chapter 5 the x-ray imaging system
DESCRIPTION
CHAPTER 5 THE X-RAY IMAGING SYSTEM SPECIFIC OBJECTIVES NOTED IN THIS POWER POINT BEGIN ON PAGE 90-101. 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? - PowerPoint PPT PresentationTRANSCRIPT
CHAPTER 5 THE X-RAY IMAGING SYSTEMSPECIFIC OBJECTIVES NOTED IN THIS
POWER POINT BEGIN ON PAGE 90-101.
• 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! (Page 90)
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 pg 92 Bushong, Chapter 8, Fauber
• 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
• APR• Page 211 Fauber
Anatomically Programmed Radiography
• What do you remember?
High Voltage Transformer
• Unrectified
• Half wave rectified
• Fully rectified
RECTIFICATION, Bushong 93
• 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 Ripplepage 26 Fauber figure 2-13, Bushong, pg 97,99
• 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 SIX!!
POWER RATING
• REVIEW THE PROTECTIVE HOUSING• Let’s dissect the cathode• What happens at the cathode?• Focusing cup
– Imbedded in cathode– Two (page 13 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 SIX, Bushong
• 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 31 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 32 Fauber, figure 2-18
Focal spot, line focus principle and anode heel effect, Bushong, 107-115,Fauber 23-32
• Effective focal spot size is always smaller than the actual focal spot size
• Fauber-pg 31 figure 2-16, figure 2-17
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?