test 1: circuits and xray tube

What type of machinery Do radiation therapists work with That is considered high frequency circuits

Linear accelerator

What type of circuit is CT Machine

Three phase circuits

What is the mAs

Amount of xray

Too much mAs does what to an image

too much amount of X-ray hitting imager and image looks dark

What is kVp

Quality (penetrating)

If u don't use enough kv

Not enough penetration so xray doesnt’t get thru patient

What happens if you don't use enough mAs

Patient will absorb the x-ray

What does a circuit convert?

X-ray circuits convert electric energy into x-ray energy

If you were to compare the electron flow in a Linear accelerator Which anatomy would you compare it to?

Veins and lymphatics because of the one-way valve

Do you have to set KV and mAs Before CT or on board imaging scans during radiation therapy, simulations or treatments

No, the table can detect the patient and use auto transformers to select the appropriate KV and mAs

Can you adjust the patient's mV From the one written in the prescription?

NO

What's the difference between an MeV and Mv in the patient's prescription?

MeV means the mega electron volts delivered in electrons For superficial stuffwhile Mv Is mega electron volts just delivered in photons for deep tissues

What are the other names for voltage?

Electrical pressure, Potential difference

What is a coulomb

s unit of electrical charge (6.2148 x 10^18 e

Direction of Electron Flow In an X-ray Tube

Electrons flow from the negative cathode to the positive anode.

Transformers

• Change low voltages to higher voltages

What does an auto transformer do?

Changes the voltage to step up or step down transformer

Step up transformer

Increases voltage

Step down transformer

Decrease voltage

What is the basis for x-ray production within radiographic equipment?

The direction of electron flow from the negative cathode to the positive anode

What is a circuit?

The complete path that electricity travels along

Linear accelerator run at how many hertz

3000 MHz

What are timing circuits?

Circuits that have timers on them that shut off the high-voltage to terminate the exposure

Shorter time circuits means

Less radiation exposure

What is the backup timer?

Back up timer that terminates the exposure when the backup time is reached

What are three types of transformers?

Auto transformer, Step up transformer, Step down transformer

operate at 3,000 Hz
CT units
Modern x-ray equipment

High frequency circuits

What happens if we increase kv

You increase the scatter, thus increasing unwanted dose to patient

What's A monitor unit

A reference field size of 10 × 10 A reference field size of 10 x 10, a distance of 100 cm So that one cgy =one monitor unit When you're delivering a dose of radiation To your patient

Automatic exposure control

measures the amount of radiation leaving the patient and turns off the x-ray beam when the correct amount has reached the detector

(In diagnostic xray monitor units is the equivalent of in therapeutic X-ray)

The cathode contains the

Filament (small/large)

The anode

Contains focal point where electrons r made

Cathode

Negative side of X-ray tube

What are the primary function of cathode

Roduces electrons and focus the electron stream towards metal anode

What are the parts of cathode

Filament, focusing cup

What is the filament made up of

Small wires made up of tungsten

current heats the filament, electrons are boiled off and are emitted from the filament

Thermionic emissions

The negative charge of the _____ helps direct electrons toward the anode to straighter less-divergent path

Focusing cup

What are the parts of the anode?

Composition, Target, Line focus principle

tungsten is on the anode On the____ which allows for dissipation of the high amount of heat

Rotor

Focal spot on target is where

Radiation is produced

Target is angled to

decrease the amount of heat produced while maintaining radiographic quality

Anode heel effect

Intensity variation in X-ray, more X-ray intensity at cathode end

Glass envelope

Glass cover of xray tube (r vaccummed sealed)

No air in the tube increases the efficiency of the tube y?

Because the removal of air from the glass envelope (x-ray tube) permits the uninterrupted flow of electrons from the cathode to anode

Unaffected by gravity ( no mass)

•Unaffected by electric fields

•Unaffected by magnetic fields

•Travel in straight lines

•Exponentially attenuated by matter

•Cannot be focused

True

Glass envelope

Establishes a vacuum

The anode is made up of

High density target material like tungsten or molybdenum

The cathode is

The source of electrons