circuit diagram.pptx

X-RAY GENERATOR CIRCUIT DIAGRAM , PRODUCTION OF X-RAYS AND INTRACTION OF X-RAY WITH MATTER.
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1. ELECTRIC CIRCUIT DIAGRAM OF X-RAY GENERATOR , PRODUCTION OF X-RAYS and interaction of x-rays with matter FAYAZ AHMAD KHAWAJA RADIOGRAPHER

2. OBJECTIVES 2 . W orking mechanism of x-ray circuit 1. B asic components of x-ray circuit 3 . The exposure timer and automatic expose timer 4. The production of x-rays 5. I nteraction of x-rays with matter

3. X-RAY GENERATOR A n x-ray generator is a device that supplies electric power to the x-ray tube. M ost radiology departments have 3 phase power available in range of 203V to 230V. MISNOMER: Permits operator to control K v , mAs and exposure time

4. XRAY TUBE REQUIRES ELECTRIC ENERGY FOR TWO PURPOSE T o boil the electrons from the filament. T o accelerate these electrons from cathode to anode. X-RAY GENERATOR HAVE CIRCUIT FOR THESE TASKS AND THESE ARE:- H igh voltage circuit F ilament circuit and T imer circuit for regulating the length of x-ray exposure.

5. WHAT IS CIRCUIT? I nterconnection between some electric elements is called circuit. its components are Battery, Wire, Resistor, Capacitor etc.

6. ELECTRIC CURRENT A n electric current is a flow of charged particles, such as electrons or ions, moving through an electrical conductor or space. TYPES ALTERNATING CURRENT DIRECT CURRENT Alternating current (AC) is an electric current which periodically reverses direction and changes its magnitude continuously with time . D irect current is one-directional flow of electric charge. an electrochemical cell is a prime example of DC power. 

7. M agnetic flux is a measurement of the total magnetic field which passes through a given area or number of magnetic lines passing through a given closed surface MAGNETIC FLUX MAGNETIC FIELD M agnetic field is the region around a magnetic material or a moving electric charge within which the force of magnetism acts. MAGNETIC FIELD MAGNETIC FLUX

8. ELECTROMAGNETIC INDUCTION C hange in magnetic flux in a conductor induces voltage in an near by conductor . AC current produces an alternating magnetic field.

9. I f suppose the current in the primary coil changes continuously, then the induced magnetic field of the primary coil produces a changing current in the secondary coil. ELECTROMAGNATIC INDUCTION MUTUAL INDUCTION T here are two types of induction process: SELF INDUCTION S elf inductance is defined as  the induction of a voltage in a current-carrying wire when the current in the wire itself is changing SELF INDUCTION

10. V oltage is the pressure from an electrical circuit's power source that pushes charged electrons (current) through a conducting loop, enabling them to do work such as illuminating a light. In brief, voltage = pressure, and it is measured in volts (V). VOLTAGE

11. TRANSFORMER TRANSFORMER USES ELECTROMAGNATIC INDUCTION TO VARY THE VOLTAGE T he basic transformer consists of an iron core , a primary winding circuit and secondary winding circuit. A n AC current flowing through the primary winding produces a changing magnetic field, which permeates the core and induces an alternating voltage on secondary coil.

12. TYPES OF TRANSFORMER T here are three types of transformers used in x-ray circuit AUTOMATIC TRANSFORMER : A llows the selection of input voltage to step –up and step-down transformers. [Incoming voltage 230V,60hz ac] STEP UP TRANSFORMER : provide high voltage to x-ray tube.[electron acceleration requires b/w 40000 and 150000 volts] STEP DOWN TRANSFORMER : provides high current to the x-ray tube filament. The incoming line voltage drops to 5 V to 15 V and amperage increases to 3A to 5 A.[ F ilament heating requires 10V] N ote: Automatic transformer is used to  allows fluctuations in the mains input voltage to be corrected before the current is fed to the high tension transformer .

13. CONTD…………… I n a step up transformer the voltage is increased but the amperage must decrease to keep the power constant (transformer law i.e. Vs/ Vp = Ip /Is =Np/Ns). S tep up transformer has a ratio of 1:1000[Np/Ns]. C onverts voltage to kilo voltage. C onversely step down transformer will decrease voltage from the primary coil to the secondary coil, with a corresponding increase in amperage.

14. AUTO TRANSFORMER V oltage supplied to x-ray room is connected to a x-ray generator through autotransformer. F unctions: S upplies voltage for x-ray tube filament. 2. Provides voltage for primary coil for high voltage transformer. 3. Provide a convenient location for Kvp meter. Consist of a single winding wound on a laminated closed core. W orks on the principle of self induction S elf induction: Self-induction is the ability of an inductor in a circuit to generate inductive reactance, which opposes a change in the circuit current. when an ac source voltage rises, and the magnetic flux expands around the circuit conductors, an opposing voltage, or counter-voltage, is induced in the circuit. THUS WITH A VERY LIMITING RANGE AUTOTRANSFORMER CAN ACT AS STEP UP AND STEP DOWN TRANSFORMER.

15. T hermionic emission (archaically known as the Edison effect) is the flow of charged particles called thermions from a charged metal or a charged metal oxide surface, caused by thermal vibrational energy overcoming the electrostatic forces holding electrons to the surface. THERMIONIC EMISSION

16. FILAMENT CIRCUIT C athode is heated by current by step down transformer or low voltage supply. O ut put is controlled by Ma selector. I ncreasing ma = More heating to cathode = Increasing temperature =Increased thermionic emission. T wo levels of heating of cathode 1. standby heating 2. during exposure heating

17. DIODE: A n electric device in which electric current flows only in one direction. RECTIFICATION : T he conversion of alternating current (ac) to direct current (dc). HALF WAVE RECTIFICATION: A half wave rectifier is defined as a type of rectifier that allows only one-half cycle of an AC voltage waveform to pass while blocking the other half cycle. FULL WAVE RECTIFICATION: A rectifier that converts the complete cycle of alternating current into pulsating DC

18. BRIDGE RECTIFIER CIRCUIT (USED IN XRAY GENERATOR WITH HTT) T he bridge rectifier is a type of full-wave rectifier that uses four or more diodes in a bridge circuit configuration to convert alternating (AC) current to a pulsating direct (DC) current.

19. TIMER CIRCUIT C ontrol the duration of x-ray exposure. Terminates after the present time has elapsed or when the receptor have received specific level of exposure. O perator controls switches and timer turns radiation on and off. TYPES : MANUAL TIMER. ELECTRONIC TIMER AUTOMATIC EXPOSURE CONTROLE(AEC) M anual and Electronic timer is subjected to human error. the exposure time is selected on the basis of thickness and density of part under examination, if the estimation is incorrect there is improper radiographic exposure.

20. EARTHING IN XRAY GENERATOR Earthing also known as grounding is an essential safety measure in electrical circuits including x-ray generator circuit. The purpose of Earthing is to provide low resistant path for the flow of electric current in the event of fault or accidental contact with high voltage components. This helps to protect both the equipment and individuals from electric shock and potential damage. The specific components that are connected to Earthing may vary depending on the design and manufacturer of the x-ray generator, but the following are common components that are often grounded. (I) X-ray tube housing. (II) High voltage power supply . (III) Control unit and user interface. (IV) Chassis and casing (V) Collimator and Accessories. (VI) Exposure switch and safety system.

21. X-RAY TUBE

22. ATOMIC STRUCTURE A n atom is the smallest particle characterizing an element. T he present concept of atomic structure is bhor’s model. T he fundamental particles of an atom are proton, neutron and electron. A tom consist of central core called nucleus, which is positively charged. N ucleus consist of proton & neutron,. Proton is positively charged and neutron has no charge. T he electrons are negatively charged particle revolving around in different orbits.

23. BINDING ENERGY AND ELECTRON ENERGY BINDING ENERGY T he energy required to remove an electron from its orbit. Binding energy of inner shell electrons are more than the outer shell electrons ELECTRON ENERGY T he electron energy is the energy of the particular electron of an atom. Electron energy of outer shell electrons is more than the inner shell electrons.

24. PRODUCTION OF X-RAYS X -rays are produced by energy conversion when fast moving electrons from filament of x-ray tube interact with the tungsten anode (target). B ased on the phenomenon of energy conversion , the x-rays are classified into two types: 1. Characteristic Radiation. 2. Bremsstrahlung Radiation. IN MANY LANGUAGES, X-RADIATION IS REFERRED TO AS RÖNTGEN RADIATION, AFTER THE GERMAN SCIENTIST WILHELM CONRAD RÖNTGEN, WHO DISCOVERED IT ON NOVEMBER 8, 1895. HE NAMED IT X-RADIATION TO SIGNIFY AN UNKNOWN TYPE OF RADIATION.

25. CHARACTERISTIC RADIATION W hen an accelerated electron having little more or equal binding energy than the orbital electron of an atom. It ejects an electron from the orbit of an atom. T he atom become ion and unstable. T he unstable atom try to become stable as soon as possible. To stable the atom electron move from outer shell to inner shell. W hile moving from outer shell to inner void shell electron losses its energy in the form of x-radiation(electron energy of outer shell electron is more than inner shell electron) T he energy of the x-ray photon is depend upon the characteristic of the target material we are using. N ame characteristic come from the fact that the binding energy of particular shell of an atom is unique for a specific element.

26. B remsstrahlung radiation is also called white radiation. When an accelerated electron passes nearer the nucleus of an atom. E lectrons have negative charge, nucleus of the atom have positive charge. There will be the electro motive force between incoming electrons and nucleus of an atom. T he electron is attracted towards the nucleus. Due to the attraction the electrons get decelerated and change their direction. Due to deceleration the electron losses its kinetic energy as a x-ray photon. T he amount of energy lost by incoming electron is depend upon : i ) How nearer they pass through the nucleus. ii) The energy of incoming electron BREMSSTRAHLUNG RADIATION

27. INTERACTION OF X-RAYS WITH MATTER ATTENUATION : I s the reduction of intensity of beam as it passes through medium. ABSORPTION : I s transfer of energy from radiation to the medium. SCATTERING: I s the change in the direction of the photon with or without loss of energy by the photon

28. INTERACTION OF X-RAYS WITH MATTER T hree possible fates awaits each x-ray photon while interacting with matter P enetration : penetrate section of matter without interaction. Absorption : interact with matter and completely absorbed by depositing its energy. S cattering: interact and can be scattered and deflected from its original direction and deposit part of its energy. No longer carries useful information because their direction is random and responsible for noise in the x-ray image .

29. ABSORPTION AND SCATTERING T here are five different process by which x-ray may be absorbed or scattered as they pass through the medium. first three play a role in diagnostic radiology or nuclear medicine COHERENT SCATTERING PHOTOELECTRIC EFFECT COMPTON SCATTERING PAIR PRODUCTION PHOTO DISINTEGRATION

30. COHERENT SCATTERING Referred by variety of names : Thomson, Rayleigh, classical and un-modified scattering. N ame coherent is given to those interactions in which x-ray photon under go change in direction with out change in wave length. W hen energy of incident photon(< 10 kev ) is less than the binding energy of strongly bound orbital electron , it may occur. I n Thomson effect energy of incident photon is absorbed temporarily by an orbital electron and release after some time with same wave length but in different direction. the same thing occurs in Rayleigh effect but the energy of incident photon is temporarily absorbed by electron cloud around the whole atom. THOMSON RAYLEIGH SCATTERING

31. PHOTOELECTRIC EFFECT T he photoelectric effect occurs when an incident photon has an energy equal to or greater than binding energy of an electron in an atom. P hoton can ionise the atom by ejecting electron. Photon gives all its energy to the atom. V acant site fulfilled by jumping inward from next shell farther away from nucleus, accompanied by emission of characteristic radiation in the form of second photon.

32. COMPTON SCATTERING I nteraction occurs between photon and outer shell electron which have negligible binding energy. E lectron is ejected from the atom and photon is scattered with some reduced energy. S cattered radiations from this interaction is called Compton scatter and ejected electron as recoil electron.

33. PAIR PRODUCTION D on't occur in diagnostic radiology. T he high energy photon interacts with nucleus of an atom. P hoton disappears. I ts energy is converted into matter in the form of two particles. O ne is electron and other is positron (positron : matter with mass as an electron but with + ve charge) C annot take place with photon energy less than 1.02mev.

34. PHOTO DISINTEGRATION O ccurs with energy more than 10mev. P art of nucleus of atom is ejected by a higher energy photon (excess incident photon causes instability in nucleus of an atom thus resulting emission ) T he ejected portion may be neutron , a proton , an alpha particle or a cluster of particles. T he photon must have sufficient energy to overcome nucleus binding energy of the order of 7-15 M ev .

35. INTERACTION OF X-RAY RADIATION WITH SOFT TISSUES XRAY PHOTON ENERGY RANGE SITE OF INTRACTION X-RAY PHOTON TYPICAL INTERACTION BY PRODUCT OF INTERACTION ENERGY DIRECTION 1 TO 50 kVp AN ATOM UNCHANGED SLIGHTLY CHANGED COHERENT SCATTERING NONE INNER SHELL ELECTRON USUALLY K OR L FULLY ABSORBED NOT APPLICABLE PHOTOELECTRIC ABSORBTION PHOTOELECTRON 60 TO 90 kVp OUTER SHELL ELECTRON REDUCED CHANGED COMPTON SCATTERING COMPTON SCATTERED ELECTRON AND CS PHOTON Above 90 kVp Up to 1.02 MeV OUT SHELL ELECTRON REDUCED CHANGED COMPTON SCATTERING COMPTON SCATTERED ELECTRON AND CS PHOTON

36. CONCLUSION This presentation has shed light on the fundamental principles behind one of the most critical imaging technologies in medicine. Understanding circuit diagram is crucial for safe and efficient generation of x-rays. As a radiation worker in medicine understanding the topics covered under this presentation can offer several benefits . Here are some of the key advantages: Safe operation O ptimising image quality. R adiation protection. M inimising patient dose. T roubleshooting and maintenance. Q uality assurance A rtefact recognition. C ontinuous education and research. C ompliance with regulation E ffective communication

37. THANK YOU SIR