Rad Review Jerry's Questions

Question 1

The formula for determining the heat units for a 3-phase, 6-pulse x0ray generator is?

Answer 1

kV x time x mA x 1.35

Question 2

The voltmeter, which reads the kVp selected, is located where in the radiographic circuit?

Answer 2

Between the autotransformer and step-up transformer

Question 3

How many rectifiers are required for a full-wave, 3-phase, 12-pulse x-ray generator?

Answer 3

Twelve

Question 4

During fluoroscopy, what is the range of mA used in the x-ray tube?

Answer 4

0.5-5 mA

Question 5

An exposure is taken with a spinning top on a single-phase, fully rectified x-ray generator at an exposure time of 1/30 sec. If the timer circuit is working properly, the radiograph should yield?

Answer 5

4 dots

Question 6

Why is it important for the x-ray tube to have a vacuum inside it?

Answer 6

This allows electrons to flow without any impedance

Question 7

A tube chart is used to

Answer 7

Provide a safe range of exposure factors that may be utilized

Question 8

Calculate the amount of heat units for the following single-phase, fully rectified unit
70 kVp; large focal spot; 8:1 portable grid; 20 mAs; 0.10 sec; 72” SID

Answer 8

1400 HU

Question 9

Which of the following methods are used to regulate the amount of thermionic emission that occurs at the filament?

Answer 9

Variable resistor

Question 10

Calculate the total resistance for the following circuit if the resisitors are connected in parallel.
5 ohms, 5 ohms, 20 ohms, 30 ohms

Answer 10

2.07 ohms

Question 11

Calculate power for the following series circuit:

20 amps, 3 resistores of 5 ohms, 3 ohms, and 6 ohms

Answer 11

5600 Watts

Question 12

How long does it take for the completion of one sine wave representing 60 hertz of current?

Answer 12

1/60 seconds

Question 13

According to the low of conservation of energy, voltage and amperage have which type of relationship across a transformer?

Answer 13

Inversely proportional to each other

Question 14

In the image intensifier, the anode serves to

Answer 14

Accelerate the electrons across the tube

Question 15

What component in the image intensifier allows images to be magnified?

Answer 15

Electrostatic focusing lens

Question 16

An x-ray tube has a heat storage capacity of 500,000 HU. How many rapid sequence exposures can be made at the following factors, before exceeding the capacity?
200 mA, 80 kVp, 0.4 sec, 30”SID

Answer 16

78

Question 17

The inverse square law relationship between intensity and distance from a source is based upon

Answer 17

Divergence

Question 18

Photomulitplers, thyratrons, and ionization chambers are devices used in

Answer 18

Automatic exposure devices

Question 19

The size of an object is 7”. The SID is 40”. The OID is 9”. What is the resultant size of the image?

Answer 19

9.03”

Question 20

When electrons approach the positive electrostatic field of the target, they are abruptly decelerated and lose energy. This energy is converted to

Answer 20

Bremsstrahlung radiation

Question 21

In the usual diagnositc kV range, insofar as energy absorption from the beam is concerned, which type of interaction between radiation and matter predominates?

Answer 21

Photoelectric effect

Question 22

In the x-ray circuit, the current flowing between the rectifier and the tube is

Answer 22

Pulsating DC

Question 23

In the exposure from an x-ray tube is 400 mR at a distance of 36 inches, what will the new exposure be at 50 inches using the same technique?

Answer 23

207 mR

Question 24

Which of the following statements is/are correct regarding the anode?
I. It is the positive pole
II. The electron cloud forms here
III. It may be stationary or rotating

Answer 24

I and III

Question 25

Minification gain occurs when

Answer 25

Electrons from the photocathode converge on the output screen

Question 26

A radiographic unit that requires an oscilloscope to detect voltage waveform irregularities would be

Answer 26

A 3-phase, 12-pulse unit

Question 27

The thickness of the tomographic section is determined by

Answer 27

Exposure angle

Question 28

The compton effect is characterized by

Answer 28

Part transfer of energy upon collision

Question 29

Gamma and x-radiation are the same in every way except

Answer 29

both do not have the same origin

Question 30

A radioactive source has a half-life of 7 hours. How many hours are required to reduce a 84-millicurie/hr. dose to a level of 5.25 milicuries/hr?

Answer 30

28 hours

Question 31

The basic reqard of the air-gap technique, improved contrast, relies on the following principle

Answer 31

Due to increased OID, the angle of the scatter will miss the film

Question 32

The M shell orbit in atomic formation is able to contain a maximum of

Answer 32

18 electrons

Question 33

X-rays produced from the movement of electrons from an outer shell to an inner shell is termed

Answer 33

Characteristic radiation

Question 34

The incident photon gives up all its energy to cause excitation; a new photon of the same energy is given off in a random direction

Answer 34

Unmodified scatter

Question 35

Produces an ion pair

Answer 35

Photoelectric effect and compton scatter

Question 36

Is responsible for true absorption

Answer 36

Photoelectric effect

Question 37

Is responsible for scattered radiation causing fogged film

Answer 37

Compton scatter

Question 38

Causes ionization in tissue

Answer 38

Photoelectric effect and compton scatter

Question 39

Concerned with only in therapy ranges of 1.02 or greater

Answer 39

Photodisintergration

Question 40

Incident photon with KeV greater than but close to the binding energy of outer shell electrons. Atomic number is high to increase probability.

Answer 40

Photoelectric effect

Question 41

Incident photon with KeV considerably greater than the binding energy of outer shell electrons

Answer 41

Compton scatter

Question 42

Results in true secondary radiation and energues characteristic of the binding energies of the shells involved

Answer 42

Photoelectric effect

Question 43

What is the efficiency of x-ray production, using a tungsten anode, at 90 kVp?

Answer 43

0.675%

Question 44

Faraday's Law is also referred to as the

Answer 44

Law of Electromagnetic Induction

Question 45

During a fluoroscopic procedure, the radiologist selects a smaller field-of-view, resulting in a magnified image on the TV monitor. How does this affect the amount of radiation that the patient receives?

Answer 45

It increases the amount of radiation the patient receives