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CHAPTER 6 THE X-RAY BEAM SPECIFIC OBJECTIVES NOTED IN THIS POWER POINT BEGIN ON PAGE 110-117. . Four timers. 1) Synchronous-min time is 1/60. Increase in equal multiples 2) Electronic-most accurate/controlled by microprocessor Where are 1 and 2 located in the circuit?
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CHAPTER 6 THE X-RAY BEAM SPECIFIC OBJECTIVES NOTED IN THIS POWER POINT BEGIN ON PAGE 110-117.
Four timers • 1) Synchronous-min time is 1/60. Increase in equal multiples • 2) Electronic-most accurate/controlled by microprocessor • Where are 1 and 2 located in the circuit? • mAs time and falling load generator-let’s discuss this! • AEC
AEC • WHAT IS THE PURPOSE OF AN AEC? • HOW DO YOU USE THEM WHEN POSITIONING? • CHAMBERS VS. PHOTOMULTIPLIERS • Can they produce the same density of radiograph for any size patient?
Ion chamber vs photomultiplier or photodiode • Collects a charge via light • Sequence • X-ray • Patient • Special cassette • photodiode • Waits for a charge • Sequence • X-ray • Patient • Ion chamber • IR
High Voltage Transformer • What do you remember?
RECTIFICATION • Unrectified • Half wave rectified • Fully rectified
Phases Voltage Ripplepage 30 Fauber figure 2-12 • 100% • 13 or 14% • 3 or 4% • Less than 1% • Single • Three phase • Three phase/6 pulse • Three phase/12 pulse • High Frequency • How do these phases impact technique??
POWER RATING • UNIT OF MEASUREMENT OF POWER IS WATTS • AMPS MEASURES THE QUANTITY OR QUALITY? • Volts measures the ________________________ • Amps=current • Volts = potential • Try this problem: If your kitchen is on a 25 amp circuit breaker and 110 volts is the available voltage what is the maximum watts this circuit can handle? • ON TO CHAPTER SEVEN!!
CHAPTER SEVEN • REVIEW THE PROTECTIVE HOUSING • Let’s dissect the cathode • What happens at the cathode? • Focusing cup • Imbedded in cathode • Two (page 15 in fauber, figure 2-1) • Confines the electron beam • Grid controlled tubes • Allows for tube to be turned off and on quickly • Space charge and space charge effect • High mAs and low kVp can be space charge limited..why?
The Anode • Three functions of the anode -What do you know already about the anode • The target • What does the rotor do? • Note: please skip induction motors at this time
Focal spot, line focus principle and anode heel effect • Focal spot and target angle (Fauber pg 16 figure 2-2) • The smaller focal spot • More concentration of heat • Better detail • Usually located in the smaller angle • Large focal spot • Less concentration of heat • Less detail • Larger angle • Page 25 Fauber, figure 2-10
Line Focus Principle • Effective focal spot size is always smaller than the actual focal spot size • Fauber-pg 34 figure 2-13 and pg 35 figure 2-14
Anode Heel effect • Bushong pg 130, pg 7-20 • The heel effect is more or less with a greater angle? • Which side has greatest intensity? • Off Focus radiation
How is heat dissipated in the tube? • Tube rating charts • Heat units • Anode cooling charts