CHAPTER 6 THE X-RAY BEAM SPECIFIC OBJECTIVES NOTED IN THIS POWER POINT BEGIN ON PAGE

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 Four timers

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? AEC

Waits for a charge Sequence –X-ray –Patient –Ion chamber –IR Collects a charge via light Sequence –X-ray –Patient –Special cassette –photodiode Ion chamber vs photomultiplier or photodiode

What do you remember? High Voltage Transformer

Unrectified Half wave rectified Fully rectified RECTIFICATION

Single Three phase Three phase/6 pulse Three phase/12 pulse High Frequency How do these phases impact technique?? 100% 13 or 14% 3 or 4% Less than 1% Phases Voltage Ripple page 30 Fauber figure 2-12

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!! POWER RATING

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? CHAPTER SEVEN

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 The Anode

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 Focal spot, line focus principle and anode heel effect

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 Line Focus Principle

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 Anode Heel effect

Tube rating charts Heat units Anode cooling charts How is heat dissipated in the tube?