Radiation Safety Flashcards
According to the NRCP 160, what are the approximate annual doses to the U.S. population from natural background and man-made sources of ionizing radiation?
310 mrem - Natural Background
300 mrem - Man-made Sources
A 100 mCi point source of I-131 is located 5.0 cm from you. What is the exposure rate at your location?
(UGamma (I-131) = 0.22 R-m^2 / Ci-h)
8.8 R/h
According to the NRC, the annual radiation exposure to members of the general public must be limited to no more than:
100 mrem
Optimum beta particle shielding consists of:
Low atomic number material followed by high atomic number material
If the distance between a radiation point source and a survey meter is doubled, the measured exposure rate is reduced to:
1/4 of the original exposure rate
If the half-value layer (HVL) for I-131 in lead is 0.3 cm, what is the minimum thickness of lead that is required to reduce the exposure rate of a I-131 source from 12 mR/hr to less than 2 mR/hr?
> 0.9 cm
A Becquerel is equivalent to:
1 Disintegration per second
The dose rate during preparation of a radiopharmaceutical is 1.66 mrem/hr. With this rate reduced by 2 HVLs, how many hours would it take a worker to accumulate 10 mrem?
24 h
Which quantity indicates the amount of radioactive substance present in a sample or source?
Activity
If the radiation intensity of a point source at 0.5 m measures 35 mR/h, at what distance will the intensity be halved?
0.7 m
The average energy required to create an ion pair in air is:
34 eV
The gray (Gy) is a unit representing which dosimetric quantity?
Absorbed Dose
The variable indicating the type of radiation used in the calculation of the equivalent dose is called the:
Radiation Weighting Factor
Which of the dosimetric quantity accounts for partial body exposure (ie., it accounts for total dose from individual organs/tissues)?
Effective Dose
Which of the following quantities is define as the energy absorbed per unit mass?
Absorbed Dose
A Sievert is defined to be:
1 J/kg
The rad is defined as the deposition of: (___ erg/g ____)
100 erg/g in any material
The dose rate outside a shield wall is found to be 0,5 mrad/h from Ra-223 (an alpha emitter). What is the equivalent dose rate of the radiation field?
10 mrem/h
A NMT measures a Tc-99m Mag-3 Dose prior to injecting a patient. The standard dose for an adult renogram procedure is 5.0 mCi. What is the highest amount of activity that can be injected, per NRC regulation?
6.0 mCi (NRC is +/- 20% Dose)
The critical organ is defined as:
The organ that is most radiosensitive.
Provide the Annual Occupational radiation Dose Limits in rem for the following:
a) Whole-Body
b) Lens of the Eye
c) Any Organ/Tissue
d) Extremity or Skin
a) 5 rem
b) 15 rem
c) 50 rem
d) 50 rem
What are the three basic principles of radiation protection?
Time, Distance, and Shielding.
Define the units:
Activity
Curie (Ci) / Becquerel (Bq)
Define the units:
Exposure
Roentgen (R) / Coulombs per Kilogram (C/kg)
Define the units:
Absorbed Dose
Radiation Absorbed Dose (rad) / Gray (Gy)
Define the units:
Equivalent Dose
Radiation Equivalent Man (rem) / Sievert (Sv)
Define the units:
Effective Dose
Radiation Equivalent Man (rem) / Sievert (Sv)
What Electron Volt energy level is considered “Non-Ionizing”
< 13.6 eV
What Electron Volt energy level is considered “Ionizing”
> 13.6 eV
Annual dose for occupational workers:
5,000 mrem/y
Annual dose for members of the public:
100 mrem/y
What is the NRC?
Nuclear Regulatory Commission
What is the DoT?
Department of Transportation
What is the FDA?
Food & Drug Administration
What is the EPA?
Environmental Protection Agency
What is the RSC?
Radiation Safety Committee
What is required in order for a facility to produce or use radionuclides, radiopharmaceuticals, or radiation equipment?
A license from the NRC
Human tissue consists of which two cells types?
Germ cells: Responsible for reproduction.
Somatic cells: responsible for maintenance of functions in the body.
Minimum energy required to produce an Ion pair
34 eV
LET = ?
(Formula)
SI (Specific Interaction) * 34 eV
Activity/Dose Rate Formula
A1 / X1 = A2 / X2
Point Source Dose Rate Formula
(Point Source) = ((Gamma Constant) * A) / d^2
ALARA = ?
As Low As Reasonably Achievable
Inverse Square Law Formula
I1 * d1^2 = I2 * d2^2
3 Principles of Radiation Safety
Time, Distance, Shielding
Intensity Formula
I = I1 * e^(-u * x)
I = Final Intensity
I1 = Initial Intensity
u = Linear Attenuation
x = Thickness
What does a cell consist of?
A nucleus surrounded by cytoplasm.
Half Value Layer Formula
I = I1 * e^(-(ln2/HVL) * x)
I = Final Intensity
I1 = Initial Intensity
u = (ln2/HVL)
x = Thickness
Tenth Value Layer Formula
I = I1 * e^(-(ln10/TVL) * x)
I = Final Intensity
I1 = Initial Intensity
u = (ln10/TVL)
x = Thickness
The denser the material is for radiation protection:
The less material that is required.
The nucleus consists of?
DNA & metabolic activities carried out by nucleus.
The primary mechanism of cellular damage is the breakdown of the strands of DNA known as a:
Mutation
The number of mutations increases with ?
increasing radiation exposure
Low exposure = ?
- Single strand breaks
- DNA repairs over time
High exposure = ?
- Double strand breaks
- Decreased chance for DNA repair
Direct
- Ionizing particle directly interacts w/ an atom
- Damages DNA directly
Indirect
- Radiation interacts w/ water near the DNA
- Subsequent attack on the DNA molecules.
Free Radicals
- Highly reactive compounds
- containing an unpaired electron
- chemically toxic to molecules
What is the Law of Bergonie & Tribondeau ?
biological damage resulting from radiation exposure, radiosensitivity greater in cells with:
- relatively undifferentiated ( primitive ).
- rapidly dividing at the tome of irradiation.
- dividing for extended periods of time.
Which factors affect the radiosensitivity of cells?
- Dose & Dose Rate
- Linear Energy Transfer
- Radiosensitizeer & Radioprotector
- Cell Cycle
Dose Rate = ?
Dose / time
Low dose & dose rate = ?
Single strand breaks, likely to be 100% repaired
High dose & dose rate =?
Double strand breaks, not likely to be repaired
LET ( linear energy transfer )
Energy given up by radiation when it interacts w/ matter
High LET = ?
Radiation gives up its energy over a short distance. (Alpha particles)
Low LET =?
Radiation that gives up its energy over long distances. (Beta particles & Gamma)
Radiosensitizers = ?
increased damage to DNA. (ex. Oxygen)
Radioprotectors = ?
protects the cell from damage. (ex. Cysteine, cysteamine)
What is the Hormesis theory?
- low doses of ionizing radiation
- mechanism that protects against diseases not active in the absence of ionizing radiation.
What is the Linear No Threshold (LNT) theory?
- an increased risk for developing cancer at lowest radiation exposures, (straight line graph)
What is the Threshold Response theory?
- a threshold below which there is no increased risk for developing cancer.
