RAD 271 Equipment Operation
cooling charts
1st: subtract max heat units & heat units you just used 2nd: go to the head used (20) & look at the time 3rd: subtract 20 time from the heat units you used time
capacitor - Construction
2 insulated metal plates with opposite charges to increase -e (electricity) to be stored on each
The exposure switch on an x-ray machine
2 part & connected to the rotating anode manufacturer recommend pressing exposure switch all the way to extend tube life
between the 7* angle & 20* degree which one dissipates heat better anode heel effect is more server with 7 or 20* SID?
20* the 7* creates more heat (more interactions) more severe 7* (smaller angle) shorter SID larger IR (14x17)
A +1 or -1 on the density control is qual to what percentage change?
25% & it controls time
The amount of mA used for fluoroscopy is: expect when?
3-5 & when you need a boost but you need high kvp
how many AC cycles/pulses in the US
60 cycles 120 pulses
when you chose 62 kvp what part of the x-ray circuit selects the 60 and what part selects the 62?
60 major kvp selector 2 minor kvp selector
What is the purpose of the line voltage compensator in the x-ray circuit?
Adjusts incoming voltage to maintain the set amount needed
What do we call electrical current that changes directions back and forth?
Alternating or AC current (side S symbol)
The purpose in the filament circuit is to reduce How is this done?
Amperes to 3-5 A and the voltage to 6-12 V. rheostat & step down transformer
What is a device capable of accumulating and storing an electric charge?
Capacitors or Capacitor-Discharge Generators in mobilt units
What happens to the exposure after the exposure switch is activated? What stops the exposure to the patient?
Continues to discharge after exposure switch starts automatic lead beam stopper or a collimator
what type of current does a capacitor use?
DC (battery) & Gives bursts of high voltage for x-ray exposure
capacitors deliver what type of voltage?
Delivers a falling voltage at approximately 1 kV drop for each mA
Name 2 places in x-ray equipment that have electromagnets.
Detent Locks and Remote controls
What do we call electrical current that flows in only one direction? & where is it created
Direct or DC Current Batteries or rectified AC Circuits
What do we call the force with which electrons move in an electrical circuit or pathway?
EMF or Electromotive Force or Voltage
movement of electrons (electricity) along a conductor or pathway such as an electrical circuit
Electrical current
A solenoid which contains an iron core and concentrates the magnetic field is the:
Electromagnet
falling load generator what 2 special generators use the falling load the tech controls? what type of timer is used
Exposure begins at maximum mA and the mA drops as the anode heats special generator used in 3 phase or high frequency generators (coin example you have to have 2 dollars you have 1 dollar 1 quarter 3 dimes 2 dimes 1 nickle 3 pennies) -tech does not control ma -synch timer
Materials such as iron have the ability to become magnetized and are called what type of material?
Ferromagnetic
What does the Filament Switch Control in the Exposure
Filament switch is your rotor on the control console it is also you mA station selection determines small or large filament
What devices stop the flow of electricity to the x-ray unit and table if an overload of the incoming current occurs? Where are they located ?
Fuses & circuit Close to incoming line or close to the table circuit.
What creates AC current?
Generators
Where in the x-ray circuit do we find a step up transformer? Step down transformer? Autotransformer?
High voltage part Filament circuit Control console
formula for amperage changes in transformers formula for transformer law
Is = Vp Vs = Ns __________ ____________ Ip = Vs Vp =Np
When a spinning atom creates a magnetic field this is called a
Magnetic moment
3 methods of electrification
1. Friction 2. Contact 3. Induction (2 wires)
x-ray units would divide it into:
1. main circuit (autotransformer & set up & rectifier etc.) 2. filament circuit
What is the unit of measurement for resistance?
Ohms (Ω)
What do Anode and Housing Cooling Charts do?
Prevent exceeding of heating capacities
What are main components of the tube ratings chart for a particular x-ray unit?
RPM (rotation per ..) rotor speed focal spot anode angle kvp exposure time generator type
What is the process of changing AC current to DC current? What types are shown?
Rectification 1. Full wave and 2. half wave
What do we call the opposition to electron or electricity movement in a circuit?
Resistance
Where would you find an AC motor in the x-ray circuit?
Rotating anode or stator
What do we call the induction of current in a conductor by passing alternating current through it? & What x-ray circuit device works on this principle?
Self induction & Autotransformer
What are the two types of circuits possible for electricity flow?
Series and Parallel
What do we call the transformer type that reduces voltage from primary to secondary coils or sides?
Step down (filament circuit) 3-5amps 6-12 volts (kvp)
Name two devices that work on mutual conduction principles
Step up and Step down transformers
If a meter is connected in a series circuit it measures
simple quantity of Amps or Volts (results after)
What do we call the transformer that increases voltage from primary to secondary sides?
step up
you need a ground for what reason in the x-ray circuit? location?
to prevent a spark (fire) the ground is located in the high voltage section
What is the unit of measurement for EMF?
volt
What two types of meters are seen in the x-ray circuit?
volt meter & amp meter
If a meter is connected in a parallel circuit it measures to and from a resistance device such as the xray tube it will measure voltage pressure as it compares the electrical flow between the two (to and from portions) of the circuit.
voltage to & from (pre-reading)
Electromagnetic induction
The production of electricity in conductors with the use of magnets.
Name the device that changes both voltage and amperage into higher or lower ratios based on the principles of mutual induction? & What type of current is required for its operation?
Transformer & AC
Solenoid
a coil of wire with an electric current in it
ammeter
a device used to measure current
if 1 reticfer fails you will no longer have? how many reticfers do you need for a full wave
a full way you will have a half way & only 50% of the reticfer will work 4
a material that allows for free movement of electrons
conductor
What does the Filament Circuit do?
contains the Filament step-down transformer to obtain the desire (amps/kvp) - Steps down incoming voltage -kvp (6-12) -amp (3-5)
What does the High Voltage Part of the X-ray Unit Circuit control?
current from autotransformer and converts from volts to kilovolts
movement of electrons between objects free movement of protons?
electricity / electrification not possible bc they are in the nucleus & tightly bound
ththe timing circuit in the control console of the x-ray circuit is usually what time of timer?
electronic
N and P-type crystals that control ____
flow of electrons in semi conductors
the steeper the anode angle = the bigger the
focal spot
the more anode is able to rotate the more
heat it can handle
the ma selector is located where?
high voltage section
What do Tube Rating Charts do?
indicate maximum safe settings (kvp & mas) to prevent overheating damage
prohibits the flow of electrons
insulator -wood -rubber -glass
What do the Rectifiers do for AC to DC Current?
it converts it to pulsating DC current in the high voltage section not present in self rectifying but in 3 phase, full wave, half wave
why will you see the ionization cambers
little exposure or w/ little kids
dioide
make current flow in 1 direction
Which has more than one pathway?
parallel this is better like Christmas tree light bc if not light bulb goes out not all of them go out
3 Phase AC
patterns such as "wye", "delta" or "star" that give 3 circuits with 3 armatures 120 degrees part with either 6 or 12 pulses per second?
Main switches and circuit breakers are present in____ in an x-ray unit. Circuit breakers also exist for___ and ____ controls. Exposure switches permit current to start, but ______ Timers ______ in accurately measured amounts of time (milliseconds)
power boxes table & tube doesn't end exposures end exposures
single phase
pulse AC 100% ripple voltage starting at zero then rising to its max then falling to zero then reversing directions and doing the same?
Rheostat
regulates amount of current flowing through equipment also called potentiometer
direction of current & direction electron flow is.. in DC
same direction
materials that can act both as a conductor and insulator and allow electricity to flow in only one direction
semi conductor -silicon
Which pathway for the circuit has one pathway?
series
What do we call the induction of electric current from one conductor to another conductor by passing AC current through it?
Mutual induction - the induction of electricity in a secondary coil by a moving magnetic field
How do High Frequency Generators operate?
Use AC and DC power converters to change incoming line voltage frequency form 60 Hz to between 500 and 25,000 Hz uses oscillator/chopper to create pulses but it never stops & never falls to 0 (gives you more output) you will not have alternating current
Ohm law
V= IR
What devices are used to rectify the AC to convert it to DC?
Valve or vacuum tubes (mini x-ray tubes) old type SCRs (silicon controlled rectifiers) or solid state rectifiers (thyristors) these are semi conductors and what are semi conductors: allowing current to flow in only one direction
What unit measures electical current?
ampere (A) current flowing
The kVp meter is set in _____ between the _____ and _______ is it a parallel or perpendicular circuit
auto transformer & step up transformer parallel
What is the transformer type that uses a single wire winding and can have varied (taps) to control ___
autotransformer to control small increases of current from the primary to secondary side
Synchronous Timers Electronic timers mAs timers AEC timers
manually set (60 cycles per sec) Times have to be multiples of 1/60 (ie. 1/30, ½, ¼ 1/10) (simple motor) Most common manual type - accurate to 1 millisecond delay 1 millisecond Commonly found on mobile units Highest possible safe mA is automatically selected for the kVp used. not controlled by tech Types of AEC devices or AECDs: (2) 1. Ionization chambers 2. Phototimers (fluorscent plate)
direction of current & direction electron flow is.. in AC
opposite
when we set kvp it controls high kvp =
the amount of coils used in the auto transformer =more coils used
Electromagnetism
the relationship between electricity and magnetism; magnetism produced by an electric current
spinning top test
the top is spin & every 60 pulses it would make a dot