final Flashcards
Artificial Radiation:
-50% man’s annual exposure
-3.2 mSv/yr
-2% consumer products
<1% industrial, security, medical, educational and research
<1% occupational exposure
48% medical and dental procedures
Radiation:
- can cause leukemia, cancer, and/or genetic effects in ALL living organisms
- amount required to produce these long term effects is unknown
- genetic = high dose (not diagnostic)
ORP
Optimizing radiation protection (ALARA)
Natural Radiation (Background) (ubiquitous): -man has no control -3 sources: Terresterial - from soil Cosmic - sun and stars Bodies - radionuclides
Artificial Radiation Medical Procedures: 24% CT 12% Nuclear Medicine 7% Interventional Fluoroscopy 5% Conventional Radiography & Fluoroscopy
Terrestrial Radiation:
- 37% of man’s annual exposure comes from radon and thoron (soils)
- 2.0 mSv / yr
- second leading cause of lung cancer
Radium:
replaces calcium in bones, exsists in some well water (leads to osteoporosis)
Cosmic Radiation:
- from sun and stars
- .5 - 1 mrem per hour of air travel
- greater in higher atmosphere
Annual Natural (ubiquitous background) Exposure:
- 50% of man’s annual dose
- 3.0 mSv/yr
- 37% radon and thoron
- 3% other terrestrial
- 5% space (cosmic)
- 5% internal
Biologic Damage: (intra cellular tissue) -cellular level: major or microscopic lethal or sub-lethal immediate or delayed -interaction: completely absorbed partially absorbed direct transmission
BERT:
- Background Equivalent Radiation Time
- Chest: 0.08 mSv/ 8 mrem / 10 days BERT
- Lumbar 3.0 mSv/ 300 mrem / 1 yr BERT
ORP:
-optimization for radiation protection
(ALARA)
Diagnostic Efficacy:
degree with which a diagnostic exam accurately reveals presence or absence of a disease
NCRP 160:
Addresses radiation dose from all sources to the US population
The amount of radiation actually received by patient from a diagnostic x-ray procedure may be indicated in terms such as:
Entrance skin exposure, bone marrow dose, gonadal dose
Which of the following processes is the foundation of the interaction of x-rays with human tissue
Ionization
Why are the long-term effects such as increased incidence of cancer in the exposed population living near Japan’s Fukushima nuclear plant unable to be accurately determined
It was difficult to measure amounts of radiation people recieved
According to the most recent available data what percentage of natural background radiation exposure comes from radon and thoron
37
Which of the following are natural sources of ionizing radiation
Radioactive elements in the crust of the earth and in the human body
And equivalent dose as low as 250 Millie sieverts delivered to the whole body may cause which of the following within a few days
A substantial decrease within a few days in the number of lymphocytes or white blood cells that are the body’s primary defense against disease
Which of the following is the total average annual radiation equivalent dose from man-made and natural radiation
6.3 mSv per year
Which of the following is recognized as the main adverse health effects from the 1986 share noble nuclear power accident
Increase in the incidence of thyroid cancer and children and adolescents
Radiation
Transfer of energy due to radioactive decay or interaction with the particle (electron)
AlARA
As low as reasonably achievable
Bert
Background equivalent radiation time
Ionizing radiation
Radiation that produces positively and negatively charged particles (ions) when passing through matter
Direct transmission
Primary x-ray photons that traverse a patient without interacting
Diagnostic efficacy
Degree with which a diagnostic exam accurately reveals presence or absence of a disease
Background radiation
Natural radiation
ubiquitous
man has no control
Radon
First decay products of radium a colorless odorless heavy radioactive gas that is always present in the air
Norm
Naturally occurring radioactive materials
photoelectron:
freed electrons energy equals the incoming photon energy minus the electrons binding energy
characteristic photon:
- aka Fluorescent radiation (secondary)
- is created when electrons move to fill shell vacancies
Photodisintegration:
- High dose radiation therapy
- greater than 10 meV
- nucleus absorbs radiation
- excess radiation is emitted in the form of a neutron
Photodisintegration:
- High dose radiation therapy
- greater than 10 meV
- nucleus absorbs radiation
- excess radiation is emitted in the form of a neutron
indirect transmission:
primary photons that undergo Compton and or coherent interactions and are scattered or deflected while passing through a patient and then still reach the image receptor
A decrease in contrast of the image by adding an unwanted additional exposure results from which of the following interactions between X radiation and matter
Compton scattering
Photoelectric absorption
Process whereby the kinetic energy of the incident photon is completely absorbed as it interacts with an Adam any checks an inner shell electron in its orbit
Compton scatter
Energetic electron dislodged from the outer shell of an Adam of the irradiated object as a result of Compton interaction with an incoming x-ray photon
Coherent Interaction:
- photon changes direction without energy change
- usually occurs below 10 kVp
- produces small amount of scatter (1%)
- aka: classical, Thompson, unmodified, and simple
Photoelectric Interaction:
- incoming photon gives up ALL of its energy
- interaction with inner (K) shell electron
- occurs between 23 and 150 kVp
Probability of PE increases as:
- energy of incoming photon decreases ( dec kVp)
- atomic # inc
- tissue mass density inc
- tissue thickness inc
Compton Interactions:
- interaction with outer shell electron
- incoming photon gives up part of its energy and is scattered (incoming photon after change of direction has occurred)
- responsible for scatter
Probability of Compton Int increases:
- due to decrease in PE interactions when kVp increases
- not affected by atomic #
Primary Radiation:
Radiation that emerges directly from the x-ray tube collimator and moves without deflection
Secondary Radiation:
The radiation that results from the interaction between primary radiation and the atoms of the irradiated object and the off-focus or leakage radiation that penetrates the x-ray tube protective housing. (scattered radiation is included)
scatter:
all radiation that arises from the interaction of an x-ray beam with the atoms of a patient or any other object in the path of the beam, X-ray photons undergo a change in direction after interaction
attenuation:
reduction in radiation intensity that results from absorption and scattering
Exit or image formation radiation is composed of which of the following
Non-interacting and small angle scattered photons
Which of the following contribute significantly to the exposure of the radiographer
Compton scattered photons
Which of the following defines attenuation
Absorption and scatter
In the radiographic killer voltage range which of the following structures undergoes the most photoelectric absorption
Compact bone
When I hi atomic number solution is either swallowed or injected into human tissue or a structure to visualize it during an imaging procedure which of the following occurs
Photo electric inner action become significantly in Hanst leading to an increase in the absorb those in the body tissues or structures that contain the contrast medium
Which of the following characteristics primarily differentiates the probability of occurrence of the various interactions of x-radiation with human tissue
Energy of the incoming photon
Binding energy
Force that holds the components of an atom or nucleus together
Photo disintegration
Interaction that occurs in high energy radiation therapy treatment machines
Pair production
Interaction between an incoming photon in an atom of a radiated biologic tissue in which the photon approach is strongly interacting with the nucleus of the Adam of the radiated tissue and disappears in the process the energy is transformed into a negatron and a positron
Auger effect:
energy released from inner shell is transferred to another electron instead of forming characteristic radiation
Pair Production:
- aka: annihilation method
- doesn’t occur diagnostically (Nuc med, PET)
- occurs at 1.022 meV
- interaction with nucleus causes photon to split into positron and negatron
- negatron absorbed by body, positron interacts with another electron and annihilates it
- energy forms 2 photons of .511 meV each
remnant radiation:
All radiation exiting the patient during exposure and ultimately striking the receptor
direct transmission:
primary xray photons that traverse a patient without interacting
absorption:
transference of electromagnetic energy from an xray beam to the atoms or molecules of the matter through which it passes (patients biological tissue)
Which of the following influences attenuation
Affective atomic number of the absorber, mass density, thickness of the absorber
The interactions of x-ray photons with any Adam of biologic matter are
Random so the effects of such interactions cannot be predicted with certainty
Indirect transmission
Primary photons that undergo Compton and or coherent interactions and are scattered or deflected while passing through a patient and still reaching image receptor
Coherent scatter
Process where in a low energy photon interacts with an atom of human tissue and does not lose kinetic energy
Air Kerma
SI method used to quantify beam intensity
Radiation concentration transferred in a point
SI unit replacing exposure
Calculation of radiation intensity in the air
•deci =
.1 or 1/10
•centi =
.01 or 1/100
Air Kerma
- SI method used to quantify beam intensity
- Radiation concentration transferred in a point
- SI unit replacing exposure
- Calculation of radiation intensity in air
- Kinetic energy released in a mass
- Measured in Gray
- Gya
EQUIVALENT DOSE cont:
•1 REM = 1/100 Sv or .01 Sv
•1 Sv = 100 REM
Linear energy transfer
How fast it’s transferred to the patient
Right energy is transferred from ionizing radiation to soft tissue per unit length
exposure
- traditional method used to quantify beam intensity
- amount of radiation an object is exposed to
- measurement of ionizations of X and gamma radiation in air
DAP
- Dose area product
- •amount of energy delivered to the patient
- area of tissue irradiated
Kerma air product=
entrance air kerma x cross sectional area of beam
EQUIVALENT DOSE cont •AD x WR = EqD •RAD x WR = REM •GRAY x WR = SIEVERT •the AD of any type of ionizing radiation produces the same biological damage as 1 RAD of x-rays
EFFECTIVE DOSE (EfD) •Combines both type of radiation and the radiosensitivity of the body part •Tissue Weighting factor (WT) •AD x WR = EqD then •EqD X WT = EfD
Collective Effective Dose Equivalent (ColEfD)
•Describes radiation exposure of a population from various sources
•Person Sievert
- decrease energy =
- decrease penetration = increase damage
- like alpha particles, they have high QF, high LET, and high WR
Which of the following is the unit of collective effective dose
Person Sievert
What is the SI radiation unit coulomb per kilogram used to specify
Radiation exposure in air only
How is the SI unit for dose area product usually specified
Sievert
•kilo =
1,000
•milli =
.001 or 1/1000
exposure -traditional unit = Roentgen -SI unit = coulomb / kg -1R = 2.58 x 10-4 Coulomb/kg Calibrate equipment
Entrance Air Kerma (EAK)
- measurement of amount of radiation intensity incident on patient having exam and measured at point where beam would enter the patient
- actual mAs, kVp, and SID are set
- patient is replaced with an ionization chamber
- many doses are estimated like organ dose and fetal dose
absorbed dose (d)
-amount of radiation transferred from ionizing radiation to the object
•increase atomic # = increase absorption and damage
•Bone atomic # 13.8; soft tissue 7.4
•increase photon energy = decrease absorption and damage to patient
absorbed dose
•traditional unit = RAD (radiation absorbed dose)
•SI unit = Gray
•measures all forms of ionizing radiation in all materials
•1 RAD = 1/100 Gy or .01 GY
•1 GY = 100 RAD
Equivalent Dose (EqD)
-quantifies biologic damage from different types of radiation
•calculates the absorbed dose for all forms of ionizing radiation at a precise point
•Exposure when person receives various types of radiation
•Radiation weighting Factor (WR) adjusts the Absorbed Dose (AD) value
•D x (WR) = EqD
Equivalent Dose (EqD) •Product of absorbed dose for tissue or organ and its radiation weighting factor (WR) •traditional unit = REM •SI unit = Sievert
TEDE
•Total Effective Dose Equivalent - sum of effective dose equivalent from external and Committed Effective Dose Equivalent (internal radiation) exposures
ACTIVITY
•measures the # of disintegrations per second of a radioactive material
•traditional unit - curie (Ci)
•SI unit - becquerel_ (Bq)
Linear Energy Transfer (LET)
•rate energy is transferred from ionizing radiation to soft tissue per unit length
•Shows need for a Quality factor
•measured in kev per micrometer
•High LET, high QF, a lot of damage in a small area (Alpha)
•Low LET, low QF, damage is spread out over a long area (X & Gamma)
- increase energy =
- increase penetration = decrease damage
- like X-ray and gamma ray, they have a low QF, low LET, and low WR
Which of the following was used as the first measure of exposure for ionizing radiation
Skin erythema
The concept of tissue waiting factor is used to do which of the following
Account for the risk to the entire organism brought on by irradiation of individual tissues and organs
To convert the number of gray into Millie gray the number of gray must be
Multiplied by 1000
Which of the following radiation quantities accounts for some biologic tissues being more sensitive to radiation damage than other tissues
Effective dose
If 100 people received an average affective dose of .35 Sv what is the collective effective dose
35 person sieverts
Traditional unit
Roentgen and REM
Tolerance dose
Occupational exposure to radiation that will not cause any apparent harmful a cute effect
Skin erythema dose
Amount of radiation it takes to redden in the skin
Exposure
Amount of radiation an object is exposed to
Method used to quantify beam intensity
Measurement of ionizations of X and gamma radiation in air
Dose Area Product (DAP)
Amount of energy delivered to the patient
Equivalent dose
Quantity attempting to numerically specified the differences in transferred energy and therefore potential biologic harm that are produced by different types of radiation
Collective effective dose equivalent
Describes radiation exposure of a population from various sources
Person Sievert
Total effective dose equivalent
Some of effective dose equivalent from external in cumulative effective dose equivalent exposures
Activity
Measures the number of disintegration per second of a radioactive material
Absorbed dose
Amount of radiation transferred from ionizing radiation to the object
ICRP
•International Commission on Radiological Protection
NCRP
• National Council on Radiation Protection and Measurements
NAS/NRC-BEIR
• National Academy of Sciences / National Research Council - on the Biological Effects of Ionizing Radiation
NRC (REGULATORY)
• Nuclear Regulatory Commission
-“right to know” workplace hazards
- Agreement States - TEXAS MEDICAL BOARD (REGULATORY)
- Department of State Health Services (TEXAS)
EPA (REGULATORY)
•Environmental Protection Agency
FDA (REGULATORY)
•Food & Drug Administration
OSHA (REGULATORY)
•Occupational Safety & Health Administration
RADIATION SAFETY OFFICER •Nuclear Regulatory Commission publishes title 10 Code of Federal regulations (10 CFR) to enforce duties of RSO •Develop RADIATION safety program •Oversee operation •Identify problems •Provide corrective action
1968 Radiation Control for Health and Safety Act
•Protect public from hazards of electronic products that release radiation
•Led to Center for Devices and Radiologic Health
•1974 Code of Standards for Diagnostic X-Ray Equipment
white paper
•2010 FDA
•Patient should receive right procedure, at right time, with right radiation dose
Consumer Patient Radiation Health and Safety Act of 1981
•established minimum standards for accrediting radiology programs
•DSHS (TDH/MRT) division requires 24 hr CE credits/2 years
•ARRT requires 24 hr CE credits/2 years
care bill
Will amend and enforce the Consumer-Patient Radiation Health & Safety Act
Currently does not have penalties for states who do not comply
CARE bill will make compliance a condition of getting Medicare payment
Radiographer - this means certification and ARRT registration which includes CE
tissue effect
Radiation Induced Response
-responses (previously called deterministic effect)
-•a somatic effect which increases in severity with increases in the absorbed dose
•ex. cataracts, blood changes, sperm count reduction
•requires high doses - threshold
stochastic effect
Radiation Induced Response
-(probabilistic) effects
-non threshold
•the probability of occurrence increases with the increased absorbed dose, but the severity does not depend on the amount
•ex. cancer and genetic effects at low doses
CURRENT PHILOSOPHYn(general) •based on the assumption that there is a linear, non threshold dose response relationship between radiation dose and biological effects
Basis for Occupational Exposure Limits
•the NCRP believes that the level of protection provided for radiation workers should, as far as possible, be comparable with that of other “safe” industries
Effective Dose Limit
•upper boundary for the amount of radiation anyone can receive and only have negligible damage
cumulative effective dose •(CumEfD) •lifetime dose •H = (age X 10 mSv) •H = (age X 1 rem)
- Annual occupational Effective Dose Limit
- 50 mSv or 5 rem per year total
NCRP DOSE LIMITS
•OCCUPATIONAL LIMITS
•Lens of eye 150 mSv (15 rem )
•Other organs 500 mSv (50 rem )
NCRP DOSE LIMITS •FETUS of TECHNOLOGIST •entire time 5 mSv (.5 rem ) •per month .5 mSv (.05 rem) •educational 1 mSv (.1 rem)
