RADT 1010 Final Exam ( LATEST EDITION
2024 ) ALL BUNDLED TO BOOST AND EASE
YOUR STUDY/ GUARANTEED PASS
Production of xrays require four factors - ANSWER source of electrons, target, high-voltage, vacuum
what is the envelope made of + the dimensions - ANSWER pyrex glass or metal, 10'' long, 6'' central
diameter, 2'' peripheral diameter
What purpose does protective housing serve? - ANSWER - controls leakage and scatter radiation
- isolates high voltages
- provides means to cool tube
what controls leakage radiation and scatter radiation - ANSWER - 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 - ANSWER - dielectric oil (insulates, promotes
cooling)
- air fan
what is the cathode made up of - ANSWER - filament(s)
- focusing cup
- associated wiring
what must the filament do - ANSWER must provide enough resistance to e- flow so that heat produced
will cause thermionic emission (occurs @ 2200 degrees)
,filament material and why - ANSWER tungsten because it has high melting point and difficult to vaporize.
Can also be rhenium and molybdenum.
Explain thermionic emission - ANSWER 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 - ANSWER - tube arcing (vaporized tungsten collection on envelop)
- filament breakage (often due to boost and hold)
what is the focusing cup made of - ANSWER nickel or molybdenum
does a focusing cup have a high/low, negative/postivite potential - ANSWER low negative
what is the mA for space charge effect - ANSWER maximum mA is 1000-1200
three functions of anode assembly - ANSWER - target surface
- conducts high voltage
- serves as primary thermal conductor
components of rotating anode assembly - ANSWER - anode
- stator
- rotor
Description of stator - ANSWER located outside envelope, is a bank of electromagnets
description of rotor - ANSWER - 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 - ANSWER - 3200-3600 rpm
- 10000-20000 rpm high speed anodes
what is the rotating anode made of and why - ANSWER tungsten-rhenium alloy, because it has high
atomic number, high melting point, has heat conducting ability
what temperature does the focal track get to - ANSWER reaches 1000-2000 degrees in normal use
what is the anode backed with and why is it backed - ANSWER molybdenum and/or graphite. backing
assists with heat loading
warmup procedure of anode benefits - ANSWER prevents cracking, helps maintain vacuum, stress
relieved anode
what is target area and what areas - ANSWER 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 - ANSWER large focal spot is better for life of anode
what size focal spot is required for image quality - ANSWER small focal spot
What is the line focus principle? - ANSWER 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 - ANSWER actual focal spot and target angle
what are the diagnostic ranges - ANSWER 10-1200 mA
0.001 to 10 seconds
, 30-150 kVp
description of xray table - ANSWER uniform, radiolucent surface, easy to clean, no crevices that could
collect contrast media, contains bucky/IR
what are the different tube supports - ANSWER - overhead
- floor
- floor to ceiling
- mobile
- c-arm
what are the uses of upright units - ANSWER chest, abdomen, AC joints, cervical spine
how is shock hazard minimized from the high-voltage cables - ANSWER 1. insulation
2. grounded wire sheath
3. secondary side of high voltage transformer is grounded
what can be selected on operating console - ANSWER power on/off, kV, mA, time, exam (hand, hip,etc.),
AEC chambers, detector being used, focal spot size, view worklist
exposure switch description - ANSWER 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 - ANSWER mobile xray exposure switch requires 3-meter
cord
what does the generator do - ANSWER - 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)
