image formed by transmitting and receiving radio waves inside a high magnetic Image formed by transmitting and receiving radio waves inside a high magnetic field.field.

•All routine MRI techniques are based on receiving and processing of the signals from protons of hydrogen atom.

•The image is mainly related to The image is mainly related to Patient hydrogen densityPatient hydrogen density

•MRI makes great pictures because of large no of protons in the body, primarily in water and fat.

•Image display on computer or multiple filmsImage display on computer or multiple films

Good Luck

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