2. Xray Machine

• 3 main parts of xray machine:

  
  

  1. Component parts
  2. X-ray tube
  3. X-ray generating apparatus
• 1. Component Parts

  • determine duration, voltage, location

  1. on-off switch
  2. exposure button / activating button
  3. control / regulating selectors or dials

  • Timer
  • kVp dial (Kilo Voltage Peak): controls voltage peak from 65-90 kV
  • mA regulator (miliampere): controls amount of energy being produced
  • volt meter
• Extension arm / support arm : supports the tube head

  x-ray tube head: contains x-ray tube

  1. PID (position indicate device)/ cone: at the end of the tube head
  2. number scale: at the side of the x-ray tube head controls vertical angulation
• Positive angulation: cone is pointing downward 


  taking upper arch radiograph
• Negative angulation : core is pointing upward 


  taking lower arch radiograph
• 6 ft: distance that is safe from radiation
• Parts of xray tube head:

  Metal housing: contains xray tube

  • prevent xray tube to be out of the cone
  • prevent radiation leakage

  Insulating oil/gas: absorbs the heat produced during xray production: locate around xray tube

  
  

  Transofrmer:changing the incoming voltage

  • step-up transformer: converts incoming volts up
  • step-down transformer: converts incoming volts down

  Voltage is needed as an enery to stimulate electrons to travel from CATHODE to ANODE.
• Tube head seal: covers the xray tube head

  • the only portion that rays can pass through

  Aluminum disk: layers of thin Al; to remove the low E xray (soft xray)

  • low E xrays cab cause damage to the tissue by absorbsing

  Lead collimator / diaphragm: changes the size or xray beam
• 2. Xray Tube

  Leaded gas housing: vacuum area surrounding the x-ray tube

  Anode (positive side electrode): allow only the electrons to travel in a certain direction

  • Electrons are converted to xrays

  Cathode (negative side electrode): source of energy
• Parts of xray tube

  1. Leaded glass housing

  • Unleaded glass window: at the end where the xray comes out after anode has producing x-rays

  2. Cathode (-)

  • Tungsten filament: thin coil of W; source of energy
  • Molybdenum cup / focusing cup: part that directs e-produce from W filament towards the anode

  3. Anode (+)

  • Copper stem: absorbs heat being produce during x-rays production; 1x3 mm
• Characteristics of Tungsten (W)

  1. High atonomic number: 74 (p+ =e-)
  2. High melting point: 3,370 Co; can withstand heat
  3. local vapor pressure
• 3. X-ray generating apparatus

  • Electricity : energy to make x-rays
  • Electric circuit : path of electrical current
  • Self-rectified
  • 60-cycle 110 voltage AC (Alternating Current)
  • Electric current : flow of electrical energy or e- through a circuit
  • Transformers : alters incoming voltages & routes it to the x-ray rube
• 2 Units to remember regarding number of electron &electrical force :

  1. Amperage : number of e- moving through a circuit or amount of electrical current

  • 10-15 mA (milliAmpere)
  • Adjusted w/ the mA dial on the control panel

  2. Voltage:

  • Measurement of electrical force needed e- from Cathode to Anode pole
  • 65-95 kV / 65,000 to 90,000 volts
• • kVp : the highest voltage to w/c current in the x-ray tube can rise during a given time
  • 60-cycle AC 110 v
  • ↓
  • Electrical current changes flow 60x / sec
  • ↓
  • Flow of current is in 2 phases :
  • 1 positive phase (+)
  • 1 negative phase (-)
• • Therefore, in x-ray production there is a change in polarity of the Anode & Cathode that occurs 60x / sec (Reverse voltage / Reverse bios / Inverse voltage)
  • * Changing from (+) to (-) is for prevent the over heating of the Anode or focal spot
  • 60-cycle AC
  • ↓
  • 60 pulses of x-rays emitted every sec
  • ↓
  • Duration : 1/120 sec*
  • * X-rays are produced in the form of impulses (not a continuous stream due to changing in polarity)
• Exposure time :

  • Length of time to produce x-ray
  • Controlled by timer
  • Expressed as:
  • Fraction of a sec
  • Whole numbers of sec
  • Impulses per exposure
  • * Different tooth has a different exposure time
• Formula to determine exposure time in second:


  Number of impulses = Exposure time in second

  ------------------

  60
• Formula to determine exposure time in impulses:


  Exposure time in second x 60 = exposure time in pulses
• 2 Electric circuits of an xray machine:

  1. Filament Circuit / Low voltage circuit : in the cathode side

  • On - off switch light
  • mA control
  • Step-down transformer
  • Fn.: pathway of circuit that decrease the voltage coming into 3-5 to 7 volts

  2. Anode-Cathode circuit / High voltage circuit

  • kVp selector
  • Voltmeter
  • Timer
  • Activating button
  • X-ray emission / sound or indicator button
  • step-up transformer
  • Fn.: to increase the voltage to 65-90 kV (from 110 volts) to move the e- from Cathode to Anode
• Steps in x-ray production

  1. Turn machine "ON" (Step-down transformer is being used)
  2. Filament produce e- to heat the filament
  3. Formation of an “Electron cloud” @ the Cathode side (-) from W filament
  4. Activating button is pressed to activate the high-voltage circuit
  5. Electron at the Cathode propel directed to focal spot of the Anode in a lightning speed (3x10⁸)
  6. X-ray photon are produced at the focal spot of Anode and directed out of the unleaded glass window to be filtered and collimated (paralleled)
• Matter:

  • The substance of which all physical things are composed
  • It is anything that occupies space and has inertia
  • Has mass
  • Can exert force or be acted on by force
  • May be divided into elements or compound
  • Occurs in 3 states

  1. Soild
  2. Liquid
  3. Gas
• • Elements: accumulation of a single species of atom
  • Compounds: recurring units of atoms in a definite arrangement, with at least 2 of the atoms different
  • Atoms: the fundamental unit of any particular element
  • Fundamental particles: electrons, protons, neutron
  • Subatomic particles
  • Electron carries an electrical charge of -1
  • Proton a charge of +1
  • Neutron no charge at all
  • Protons and neutrons concentrated in the nucleus
• Ionization 


  When the number of orbiting e- in an atom is equal to the number of protons in its nucleus, the atom is electrically neutral. When an electrically neutral atom loses an electron, it be comes a positive ion and the free electron a negative ion. The process of converting atoms to ion is termed “Ionization.” Ionization also occurs by the addition of an e- to an electrically neutral atom, resulting in a negative ion. Note that protons do not participate in this process; their role is entirely passive.