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