1

G. H. Raisoni College of Engineering

Department of First Year Engineering

(Section: G Department: Mechanical engineering)

Subject: Bio Systems in EngineeringTAE II: Technical Presentation

Topic: X-ray

Presented by: Rupesh Kumar Shubham dhore Shivam singh Yash bais

X-rays were discovered by the German physicist W. C. Röntgen in 1895. When he accidentally noticed that fluorescent materials showed a faint glow when placed near a cathode-ray tube powered by a high voltage induction coil. Although others had observed similar phenomena earlier, Röntgen was the first one who concluded that he had found “a new kind of rays”. He called them “X-rays” (X = unknown) and began a systematic research on their properties. His work was so thorough that it took seventeen years until significant new facts became known. Some scientists thought that X-rays were a kind of ultraviolet light, but nobody was able to prove it at that time. Finally, crystal diffraction experiments done by M. v. Laue in 1912 confirmed that X-rays are electromagnetic waves.

Production And Characteristics Of X-ray

Production of x-ray X-ray production whenever electrons of high energy strike a heavy

metal target, like tungsten or copper. When electrons hit this material, some of the electrons will approach

the nucleus of the metal atoms where they are deflected because of there opposite charges (electrons are negative and the nucleus is positive, so

the electrons are attracted to the nucleus). This deflection causes the energy of the electron to decrease, and

this decrease in energy then results in forming an x-ray.

X-rays are produced when high energetic electrons interact with matter.

Current estimates show that there are approximately 650 medical and dental X-ray examinations per 1000 patients per year. The kinetic energy of electron is converted into electromagnetic energy of electron.

W. c. Rontgen

Some Facts about X-Rays

With a wavelength of approx. 10nm to 0.001nm. X-rays occupy the range between UV light and gamma rays in the electromagnetic spectrum. The definition of the upper and lower wavelength limit is more or less arbitrary and not marked by a sudden change of properties. X-rays with a short wavelength, for example, overlap with gamma rays of long wavelength. Radiation in this region is usually named after the mechanism of emission. Gamma rays are released by nuclear processes, X-rays are emitted when fast electrons collide with matter. Technically, X-rays are produced by means of an X-ray tube, a simple form of a linear particle accelerator.

The major components of the modern X-ray tube are:

Cathode (electron source)

Anode (acceleration potential)

Rotor/stator (target device)

Glass/metal envelope (vacuum tube)

The X-ray tube provides an environment for X-ray production via bremsstrahlimg and characteristic radiation mechanisms.

Electron source Electron acceleration potential Target for X-ray paroduction

The classical X-ray tube requires:

The intensity of the electron beam determines the intensity of the X-ray radiation. The electron energy determines the shape of the bremsstrahlungs spectrum, in particular the endpoint of the spectrum. Low energy X-rays are absorbed in the tube material.

Properties of X-ray

X-rays

White radiation

Produced upon "collisions" with electrons in targetAny amount of energy can be lost up to a max. amountContinuous variation of wavelength

Characteristic radiation

Specific energies absorbed

Specific x-ray wavelengths emitted

Wavelengths characteristic of target atom type

X-rays

Mechanism

Decelerating charges give off radiation

X-rays

Mechanism

Decelerating charges give off radiation

Mechanism

Decelerating charges give off radiation

X-rays

Mechanism

Decelerating charges give off radiation

X-rays

Mechanism

Decelerating charges give off radiation

X-rays – vary tube voltage

Inte

nsity

Wavelength

E ≈ hc/Kedge

E >> hc/Kedge

E > hc/Kedge

Iconts = AiZV~2

Ichar = Ai(V-Vcrit)~1.5

X-rays

Typical tube spectrum

X-ray source

X-ray sources abound around us. They include the following Natural X-ray sources 1) Astrophysical X-ray source, as viewed in X-ray astronom 2) X-ray background

3) Naturally occurring radionuclide Artificial X-ray sources 1) Radiopharmaceuticals in radiopharmacology 2) Radioactive tracer 3) Brachytherapy 4) X-ray tube, a vacuum tube that produces X-rays when current flows through it 5)X-ray laser 6) X-ray generator, any of various devices using X-ray tubes, lasers, or radioisotopes 7)Synchrotron, which produces X-rays as synchrotron radiation 8)Cyclotron, which produces X-rays as cyclotron radiation

Other X-ray sources

Rotating anode

high power - 40 kWdemountablevarious anode types

Other X-ray sources

Synchrotron need electron or positron beam orbiting in a ringbeam is bent by magnetic field

x-ray emission at bend

Advantages

10-4 - 10-5 radians divergence (3-5 mm @ 4 m)

high brilliancewavelength tunable

Other X-ray sources

Synchrotron

Advantages

10-4 - 10-5 rad divergence (3-5 mm @ 4 m)

high brilliancewavelength tunable

Other X-ray sources

Synchrotron need electron or positron beam orbiting in a ringbeam is bent by magnetic field

x-ray emission at bend

Advantages

10-4 - 10-5 rad divergence (3-5 mm @ 4 m)

high brilliancewavelength tunable

high signal/noise ratio

Properties of X-ray

X-ray photons carry enough energy to ionizee atoms and disrupt molecular bonds. This makes it a type of ionizing

radiation, and therefore harmful to living tissue. A very high radiation dose over a short amount of time causes radiation

sickness, while lower doses can give an increased risk of radiation-induced cancer. In medical imaging this increased cancer risk is generally greatly outweighed by the benefits of

the examination. The ionizing capability of X-rays can be utilized in cancer treatmentto kill malignant cells using

radiation therapy. It is also used for material characterization using X-ray spectroscopy.

Hard X-rays can traverse relatively thick objects without being much absorbed or scattered. For this reason

X-ray production

X-rays are widely used to image the inside of visually opaque objects. The most often seen applications are in medical radiography and airport security scanners, but similar techniques are also important in industry (e.g. industrial radiography and industrial CT scanning) and research (e.g. small animal CT). The penetration depth varies with several orders of magnitude over the X-ray spectrum. This allows the photon energy to be adjusted for the application so as to give sufficient transmission through the object and at the same time good contrast in the image.X-rays have much shorter wavelength than visible light, which makes it possible to probe structures much smaller than what can be seen using a normal microscope. This can be used in X-ray microscopy to acquire high resolution images, but also in X-ray crystallography to determine the positions of atoms in crystals.

X-ray mechine

X-ray mechine working

Rontgeon with x-ray mechine