RADT 1010 Final Exam Questions/Answers 2025 GUARANTEE A+
Production of xrays require four factors - source of electrons, target, high-voltage, vacuum
what is the envelope made of + the dimensions - pyrex glass or metal, 10'' long, 6'' central diameter, 2''
peripheral diameter
What purpose does protective housing serve? - - controls leakage and scatter radiation
- isolates high voltages
- provides means to cool tube
what controls leakage radiation and scatter radiation - - housing made of lead-lined cast steel
- leakage radiation limit (100 milliroentgens per hour at 1 meter)
what controls high-voltage isolation and tube cooling - - dielectric oil (insulates, promotes cooling)
- air fan
what is the cathode made up of - - filament(s)
- focusing cup
- associated wiring
what must the filament do - must provide enough resistance to e- flow so that heat produced will cause
thermionic emission (occurs @ 2200 degrees)
filament material and why - tungsten because it has high melting point and difficult to vaporize. Can also
be rhenium and molybdenum.
Explain thermionic emission - occurs when filament heated at 2200 degrees, causes electrons to be
released from filament. when high voltage released at exposure, e- are driven toward anode
what causes tube failure - - tube arcing (vaporized tungsten collection on envelop)
,- filament breakage (often due to boost and hold)
what is the focusing cup made of - nickel or molybdenum
does a focusing cup have a high/low, negative/postivite potential - low negative
what is the mA for space charge effect - maximum mA is 1000-1200
three functions of anode assembly - - target surface
- conducts high voltage
- serves as primary thermal conductor
components of rotating anode assembly - - anode
- stator
- rotor
Description of stator - located outside envelope, is a bank of electromagnets
description of rotor - - is a copper cylinder connected to an anode disk by a molybdenum stem.
- It turns when the stator is energized.
- contains ball bearings.
at what speed does the rotor turn at - - 3200-3600 rpm
- 10000-20000 rpm high speed anodes
what is the rotating anode made of and why - tungsten-rhenium alloy, because it has high atomic
number, high melting point, has heat conducting ability
what temperature does the focal track get to - reaches 1000-2000 degrees in normal use
,what is the anode backed with and why is it backed - molybdenum and/or graphite. backing assists with
heat loading
warmup procedure of anode benefits - prevents cracking, helps maintain vacuum, stress relieved anode
what is target area and what areas - portion of anode that electron stream contacts, point source of xray
photons
- target, focus, focal point, focal spot, focal track
is a large or small focal spot better for life of anode - large focal spot is better for life of anode
what size focal spot is required for image quality - small focal spot
What is the line focus principle? - by using a small anode angle you can change the size of the effective
focal spot (make it smaller for better resolution) without increasing the heat and damaging the anode.
what is effective focal spot controlled by - actual focal spot and target angle
what are the diagnostic ranges - 10-1200 mA
0.001 to 10 seconds
30-150 kVp
description of xray table - uniform, radiolucent surface, easy to clean, no crevices that could collect
contrast media, contains bucky/IR
what are the different tube supports - - overhead
- floor
- floor to ceiling
- mobile
, - c-arm
what are the uses of upright units - chest, abdomen, AC joints, cervical spine
how is shock hazard minimized from the high-voltage cables - 1. insulation
2. grounded wire sheath
3. secondary side of high voltage transformer is grounded
what can be selected on operating console - power on/off, kV, mA, time, exam (hand, hip,etc.), AEC
chambers, detector being used, focal spot size, view worklist
exposure switch description - deadman switch, pressing halfway down starts rotor and filament boost
circuit, depress in one motion to maximize tube life
how long do moblie xray unit cord need to be - mobile xray exposure switch requires 3-meter cord
what does the generator do - - supplies electrical power to xray tube (high voltage b/w anode and
cathode, filament voltage/current)
- controls exposure timing (turns exposure on and off, high voltage switched on and off)
what does the main xray circuit contain - exposure switch, timer circuit
incoming line current description - - 60 Hz alternating current (mains supply/incoming line current; 3-
phase)
- 120 V
- will be converted to high voltage and to high current in different parts of the xray circuit
line compensation description - - most imaging systems operate on 220 V (some 110 or 440)
- incoming power is not always accurate
Production of xrays require four factors - source of electrons, target, high-voltage, vacuum
what is the envelope made of + the dimensions - pyrex glass or metal, 10'' long, 6'' central diameter, 2''
peripheral diameter
What purpose does protective housing serve? - - controls leakage and scatter radiation
- isolates high voltages
- provides means to cool tube
what controls leakage radiation and scatter radiation - - housing made of lead-lined cast steel
- leakage radiation limit (100 milliroentgens per hour at 1 meter)
what controls high-voltage isolation and tube cooling - - dielectric oil (insulates, promotes cooling)
- air fan
what is the cathode made up of - - filament(s)
- focusing cup
- associated wiring
what must the filament do - must provide enough resistance to e- flow so that heat produced will cause
thermionic emission (occurs @ 2200 degrees)
filament material and why - tungsten because it has high melting point and difficult to vaporize. Can also
be rhenium and molybdenum.
Explain thermionic emission - occurs when filament heated at 2200 degrees, causes electrons to be
released from filament. when high voltage released at exposure, e- are driven toward anode
what causes tube failure - - tube arcing (vaporized tungsten collection on envelop)
,- filament breakage (often due to boost and hold)
what is the focusing cup made of - nickel or molybdenum
does a focusing cup have a high/low, negative/postivite potential - low negative
what is the mA for space charge effect - maximum mA is 1000-1200
three functions of anode assembly - - target surface
- conducts high voltage
- serves as primary thermal conductor
components of rotating anode assembly - - anode
- stator
- rotor
Description of stator - located outside envelope, is a bank of electromagnets
description of rotor - - is a copper cylinder connected to an anode disk by a molybdenum stem.
- It turns when the stator is energized.
- contains ball bearings.
at what speed does the rotor turn at - - 3200-3600 rpm
- 10000-20000 rpm high speed anodes
what is the rotating anode made of and why - tungsten-rhenium alloy, because it has high atomic
number, high melting point, has heat conducting ability
what temperature does the focal track get to - reaches 1000-2000 degrees in normal use
,what is the anode backed with and why is it backed - molybdenum and/or graphite. backing assists with
heat loading
warmup procedure of anode benefits - prevents cracking, helps maintain vacuum, stress relieved anode
what is target area and what areas - portion of anode that electron stream contacts, point source of xray
photons
- target, focus, focal point, focal spot, focal track
is a large or small focal spot better for life of anode - large focal spot is better for life of anode
what size focal spot is required for image quality - small focal spot
What is the line focus principle? - by using a small anode angle you can change the size of the effective
focal spot (make it smaller for better resolution) without increasing the heat and damaging the anode.
what is effective focal spot controlled by - actual focal spot and target angle
what are the diagnostic ranges - 10-1200 mA
0.001 to 10 seconds
30-150 kVp
description of xray table - uniform, radiolucent surface, easy to clean, no crevices that could collect
contrast media, contains bucky/IR
what are the different tube supports - - overhead
- floor
- floor to ceiling
- mobile
, - c-arm
what are the uses of upright units - chest, abdomen, AC joints, cervical spine
how is shock hazard minimized from the high-voltage cables - 1. insulation
2. grounded wire sheath
3. secondary side of high voltage transformer is grounded
what can be selected on operating console - power on/off, kV, mA, time, exam (hand, hip,etc.), AEC
chambers, detector being used, focal spot size, view worklist
exposure switch description - deadman switch, pressing halfway down starts rotor and filament boost
circuit, depress in one motion to maximize tube life
how long do moblie xray unit cord need to be - mobile xray exposure switch requires 3-meter cord
what does the generator do - - supplies electrical power to xray tube (high voltage b/w anode and
cathode, filament voltage/current)
- controls exposure timing (turns exposure on and off, high voltage switched on and off)
what does the main xray circuit contain - exposure switch, timer circuit
incoming line current description - - 60 Hz alternating current (mains supply/incoming line current; 3-
phase)
- 120 V
- will be converted to high voltage and to high current in different parts of the xray circuit
line compensation description - - most imaging systems operate on 220 V (some 110 or 440)
- incoming power is not always accurate
