Radtech Bootcamp Quiz Questions - Image production

The resistance of electric flow through a circuit is measured in?

Ohm Ω

What is the unit of electromotive force in a circuit?

Volt

What is the unit of electric current in a circuit?

Ampere

Force in a circuit is found by doing what?

mass multiplied by acceleration

A series circuit is a circuit in which components are connected?

To the power source end to end in a line

• Does not need to be in a shape or pattern. (Christmas lights) the circuit is a long string of lights that can be wrapped around any shape.

What is a disadvantage of a series circuit?

If one component fails, the whole circuit fails

*voltage drops do NOT cause a series circuit to fail

What remains constant in a series circuit?

Current

What is the formula for calculating the total resistance in a series circuit?

Total resistance (Rt) = Resistance 1 (R1) + Resistance 2 (R2) + Resistence 3 (R3)

*The total resistance in a series circuit is equal to the sum of all individual resistances

What is the total resistance (Rt) of a series circuit where the first resistance (R1) is 3 ohms Ω, the second is resistance (R2) is 2 Ω, and the third resistance (R3) is 5Ω?

10 Ω

*Rt = 3 + 2 + 5

In a series circuit, all resistors share which of the following?

Total voltage of the circuit (causes changes known as voltage drop)

What are joules a measure of?

energy or work and equaled force multiplied by distance

What is the equation to use when computing total voltage (VT) in a series circuit?

Total voltage (VT) = Voltage Drop 1 (V1) + Voltage Drop 2 (V2) + Voltage Drop 3 (V3)

Given a series circuit with a total current of 3 amps (A) and resistance one equal to 5 ohm Ω and resistance two equal to 2 Ω, what is the total voltage (VT) for the series circuit?

21 V

3 amps (A) x 5 ohms (Ω) = 15 volts (V)

3 A x 2 Ω = 6V

Then add the voltage drops together to determine the total voltage of the circuit

15 V = 6 V = 21 V

Given a series circuit with the resistances of 4 ohms Ω, 6 Ω and 10 Ω, what is the total resistance (Rt) of the circuit?

20Ω

Rt = 4Ω +6Ω+10Ω

Rt = 20Ω

Which of the following measurements remains constant in a parallel circuit?

Volts (V)

How is the total current (I) calculated for the following parallel circuit?

I = voltage (V) / resistance (R)

How are the components of a parallel circuit connected?

To the power source by a different path

Given a parallel circuit with a total voltage of 33 volts (V) what is the voltage at each resistor?

33 V

*Bc voltage Is constant in a parallel circuit, so voltage at each resistor is 33 volts

Which formula is used to find total resistance (Rt) in a parallel circuit?

1/Rt = 1/R1 = 1/R2 + 1/R3

Given a parallel circuit with a total voltage of 33 Volts (V) and a total resistance (Rt) of 1.5 ohms, what is the total current (I) of the circuit?

22 A

I=V/R

I=33/1.5

Given a pall circuit with a total resistance of 1.5 ohms, and a total current of 10 amps, what is the total voltage of the circuit

15 V

V=I x R

V=1.5 × 10

A circuit carrying a current of 20 amps (A) has a resistance of 5 ohm’s. What is th voltage across the circuit?

100

V= I x R

V = 20 × 5

V = 100

A dental xray machine has a current of 5 amps (A). If the voltage inside the unit is 60 volts (V), what is the resistance of the circuit?

12

What is the resistance of the circuit when the current is 15 amps (A) and the voltage is 180?

12

A circuit carrying a current of 70 amps (A) has a resistance of 12 Ohm’s. What is the voltage (V) within the circuit?

840

What is the resistance of a circuit that contains a current of 30 amps (A) and a voltage (V) of 690?

23

What is the relationship between current and voltage according to Ohm’s Law?

As current increases, voltage decreases

What is the relationship between current and resistance according to Ohm’s Law?

As current increases, resistance decreases

Voltage is best described as the

Force that pushes electrons through a circuit

Resistance is best described as the

Force that slows down electrons in a circuit

Current is best described as

Rate at which electrons flow through a circuit

Wha component of the xray tube is the source of free electrons?

cathode

What component of the xray tube is the source of xrays?

Anode

The term “space charge” within the xray tube refers to

free electrons

The space charge effect limits the functional milliamperage (mA) of the xray tube to approximately

1,000 mA

What is the principal advantage of using the large filament within a dual focus xray tube?

Increased heat capacity

Which of the following situations will require the use of the large filament within a dual focus xray tube?

Abdominal imaging on a bariatric patient

Which components of the xray tube diagram represents the electromagnets of the induction motor assembly?

Stators

The anode heel effect is defined as a variation in which of the following?

Beam quantity across the x-ray field

As a result of the anode heel effect, the anode side of the x-ray field demonstrates

Lower intensity

The use of an x-ray tube with a large anode angle results in what?

Increased focal spot size & increased heat capacity

What is the anode heel effect caused by?

X-ray absorption within the anode

Directing the anode side of the x-ray field towards the toes during an AP projection of the foot results in which of the following?

More uniform receptor exposure

The use of an x-ray tube with a small anode angle results un what?

Decreased focal spot size and decreased heat capacity

What is one of the following exposure modifications that will increase the anode heel effect?

Decreased source to image distance (SID)

When using a 14 × 17 inch exposure field, the intensity of the central ray measures 100 milligrams (mGy). What is the approximate intensity of the beam within the cathode side of the x-ray field?

120 mGy

The cathode side if the x-ray field us approximately 120 milligray (mGy). The cathode side is always higher intensity than the central ray, so this is the only logical answer

What is one potentially negative consequence of an increased anode angle?

Increased effective focal spot

What occurs when the anode angle decreases?

Effective focal spot size decreases and the heel effect increases

The source of x-ray emission within an x-ray tube is called the

actual focal spot

The area of the x-ray beam projected towards the patient is described as the

effective focal spot

The line focus principle describes the geometric relationship between which of the following factors within an x-ray tube?

Anode angle and the effective focal spot size

Which of the following anode angles with the same size actual focal spot can create a radiographic image demonstrating the highest spatial resolution

6 degrees

Which of the following anode angles with the same size actual focal spot can tolerate the highest technical setting without overheating?

2o degrees

When comparing a small anode angle to a large anode angle, a small anode angle with the same size focal spot will result in which of the following?

Increased spatial resolution and decreased anode heat capacity

Utilizing an x-ray tube with a large anode angle compared to a tube with a small angle and the same size actual focal spot will result in

Decreased spatial resolution and increased anode heat capacity

A radiographer has the choice of multiple radiographic systems, each using a different anode angle. Which system should be used if maximum spatial resolution is desired?

7 degrees

A radiographer has the choice of multiple radiographic systems, each using a different actual focal spot size. Which system should be used if maximum heat dissipation is required?

2.4 cm

Which component of the x-ray tube contains the focal spot>

Anode target

Off focus radiation is the product of electron interactions occurring within which three components of the x-ray tube?

1. Cathode assembly

2. Vacuum envelope

3. Anode disk

The loss of structural sharpness from off focus radiation within the primary beam us described as decreased

spatial resolution

What characteristic of off focus radiation results in a loss of structural sharpness in a radiographic image?

off focus radiation is out of alignment with the primary beam

The loss of visually distinct brightness level from off focus radiation within the primary beam is described as decreased

contrast

Which type of xrays create diagnostic information

primary

During the histogram process, the computer may identify off focus radiation as

Values of interest

What areas of an image should be shuttered?

Bright white and collimator shadows

The term “tube loading” refers to which of the following?

Heat energy created in the x-ray tube

Approximately what percentage of the electron energy is converted to heat at the anode during x-ray production.

99%

Which of following formulas express the total units created during a series of x-ray exposures?

Kilovolatge peak (Kvp) x milliamperafe (mA) x seconds (s) x waveform factor (W)

What is the waveform factor (W) for a three phase six pulse x-ray generator?

1.35

How many heat units (HU) are created from a single x-ray exposure using a single-phase x-ray machine with an exposure technique of 70 kilovolatge peak (KVP) and 25 milliampere seconds (mAs)

heat units = kVp x mAs x W

70 × 25 × 1 (single phase)

= 1,750 HU

How many heat units are created from a 20 second fluoroscopy study using a high frequency x-ray machine set at 110 kilovoltage peak (kVp) and 5 milliamperage (mA)

heat units = kVp x mAs x W

110 × 20 × 5 × 1.45 (high frequency)

=15,950

An acute abdomen series is completed with three exposure acquired at 80 kilovoltage peak (kVp) and 30 milliampere seconds (mAs) using a three phase six pulse machine. What is the total number of accumulated heat units (HU) for this series?

heat units = kVp x mAs x W

80 × 30 × 3 (exposures) × 1.35 (three phase six pulse)

=9,720

Which three of the following factors has an influence on the heat capacity of an x-ray tube?

• anode rotation speed

• focal spot size

• exposure time

What will increase the heat capacity of an x-ray tube?

Increased anode rotation speed

Technologists can reduce the chance of excessive heat production and x-ray tube damage by modifing the

Filament size

The production of x-rays at the anode target produces what percentage of heat?

99%. heat

The purpose of an anode cooling chart is to determine the proper amount of

Time before taking another exposure

An anode has a maximum of 40,000 heat units. One exposure of 10,000 heat units is produced. What are the remaining heat units available?

30,000

Taking exposures over the maximum heat units allowed without a cooling off period would result in

An overheated anode

Was would result in the largest amount of heat units, thus requiring the longest anode cooling time?

Routine abdomen series on a hypersthenic patient

What would result in the least amount of heat units and require the shortest anode cooling time?

1 posterior (PA) hand for bone age study

In an imaging system with a maximum heat unit of 40,000 which of the following combinations of exposures could be produced without a cooling off period?

2 consecutive exposures of 5,000 heat units each

On a system with a maximum of 40,000 heat units, which combination of consecutive exposures should not be taken because it would cause overheating the anode?

Exposure 1 - 40,000 heat units, Exposure 2 - 20,000 heat units

Within an electrical circuit, the term current refers to the

Movement of electrons through the circuit

Within an electrical circuit, the term voltage refers to the

Electrical force that creates movement in the circuit

The waveform of commercial power supply to the x-ray circuit is a (n)

Alternating current

What is the primary difference between direct current (DC) and alternating current (AC) within an electrical circuit?

Direction of electron flow

Which component of the x-ray circuit must be powered by alternating current (AC) in order to function correctly?

Transformers

To avoid damaging the x-ray tube components, the electrical power supplied to the x-ray current must be

Direct current

The difference in electrical charge between two points in a circuit is called the

Voltage

The rectifier(s) function within the x-ray circuit is to convert which of the following?

Alternating current (AC) to direct current (DC)

For the x-ray circuit to function properly, the rectifiers must be located between the

Step up transformer and the x-ray tube

Alternating current (AC) is best descried as a current that alternatives between

Positive and negatively polarity

A waveform with large gaps between positive voltage peaks Is a result of which of the following?

Half wave rectification

What type of rectifier is used in modern x-ray equipment

Diode

What type of rectification occurs when the negative voltage peak is inverted to positive voltage?

Full wave rectification

While servicing a manufacturing x-ray tube, the engineer observes that the x-ray tube is receiving alternating current (AC). What device within the x-ray tube circuit is likely responsible for this malfunction

Rectifier

Which three represent an acceptable power supplies for the x-ray tube portion of an x-ray circuit?

1. Half wave rectified alternating current (AC)

2. Full wave rectified alternating current (AC)

3. Direct current (DC)

A transformer operates on what principle?

Electromagnetic induction

Step up transformers affect voltage and amperage in which of the following ways?

Increase voltage and decrease amperage