Cedo - (Section 3) Radiation Quantities And Units Flashcards
How many disintegrations (nuclear transformations) does 1 gram of radium undergo in 1 second?
3.7 x 10*10 or 37 Billion (37 000 000 000)
Who is the organization that is selects and defines units and quantities of radiation?
The International Commission on Radiological Units and Measurements, in conjunction with the International Commission on Radiological Protection (ICRP)
What is the activity of 1 gram of radium called?
1 Curie (Ci)
1 curie is?
The amount of substance in which 37 billion atoms per second undergo radioactive disintegration.
How is the activity of a radioactive isotope determined?
By the number of atoms of the material that will decay (disintegrate or stabilize) in a given period of time.
1 curie (Ci) equals?
37 Billion disintegrations/second.
The radioactivity in a material is determined by?
How Curies of the material are present.
What does SI stand for?
The International System of Units.
What does dps stand for?
Disintegrations per second.
A Becquerel (Bq) is a measure of what?
A measure of disintegrations per second (dps).
How many dps is a Becquerel?
1 dps.
How many Becquerels is equal to 1 Curie?
37 Billion.
What are some the prefixes, symbols and multiples used in conjunction with the SI system?
tera (T) - 10*(12) giga (G) - 10*(9) mega (M) - 10*(6) kilo (k) - 10*(3) centi (c) - 10*(-2) milli (m) - 10*(-3) micro (u) - 10*(-6) nano (n) - 10*(-9)
The degree of concentration of radioactive material within a radioactive source is referred to as what?
Specific activity.
How is specific activity measured?
In Curies (Ci) per gram or Becquerels (Bq) per gram of source material.
What is the advantage to having a physically smaller source?
It will produce sharper radiograph images.
1 Ci equals how many GBq and how many TBq?
37 GBq, 0.037 TBq
50 Ci equals how many GBq and how many TBq?
740 GBq, 0.740 TBq
How many disintegrations per second (dps) does 1 Bq equal?
1 dps.
Even if the specific activity of two isotopes are the same what could differ between the two?
The number of Gamma rays resulting form the decay.
How is intensity measured?
Roentgens per hour @ 1 metre.
What is the characteristic intensity of Iridium, Cobalt and Selenium at 1 metre? Give answers in Ci and GBq.
Iridium - 550 mR/hr, 0.15 mSv/hr
Cobalt - 1350 mR/hr, 0.36 mSv/hr
Selenium - 200 mR/hr, 0.05 mSv/hr
What does “exposure” refer to in Industrial Radiography?
The Quantity of radiation incident upon an object.
What is the unit of radioactivity in the International System of units (SI)?
The Becquerel (Bq)
Exposure is expressed in units referred to as?
Roentgens (R).
- there is no SI unit for exposure but the metric system expresses exposure in Coulomb/Kilogram(c/kg)
Radiation intensity is also known as?
Dose Rate.
Define Radiation intensity?
Energy absorbed by any matter placed in a radiation beam.
Radiation effect can be in what forms?
Blackening of radio graphic film, biological killing of living cells, induction of cancer, etc
Radiation effect is proportional to?
Radiation intensity.
Radiation intensity is measured in what?
Roentgens/hour (R/hr) or the SI unit of Sieverts/hour (Sv/hr)
Absorbed radiation dose is measured in what?
The SI unit Gray (Gy) or energy absorbed in joules/kg. Old unit of measurement is the RAD.
What is the Quality Factor (Q) or Relative Biological Effectiveness (rbe) the four main types of radiation?
y-rays - 1Q (rbe)
x-rays - 1Q (rbe)
β particles - 1Q (rbe)
Α particles - 20Q (rbe)
How much more harmful are Alpha particles (a) then Beta particles (β), Gamma rays (y) and X-rays (x)?
20 times.
1 RAD (R) equals? 1 Gray (Gy) equals?
10 mGy.
100 RADs.
What does rem stand for?
Roentgen Equivalent in Man
If you multiply the absorbed dose rate (in R or Gy) by the Q factor, what is the resultant?
Dose Equivalent.
rem = RAD x Q or RBE
Dose equivalent is measured in?
The SI unit Sievert (Sv) or the CGS unit Roentgen Equivalent in Man (rem).
What’s is the relationship between Sieverts (Sv) and Roentgen Equivalent in Man (rem)?
1 Sievert (Sv) = 100 Roentgen Equivalent in Man (rem). 1 Roentgen Equivalent in Man (rem) = 10 millisieverts ( mSv) or 0.01 Sv
The (rem) is the dose from any radiation that?
Produces biological effects in man equivalent to 1 RAD of X-Ray, Gamma-Ray or Beta Rays.
What is Half Life?
The length of time required for the activity to decay to one-half it’s initial activity.
What are the Half Life’s of Iridium 192 (IR 192), Cobalt 60 (Co 60) and Selenium 75 (Se 75)?
IR 192 - 74 days
Se 75 - 120 days
Co 60 - 5.3 years
What are the formulas to calculate half-life?
See Pg 23-24
