Nature of Ionizing Radiation 1/11/17 Flashcards
What is radiation?
-Transmission of energy through space an matter
Is higher or lower energy radiation ionizing?
-Higher energy
What two things can happen in living cells from ionizing radiation?
- Cell death
- Molecular alteration leading to harmful effects
What are four sources of natural radiation?
- Cosmic
- Terrestrial
- Radon
- Internal
What percentage of radiation that we are exposed to is natural radiation?
50%
What is the largest source of natural radiation that we are exposed to?
-Radon at 37%
What percentage of radiation that we are exposed to is man made?
-50%
What are four major man made sources of radiation that we are exposed to?
- Medical x-rays
- CT scans
- Nuclear medicine
- Consumer products
What is the largest source of man made radiation that we are exposed to?
-CT scans
What are the two types of Ionizing radiation?
- Particulate
- Electromagnetic Radiation (photons)
What makes up the particulate radiation?
- Alpha particles
- Beta particles
- Neutrons
What makes up Electromagnetic radiation (photons)?
- Gamma rays
- X-rays
Which of the following is not a form of ionizing radiation? A) Xrays B) microwaves C) gamma rays D) ultraviolet wavelength light
B) Microwaves
What are four types of ionizing radiation?
- X-rays
- UV rays
- Gamma rays
- Blue light *(right on the border)
What are the SI units for exposure?
-Coulomb/kilogram
What are the SI units for Absorbed Dose?
-Gray (Gy)
What are the SI units for equivalent Dose?
-Sievert (Sv)
What are the SI units for effective dose?
-Sievert (Sv)
What are the SI units for Radioactivity?
-Becquerel (Bq)
What does the measurement of radioactivity describe?
-The decay rate of a radioactive material
What is Dosimetry?
-How radiation is measured
What is exposure in radiation?
-The potential for energy transfer (intensity of the radiation field)
What is the amount of electrical charge, or kinetic energy transferred to matter, by ionizing radiation per mass of air called?
-Air kerma
Define the absorbed dose?
-The energy absorbed by any type of matter
What is the equivalent dose?
-Compares the biologic effect on a tissue from different types of radiation
What is the equivalent dose dependent on?
-Linear Energy Transfer (LET)
Do photons or particulate radiation have a higher LET?
-Particulate
What is the effective dose used to measure?
-Estimated risk to humans
What two things does effective dose take into consideration?
- Type of radiation
- Nature of organ or tissue
What types of cells are most susceptible to damage from radiation?
-More rapidly dividing and less differentiated cells
T/F
The equivalent dose deals with effects to the whole body
False
-The effective dose deals with effects to the whole body
The reason we may wish to cover the reproductive organ of a patient when taking radiographs can best be explained by the concept of: A) equivalent dose B) LET C) Effective dose D) Radioactivity
C) Effective dose
What is the Direct effect in radiation chemistry?
-When a photon or secondary electron ionizes biologic macromolecules (DNA)
T/F
When you have a direct effect that involves dissociation or cross linking with free radicals you have altered molecules resulting in biological change.
True
What does the ionization of water lead to?
-Free radical production
In radiolysis of water what ultimately builds up in tissues causing damage?
-Toxins
What is the indirect effect of radiation chemistry?
-Free radicals and toxins produced in the intermediate step of water radiolysis interact with biologic macromolecules to cause changes
T/F
Organic free radicals are unstable and transform quickly to stable altered molecules
True
T/F
Altered molecules have different chemical and biologic properties that may lead to cell death, mutation or carcinogenesis
True
______ accounts for 1/3 of biologic damage from xrays and _____ invovles radiolysis of water and accounts for 2/3 of biologic damage from xrays.
- Direct effect
- Indirect effect
The presence of which of the following does not contribute to the indirect effect of ionizing radiation on altering DNA? A) Water B) Oxygen C) photons D) Hydrogen peroxide
D) Hydrogen peroxide
What are the two basic classifications of cellular changes in radiation?
- Deterministic effect
- Stochastic effect
What is radiation injury dependent on?
-The dose (greater the dose = greater the severity of injury)
Do you need a higher level or lower level of exposure to produce a clinically observable effect?
-Higher level
Deterministic effects are related to what?
-Tissue
What are four modifying factors for deterministic effects?
- Dose
- Dose rate
- Oxygen
- LET
What are six oral manifestations of irradiation?
- Taste loss
- Mucositis
- Hyposalivation
- Radiation caries
- Trismus
- Osteoradionecrosis
What is the stochastic effect?
-Probability of occurrence of radiation injury with no threshold level (if you do it there is a chance)
T/F
When taking a single periapical radiograph on a patient you can assure them that the exposure is so low that there is absolutely no risk of long term damage
False
What is the average annual effective dose of ionizing radiation from natural sources?
-3.1 mSv
What is the average annual effective dose of ionizing radiation from man made sources?
-2.5 uSv
What is the amount of dental radiology effect dose?
- < 0.01 uSv
You are preparing to take a digital panoramic radiograph on a patient, but the patient is concerned about the amount of radiation they might be receiving and the long term risk. You try to allay their fear by comparing it to which of the following?
A) 3 days of exposure to normal background radiation
B) Flying round trip from SLC to New york
C) Driving to St. George
D) All of the above
D) All of the above
What are the three guiding principles in radiation safety?
- Justification
- ALARA
- Dose limitation
What letters of film speed should you use?
- E
- F
Why do you want to use that fastest film speed?
-You can expose it with a lower dose
How far away should you stand from radiation sources?
-2 meters
How many degrees should the operator be positioned from the primary xray beam?
90-135
