RB ASTRO topic 1 Flashcards
1
Q
What is the primary focus of radiation biology?
A
The intersection of radiation with matter
2
Q
Who discovered X-rays and in what year?
A
Wilhelm Conrad Röntgen in 1895
3
Q
What significant event occurred in the year following the discovery of X-rays?
A
The first patient was treated with radiotherapy
4
Q
What concept was developed in the 1920s regarding radiation?
A
Fractionation
5
Q
What major advancement in radiation therapy occurred in 1953?
A
Introduction of the LINAC (linear accelerator)
6
Q
What was the significance of cobalt machines introduced in 1956?
A
Allowed for measurement of radiation effects in tissues
7
Q
Which Nobel Prize-winning scientist is credited with discovering radioactivity?
A
Henri Becquerel
8
Q
What does the term ‘brachytherapy’ mean?
A
Short-range radiation therapy
9
Q
What is ionizing radiation?
A
Radiation that causes the ejection of one or more orbital electrons from an atom
10
Q
List the types of radiation that fall under the particulate category.
A
- Protons
- Electrons
- Alpha particles
- Beta particles
11
Q
What are the two types of ionizing radiation in the electromagnetic spectrum?
A
- Gamma rays
- X-rays
12
Q
True or False: Ultraviolet light is considered ionizing radiation.
A
False
13
Q
What does the term ‘excitation’ refer to in the context of radiation?
A
Raising an electron to a higher energy without ejection
14
Q
What are the main methods for delivering radiotherapy?
A
- External beam
- Brachytherapy
- Radio surgery
- Intraoperative radiotherapy
15
Q
What is the significance of the 4 gray dose in radiation therapy?
A
It is near the lethal dose to kill 50% of the population in 60 days
16
Q
Fill in the blank: The first patient treated with radioactive iodine for thyroid cancer occurred in _______.
A
1946
17
Q
What was the first publicly available radiograph taken by Röntgen?
A
Supposedly of his wife with her wedding ring
18
Q
What innovation did Eastman Kodak introduce in 1918?
A
The first X-ray film to be used in the clinic
19
Q
What is the primary difference between X-rays and gamma rays?
A
X-rays are produced outside the nucleus; gamma rays are produced inside the nucleus
20
Q
What did the introduction of the cyclotron in 1931 lead to?
A
First synthesis of radioactive elements
21
Q
What is the energy threshold for ionizing radiation in terms of electron volts?
A
Greater than 124 electron volts
22
Q
What does the term ‘LINAC’ stand for?
A
Linear Accelerator
23
Q
True or False: Radio waves are associated with an increased incidence of cancer.
A
False
24
Q
What are Hounsfield units used to measure?
A
CT intensity
25
What was the major development in the 1970s regarding medical imaging?
Advancement of CT scans
26
What are the primary types of non-ionizing radiation?
* Radio waves
* Microwaves
* Infrared light
* Visible light
27
Fill in the blank: The first lawsuit related to radiation therapy was filed in _______.
1896
28
What type of radiation therapy is delivered during surgery?
Intraoperative radiotherapy
29
What historical event in the 1930s and 1940s contributed to advancements in radiation therapy?
Development of atomic bombs
30
What is the main purpose of collimation in radiation therapy?
To focus the radiation beam on the target area
31
What is the relationship between wavelength and energy in radiation?
Shorter wavelength corresponds to higher energy
32
What is usually going to involve two protons and two neutrons?
An alpha particle
33
What is the definition of the electron volt?
A unit of energy equal to the amount gained by an electron when it is accelerated through an electric potential difference of one volt
34
When x-rays travel as waves, they follow which formula?
Velocity = Wavelength × Frequency
35
What formula do x-rays follow when they travel as streams?
Lambda = 12.4 / Energy
36
What is the mass comparison between a proton and an electron?
A proton is 2000 times the mass of an electron
37
What is the net charge of an electron?
Negative charge
38
What is the net charge of an alpha particle?
Net two plus charge
39
What is the neutron most famous for?
Its ability to split atoms
40
What happens when neutrons interface with matter?
They release a proton called a recoil proton
41
What are the two types of radiations based on LET?
High LET and Low LET
42
Which types of radiation are considered low LET?
* Gamma rays
* X-rays
* Protons
43
Which types of radiation are considered high LET?
* Carbon ions
* Helium ions
* Neon ions
* Alpha particles
44
What does LET stand for?
Linear Energy Transfer
45
What is the Compton process?
A process where a photon intersects with an outer shell electron, causing it to be ejected
46
What occurs during the photoelectric process?
A photon causes the ejection of an electron in an inner shell
47
What is the basis of the X-ray?
The photoelectric process
48
What is pair production?
A process where an electron and a positron are produced and then annihilate each other
49
What type of radiation does radium-226 decay into?
Radon and an alpha particle
50
Why is alpha radiation considered dangerous when inhaled?
It can remain in the lungs for years, causing radiation damage
51
What type of shielding is effective against alpha particles?
A piece of paper
52
What type of shielding is effective against beta radiation?
A glove or plexiglass
53
What type of shielding is effective against gamma radiation?
Lead
54
What distinguishes direct ionization from indirect ionization?
Charged particles are directly ionizing, while uncharged particles are indirectly ionizing
55
What is the most important target for radiation injury in a cell?
Nuclear DNA
56
What is the definition of a free radical?
Anything that has an unpaired electron in its outer shell
57
What is indirect action in radiation biology?
Indirect action occurs when radiation interacts with a water molecule near DNA, producing hydroxyl radicals that can damage DNA.
## Footnote
Hydroxyl radicals are highly reactive due to their unpaired electron.
58
Define a free radical.
A free radical is anything that has an unpaired electron in its outer shell.
59
What is the significance of the four nanometer distance in radiation damage?
A water molecule must be within four nanometers of DNA to cause damage through indirect action.
60
What proportion of damage is caused by indirect action for low LET radiation?
For low LET radiation, two-thirds of the damage is by indirect action, and one-third is by direct action.
61
How does high LET radiation primarily cause damage?
Most but not all damage from high LET radiation is by direct action.
62
What are the types of DNA damage caused by ionizing radiation?
* Base damage
* Single strand breaks
* Double strand breaks
* Cross links
63
Which type of DNA damage is most common?
Base damage is the most common type of DNA damage.
64
Why are single strand breaks more common than double strand breaks?
Single strand breaks are more common because a double strand break occurs when two single strand breaks are close together.
65
What is the role of glutathione peroxidase in radiation exposure?
Glutathione peroxidase helps convert hydroxyl radicals into peroxide, reducing DNA damage.
66
What is a radio protector?
A radio protector is any molecule that can help reduce damage from free radicals, particularly those with free thiol groups.
67
True or False: All damage from neutrons is from direct action.
False. Most but not all damage from neutrons is from direct action.
68
What does the stochastic nature of radiation imply?
The stochastic nature means that radiation effects are random, making it difficult to predict individual outcomes.
69
What are the four timeframes of events following radiation exposure?
* Physical
* Physical-chemical
* Biochemical
* Biological effect
70
What is the definition of a gray in radiation measurement?
A gray is defined as one joule of energy deposited per kilogram of soft tissue.
71
How does a gray relate to rads?
One gray is equal to 100 rads.
72
What is the old unit of radioactivity and its new equivalent?
The old unit is the curie, and the new unit is the becquerel.
73
What is the equivalent dose expressed in severts?
One sievert is equal to 100 rems.
74
What are the short-term effects of radiation exposure on DNA?
Short-term effects include immediate DNA damage that can be repaired or lead to mutations.
75
Fill in the blank: The two most common kinds of base damage are _______ and _______.
thymine glycol, adhydroxy guanine.
76
What is the relationship between ionization events and DNA damage?
Ionization events can directly damage DNA or create free radicals that lead to indirect damage.
77
What is the importance of antioxidants during radiation therapy?
Antioxidants may protect cancer cells by neutralizing hydroxyl radicals produced by radiation.
78
What can happen if DNA damage is misrepaired?
Misrepaired DNA can lead to mutations, cell death, or cancer.
79
What is the significance of the Fenton reaction in radiation biology?
The Fenton reaction describes how hydroxyl radicals can be converted to less harmful peroxide, reducing DNA damage.
80
What is the term used for equivalent dose and effective dose?
Sievert
## Footnote
The sievert is used to compare the biological effects of different types of radiation.
81
What was the old term for dose equivalent before sievert?
REM
## Footnote
REM stands for Roentgen Equivalent Man.
82
How is the relative biological effectiveness (RBE) determined?
Experimentally determined
## Footnote
RBE is determined by comparing the effects of different types of radiation on cell death.
83
What is the radiation weighting factor for x-rays and gamma rays?
1
## Footnote
This means that the dose in gray is equal to the dose in sievert for x-rays and gamma rays.
84
What is the radiation weighting factor for thermal neutrons?
5
## Footnote
This indicates that thermal neutrons are five times more effective than x-rays.
85
What is the average natural background radiation in the U.S. per year?
3 millisieverts
## Footnote
This includes contributions from gamma rays, x-rays, and radon.
86
What is the dose limit for the general public over the natural background?
1 millisievert per year
## Footnote
This limit is set for radiation exposure beyond natural background levels.
87
What type of radiation damage is caused by direct action?
Direct attack on DNA
## Footnote
Direct action involves the radiation interacting directly with the DNA.
88
What type of radiation damage is caused by indirect action?
Production of hydroxyl radicals
## Footnote
Indirect action occurs when radiation damages water molecules, creating free radicals that then damage DNA.
89
What are the three main types of damage caused by ionizing radiation?
* Single strand breaks
* Double strand breaks
* Base damage
## Footnote
These types of damage can occur in nuclear DNA following radiation exposure.
90
Is there a characteristic mutation caused by radiation damage in DNA?
No
## Footnote
Unlike UV radiation, ionizing radiation does not produce specific mutations that can be identified.
91
What conversion factor relates Becquerel to Curie?
1 Becquerel = 2.7 x 10^-10 Curie
## Footnote
This conversion is useful for understanding different units of radioactivity.
92
What is the formula to calculate sievert from gray and quality factor?
Sievert = Gray x Quality Factor
## Footnote
The quality factor adjusts the absorbed dose based on the type of radiation.
93
Fill in the blank: The major target for radiation damage in cells is _______.
Nuclear DNA
## Footnote
Nuclear DNA is the primary target for damage from radiation exposure.
94
True or False: Ionizing radiation causes specific types of mutations in DNA.
False
## Footnote
Ionizing radiation causes random types of DNA damage without characteristic mutations.
95
What is the RBE of protons compared to x-rays?
Approximately 1.1 or 1.2
## Footnote
This indicates that protons have a slightly higher effectiveness than x-rays.
