Radiation Protection Flashcards
What is Dose equivalent
The quantity that accounts for the difference in radiation types and how their equivalence in effects is achieved
What is the Dose equivalent equation
H=D x Q
H= Dose Equivalent D= Dose Q= Quality factor of radiation
Dose in Rad converts to?
Rem
Dose in Gy converts to?
Sv
What is Xray, Gamma and Beta radiations quality factor?
1
What is Neutrons of unknown energy quality factor?
10
What is Alpha particle, multiple charged particles or heavy particles quality factor?
20
What is high energy protons quality factor?
10
What are thermal neutrons?
Neutrons in thermal equilibrium
What are fast neutrons?
Neutrons produced by fission reactions, before being slowed by nuclear collision
What is the primary biological effects of concern?
Cancer Induction
Which are more dangerous Low LET or High LET?
High LET particles like alpha particles
What is effective dose equivalent
HE, its a factor that gives an equivalent “detriment” to health as measured by excess fatal cancers. Exposure limits by the NRC are given in this term
What is the equation for Effective Dose Equivalent?
HE= W(t1) x H1 x W (t2) x H2 x W(t3) x H3
HE is the mean dose equivalent received by Tissue (t) and Wt is a weighing factor based on the relative risk of induction of fatal cancer
What is deep dose equivalent?
For whole body exposure is the dose equivalent at a depth of 1cm
What is committed dose equivalent?
is a dose equivalent of radioactive intake by the tissue (absorbed, inhaled or ingested) during a 50 year period following intake
What is shallow dose equivalent?
dose equivalent at a depth of .007 cm avg over an area of 1cm^2 (External Exposure to Skin)
What is the eye dose equivalent?
Dose equivalent at a tissue depth of .3cm (Lens of the eyes)
What are some examples of natural occurring radiation?
Cosmic rays, Terrestrial, Radon
What are some examples of man made radiation?
Medical, Nuclear power, Fallout
What are cosmic rays?
high energy (most protons) from outer space, that interact with the atmosphere and produce a shower of secondary particles such as Electrons, Photons, Neutrons and Muons
Where are cosmic radiation levels higher?
In high elevation areas such as denver
What is terrestrial radiation?
radiation that comes from the radioactive material in the earth/building materials such as K40 and uranium.
What is internal radiation?
radiation that is found in the body, cause off of foods that are ingested and/or natural creation
What is Radon?
Radioactive gas that is produced by natural decay of radium in soil/rocks. Can be present in lower regions of residence such as basements.
What type of emitter is radon?
Alpha Emitter, meaning its not able to penetrate skin, but when inhaled can cause damage to bronchial endothelium
What is the EPA limits on concentration of radon in a living area?
4.0 pCi per liter of air
What is the second leading cause of lung cancer in US?
Radon exposure
What is the predominant source of man made radiation?
Medical Procedures
What are some consumer produces that are sources of radiation?
Smoked detectors, older TV/computers, airport baggage inspection
What is the acute whole bod radiation which is lethal to 50% of those exposed?
400 cGy
What are some of the results of radiation injury?
Cell Death (Apoptosis), Failure to reproduce (death results), Mutation (primary concern in rad protection)
What are deterministic effects?
effects that increase in severity with increasing dose and require high does
What is an acute, early effects of radiation?
Erythema
What is a late effect of radiation?
Cataracts, Fibrosis
Deterministic effects are typically associated with what two aspect on a cell level?
Cell death and reproductive failure
What is stochastic effect?
probability of an effect increases with dose, but the severity is independent of dose
Stochastic effects are typically associated with what on a cell level?
Mutations
What is human data on radiation carcinogenesis based off of?
Medical irradiation, Atomic Bomb survivors and early occupation exposure
What is a latency period?
The period of time between irradiation and appearance of malignancy
What does the Linear No-Threshold graph represent?
Quantify radiation exposure and set regulatory limits, coincides with the idea that there is no safe dose of radiation
What is hormesis
controversial theory that small amounts of radiation may be beneficial to health
What does ALARA stand for?
As low as reasonable achievable, not necessarily the lowest dose, but within reason
What are the 3 facts that are important in radiation protection?
Time, Distance and Shielding
In terms of ALARA, what are 3 factors that are taken in consideration?
Social, Economical, and Technical
What is the NRC exposure limit for occupation dose?
5 rem
What is the NRC Exposure limit for the general public?
.1 rem
What is the NRC exposure limit for an embryo-fetus?
0.5 rem for entire gestation period
What is the NRC exposure limit for embryo-fetus for any one month?
0.05 rem
What type of storage is used for brachytherapy sources?
Lead-lined safes with lead filled drawers
What are some requirements for source preparation?
Suitable barrier/L-block (Shield the operator), long forceps to handle sources, minimize time handling the source
What is required during source transportation for brachytherapy?
- Proper Lead container
2. Logging of the source departure and arrival to/from the storage room.
What does a periodic leak test consist of?
- radium placed in a test tube with activated carbon or a cotton ball.
- after 24 hrs, the carbon is counted in a scintillation-well counter
- source is leaking if .0005 microCi is found
What are medical events?
- total dose is greater than +/- 20% of the prescribed dose or falls outside the prescribed dose range for teletherapy/gamma
- single fraction exceeds +/- 50% of the prescribed dose
Medical events do NOT have to be reported to a supervisor and/or radiation safety officer. True or False?
FALSE
What are some important things to ensure when patients have pacemakers?
- No direct radiation
- 1cm margin minimum
- <2 Gy point dose (monitored with TLD)
- Check with vendor on microwaves interference
What are the three periods of fetal dose?
Pre-implantation, Organogenesis, Fetal
What is the pre-implantation period?
Radiation has all or nothing effect, aka its lives or dies (spontaneous abortion)
What is the organogenesis period?
period of rapid cell differentiation and organ development. Can last 10 days to 6 weeks. Radiation may cause abnormalities or neonatal death
What is the fetal period?
6 weeks to term. Radiation may cause permanent growth retardation and/or cancer
How much of fetal dose is a significant risk during the 1st trimester?
10-50 rem
What fetal dose assumes high risk?
> 50 rem
Less than 10 cm away, contributes to what type of dose outside the field?
Pt Scatter and Collimator Scatter
10-20cm away contributes to what type of dose outside the field?
Pt Scatter
20-30cm away contributes to what type of dose outside the field?
Pt Scatter and Leakage
Greater than 30 cm away contributes to what type of dose outside the field?
Leakage
Testicular dose is dependent on what factors?
Dose, Energy and Field size
How much reduction do clamshells provide in testicular dose?
3x-10x reduction
What is the composition of a clamshell?
1.2cm thick Pb Alloy
