* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Chapter 5 - RadTherapy
Electrical ballast wikipedia , lookup
Electric power system wikipedia , lookup
Electrification wikipedia , lookup
Power over Ethernet wikipedia , lookup
Power inverter wikipedia , lookup
Stray voltage wikipedia , lookup
Electrical substation wikipedia , lookup
Three-phase electric power wikipedia , lookup
Power engineering wikipedia , lookup
Amtrak's 25 Hz traction power system wikipedia , lookup
Vacuum tube wikipedia , lookup
History of electric power transmission wikipedia , lookup
Buck converter wikipedia , lookup
Cavity magnetron wikipedia , lookup
Photomultiplier wikipedia , lookup
Rectiverter wikipedia , lookup
Mercury-arc valve wikipedia , lookup
Voltage optimisation wikipedia , lookup
Alternating current wikipedia , lookup
Chapter 5 X-ray Equipment Diagnostic x-ray units: 10 – 1200 mA 10 second exposures 25 – 150 kVp Therapeutic x-ray units: 20 mA 1 – 60 minute exposures 4 – 40 meV Radiographic table: (bakelite / carbon fiber) Radiolucent: permits x-ray to travel through Flat or curved Easy to clean Space for film cassette and grid Bucky tray Tables move and/or float and lock Compression bands: uniform density, restraint Fixed or tilting o Foot boards o Shoulder supports / hand grips Tube supports: move the tube around easily different directions Overhead – telescoping Floor to ceiling Mobile Floor mounted C – arm: mobile units, fluoroscopy Head units: floor to ceiling mounted Upright units: chest x-ray – fluid levels in chest, shoulder separation, cervical spine x-rays, free air in abdomen Special diagnostic equipment: Mammography units Dental panoramic units Pediatric unit: holds babies in position Tomography units: rotating mechanism, center is more clearly visualized, axial scans (CT, PET CT) RTH simulator: similar to diagnostic, movement like treatment machine to duplicate treatment Urology unit Single-phase power: power supply that allows the potential difference to drop to zero with every change in the direction of current flow. No potential difference and thus no xray production 120 times each second. Three –phase power: power supply generated as each wave peak drops toward zero. The overall potential difference is boosted back to peak by the next phase wave; the sum of the phasing power never drops to zero. Automatic exposure control: a device programmed to terminate the radiographic exposure after a desired exposure has been reached. (photo-timer, ionization chamber) Allows tech to set kV only Back up law: 150% o Generators must terminate at 600 mAs if ste above 50 kVp o Generators must terminate at 2000 mAs if set below 50 kVp Main circuit: supplies the x-ray tube with properly modified power to get the speed necessary to make x-rays. Main switch: the switch that generates the power to the x-ray tube, contains power box and circuit breakers. Exposure switch: a remote control device that permits current to flow by closing the circuit and beginning the exposure; switch is depressed through duration, activates rotating anode which is necessary for heat to be evenly distributed. Unit can not make exposure until anode at the proper speed, dead mans switch is a safety device; Autotransformer: a transformer that automatically sets by adjustments allows tech to choose number of turns to increase / decrease voltage. Timer-circuit: device used to end the exposure at an accurately measured preset time. Step-up transformer: a device used to increase the voltage from the primary to secondary coil. Four-diode rectifier: electrons are permitted to flow in only one direction, turning AC to DC. Filament circuit: supplies the filament of the x-ray tube with properly supplied power to produce an e-cloud by thermionic emission, an increase in voltage will then drive the electrons to hit the anode target. Filament circuit variable resistance: allows change in voltage amount, incoming voltage in decreased. Filament step-sown transformer: 3 – 5 A, 6 – 12 volts X-ray tube: Cathode: the negative side of the x-ray tube; produces a thermionic cloud, (Thermionic emission: the ejection of electrons from the surface of the wire due to increased heat, causing an electron cloud; also called the space charge cloud). Conducts the high voltage to the gap between the cathode and anode, and focuses the electron stream as it heads for the anode. Anode: the positive side of the x-ray tube; serves as a target surface for high voltage electrons from the filament, conducts high voltage from the cathode back into the x-ray generator circuitry, and serves as the primary thermal conductor. Rotor: a hollow cylinder or cuff that is attached to the anode disk by a molybdenum shaft. Stator: induction motor electromagnets that turn the anode. Power rating of x-ray generators: determined by the greatest load the generator is capable of sending to the tube and serves as a guide for the comparison of generators.