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F24 125 Radiographic Process > Radiographic Process exam 1 > Flashcards

Radiographic Process exam 1 Flashcards

1
Q

What x-rays provide the useful information in an image?

A

Transmitted primary beam x-rays:

These are the x-rays that pass through the patient and hit the detector without being absorbed or scattered, providing the information needed to create the image.

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2
Q

What diagnostic image modality does not produce radiation, and instead use electromagnets?

A

MRI

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3
Q

What diagnostic modalities are normally used in clinic and operate at 50-150 kilo voltage range?

A

X-Ray & CT

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4
Q

Diagnostic kilovoltage imaging machines usually operate in what potential range?

A

50 to 150 kVp

Explanation: Diagnostic x-ray machines typically operate in this range to provide enough energy for effective imaging while minimizing patient exposure.

Sylvia’s Notes: 40 to 150 kVp came from W&L, Chapter 6, pg 108 - remember that kilovoltage ranges for x-ray application overlap and differ depending on the source.

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5
Q

Megavoltage energies are normally used to produce x-rays in what machines?

A

Linacs

Explanation: Linear accelerators (Linacs) are used in radiation therapy and operate at megavoltage energy levels (above 1 MeV), primarily for treatment, not for diagnostic imaging.

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6
Q

What percentage of the electron beam energy results in useful x-rays?

A

< 1%

Explanation: In diagnostic x-ray production using thick tungsten targets, less than 1% of the electron beam energy is converted into useful x-rays; most of the energy is lost as heat.

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7
Q

How does increasing mA affect radiation production?

A

Increases quantity

Explanation: Increasing mA (milliamperes) increases the number of x-rays produced (quantity), but it doesn’t affect the quality or energy of the x-rays.

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8
Q

How does increasing kVp affect radiation production?

A

Increases quantity and increases quality

Explanation: Increasing kVp (kilovolt peak) increases the energy (quality) of the x-rays and also increases the total number of x-rays (quantity).

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9
Q

What contrast agent(s) are commonly used in diagnostic x-ray imaging?

A

Air, Barium, and Iodine

Explanation: Common contrast agents include air (used for double contrast studies), barium (for gastrointestinal imaging), and iodine (for vascular and other types of imaging). Gadolinium is used in MRI, not x-ray imaging.

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10
Q

What contrast agent is NOT commonly used in diagnostic x-ray imaging, and is instead used in MRI?

A

Gadolinium

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11
Q

Filtration ____________ the average energy of the x-ray beam, and _____________ the x-ray beam quantity.

A

Increases; Decreases

Explanation: Filtration removes low-energy x-rays, which increases the average energy (quality) but reduces the total number of x-rays (quantity).

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12
Q

Attenuation is common in ______________ energy x-rays, as penetrability is common in ______________ energy x-rays.

A

Low; High

Explanation: Low-energy x-rays are more easily attenuated (absorbed or scattered), while high-energy x-rays have greater penetrability.

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13
Q

Radiation that has particles/photons with enough energy to cause an electron to become free from its atom is called what?

A

Ionizing

Explanation: Ionizing radiation has enough energy to remove an electron from an atom, leading to ionization, which is crucial in radiation therapy and imaging.

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14
Q

What happens in excitation?

A

the electron gains energy from the radiation like in ionization, but it is not enough to free the electron from the atom.

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15
Q

What is an electron’s mass-energy equivalent?

A

Explanation: The mass-energy equivalent of an electron is approximately 0.511 MeV, based on Einstein’s equation E=mc^2

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16
Q

Which is not another name for a photon?

A

Quark

Explanation: Quarks are fundamental particles that make up protons and neutrons, while photons are particles of light and electromagnetic radiation.

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17
Q

Which has the highest frequency and shortest wavelength?

A

Gamma rays

Explanation: Gamma rays have the highest frequency and shortest wavelength in the electromagnetic spectrum, exceeding that of ultraviolet light and visible light.

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18
Q

As wave frequency increases, wavelength?

A

Decreases

Explanation: Frequency and wavelength are inversely related; as frequency increases, the wavelength decreases.

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19
Q

Alpha decay

A

a particle of two neutrons and two protons is released from an unstable nucleus

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20
Q

Beta decay (electron) e- or B-

A

occurs when a neutron converts to a proton

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21
Q

Beta decay (positron) e+ or B+

A

occurs when a proton is converted to a neutron

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22
Q

What type of radioisotope would be used in PET imaging?

A

One that undergoes beta-positron decay

Explanation: PET imaging uses positron-emitting isotopes, which decay by beta-positron emission.

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23
Q

X-rays were discovered by _____________________ in the year ___________.

A

Wilhelm Roentgen; 1895

-designated them X for unknown
-first image of wife’s hand/wedding ring
-“I have seen my own death”!

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24
Q

Radioactivity was discovered by __________________

A

Henri Becquerel

Explanation: Henri Becquerel discovered radioactivity in 1896 while studying uranium salts.

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25
Q

In which direction to electrons travel in the X-Ray tube?

A

Electrons travel from the cathode (negative) to the anode (positive) in an x-ray tube.

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26
Q

What is kVp?

A

the kVp is the peak voltage applied between the anode and cathode

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27
Q

In what position is the target in the X-Ray tube?

A

the target is angled and rotating to increase its heat capacity

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28
Q

The purpose of the x-ray tube filament found in an x-ray circuit is to

A

create thermionic emission

Explanation: The filament heats up and emits electrons through thermionic emission, which are then accelerated to produce X-rays.

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29
Q

What is the difference between x-rays and gamma rays?

A

origin

Explanation: The main difference is their origin: X-rays are produced by electronic transitions in atoms, while gamma rays come from nuclear reactions.

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30
Q

The primary reason rotating anode tubes are used in diagnostic radiography is to increase what?

A

heat capacity

Explanation: Rotating anode tubes distribute heat more effectively, allowing for higher radiation output without overheating.

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31
Q

Which part of an atom has a +1 charge?

A

Proton

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32
Q

When electrons “jump” orbital energy levels, what is emitted?

A

Electromagnetic radiation/photons

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33
Q

Electromagnetic waves attributes?

A

Velocity, frequency, Wavelength, amplitude

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34
Q

What is another name for Photon Radiation

A

Electromagnetic wave

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35
Q

What is a Photon

A

an atom of light, also called a quantum. It is the smallest quantity of any type of electromagnetic energy.

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36
Q

At what speed do electromagnetic waves travel?

A

The Speed of light, in a vacuum

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37
Q

What does Wave-Particle Duality mean in relation to photons

A

it means photons can behave either like a particle or like a wave, but never simultaneously, it depends on the observation or experiment being conducted

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38
Q

Velocity

A

The speed of an electromagnetic wave, which is constant at 3 x 10^8 m/s.

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39
Q

Which electromagnetic waves are not detected by the human eye?

A

radio, infrared, ultraviolet rays, and x-rays.

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40
Q

Frequency

A

The rate of rise and fall, identified as cycles per second.

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41
Q

Amplitude

A

One-half the range from crest to valley over which the sine wave varies.

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42
Q

Wavelength

A

The distance from one crest to another, from one valley to another, or from any point on the sine wave to the next corresponding point.

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43
Q

The energy of a photon is _________________ to its frequency.

A

directly proportional

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44
Q

Which electromagnetic wave has a LONG wavelength?

A

Radio

which means their frequency DECREASES

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45
Q

The wavelength of a electromagnetic wave is_________________ to its frequency.

A

Inversely proportional

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46
Q

Visible Light, Ultraviolet,X-rays,Gamma Rays have short wavelengths, which means their frequency?

A

Increases

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47
Q

Because of their electron configuration, what do all atoms strive to be like?

A

Noble gasses

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48
Q

Atomic number Z is equal to what?

A

The number of protons

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49
Q

How is the atomic mass calculated?

A

The sum of the number of protons and neutrons

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50
Q

Radioactive decay is a process by which radionuclides try to become stable by emitting what?

A

Energy and particles

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51
Q

How many half-lives would it take for a radioactive material to reach less than 1%?

A

7

Because: start at 100%
1) 50%
2) 25%
3) 12.5%
4) 6.25%
5) 3.125%
6) 1.56%
7) 0.78%

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52
Q

What is Half-Value Layer (HVL) in radiation?

A

The Half-Value Layer (HVL) is the thickness of a material required to reduce the intensity of a radiation beam to half of its original value.

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53
Q

What is Intensity in radiation?

A

Intensity refers to the amount of energy a radiation beam delivers per unit area, and it decreases as the distance from the source increases, following the inverse square law.

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54
Q

A positron is considered

A

a form of antimatter

Because when they collide with an electron they cancel eachother out and form a gamma particle.

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55
Q

When an electron is removed from an atom, the atom is said to be:

A

ionized

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56
Q

Absorbed Dose

A

the amount of energy absorbed per mass of any material while radiation interacts in the material.

“Not limited to air. Traditional unit is the Rad, while SI unit is the Gray (Gy).”

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57
Q

Air KERMA

A

(Kinetic Energy Released per unit Mass in a medium at a specified point of interest) refers to the response of air to radiation, similar to roentgen.

“Measured in units of joules/kg, which is called gray (Gy).”

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58
Q

Exposure

A

the amount of ionization produced by photons in air per unit mass of air.

“Only applies to photons (x-rays and gamma rays) and only applies to interactions in air.”

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59
Q

Skin Erythema Dose

A

The amount of radiation necessary to barely perceptibly redden the skin of a light-skinned person.

the very first radiation unit of measurement?

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60
Q

Equivalent Dose

A

is an attempt to account for the biologic effects of different types of radiations as they interact in tissue.

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61
Q

Activity

A

the number of radioactive disintegrations per unit of time.

“Originally based on 1 g of radium in equilibrium with its daughter products.”

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62
Q

Background radiation (accounts for approximately what % of exposure)

A

50%

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63
Q

Medical Exposure to radiation accounts for what % of yearly exposure

A

(15% of total in 1987, 48% in 2009, and estimated to be close to natural background in 2021)

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64
Q

Treatment Room Safety Devices:

A

Door Interlocks
Safety Edges
Warning Lights
Visual and Auditory Communication
Cameras and intercom
Emergency Power-Off Switches

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65
Q

ALARA

A

As Low As Reasonably Achievable

Time: Less time means less exposure.
Distance: Increasing distance will reduce exposure.
Shielding: Protection reduces exposure.

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66
Q

Therapist Radiation Safety

A

-Always wear your radiation badge.

-Do not stand by the treatment room door.

-Do not remain in the room during any diagnostic imaging scan or during any radiation treatment session.

-Following brachytherapy, the physicist with a Geiger counter should enter the room first and confirm it is safe.

-Practice ALARA.

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67
Q

Pregnant Radiation Patients Precautions

A

-Ask patients if they are currently pregnant or trying to get pregnant before creating a radiation treatment plan.

-If the answer is yes, inform the doctor and have the patient take a pregnancy test.

-Do not image on a CT scanner without informing the doctor and getting permission to proceed.

-Do not treat without informing the doctor and getting permission to proceed.

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68
Q

Dose to Fetus/Embryo

A

Must not exceed 5 mSv during the entire pregnancy.

Recommendation is that fetus receive no more than 0.5 mSv per month.

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69
Q

Film Badge

A

A piece of film in a light-tight wrapper. Exposure darkens the film. After exposure, the film is compared to a base for changes in optical density.

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70
Q

Thermoluminescent Dosimeters (TLD)

A

The most common crystalline structure is made from lithium fluoride (LiF). After use, the crystals are heated and release energy as light. The light is proportional to radiation exposure.

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71
Q

Optically Stimulated Luminescence Dosimeters (OSL)

A

Crystal structure is measured by a laser. They are starting to replace film badges.

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72
Q

Phantom

A

A phantom is a mass of material similar to human tissue used to investigate the effect of radiation beams on human beings.

Materials: Can range from water to complex chemical mixtures that faithfully mimic the human body as it would interact with radiation.

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73
Q

Gas Ionization Detectors

A

Read exposure per unit of time. Most well-known type is the Geiger-Muller Counter, which is sensitive for a gas ionization detector.

Use: Best for locating contamination and low levels of radiation.

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74
Q

Solid-State (Scintillation) Detectors

A

Thermoluminescent and optically stimulated luminescence dosimeters use crystals and can be reused after getting an exposure reading.

Use: Best for finding lost sources and detecting low levels of radiation.

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75
Q

Solid-State (Diode) Detectors

A

Diodes are small, solid-state devices that are used to confirm the photon radiation output of the Linac.

Use: Give real-time readings.

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76
Q

Neutron Survey Meters

A

Specifically used to detect neutrons.

Use: Only necessary when radiation energy is above 10 MV

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77
Q

Medical Reportable Patient Events

A

Events that result in a dose that differs from the prescribed dose by 20% or more, or falls outside the prescribed dosage range.

Examples:
Wrong radioactive drug
Wrong patient
Wrong mode of treatment
Wrong anatomical area on patient
Source leakage

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78
Q

Practical Precautions to Avoid Mistakes

A

Timeout: Make sure you have the correct patient.

Treatment Plan: Make sure you have loaded the correct treatment plan.

Accuracy: Treat patients carefully and accurately.

Distractions: Avoid distractions while treating (HOBO: Hold On, Beam is On).

Charts: Check charts for potential errors that could lead to a misadministration.

Prescription: Check for changes to the prescription which could alter the treatment plan.

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79
Q

Annual Occupational Dose Limits

A

50 mSv (5000 mrem): Total effective dose equivalent

500 mSv (50 rems): Deep dose equivalent + committed dose equivalent to any organ or tissue (except eye)

150 mSv (15 rem): Lens of the eye

500 mSv: Shallow dose to skin or extremities

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80
Q

Dose to Individual Members of the Public

A

1.0 mSv (100 mrem): Total effective dose equivalent

0.02 mSv: Dose equivalent in any unrestricted area (per hour)

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81
Q

Risks to Fetus/Embryo

A

Growth retardation

Pre-natal or neonatal death

Congenital malformation

Mental retardation

Childhood cancer (primarily leukemia)

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82
Q

Pregnant Radiation Therapists Precautions:

A

Wear a second radiation badge (fetal monitor) at the waist level.

Wear a lead apron if dealing with live or natural brachytherapy sources.

Do not enter the CT room while it is still running.

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83
Q

Workload and Use & Occupancy Factors

A

Workload: Essentially how many patients will be treated and/or the time the Linac will be in use

Use: How much the primary beam will be pointed at area to be shielded (25% is often considered a normal percentage)

Occupancy: Considers the probability of occupancy of the area to be shielded## Radiation Safety Principles

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84
Q

Time

A

The amount of time an area protected by shielding is in use. The occupancy factor for controlled areas must always be 1.

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85
Q

Distance

A

The further the walls and ceilings are from the Linac, the less radiation they will receive. Consider the inverse square formula

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86
Q

Shielding

A

Protection reduces exposure.

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87
Q

Primary Barrier Walls

A

Wall and/or ceiling with which the primary radiation beam can make contact

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88
Q

Secondary Barrier Walls

A

Walls that only have to deal with leakage radiation and scatter radiation

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89
Q

The Maze

A

Reduces radiation levels at the door

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90
Q

Hertz

A

Hertz (Hz) is the unit of frequency, measuring the number of cycles per second of a wave.

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91
Q

Planck’s constant

A

Planck’s constant (h) is 6.626 x 10⁻³⁴ joule-seconds (J·s), relating the energy of a photon to its frequency.

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92
Q

Curie (Ci)

A

Traditional unit=3.7 x 10^10 Bq disintegrations / second

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93
Q

Becquerel (Bq)

A

SI unit, 1 disintegration / second

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94
Q

Rem

A

Traditional unit, absorbed dose in rads multiplied by quality factor

Rem (Roentgen Equivalent Man) is an older unit used to measure the biological effects of ionizing radiation, where 1 rem = 0.01 sievert (Sv).

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95
Q

Sievert (Sv)

A

SI unit, absorbed dose in Gy multiplied by quality factor

Sievert (Sv) is the unit used to measure the biological effect of radiation, taking into account the type of radiation and its impact on living tissue.

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96
Q

1 Rad

A

Rad is an older unit of absorbed radiation dose, where 1 rad = 0.01 gray (Gy).

1 rad = 100 erg/g

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97
Q

Gray (Gy)

A

Gray is the unit of absorbed radiation dose, equivalent to one joule of radiation energy absorbed per kilogram of matter.

1 Gy = 1 J/Kg = 100 rads

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98
Q

Erg

A

Unit of energy

1.6x10^-12=1eV

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99
Q

Joule (J)

A

Unit of energy

1eV=1.6x10^-19 J

1J=6.24x10^18 eV

100
Q

Roentgen (R)

A

1 R = 2.58 x 10^-4 coulomb of charge per kilogram (kg) of air

101
Q

Coulomb (C)

A

Unit of charge

one unit of charge is 1.6x10^19 Coulombs

102
Q

What is Radioactive decay?

A

Radioactive decay is the process by which an unstable atomic nucleus loses energy by emitting radiation.

103
Q

What types of radiation are emitted when a nucleus undergoes radioactive decay?

A

Alpha, beta, and gamma radiation are commonly emitted during radioactive decay.

104
Q

How do kVp and mAs affect quality and quantity?

A
  • kVp (kilovoltage peak): Affects the quality (penetrability) of the radiation beam.
  • mAs (milliampere-seconds): Affects the quantity (number of photons/x-rays) of the radiation beam.
105
Q

What type of radiation does more biological damage?

A

Higher linear energy transfer (LET) radiations like alpha particles do more biological damage compared to low LET radiations like x-rays and gamma rays.

106
Q

What are atoms called when they gain energy?

A

Excited atoms aka excitation

107
Q

What do you call an atom that loses an electron?

A

An ion (specifically, a positive ion).

108
Q

Define Hertz.

A

Hertz (Hz) is the unit of frequency, measuring cycles per second.

109
Q

Define Ionizing radiation

A

Ionizing radiation is radiation with enough energy to remove tightly bound electrons from atoms, thus creating ions.

110
Q

What are the components of an X-ray tube?

A
  • Anode (positive)
  • Cathode (negative)
  • Rotor/Stator
  • Target (often tungsten)
  • Filament (coil)
  • Focusing cup
  • Housing
  • Heel effect
  • Window
111
Q

What is Thermionic emission?

A

Thermionic emission is the release of electrons from a heated filament (in the X-ray tube’s cathode) used to create X-rays.

112
Q

Who discovered Radioactivity?

A

Becquerel

113
Q

What is the Inverse Square Law in radiation?

A

The intensity of radiation is inversely proportional to the square of the distance from the source of radiation.

114
Q

How are Rad & Gray related?

A

1 Gray (Gy) is equal to 100 rad, both are units measuring absorbed radiation dose.

115
Q

What is Characteristic radiation?

A

Characteristic radiation occurs when an electron from an outer shell fills a vacancy in an inner shell of an atom, releasing energy in the form of X-rays.

116
Q

What is Bremsstrahlung radiation?

A

Bremsstrahlung radiation is produced when a high-speed electron is deflected by the electric field of a nucleus, causing it to lose energy, which is emitted as X-rays.

117
Q

What is Coherent scattering?

A

Coherent scattering occurs when an incoming low-energy X-ray photon interacts with an atom, causing the photon to change direction without losing energy.

118
Q

What is Pair production?

A

Pair production occurs when a high-energy photon (above 1.02 MeV) interacts with a nucleus, resulting in the creation of an electron-positron pair.

119
Q

What is the Photoelectric effect?

A

The photoelectric effect is the absorption of an X-ray photon by an atom, causing the ejection of an electron from the atom’s inner shell.

120
Q

What is Photodisintegration?

A

Photodisintegration occurs when a high-energy photon (above 10 MeV) is absorbed by a nucleus, resulting in the emission of nuclear particles like neutrons.

121
Q

What radioactive elements did Curie work with?

A

Marie Curie is best known for her discovery of the elements polonium and radium while researching radioactive materials.

Curie was the first woman to win a Nobel & the only person to win twice.

122
Q

How are Quality and Quantity affected by filtration in radiographic processes?

A
  • Quality: Filtration increases the quality (average energy) of the X-ray beam by removing lower-energy (softer) photons, making the beam more penetrating.
  • Quantity: Filtration reduces the quantity of the X-ray beam by removing some photons from the beam, thus reducing the overall intensity or number of X-rays.
123
Q

Front: What are the effects of Quality and Quantity on radiation beam photons?

A

Quality: Higher quality (higher energy) increases the average energy of photons.

Quantity: More photons are produced with higher quantity (increased mAs).

124
Q

What are the effects of Quality and Quantity on penetrability?

A

Quality: Higher quality increases the penetrability of the beam, allowing it to pass through tissues more easily.

Quantity: Quantity does not directly affect penetrability, as it only affects the number of photons, not their energy.

125
Q

What are the effects of Quality and Quantity on patient dose?

A

Quality: Higher quality (higher energy) reduces patient dose for a given image, as fewer photons are absorbed by the patient.

Quantity: Increased quantity increases the patient dose since more photons interact with the patient’s tissues.

126
Q

What do all atoms want to be like, and why?

A
  • All atoms want to be stable like noble gases (elements in Group 18 of the periodic table).
  • Atoms achieve stability by having a full outer electron shell, which minimizes their potential energy. Atoms will gain, lose, or share electrons to achieve this stable configuration.
127
Q

What units are used to measure an electron’s binding energy?

A
  • An electron’s binding energy is measured in electron volts (eV) or kiloelectron volts (keV), where 1 keV equals 1,000 eV.
128
Q

Non-ionizing radiation

A

Non-ionizing radiation refers to radiation that does not have enough energy to ionize atoms, examples include radio waves and microwaves.

129
Q

Directly ionizing

A

Directly ionizing radiation consists of charged particles (such as electrons or protons) that can ionize atoms directly by interacting with their electrons.

130
Q

Indirectly ionizing

A

Indirectly ionizing radiation includes uncharged particles (such as neutrons or photons) that ionize atoms by creating secondary charged particles.

131
Q

Absorption

A

Absorption is the process by which radiation energy is absorbed by matter, such as tissues in the body, reducing the intensity of the radiation beam.

132
Q

Attenuation

A

Attenuation is the reduction in the intensity of a radiation beam as it passes through matter, due to absorption and scattering.

133
Q

Electron Volt

A

An electron volt (eV) is a unit of energy equal to the amount of kinetic energy gained or lost by an electron when it moves through an electric potential difference of one volt.

134
Q

How does radiolysis relate to indirectly ionizing radiation?

A
  • Indirectly ionizing radiation (such as X-rays or gamma rays) can cause water splitting (radiolysis) by creating secondary charged particles (e.g., free radicals).
  • These free radicals, produced from water molecules, can cause further chemical reactions that damage biological tissues, including DNA.
  • The primary free radicals produced during the radiolysis of water are:
    Hydroxyl radical (OH)
    Hydrogen radical (H    )
    Hydrogen peroxide (H₂O₂) (not a radical but a reactive product)
    Hydrated electron (e⁻aq)
135
Q

Energy range for Diagnostic X-rays

A

40 to 150 kVp (used in quiz)

or

10 to 50 keV (on slide)

or

20 to 120 kVp (on slide)

136
Q

Energy range for Orthovoltage X-rays

A

150 to 300 kVp

137
Q

Energy range for Megavoltage radiation

A

Above 1 MV (1 million volts)

138
Q

Energy range for Therapeutic radiation

A

(50 keV to 25 MeV).

or

1 MV to 25 MV or higher

139
Q

Energy range for Superficial X-rays

A

50 to 150 kVp (treat skin conditions)

140
Q

What is the difference between kVp & keV.

A

kVp: short for kilovolts-peak, is the potential difference across the tube and is usually quoted in terms of the maximum value in units of 1000 volts.

keV: is a measure of kinetic energy, the energy that an electron gains when it travels through a potential of one thousand volt.

141
Q

define voltage

A

is a unit for electrical potential difference between two points

142
Q

Quality/Weighting Factors

A
  • X-ray photons: 1
  • Gamma ray photons: 1
  • Electrons: 1
  • Beta particles: 1
  • Protons & Pions: 2
  • Thermal neutrons: 5
  • Neutrons (general): 10
  • High-energy protons: 10
  • Fast neutrons: 20
  • Alpha particles: 20
  • Heavy recoil nuclei: 20
143
Q

Convert 10 rads of X-rays to Sieverts using quality factor

A
  • Step 1: Identify the quality factor for X-rays = 1
  • Step 2: Multiply the dose in rads by the quality factor
    10 rads × 1 = 10 rem
  • Step 3: Convert rem to Sieverts
    1 rem = 0.01 Sv
    10 rem × 0.01 = 0.1 Sv
144
Q

Convert 5 rads of fast neutrons to Sieverts using quality factor

A
  • Step 1: Identify the quality factor for fast neutrons = 20
  • Step 2: Multiply the dose in rads by the quality factor
    5 rads × 20 = 100 rem
  • Step 3: Convert rem to Sieverts
    1 rem = 0.01 Sv
    100 rem × 0.01 = 1 Sv
145
Q

Convert 8 rads of alpha particles to Sieverts using quality factor

A
  • Step 1: Identify the quality factor for alpha particles = 20
  • Step 2: Multiply the dose in rads by the quality factor
    8 rads × 20 = 160 rem
  • Step 3: Convert rem to Sieverts
    1 rem = 0.01 Sv
    160 rem × 0.01 = 1.6 Sv
146
Q

Convert 2500 rad to Gray (Gy)

A
  • Step 1: Recall that 1 Gray = 100 rad
  • Step 2: Divide rad by 100 to get Gray

2500 rad ÷ 100 = 25 Gy

147
Q

Convert 0.75 Gray to rad

A
  • Step 1: Recall that 1 Gray = 100 rad
  • Step 2: Multiply Gray by 100 to get rad

0.75 Gy × 100 = 75 rad

148
Q

Convert 1500 curies to becquerels (Bq)

A
  • Step 1: Recall that 1 curie = 3.7 × 10¹⁰ Bq
  • Step 2: Multiply curies by 3.7 × 10¹⁰

1500 curies × 3.7 × 10¹⁰ = 5.55 × 10¹³ Bq

149
Q

Convert 2.5 becquerels (Bq) to curies

A
  • Step 1: Recall that 1 curie = 3.7 × 10¹⁰ Bq
  • Step 2: Divide becquerels by 3.7 × 10¹⁰

2.5 Bq ÷ 3.7 × 10¹⁰ = 6.76 × 10⁻¹¹ curies

150
Q

How does the peak of the emission spectrum affect the quality of radiation?

A

The higher the peak of the emission spectrum, the more energetic (higher quality) the X-rays, leading to greater penetrability.

151
Q

How does a change in mAs or kVp shift the amplitude of the emission spectrum?

A
  • Increasing mAs: Shifts the amplitude upwards (increasing the number of X-rays produced).
  • Increasing kVp: Shifts the amplitude upwards and to the right (increasing both the number and energy of X-rays produced).
152
Q

Do electrons closer to the nucleus have more or less binding energy than those farther away?

A

Electrons closer to the nucleus have greater binding energy but less individual energy than electrons farther away.

153
Q

What is binding energy measured in?

A

Binding energy is measured in electron volts (eV) or kiloelectron volts (keV).

154
Q

What type of decay does uranium undergo when producing daughter particles?

A

Uranium primarily undergoes alpha decay, where it emits alpha particles (2 protons and 2 neutrons).

155
Q

What are the three primary ways that naturally occurring radioactive materials decay?

A
  • Alpha decay (emission of an alpha particle) 2 protons & 2 neutrons aka Helium
  • Beta decay (emission of an electron or positron) e- or e+
  • Gamma decay (emission of gamma radiation)
156
Q

What kind of decay involves neutrons becoming protons?

A

Beta minus decay involves a neutron transforming into a proton while emitting a beta particle (electron) and an antineutrino.

157
Q

What is a high voltage generator

A
  • Responsible for increasing the output voltage and necessary differential in kVp to accelerate electrons between the cathode and anode with enough energy and quantity for x-ray production
  • The generator also must supply the voltage to the filament for thermionic emission.
158
Q

What are the three fundamental quantities of radiographic exposure set by the generator?

A

1.Tube voltage (measured in
kilovolt peak (kVp))
2.Tube current (measured in
milliamperes (mA))
3.Time of the exposure (usually
measured in seconds (s))
* This is accomplished using a
transformer

159
Q

How can a single power source supply low voltage to the filament and high voltage to the anode in an X-ray tube?

A

through the use of transformers:

Step-down transformer: Reduces the voltage to supply the low voltage needed for the filament (typically 10-12 volts) to heat it and create thermionic emission.

Step-up transformer: Increases the voltage to supply the high voltage required for the anode (thousands of volts, or kilovolts) to accelerate electrons from the cathode to the anode, producing X-rays.

160
Q

Transformers

A
  • Change the intensity of alternating voltage and current
  • Only works within AC circuits, not DC circuits
161
Q

Step-Up Transformers

A

Transformers with a turns ratio >1 is a step-up transformer because voltage is increased

Current decreases

Step-up transformer supplies the anode side to create a high potential difference

162
Q

Step-down Transformers

A

*Transformers with a turns
ratio <1 is a step-down
transformer because
voltage is decreased

*Current increases

  • Step-down transformer
    supplies the filament
163
Q

Voltage Rectification

A

*The rectifier converts the AC voltage that has passed through the
transformer into DC voltage.

*Think of it as a check valve in a plumbing system, or the valves in
the body’s veins.

164
Q

Cathode Filament

A

*Emits electrons when heated by
“boiling off” outer-shell electrons of
the filament, like a toaster wire
*This process is thermionic emission
*Filaments usually made of thoriated
tungsten
*Most rotating anode x-ray tubes
have two filaments mounted in the
cathode creating large and small
focal spot sizes

165
Q

What can form around the filament in an X-ray tube?

A

A space charge can form around the filament. This is a cloud of electrons that are emitted from the heated filament during thermionic emission. These electrons gather near the filament before being accelerated toward the anode when high voltage is applied.

166
Q

Cathode Focusing Cup

A

*Metal cup surrounding the filament

*Cup is negatively charged to
confine the electron beam

*Because all the electrons
accelerated from cathode to anode
are negative, the electron beam
tends to spread outward

*Like charges repel each other, so
the neg. charged focusing cup
contains the spreading electrons

167
Q

The number of electrons emitted by the filament is determined by?

A

temperature of the filament

As the filament current increases, the filament becomes hotter and
more electrons are released

168
Q

Operating Console

A
  • Allows control of the x-ray
    tube current and voltage so
    that the useful beam is of
    proper quantity and quality
  • Usually provides for control of
    line compensation, kVp, mA,
    and exposure time
169
Q

Radiation Quality

A
  • Refers to the penetrability of the x-ray beam
  • Expressed in kilovolt peak (kVp), or more precisely, half-value layer
    (HVL)
170
Q

Radiation Quantity

A
  • Refers to the number of x-rays or the intensity of the x-ray beam
  • Usually expressed in milliampere-second (mAs)
171
Q

Anode

A

The positive side of the x-ray tube; it conducts electricity and
radiates heat and contains the target

172
Q

What two types of Anodes are there?

A

stationary & rotating

Stationary anodes are units in which high tube current and power
are not required (ex. dentistry)

173
Q

What type of Anode do general purpose X-ray tubes use?

A

rotating anode

174
Q

In the Anode more than 99% of electron kinetic energy is converted into?

A

Heat

175
Q

What are the most common anode materials?

A

Copper, molybdenum, and graphite

176
Q

Target

A

The area of the anode struck by electrons from the cathode

In rotating anode tubes, the entire rotating disk is the target

177
Q

What are targets usually made out of & why?

A

Targets are made of tungsten due to:
* Atomic number – is high (74), resulting in high-efficiency x-ray production and high-energy x-rays

  • Thermal conductivity – nearly equal to copper, and is efficient at dissipating the heat produced
  • High melting point – 3400 degrees Celsius and can stand up under high tube current
178
Q

Why rotate the Anode?

A
  • Allows electron beam to interact with a much larger target area
    Heating of the anode isn’t confined to one small spot
179
Q

Treatment linear accelerators generate radiation via?

A

Electricity

not radioactive material (ignore the antiquated Co-60 machines)

180
Q

In an atom, the number of
neutrons determines the?

A

isotope

Some isotopes are unstable and give off energy (i.e., decay) to become more stable. In this context, an unstable atom is said to be “radioactive,” and the energy it releases is referred to as “radiation.”

181
Q

Radioactivity Stated Another Way

A
  • Radioactivity results when unstable nuclei attempt to minimize their
    energy (make it as negative as possible) thus becoming more tightly bound.

The “parent” nucleus undergoes a spontaneous transformation into a
“daughter” nucleus. Remember that all atoms want to become stable like
the noble elements.

182
Q

Radionuclides

A

unstable atoms that are trying to seek a ground state, one that the nuclear force can maintain

183
Q

Gamma Rays

A

These are high energy photons
(neutral).

Any photons emitted by nuclei or in
electron-positron annihilation are
called gamma rays.

High-energy photons from other
sources are called x-rays.
Note: The distinction is one of
origin, not energy.

An x-ray photon may have more
energy than a gamma-ray photon or
vice versa.

184
Q

Only heavy radioisotopes like radium, uranium, or plutonium are capable of?

A

alpha decay

185
Q

proton is converted into a neutron in?

A

positron beta emission

186
Q

neutron is converted to a proton in?

A

(electron) negatron beta emission

187
Q

In both types of beta decay, what becomes of the atom as a whole

A

It becomes a new element

188
Q

What term do we apply to matter like a β+?

A

positron

189
Q

In both types of beta decay, what is released

A

the antiparticle/neutrino.

190
Q

Beta decay occurs much more frequently than alpha decay

A

True

191
Q

The average energy of an emitted β particle is what % of its maximum energy?

A

30-40%

192
Q

Positrons (β+) rapidly lose kinetic energy and are stopped within?

A

approximately 0.5 mm of the site of emission in tissue.

193
Q

What type of decay is used in positron emission tomography (PET scans)?

A

Beta Decay

Positron detection reveals where the radionuclide was taken up within the body

Cancerous tissue uptakes the radionuclides either more than or less than normal
tissue resulting in “hot spots” or “cold spots” respectively on a PET scan

194
Q

Electron Capture Decay

A
  • As an alternative to positron emission (β+ decay), the nucleus of a proton-rich atom may capture one of its own inner shell electrons via electron capture
  • The captured electron combines with a proton in the nucleus to produce a neutron (that stays in the nucleus) and a neutrino (which is emitted with kinetic energy)
195
Q

What happens to an atom after electron capture decay? What does the atom become?

A

After electron capture decay, the atom becomes a different element. The nucleus captures an inner electron, which combines with a proton to form a neutron. This process decreases the atomic number by 1, transforming the atom into a new element with one less proton while keeping the atomic mass the same.

196
Q

On what radioactive material was the curie (Ci) radioactive unit based?

A

The curie (Ci) unit was originally based on the radioactive decay of radium-226. One curie is defined as the amount of radiation emitted by 1 gram of radium-226, which is equal to 3.7 × 10¹⁰ disintegrations per second.

197
Q

Radioactive Activity Formula

A
  • A = Aoe-λt
  • In this formula, the symbols are defined as…
  • A = Activity remaining in the radioactive material after time (t) from when the initial
    activity was measured (at time of purchase)
  • Ao = Initial Activity of the radioactive material (time of purchase)
  • e = Base of the natural logarithm
  • λ = Decay constant (ln2/T½)
  • t = Time (in days) since the initial activity was measured
  • In order to calculate a radioactive material’s current activity one needs to know the
    materials initial activity (Ao) at some point in time, the half-life of the isotope in days
    (T½) and the time in days (t) since the initial activity was measured. The (–) means
    exponential decay
198
Q

Activity

A
  • The emission of ionizing radiation or particles caused by the
    spontaneous disintegration of atomic nuclei.
  • Given sufficient information it is possible to calculate the original
    or remaining radiation from a source of radioactive material.
199
Q

True or False?

Radioisotopes disintegrate at a decreasing rate so that the quantity of radioactive material never quite reaches 0 in actuality.

A

TRUE

200
Q

What is the most common isotope used in diagnostic imaging?

A

Technetium-99m (99mTc)

201
Q

What are the most common isotopes used in Brachytherapy?

A

*Palladium-103 (103Pd)
*Iodine-125 (125I)
*Cesium-137 (137Cs)
*Iridium-192 (192Ir) are all commonly used in brachytherapy

202
Q

X-ray Tube Failure Due to Heat

A

Enormous heat is generated in the anode during x-ray exposure

Heat can be dissipated through radiation, conduction, or
convection

All 3 modes of heat transfer occur in x-ray tube, with most of the
heat dissipated by radiation during exposure

If the temperature of the anode increases too rapidly, the anode
may crack

The anode should be warmed first by low-technique operation

203
Q

Induction Motor in X-Ray Tube

A

*Used to turn the anode inside the
enclosure

*Outside the enclosure is the stator,
which consists of a series of
electromagnets

*Inside is a shaft made of bars of copper and soft iron called the rotor

*Stator energizes sequentially so that the induced magnet field rotates on the axis of the stator

204
Q

Line-focus Principle in X-Ray Tube

A

Focal spot – area of the target from which x-rays are emitted

The smaller the focal spot, the better the spatial resolution of the image

But as focal spot size decreases, the heating of the target is concentrated
onto a smaller area, which is the limiting factor to focal spot size

*Line-focus principle allows for a larger area to be heated while maintaining a small focal spot by angling the target

  • Diagnostic x-rays have target angles that vary from 5-20 degrees
  • Limiting factor in target angle is the ability of the cone of x-rays
    produced to adequately cover the largest field size used

Line-focus principle improves spatial resolution and heat capacity

205
Q

Heel Effect

A

One unfortunate consequence of the line-focus principle is that the
radiation intensity on the cathode side of the x-ray field is greater than
on the anode side

The useful beam on the anode side must traverse a greater thickness of
target material than the x-rays emitted toward the cathode

Intensity of x-rays emitted through the “heel” of the target is reduced
because they have a longer path through the target and suffer increased absorption = heel effect

The smaller the anode angle, the larger the heel effect

Positioning the cathode side of the x-ray tube over the thicker part of the anatomy provides more uniform radiation exposure of the image receptor

206
Q

Penumbra

A

Geographical penumbra is an optical property of electromagnetic radiation

  • Seen on portal film as the fuzzy edge next to the dark shadow
  • A large penumbra causes problems because a larger field size must be used to cover the tumor with a uniform dose, which results in irradiating more healthy tissue
  • The smaller the penumbra, the more radiation is confined to just the tumor
207
Q

What does Bremsstrahlung mean?

A

Bremsstrahlung is a German word that means “braking radiation.” It refers to the radiation produced when high-speed electrons are decelerated or “braked” as they pass near the nucleus of an atom, causing the release of X-ray photons.

208
Q

True or False

Bremsstrahlung is far more common than Characteristic radiation

A

TRUE

209
Q

The most useful characteristic x-ray in tungsten is when what electron shell is ejected?

A

K shell

210
Q

The average energy of
an x-ray beam is approximately _____ of the maximum x-ray energy.

A

1/3

211
Q

What happens to the other 99% of the energy in X-ray production?

A

In X-ray production, approximately 99% of the energy is converted into heat rather than X-rays. Only about 1% of the energy is used to produce X-rays, while the remaining energy is lost as heat in the anode of the X-ray tube.

212
Q

Efficiency
* Diagnostic (10 to 100keV)

A

< 1% efficient

213
Q

Efficiency
* Therapeutic (above 1 MeV)

A

can approach 50%

214
Q

Protective Housing X-Ray Tube

A
  • X-rays are emitted isotopically – with equal intensity in all directions
  • The useful beam is only those emitted through a special section of the x-ray tube called the window (in the enclosure)
  • X-rays that escape the protective housing are leakage radiation
  • Protective housing reduces leakage radiation to less than 100 mR/hr at 1 m when operated at maximum conditions
  • Some protective housings contain oil that serves as both an insulator
    against electric shock and as a thermal cushion to dissipate heat
  • Some also have a cooling fan to air-cool the tube or oil
215
Q

Glass or Metal Enclosure X-Ray Tube

A
  • X-ray tube is an electronic vacuum tube with components contained
    within a glass or metal enclosure
  • Enclosure maintains a vacuum inside the tube which allows for more efficient x-ray productions and longer tube life
  • Even a little gas in the tube reduces the electron flow from cathode to anode, producing fewer x-rays and generating more heat
216
Q

X-Ray Tube Window

A
  • X-ray tube window is an area of the enclosure that is thin through
    which the useful beam is emitted
  • The window allows for maximum x-ray emission with minimum
    absorption
217
Q

Focal Spot Size X-Ray Tube

A
  • The larger the focal
    spot, the wider the
    penumbra
  • The closer the source to
    the object, the wider
    the penumbra
218
Q

K Shell

A

Innermost energy level

219
Q

L Shell

A

Second energy level

220
Q

M shell

A

Third energy level

221
Q

Bremsstrahlung radiation is the result of the ____________ ___________ between the electron and the positively charged protons in the nucleus. The closer the electron passes to the nucleus, the stronger the attraction and the _______ the change in the electron’s direction and velocity.

A

electromagnetic attraction

greater

222
Q

No lower limit on the energy of photons produced.

Characteristic or Bremsstrahlung?

A

Bremsstrahlung

223
Q

Maximum energy limited by the potential difference between cathode and anode.

Characteristic or Bremsstrahlung?

A

Bremsstrahlung

224
Q

Peak in the spectrum occurs at one-third maximum photon energy.

Characteristic or Bremsstrahlung?

A

Bremsstrahlung

225
Q

What produces most of the scatter that degrades the image

A

Compton Scattering

226
Q

Compton scattering dominates between what energy range?

A

between 25 keV (60-100 kV) to 10 MeV

227
Q

Maximum energy of a backscattered photon is 0.255 MeV

what type of interaction?

A

Compton scattering

228
Q

90-degree scattered photon has a maximum energy of 0.511 MeV

what type of interaction?

A

Compton scattering

229
Q

Reduction in energy is directly related to the angle of scatter

what type of interaction?

A

Compton scattering

230
Q

The minimum wavelength in an x-ray beam depends on:

A

the peak kilovoltage

231
Q

The rotating anode is turned by a ______________.

A

Magnetic field

Because of the stators u stupid bitch how could u get that one wrong!

232
Q

The ________ is the source of the x-ray beam in the x-ray tube.

A

Focal spot

233
Q

The ________ is the source of the x-ray beam in the x-ray tube.

A

Focal spot

234
Q

A full outer electron shell produces what?

A

Little chemical reactivity

235
Q

Matter is measured in kilograms (kg).

True or False

A

TRUE

236
Q

Matter is measured in kilograms (kg).

True or False

A

TRUE

237
Q

Matter can transform in size, shape, form and mass.

True or False

A

FALSE

238
Q

Matter can transform in size, shape, form and mass.

True or False

A

FALSE

239
Q

X-rays in the kV and MV range can be used diagnostically.

True or False

A

TRUE

The linear accelerator has an MV x-ray imager. Also, there is an uncommon type of CT that operates in the MV range; MV CBCT.

240
Q

The x-ray tube window allows for what?

A

Maximum emission and minimum absorption

241
Q

1 Curie equals?

A

3.7 x 10^10 dps

dps=disintegration per second u stupid fawking bitch

242
Q

Above 10MeV, what is the dominant interaction with matter?

A

Pair production

243
Q

Coherent scattering is also known as all of the following, except?

Inelastic
Classical
Thompson
Simple

A

Inelastic

244
Q

How are different types of radiation compared?

Hint: Choose the best possible answer with regards to damage

A

RBE

245
Q

Radiation beam penetrability is often measured using what term?

A

Half-Value Layers

246
Q

True or False. A Geiger-Muller Counter is more accurate than an Ion Chamber Survey Meter.

A

False

The opposite is true

247
Q

40 to 150 KV energies in radiation therapy represents what modality?

A

Superficial

F24 125 Radiographic Process (6 decks)

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