Radiation Measurements Flashcards
What is the base unit for measuring radioactivity?
Becquerel (Bq)
1 Becquerel is defined as 1 decay per second.
What is the equivalent of 1 Microbecquerel (µBq) in Becquerels?
0.000001 Bq
Millionth
## Footnote
1 µBq corresponds to 1 decay per million seconds.
What is the value of 1 Kilobecquerel (kBq) in Becquerels?
1,000 Bq
Thousands
## Footnote
1 kBq represents 1,000 decays per second.
What is the equivalent of 1 Curie (Ci) in Becquerels?
37,000,000,000 Bq
Ci is used for high radioactivity sources.
What is the base unit for absorbed dose?
Gray (Gy)
1 Gray is defined as 1 joule per kilogram.
1 Rad is equivalent to how many Grays?
0.01 Gy
Rad is an older unit for measuring absorbed dose.
What is the value of 1 Megagray (MGy) in Grays?
1,000,000 Gy
Millions
## Footnote
MGy represents 1 million Grays.
What is the base unit for effective dose?
Sievert (Sv)
1 Sv is defined as 1 Gray multiplied by the radiation weighting factor.
What is the equivalent of 1 Microsievert (µSv) in Sieverts?
0.000001 Sv
1 µSv is equal to 1 millionth of a Sievert.
How many Sieverts are in 1 Megasievert (MSv)?
1,000,000 Sv
MSv represents 1 million Sieverts.
What is the base unit for exposure to radiation?
Roentgen (R)
R measures ionization of air.
What is the equivalent of 1 Milliroentgen (mR) in Roentgens?
0.001 R
Thousandths
## Footnote
mR is a common background level of exposure.
Fill in the blank: 1 Gray (Gy) is equivalent to _______/kg
1 joule/kg
What are the smaller units of Radioactivity?
In Bq?
- Microbecquerel (µBq)
- Millibecquerel (mBq)
These units are used for measuring lower levels of radioactivity.
What are the lethal amounts of Absorbed Dose?
5Gy 50% fatality
10Gy near 100%
100Gy instant tissue destruction
1000Gy vaporization of tissue
True or False: 1 Rem is equivalent to 0.01 Sv.
True
What are the lethal units of Effective Dose?
4-5 Sv 50% fatality
10 Sv near 100%
50 Sv immediate nervous system failure-certain death soon
100 Sv immediately fatal
List the smaller units of Exposure.
- Microroentgen (µR)
- Milliroentgen (mR)
These units represent smaller levels of radiation exposure.
Is exposure (Roentgen, R) the only measurement that indicates dangerous radiation levels?
No, it is not the only measurement
The actual danger depends on multiple factors, including the type of radiation and its effects on the body.
What does exposure (Roentgen, R) measure?
Ionization of air
High R levels indicate potential for harm but do not account for biological effects.
What is absorbed dose measured in?
Gray (Gy)
It measures the energy deposited in material/tissue.
What level of absorbed dose (Gy) can cause acute radiation sickness?
> 1 Gy
Absorbed dose is a critical measure of radiation exposure.
What is effective dose measured in?
Sievert (Sv)
It measures biological damage to human tissue.
What effective dose (Sv) is harmful to humans?
> 1 Sv
A dose of >4 Sv is lethal for 50% of people.
What does radioactivity measure?
The amount of radiation being emitted
Measured in Becquerels (Bq) or Curie (Ci).
True or False: High radioactivity always indicates danger.
False
The danger depends on the type of radiation and shielding.
Why is exposure (Roentgen, R) alone not enough to assess danger?
It only tells you ionization in the air
It does not measure how much radiation is absorbed by the body (Gy) or its biological effect (Sv).
What is a better indicator of danger than exposure (R)?
Effective Dose (Sievert, Sv)
1 Sv can cause radiation sickness; 4-5 Sv has a 50% fatality rate.
What absorbed dose (Gy) can often be fatal without medical intervention?
> 5 Gy
It is critical to understand the severity of different dose levels.
What dose rate (mSv/hr) indicates potential long-term cancer risk?
50 mSv/hr
Higher rates indicate more immediate health effects.
Fill in the blank: For immediate response, use ______ to determine if it’s unsafe to stay in an area.
Roentgen (R/hr)
Quick assessments are crucial in high-radiation environments.
What is the immediate health effect dose rate (mSv/hr) that can cause acute radiation syndrome (ARS)?
1 Sv/hr or higher
Understanding dose rates is essential for emergency response.
List three better indicators of danger than exposure (Roentgen, R).
- Effective Dose (Sievert, Sv)
- Absorbed Dose (Gray, Gy)
- Dose Rate (mSv/hr or R/hr)
These measurements provide a clearer picture of biological harm.
When is exposure (R) still useful?
- Initial detection of high-radiation areas
- Determining shielding needs
- Quick decision-making
While not the best indicator, it serves specific purposes in radiation safety.
What does Becquerel (Bq) measure?
Radioactivity (1 decay per second)
Becquerel is the SI unit for measuring the activity of a radioactive substance.
What is the equivalent of 1 Curie (Ci) in Becquerels?
37 billion Bq
Curie is a non-SI unit of radioactivity named after Pierre and Marie Curie.
What does Gray (Gy) measure?
Absorbed dose (energy deposited in material)
Gray is the SI unit for measuring the absorbed dose of radiation.
What is the relationship between Rad and Gray?
1 rad = 0.01 Gy
Rad is an older unit of absorbed dose, now largely replaced by Gray.
What does Sievert (Sv) measure?
Biological effect of radiation (1 Sv = 100 rem)
Sievert is the SI unit used to measure the health effect of ionizing radiation.
How many millisieverts (mSv) are in 1 Sv?
1,000 mSv
Millisievert is used for small doses of radiation.
What is the value of 1 microsievert (µSv) in relation to a Sievert?
1 µSv = 1/1,000,000 Sv
Microsieverts are typically used to measure background radiation.
What does Rem measure?
Biological effect (1 rem = 0.01 Sv)
Rem is an older unit of dose equivalent, now largely replaced by Sievert.
What does Roentgen (R) measure?
Radiation exposure in air
Roentgen is a legacy unit used to measure exposure to X-rays and gamma rays.
What is Dose Equivalent?
Absorbed dose adjusted for biological harm (Gy × weighting factor)
This accounts for the type of radiation and its potential biological effects.
What is Activity in the context of radioactivity?
The rate of radioactive decay, measured in Bq or Ci
Activity indicates how many decays occur in a given time period.
What is Half-Life?
The time for half of a radioactive substance to decay
Half-life is a crucial concept in understanding the stability and longevity of radioactive materials.
Roentgen is pronounced as:
“RUNT-gen” (/\ˈrʌntɡən/ or /ˈrɛntɡən/ in English)
What is a joule
1 Joule = The amount of energy required to move 1 Newton (roughly 100G) of force a distance of 1 meter.
