ORANGE BOOK Flashcards
‘Z’ is the number of protons in the nucleus
True: Z is the atomic number and indicates the number of protons in the nucleus.
‘A’ determines an element’s place in the periodic table.
False: A is the mass number. Z determines place in the periodic table.
A stable nucleus contains equal numbers of protons and neutrons.
False: Higher atomic number nuclei require more neutrons than protons for stability.
Binding energy is that required to excite an electron to a higher energy shell.
False: Binding energy is expended completely removing the electron from the atom.
Protons are loosely bound to neutrons in the nucleus.
False: They are tightly bound.
Electrons are arranged in shells around the nucleus at specific energy levels.
True
A proton has a mass approximately 1850 times that of an electron.
True
Characteristic radiation is produced from the valence shell.
False: Characteristic radiation is from inner shells.
The valence shell gives the chemical properties.
The binding energy is highest for a valence shell electron.
False: It is lowest for valence shell electrons and highest for the K shell.
K shell binding energy increases with increasing atomic number.
True
In a vacuum, velocity of radio waves is equal to that of infrared light.
D. True All electromagnetic radiation travels at the speed of light in a vacuum.
There can be up to 8 electrons orbiting the nucleus in the L shell.
True:There can be up to 2 electrons in the K shell, 8 in the L shell, 18 in the M shell and 32 in the N shell.
Nuclides have the same chemical properties between isotopes of a particular element.
True: Isotopes have the same number of protons and therefore when neutral the same number of electrons.
An electron is not a nucleon.
True: Neutrons and protons are nucleons.
Nuclides are isotopes if they have the same atomic mass but different atomic number.
False: Nuclides with the same number of protons but different number of neutrons are isotopes, therefore they have the same atomic number and different atomic mass.
Velocity of electromagnetic radiation increases as energy increases.
False: Frequency increases with energy, but velocity is constant.
Frequency and wavelength of electromagnetic radiation are directly proportional to each other
FALSE. They are inversely proportional.
Visible light has a shorter wavelength than ultraviolet light.
FALSE. UV light has a shorter wavelength than visible light and is part of the electromagnetic spectrum
EM radiation includes beta radiation
False: Beta particles are electrons emitted from the nucleus.
EM radiation travels in straight lines if unattenuated.
True
Ionising radiation:
Causes direct damage if it is absorbed in tissue
True
EM radiation has energy that is usually expressed in Joules in diagnostic radiography
False: Electron volts (eV), which give manageable numbers for calculations (1eV = 1.6 x 10-19Joules).
Ionising radiation:
Causes indirect damage through ionization of water and production of free radicals
True
Ionising radiation:
Always obeys the inverse square law.
False: Only applicable to types of electromagnetic radiation from a point source and without attenuation.
Ionising radiation: Is useful in medical imaging in all its forms.
False: Gamma and x-rays are useful, neutrons, alpha, and beta particles are not.
Ionising radiation: May require only to be shielded with Perspex.
True: Beta radiation may require only Perspex shielding, however optimal shielding is achieved with Perspex backed with lead.
Secondary electrons: They are recoil electrons produced during Compton scattering events.
True
Secondary electrons: range depends only upon the density of the material through which they are travelling.
True
Secondary electrons can interact with inner shell electrons of atoms they pass causing ionization.
False: They interact with outer shell electrons to cause ionization.
Secondary electrons are the reason that x-ray and gamma rays are indirectly ionizing.
True: Alpha and beta particles are directly ionizing as they are charged.
Secondary electrons cause heat
Energy from the x-ray beam is converted into increased molecular motion and therefore heat.
β minus decay reduces atomic number by 1
False. Neutron -> Proton increases Z / atomic number by 1
Alpha particles are helium nuclei.
True
Some radionuclides emit electrons and characteristic x-rays
True: During internal conversion a K shell electron is ejected, producing characteristic x-rays when the K shell vacancy is filled with an electron from the L shell.
Radioactive decay is the number of disintegrations per minute.
False: Disintegrations per second (Bequerels (Bq)).
Most nuclides left in a metastable state after beta decay, emit gamma rays to reach ground state.
True:This is isomeric transition.
Positron emission reduces the number of protons in an atom by 1.
True.
Decay rate can be increased by increasing temperature.
False: Decay rate is not affected by physical conditions.
If stored long enough, the radioactivity of a radionuclide will drop to zero.
False. Radioactivity never reaches zero because of exponential decay.
Gamma emitting radionuclides with shorter half life are safer to use and store than those with longer life
True: Shorter time to decay to negligible activity is safer.
Beta emission is at a continuous range of energies.
True: Beta emission is at a continuous range of energies up to a maximum (Emax) and with average energy approximately Emax / 3.
Radioactive decay constant is the probability of nuclear decay per unit time.
True: Decay constant is the fraction of nuclei decaying per unit time.This is the
probability of decay, as decay of individual atoms occurs at random and cannot be predicted.
Physical half-life (t1/2) is the time taken for the activity to decay to ½ the original value.
True
Gamma rays are emitted at a single photon energy.
False: More than 1 photon energy may be emitted.
In 10 half-lives the activity is reduced by a factor of approximately 1000.
True - factor of 1024
Only one type of radiation is emitted by a radionuclide.
False: Often there is beta and gamma, or alpha and gamma emission together.
Direct emission from radioactive decay includes:
A. Beta minus emission.
B. Characteristic x-rays.
C. Bremsstrahlung.
D. Alpha particles.
E. Positron emission.
A.True: Occurs in radionuclides with neutron excess.
B. True: Through internal conversion or K-shell capture.
C. False: This is due to interactions of electrons with the electric field around the nucleus and not of decay directly.
D. True.
E. True: Occurs in radionuclides with neutron deficit.
Beam intensity is the total energy per unit area per unit time.
True
The inverse square law applies to all x-ray beams
False: This only applies to x-rays from a point source.
X-rays have lower linear energy transfer than alpha particles.
True: Alpha particles are heavy and produce ionizing events closely spaced along a short path, causing maximum DNA damage.
All electromagnetic radiation can cause ionization
False: Only high-energy photons (x-rays/gamma rays) are ionizing.
At equivalent energy, an x-ray cannot be distinguished from a gamma ray.
True: How they are produced differs, but they are indistinguishable at equivalent energies.
X-rays
Produced when electrons are accelerated or decelerated, or when they rearrange within an atom. X-rays can be produced naturally or by machines.
Gamma rays
Produced when an excited nucleus of a radioactive element undergoes radioactive decay. Gamma rays can also be produced by particle annihilation.
Usually a voltage of 10V and a current of 10A pass through the filament.
True: This heats the filament to incandescence, so that electrons can be boiled off by thermionic emission in order to be accelerated across the tube.
The accelerating voltage of the tube is typically in the range 60-120kV.
The process of thermionic emission occurs on the surface of the anode.
False: It occurs at the surface of the cathode.
When an accelerating electron interacts closely with a target nucleus it is deflected and slowed, losing energy that is emitted as an x-ray photon.
True: This is Bremsstrahlung, or braking radiation, which results in the continuous spectrum of radiation.
The angle of the target ensures that all x-rays produced pass through the window in the tube to form a beam.
False: X-rays will be produced in many directions, but only those that pass through the window will contribute to the useful beam, the others will be absorbed by the tube housing.
X-ray production in a diagnostic x-ray tube:
Is more efficient with a rotating compared to a stationary anode.
True
X-ray production in a diagnostic x-ray tube:
Requires a cooling air current at all times within the tube.
False: The tube contains a vacuum.
Radiation output from an x-ray tube increases with:
A constant potential compared to a single phase waveform.
True
Heat is only removed to the tube envelope by conduction.
False: Heat is radiated through the vacuum to the envelope.
X-ray Rotor bearings are lubricated with oil.
False: Silver is used oil would evaporate in the vacuum.
The anode stem is a poor heat conductor.
True: Prevents damage to the rotor assembly.
The addition of rhenium to the tungsten target increases toughness and lifespan of the target.
True: This alloy reduces surface pitting and increases lifespan.
X-ray anode angle is generally 20-35°.
False: The angle is generally 7-20°.
X-ray tube the anode angle increases the tube rating if the angle is reduced.
True
An x-ray tube rating is the maximum amount of kilowatts (kW) that can be safely used in a 0.1 second period
Diagnostic x-ray tube the anode angle
determines the size of field covered by the x-ray beam at a given focus-film distance.
True
Spectrum of an x-ray beam is not affected by filtration.
False: Increasing mA merely increases the number of photons.
Their energy and therefore the shape of the spectrum remains the same if kV is unaltered.
Double check - does it not increase the area under the curve
x-ray beam spectrum MAX/PEAK (as in photon number) is 3/4 kVp
FALSE. 1/3-1/2 Max kVp
Tungsten is used as a filament because of its high atomic number.
False:This is the reason that it is chosen for the anode.
Tungsten used because of high melting point and high resistance.
x-ray tube filament should have a low vapour pressure
True: A good property for thermionic emission
Anode heel effect results in more attenuation on which side
Photons on the ANODE side of the beam have more target material to travel through, so are attenuated and the intensity reduced.
Anode-heel effect is not advantageous in radiography
False: Mammography
Anode-heel effect is greater if target angle is steeper
True: The steeper the target, the further through the target material the photons on the anode side of the beam have to travel and the more attenuated they are.
Steeper = SMALLER angle
Anode-heel effect more noticeable if the focus-film distance is increased
False: With increased distance the beam diverges further and the film only intercepts the central part of the beam.
22 Increasing tube kV (with all other factors constant) increases:
Patient entrance surface dose.
True
22 Increasing tube kV (with all other factors constant) increases:
Scattered compared to primary radiation at the film.
True: Higher kV x-rays are more penetrating so scattering events occur deeper in the patient nearer the film.Also, the scattered photons are more penetrating.
22 Increasing tube kV (with all other factors constant) increases:
Radiographic contrast.
False: Contrast decreases as kV increases.
22 Increasing tube kV (with all other factors constant) increases:
Film blackening.
True: Increased kV causes increased exposure and increased film density.
22 Increasing tube kV (with all other factors constant) increases:
Photoelectric interactions compared to Compton interactions.
False:At higher kVs Compton events predominate
Increased tube filtration increases the half value layer.
True: Through beam hardening. Average beam energy is higher
Total attenuation is the product of Compton, photoelectric, and elastic attenuation effects.
True: This is the total attenuation. Attenuation coefficient is the sum of each process.
Half value thickness is inversely proportional to the linear attenuation coefficient.
True: Half value layer is 0.69/µ (µ = linear attenuation coefficient = fraction of the primary beam that is removed per unit distance).
Attenuation is altered by atomic number
True: Attenuation is increased with increasing Z number and increasing density of the attenuating material, through increased Compton scatter and photoelectric absorption. (The probability of photoelectric absorption is proportional to X
Attenuation is related inverse square law
False: Attenuation is the reduction in intensity due to interactions in matter, whereas the inverse square law is the reduction in intensity due to beam divergence from a point source.
HVL is thickness of a material that will reduce the intensity of a narrow x-ray beam to 50%
True. Exponential as 50% for every HVL.
HVL is a measure of the penetrating power of an x-ray beam.
True
HVL is for lead is greater than for aluminium at a given energy of x-ray beam.
False. Lead has a higher Z, no HVL needed is smaller
HVL is reduced as the photon energy of the radiation decreases.
True
Mass attenuation coefficient: Is measured in cm2/g.
True
Mass attenuation coefficient: Linear attenuation coefficient / density
True
Mass attenuation coefficient is less for water than for ice
False: It is equal for water and ice, as it is independent of physical density.
Mass attenuation has many practical applications in diagnostic radiology.
False: The linear attenuation coefficient has more practical applications, as film density produced by a certain depth of tissue is more useful than that produced by a certain mass of tissue.
Mass attenuation coefficient is proportional to the linear attenuation coefficient.
True. Mass attenuation coefficient is the linear attenuation coefficient / density
Linear attenuation coefficient: fractional reduction in intensity per unit thickness.
True. fractional reduction in intensity per unit thickness.
Linear attenuation coefficient: can be used to calculate the half value thickness.
True: HVL = 0.693 / linear attenuation coefficient.
So HVL is INVERSELY PROPORTIONAL to LAC
Linear attenuation coefficient: increases as photon energy increases.
False: It decreases as photon energy increases.
Less fractional reduction in intensity per unit thickness due to higher energy and more penetrance
Linear attenuation coefficient: It is measured in mm.
False. Its PER mm or mm^-1
The greater the difference in linear attenuation coefficients between two tissues, the greater the contrast between them.
True: Contrast is proportional to the product of the difference between the 2 linear attenuation coefficients and the thickness of the tissues involved.
Regarding scattered radiation: More is measured on the tube side of the patient in diagnostic radiology.
True: Most interactions occur at the entrance surface of the patient and forward scattered photons are more attenuated than backscattered ones.
Regarding scattered radiation: A Compton scattered photon is deflected from its path with no loss of energy.
False: This is elastic scattering.
Regarding scattered radiation: There is no ionization with elastic scattering.
True
Regarding scattered radiation: During a Compton interaction a photoelectron is produced.
False: These are formed in photoelectric interactions.
Regarding scattered radiation: At higher kV more photons are deflected through large angles.
C. True.
In Compton scattering: There is an interaction with a free electron.
True: The incident photon interacts with an outer shell an electron.
In Compton scattering: The recoil electron can be scattered in any direction.
False: The scattered photon can be emitted in any direction, but the recoil electron can be projected only forwards or sideways.
In Compton scattering: The larger the angle of scatter, the greater the reduction in energy of the incident photon.
True
In Compton scattering: All the photon’s energy can be transferred to the electron.
FALSE. The photon is scattered and therefore still retains some energy.Total absorption occurs in photoelectric interactions.
In Compton scattering: The amount of scatter is proportional to electron density.
True: The greater the concentration of electrons, the greater the probability of an interaction.
Concerning the photoelectric effect: incident photon completely disappears
True. NO SCATTERED RADIATION
Compton Scatter predominates in bone above
50kV
Compton Scatter predominates in tissue above
30kV
Concerning the photoelectric effect: main attenuation process in bone at 80kV.
False: The photoelectric effect predominates over Compton scatter in bone BELOW 50kV
The probability of a photoelectric interaction increases as photon energy increases.
FALSE. The probability of photoelectric interaction is inversely proportional to photon energy cubed.
The photoelectric effect: Involves free electrons.
False: It involves inner shell electrons. And produces characteristic radiation. Not just K shells but L.
The photoelectric effect: Is most important at the lower end of the diagnostic range of energies.
True: As an electron is removed a net negative charge results.
The K-absorption edge is important when choosing an x-ray filter, a contrast medium or an imaging phosphor.
True
An x-ray filter does not transmit photons well if they are of an energy equivalent to its own K-absorption edge.
False: It will be relatively transparent to photons of the energy of its absorption edge.
Barium has such a high atomic number that its K-absorption edge does not play a role in diagnostic imaging when it is used as a contrast medium.
False: The atomic number of barium is 56 and the K-absorption edge is 37keV. Diagnostic x-ray beams contain a high proportion of photons around this energy, ensuring a high probability of photoelectric interactions.
Filtration of an x-ray beam: Reduces the maximum photon energy (kVp).
False:The kVp remains the same, but lower energy photons are filtered out and average kV increases.
Filtration of an x-ray beam: By the patient is known as inherent filtration.
False: Inherent filtration results from absorption of x-rays as they pass through the X-RAY TUBE.
Filtration of an x-ray beam: Improves the rating of the x-ray tube
True.
Filtration of an x-ray beam: Is more effective for filtering high energy x-rays using a copper rather than an aluminium filter.
True: Copper has a higher atomic number than aluminium, so is better at filtering higher energy x-rays.
Filtration of an x-ray beam: Results in an image with improved contrast.
False: Filtration hardens the beam by increasing the mean energy of the photons, therefore contrast in the image is decreased.
Inherent filtration of an x-ray tube: Absorbs high energy x-rays.
False:Absorbs low energy x-rays.
Inherent filtration of an x-ray tube: Causes beam hardening.
True: By removing low energy photons and increasing the average energy of the beam.
Inherent filtration of an x-ray tube: Is increased if beryllium instead of glass is used in the tube window.
False: Beryllium has a lower atomic number than glass, therefore filtration is less.
Inherent filtration of an x-ray tube: Is usually equivalent to 2.5mm aluminium.
False: Total filtration is approximately 2.5mm Al, inherent is 0.5 - 1mm.
Inherent filtration of an x-ray tube: Is mostly due to the oil.
False: Due to target, tube window, and the oil.
Added filtration: Does not affect patient entrance dose.
False: Absorbs low energy x-rays.
Added filtration: Alters the quality of the x-ray beam.
True. By removing low energy photons and increasing the average energy of the beam.
Added filtration: May consist of a compound filter.
True: Copper is used with a backing of aluminium on the patient side to absorb the 9kV characteristic radiation from the copper.
Added filtration: Is generally made of aluminium in diagnostic tubes.
True.
Added filtration: Does not affect the intensity of the beam.
False: Intensity or amount of radiation is decreased by the filter.
X-ray tube rating increases with: Rotating compared to stationary anodes.
True: There is more efficient heat loss from a rotating anode, so the rating is higher.
X-ray tube rating increases with: Larger focal spot size.
True: A larger focal spot causes less heating than if the beam were focused onto a smaller area.
X-ray tube rating increases with: Increasing the anode angle with fixed focal spot size.
False: A smaller anode angle has a higher heat rating.
X-ray tube rating increases with: Half wave compared to full wave rectification.
False: Rating is increased with full wave rectification.
X-ray tube rating increases with: Quicker production of heat.
E. False: This makes the tube rating lower.
Measurement of radiation dose: Can be read directly through an electronic read-out from photoconductive silicon diodes.
True: Useful for personal dosimeters and quality assurance
Measurement of radiation dose: Is useful for personal and patient dosimetry with the use of thermoluminescent dosimeters.
True
Measurement of radiation dose: With a dose area product meter provides a figure with the units cGy cm3.
False: It is the product of dose and area with units cGy cm2.
SQUARED NOT CUBED
Measurement of radiation dose: May be carried out using thimble ionization chambers within the field of interest.
True
Measurement of radiation dose: For staff may utilize the photographic effect of silver bromide in a film badge.
True
Film badges: Use double emulsion film.
True: If the fast emulsion is over-exposed by a high-dose exposure, the slow emulsion can be read.
The following are true of thermoluminescent dosimeters:
The phosphor used is commonly lithium chloride.
False: Lithium FLUORIDE.
Film badges: Use cadmium nuclei to detect neutron exposure.
True: The interaction of neutrons with the cadmium nuclei results in gamma ray emission that is detected by the film.
Film badges: Are calibrated with a caesium source.
True.
Film badges: Have an open window for the detection of beta particles.
True.
Film badges: Should be analysed once a year when monitoring staff.
False: They are subject to environmental effects, so should not be used for longer than a month.
The following are true of thermoluminescent dosimeters:
X-ray interactions involve outer shell electrons of the thermoluminescent phosphor.
True: Valence shell electrons are involved.
The following are true of thermoluminescent dosimeters:
When exposed to radiation, interactions excite electrons that become trapped in the forbidden energy band.
True: A valence shell electron is excited into the conduction band and then falls back into an electron trap in the forbidden energy band.
The following are true of thermoluminescent dosimeters:
The amount of light produced depends on the energy of the photons involved in the exposure.
True.
Regarding luminescence:
It is the process by which a material absorbs energy from an external source and re emits it as light.
True.
The following are true of thermoluminescent dosimeters:
Their response is linear with dose over a wide range.
True.
Regarding luminescence:
Fluorescence is the delayed emission of light following energy input.
False: Fluorescence is the instantaneous emission of light following energy input.
PHOSPHORESCENCE is the delayed emission of light.
Regarding luminescence:
For light to be emitted from a phosphor, electrons in the electron traps must fall to the conduction band.
FALSE.
False: The x-ray photons excite electrons from the valence band to the conduction band, where they then fall into electron traps.
They must fall BACK TO VALENCE BAND for light to be emitted.
Regarding luminescence:
After irradiation, a thermoluminescent phosphor must be stimulated with a laser for light to be emitted.
False: THERMOluminescence requires HEATING.
PHOTOstimulable luminescence requires light.
Regarding luminescence:
Intensity of light emitted from a phosphor is proportional to the intensity of the irradiating x-ray beam.
True.
Deterministic effects of ionizing radiation include:
A Cataract
B. Epilation
C. Leukaemia
D. Lung cancer
E. Erythema
The deterministic effects are: Cataract, Epilation, Erythema
Deterministic: Damage depends on absorbed dose, Threshold exists
Stochastic effects of radiation include:
A Infertility
B. Leukaemia
C. Cataract
D. Cancer
E. Hair loss
The Stochastic effects are: Leukaemia and cancer
Stochastic:
Severity is independent of absorbed dose
Threshold does not exist
Probability of occurrence depends on absorbed dose
Equivalent dose: Is derived from absorbed dose multiplied by a tissue weighting factor.
FALSE. Equivalent dose = Absorbed dose x radiation weighting factor
ED = AD x RWF
Equivalent dose: Is measured in Sieverts (Sv).
True
Equivalent dose:
Is averaged over all tissues of the body.
False. Equivalent dose = absorbed Dose multiplied the appropriate radiation weighting factor.
Equivalent dose is calculated for individual organs.
Equivalent dose is expressed in millisieverts (mSv) to an organ.
Effective dose is calculated for the whole body.
It is the addition of equivalent doses to all organs, each adjusted to account for the sensitivity of the organ to radiation.
Effective dose is expressed in millisieverts (mSv).
Equivalent dose: Is the same as absorbed dose for neutrons.
False. As the radiation weighting factor for neutrons range from 5 to 20.
Equivalent dose: Is the same as absorbed dose for neutrons.
False. Equivalent dose = absorbed Dose multiplied the appropriate radiation weighting factor.
Equivalent dose: Takes into account sensitivity of the tissues to radiation.
False. It is based on the absorbed dose to an organ, adjusted to account for the effectiveness of the type of radiation (radiation weighting factor).
The radiation weighting factors are needed because different types of radiation (like alpha, beta, gamma, and neutrons) can have different effects even if the absorbed dose is the same.
Absorbed dose:
Absorbed dose is the amount of energy deposited by radiation in a mass.
The mass can be anything: water, rock, air, people, etc.
Absorbed dose is expressed in milligrays (mGy).
Absorbed dose: Relative to an organ depends on its mass.
Depends on the radiation weighting factor.
Is the amount of energy deposited per unit mass to a medium.
False.
Absorbed dose is the amount of energy deposited by radiation in a mass.
Absorbed dose: Is measured in Joules/Kg.
True. The unit is Gray & 1 Gray= 1 Joule/Kg.
Absorbed dose: Is measured in Sieverts.
False. Equivalent and effective doses are measured in Sieverts (Svt)
Absorbed dose = Gy or Joules/Kg
Absorbed dose: depends on radiation weighting factor
False. Energy deposited per unit mass
Equivalent dose for radiation weighting factor.
DOSE EQUIVALENT FOR EACH TYPE OF RADIATION.
Absorbed dose: Is the amount of energy deposited per unit mass to a medium.
True.
Effective dose: Is derived from absorbed dose multiplied by a tissue weighting factor.
False. EQUIVALENT Dose x tissue weighting factor
Effective dose: Is measured in Gray.
False. Measured in Sv
Effective dose: Takes into consideration the different radiosensitivity of tissues.
True
Effective dose: Combines organ doses to give a whole body dose.
True
In a dental film is in the order of 0.004mSv.
True
Regarding ionizing radiation:
A Neutrons are low LET (linear energy transfer) radiation.
False. Neutrons are high-LET radiation.
The radiation weighting factor for alpha particles is 20.
True. The radiation weighting factor for alpha particles is 20.
X-rays and beta particles have the same radiation weighting factor.
TRUE. The radiation weighting factor for both is unity.
The radiation weighting factor for neutrons is unity.
False. Neutrons is is 5-20 depending on the radiation energy.
For x-rays absorbed dose is equal to the equivalent dose.
True. RF for XRs, Gamma and beta particles is 1.
The following tissues have a high carcinogenic risk from radiation (more than or equal to 0.12 tissue-specific weighting factor):
Colon
Skin
Breast
Bone marrow
Oesophagus
Colon T
Skin F
Breast T
Bone marrow T
Oesophagus F
Lung Breast Stomach 0.12
Colon 0.12
Red bone marrow 0.12
Gonads LOWERED from 0.2 to 0.08
The following tissues have a moderate carcinogenic risk from radiation (0.05 in tissue-specific weighting factor):
Skin
Gonads
Lung
Breast
Bone
Skin F
Gonads F
Lung F
Breast F
Bone F
BLOT
Bladder 0.05
Liver 0.05
Oesophagus 0.05
Thyroid 0.05
tissues with the LOWEST carcinogenic risk WT 0.1
Tissue weighting factor of 0.1:
Bone surface, skin,
brain, salivary glands
Unit for entrance surface dose is
Gy
Unit for equivalent dose
Sv
Dose area product (DAP) units
Dose area product (DAP)-Gy cm2
AREA = CENTREMETRES SQUARED
Absorbed dose units
Joules/kg or Gy
Effective dose units
Sv
Regarding deterministic effects:
Diarrhoea and vomiting are examples.
There is a threshold dose above which they do not occur.
Effects occur by chance.
The threshold dose is the same for different deterministic effects.
Severity increases with increasing dose.
Regarding deterministic effects:
True. Diarrhoea and vomiting are example
False. Threshold BELOW that deterministic effects do not occur.
False. Occur dose dependantly
False. Different thresholds
True. Severity increases with increasing dose.
Regarding stochastic effects:
The probability of a stochastic effect is independent of dose.
Occur immediately after exposure to ionising radiation.
Have a linear no threshold theory.
Sterility is an example.
Breast cancer is an example.
Regarding stochastic effects:
False. Probability increases with increasing dose.
False. They occur after a latent period which lasts for many years.
True. Have a linear no threshold theory. They occur by chance and are not dose dependent but the chance of developing stochastic effects increases with the dose.
Sterility is NOT example.
Breast cancer IS an example.
In the daily practice of diagnostic radiology stochastic effects are commoner than deterministic effects.
FALSE. Deterministic effects are more common (think therapeautics)
The chances of producing deterministic effects is the same for x-rays and gamma rays.
True. Both RF =1
No dose is considered safe for deterministic effects.
False. Thresholds exist for deterministic effects.
No dose safe for stochastic effects.
Deterministic effects may be non-additive.
True. Deterministic effects may be non-additive.
Beta particles travel through matter at high speeds.
True
Alpha particles travel through matter at low speeds.
Alpha particles have a large mass and double charge making them travel slowly through matter.
Alpha particles are similar to the nucleus of hydrogen.
False: They are similar to helium nucleus with 2 protons and 2 neutrons.
Beta particles are heavier than alpha particles.
False: Alpha particles are heavier.
Alpha particles have useful applications in diagnostic radiology.
False:They produce a large amount of ionization per unit length of the medium through which they travel making them unsafe for use in radiology.
Entrance surface dose are typical for PA chest film - 0.15 mGy.
True. Entrance surface dose are typical for PA chest film - 0.15mGy.
Entrance surface dose are typical for Lateral lumbar spine x-ray - 12 mGy.
True. Entrance surface dose are typical for Lateral lumbar spine x-ray - 12mGy.
Entrance surface dose are typical for AP skull x-ray - 2mGy.
True: DRL is 3mGy.
Entrance surface doses are typical for AP abdomen film - 8 mGy.
False: Entrance surface dose is usually 5mGy. The DRL for an abdominal film is 7 mGy.
Fluoroscopy ENTRANCE surface dose rate - 100 - 150 mGy/min.
False: The skin or entrance surface dose rate of fluoroscopy is 5-50 mGy/min.
Abdominal Imaging:
Approximate Effective Doses for
Intravenous Urography (IVU)
CT Colonoscopy
Computed Tomography (CT)–Abdomen and Pelvis
Computed Tomography (CT)–Colonography
Barium Enema (Lower GI X-ray)
Upper GI Study with Barium
Computed Tomography (CT)–Abdomen and Pelvis, repeated with and without contrast material
https://www.radiologyinfo.org/en/info/safety-xray
Intravenous Urography (IVU) 3mSV
CT Colonoscopy = 6mSV
All double = 8mSV
Dual Phase = 15mSV
Head imaging:
Approximate Effective Doses for
CT H&N
CT Brain repeated with and without contrast
CT Chest
CT CA
CT Spine
CT H&N 1.2 mSv
CT Brain 3.2 mSv
CT Chest 5
CT CA 9
CT Spine 9
The effective dose typical for a CT head - 2mSv
False
CT Head = 1.2
The effective dose typical for a CXR 0.15mSV
FALSE 0.1mSV
The effective dose typical for a CT Chest 4 mSV
FALSE. About 6mSV
Barium enema - 7mSv
True about 7 or 8 mSV
Lumbar spine x-rays - 0.8mSv
True Lumbar spine x-rays - 0.8mSv
RADIATION interactions: Biological damage to tissue occurs immediately on interaction with tissue.
False
Following exposure to ionizing radiation, chemical changes occur practically immediately (in seconds to minutes) and then molecular damage (in hours to decades).
Molecular damage to tissue occurs hours after ionising interaction with tissues.
True.
Following exposure to ionizing radiation, chemical changes occur practically immediately (in seconds to minutes) and then molecular damage (in hours to decades).
Chemical changes in tissue occurs hours after ionising interaction.
False.
Following exposure to ionizing radiation, chemical changes occur practically immediately (in seconds to minutes) and then molecular damage (in hours to decades).
The principal radiation sources for medical exposures is x-rays and gamma radiation.
True
Radiation interactions depends on the radiosensitivity of tissues.
Direct ionising radiation damage to tissue occurs by the production of free radicals.
False. INDIRECT.
Direct damage to tissue occurs by the rupture of covalent bonds and indirect damage by the production of free radicals.
Indirect ionising radiation damage to tissue occurs by the rupture of covalent bonds.
False. DIRECT.
Direct damage to tissue occurs by the rupture of covalent bonds and indirect damage by the production of free radicals.
Cell death occurs when there is insufficient time for tissues to recover between subsequent irradiation events.
True.
Free radicals produced secondary to ionization causes chemical changes in tissues.
True.
Biological effects of ionizing radiation is independent of the type of ionising radiation.
FALSE. Depending on LINEAR ENERGY TRANSFER.
Threshold for deterministic effects
Threshold for deterministic effects: Cataract 5 Gy
FALSE.
The most recent guidelines state that the threshold dose for radiation-induced cataracts is 500mSv (0.5Gy)
Threshold for deterministic effects: Temporary Hair Loss 3-4 Gy
True 3-4 Temporary Hair Loss Gy
Threshold for deterministic effects: Erythema 3 - 6 Gy
True. Erythema 3 - 6 Gy
Depression of blood cell production 0.5 Gy
True. Depression of blood cell production 0.5 Gy
Permanent sterility 3-6 Gy
True. Permanent sterility 3-6 Gy
- The potential risks to the foetus from radiation in utero include:
A. Development of cancer
B. Mental retardation
C. Decrease in IQ
D. Intrauterine growth retardation
E. Leukaemia
ALL TRUE.
Max potential for foetal abnormalities received during pregnancy weeks 3 - 8.
True: Weeks 3-8 is the period of organogenesis when the potential is highest.
Mental retardation if max radiation during pregnancy weeks 8 - 15
True: A decrease in IQ is, however, seen up to the 25th week of pregnancy.
Max potential for GROWTH RETARDATION if max radiation given during weeks 8 - 25.
TRUE. Growth retardation weeks 8-25
Max potential for foetal death if max radiation given during 1st Trimester.
FALSE. During pre-implantation phase
Max potential for childhood cancers if max radiation given during 3st Trimester.
FALSE.
The risk is almost nil up to 3 weeks following which the risk remains for the rest of the pregnancy but is maximum in the first trimester.
The risk of fatal cancer from a uniform whole body irradiation is 1 in 200,000 per mSv.
FALSE.
0.005% per millisievert mSv
OR
1 in 20,000 per mSv
The International Commission on Radiological Protection (ICRP) quantifies the radiation risk factor as 5% (5 in 100) per Sv, or 0.005% (1 in 20,000) per mSv.
The risk of developing fatal childhood cancer from irradiation in utero is 1 in 50,000 per mGy.
FALSE.
False: It is 3% per Gy or 1 in 33,000 per mGy. Check
The risk of developing childhood cancer from irradiation in utero is 1 in 10,000 per mSv.
TRUE
The cornea is more radiosensitive than the lens.
False
Radiation dose to the hands of staff arises from the use of radionuclides as well as from x-rays.
True.
Deterministic effects are hereditary.
False.
No, deterministic effects are not considered hereditary; they are tissue reactions that occur directly from a high radiation dose to an individual and do not pass on to their offspring, unlike stochastic effects which can be genetic and therefore heritable
Regarding the natural and artificial sources of radiation:
Sodium is the commonest contributor of radiation from internal sources.
FALSE.
Potassium-40, a radioactive isotope of potassium is the commonest contributor of radiation from internal sources.
The average dose of radiation to the UK population from natural sources is 1.7mSv per year.
FALSE.
Average dose is 2.7mSv per year.
https://www.ukhsa-protectionservices.org.uk/radiationandyou/
Average dose in Cornwall is 7mSv
So just over double the national average of 2.7mSv
True.
The decay of radon is primarily associated with the emission of …
Alpha Particles
The dose received from medical diagnostic procedures averaged over the whole population in the UK is 250µSv.
False: It is 370 µSv and accounts for 14% of the radiation from natural and artificial sources in the UK.
Dose area product (DAP): Decreases with the square of the distance from the x-ray focus.
DAP is absorbed dose x area =
Gy cm^2
INDEPENDANT OF DISTANCE
Dose area product (DAP): Is an appropriate quantity for dosimetry in fluoroscopy.
True
Dose area product (DAP): Is an appropriate quantity for dosimetry in CT.
FALSE.
The quantities used in CT dosimetry include the CT dose index (CTDI), weighted CT dose index (CTDIw), and dose length product (DLP). The effective dose is measured in millisieverts (mSv
Dose area product (DAP): May be used to set diagnostic reference levels.
True. DAP can used to set diagnostic reference levels.
Dose area product (DAP):
Can be measured with a thermoluminescent dosimeter (TLD).
FALSE. Using an ionising chamber!
Entrance surface dose (ESD):
Is measured in Gycm2
False. ESD measured in Gray
Entrance surface dose (ESD): Increases in proportion to x-ray field size.
True. As it includes Scatter.
https://radiopaedia.org/articles/entrance-skin-dose?lang=gb
Entrance surface dose (ESD):
Can be calculated from knowledge of exposure factors and x-ray output data.
TRUE.
Entrance surface dose (ESD):
Can be measured from DAP if the x-ray field size and back scatter are known.
TRUE.
Entrance surface dose (ESD):
Can be measured using a TLD.
TRUE. ESD can be measured using a TLD.
Regarding thermoluminescent dosimeters:
They are generally used in conjunction with filters.
True.
three filters against each disc
top: aluminium and copper
middle: perspex
lower: open
Regarding thermoluminescent dosimeters:
They contain a crystal of lithium iodide.
FALSE.
They contain a crystal of lithium FLUORIDE.
nickel-coated aluminium card with TLD discs
the discs are made of a thermoluminescent material, commonly calcium sulphate doped with dysprosium (CaSO4:Dy) or lithium fluoride (LiF)
Regarding thermoluminescent dosimeters:
They have a linear response over a wide dose range.
True. That’s why we use them/ TLDs!
Regarding thermoluminescent dosimeters:
They can differentiate between radiation types.
FALSE.
TLDs CANNOT differentiate between radiation types.
Regarding thermoluminescent dosimeters:
False. ENTRANCE SURFACE DOSE.
Advantages of thermoluminescent dosimeters: They can measure dose rates.
FALSE.
Advantages of thermoluminescent dosimeters: They can be reused.
TRUE.
Advantages of thermoluminescent dosimeters: The sensitivity is significantly better than film.
FALSE. TLD and Film sensitives are SIMILAR.
Advantages of thermoluminescent dosimeters: They can be used to measure both shallow and deep doses.
True. Hence the different filters?
Advantages of thermoluminescent dosimeters: They can be used to monitor eye doses.
True: TLDs can be made into various shapes, they can be used for the assessment of finger and eye doses.
Film badges: Are able to identify the type of exposure.
TRUE.
Film badges: Utilize a single sided film emulsion.
FALSE. Utilize a DOUBLE sided film emulsion.
Film badges: Are relatively resistant to environmental effects.
False:
FILM BADGES are subject to the environmental effects of HEAT, HUMIDITY, and CHEMICAL CHANGE
Film badges: Utilize a double sided film emulsion with screen.
FALSE. Thy use a double sided film emulsion BUT WITHOUT a screen.
Film badges:
TRUE. TLDs and Film badges HAVE SIMILAR SENISITIVIES.
But unlike TLDs - PERMANENT + NON-REUSABLE.
TLDs can provide a direct reading of dose.
FALSE. INDRECT as LUMINESCENCE
TLDs provide a permanent record of dose.
FALSE. TLDS are TEMPORARY and can be REUSED.
Film badges do not require calibration.
FALSE. FILM BADGES DO REQUIRE CALIBRATION.
Aluminium oxide is used in optical stimulated luminescent dosimeters.
True.
Optical stimulated luminescent dosimeters give readings down to 0.01mSv.
True.
TLDs: Are used for assessment of finger doses.
True.
TLDs: Are relatively cheaper than film badges.
False. TLDs are more expensive but reusable.
TLDs: Are used to detect radioactive contamination.
FALSE.
TLDs: The dose can be read only once.
D. True: They can only read a dose once but TLDs can be re-used and read many times.
TLDs: Are unaffected by environmental effects.
False: They are affected by environmental effects (especially heat).
TLDs: An immediate read out is possible.
FALSE.
TLDs: Sensitivity is relatively energy dependent.
False: TLDs are relative energy independent.
TLD crystal needs to be heated to about 300°C to be read.
True.
TLDs need to be annealed after read out.
True
TLD crystal can be calcium fluoride.
True
Film badges: Sensitivity is about 0.1-0.2mSv.
True.
Film badges: Can be used for assessment of finger dose.
False. TLDs used for finger and eye doses.
Film badges: Provide a permanent record of exposure.
True.
Film badges: Are usually replaced 3 monthly.
False.
Film badges are subject to the environmental effects of heat, humidity, and chemical change
UNSUITABLE OVER 1 MONTH.
Film badges: Measure the effective dose received.
FALSE.
Film badges measure the ABSORBED dose, which we presume represents the whole body dose.
TLDs have a precision better than 1%.
False: Only electronic dosimeters have a precision better than 1%.
TLDs can be used to measure dose to a patient.
TRUE.
Dosimeters: Dose to a patient can be measured with an ionization chamber.
True.
Geiger Muller counters require a quenching agent.
True.
How a Geiger Muller tube works:
When radiation enters the tube, it ionizes the gas inside, creating an avalanche of electrons towards the central anode.
Problem without quenching:
If left unchecked, this avalanche could continue indefinitely, causing a continuous discharge and preventing the detection of further radiation events.
Role of the quenching agent:
A small amount of a special “quench” gas like a halogen or organic vapor is added to the tube, which absorbs the energy released during the avalanche, preventing further ionization and allowing the tube to reset for the next detectio
The outer case of the Geiger Muller counter is the anode.
False: The outer case is the cathode.
Electronic personal dosimeters: Are more than 100 times sensitive than TLDs.
True. On Electronic personal dosimeters have a better than 1% accuracy.
Electronic personal dosimeters:
Measure both dose and dose rates.
True. Electronic personal dosimeters measure BOTH DOSE and DOSE RATES.
Electronic personal dosimeters:
Have sensitivity to the nearest 1µSv.
True.
Electronic personal dosimeters:
Do not provide a direct reading.
FALSE. Electronic personal dosimeters DO provide a direct reading.
Electronic personal dosimeters:
The silicone diode detector is a common type.
True.
TLD should not be used without a dosimeter holder.
True.
During interventional procedures the TLD must be worn above the protective lead apron.
FALSE. KEEP TLD UNDER APRON.
Electronic personal dosimeters are used to detect radioactive contamination.
True.
Electronic personal dosimeters are used to detect radioactive contamination.
The TLD holder helps to differentiate between skin doses and deeper doses.
True.
True: The holder has filters which are responsible for this function.
The precision of a TLD is approximately 15% for low doses.
True.
TLD = 15% for low doses
TLD = 3% for high doses
The precision of a TLD is approximately 3% for high doses.
True.
TLD = 15% for low doses
TLD = 3% for high doses
Geiger Muller tubes:
Have a dead time when no reading can be done.
TRUE.
Geiger Muller tubes:
Are used mainly for patient monitoring.
False: They are used mainly in nuclear medicine to detect contamination.
Geiger Muller tubes: Detect all types of radiation.
True.
Geiger Muller tubes: Can distinguish between all types of radiation.
FALSE.
Can detect ALL types of radiation but CANNOT DIFFERENTIATE between them
Geiger Muller tubes: Contain a central wire cathode.
FALSE.
OUTER HOUSING is the CATHODE
CENTRAL WIRE is the ANODE.
IRR 1999 (99) has been replaced with
Ionising Radiation Regulations 2017
https://www.legislation.gov.uk/uksi/2017/1075/contents
IRMER (2000) has been replaced with
IRMER (2017)
Regarding controlled areas:
Are required where a person working is likely to receive an effective dose more than 3 mSv per year.
FALSE.
IRR 2017:
Regarding controlled areas are required where a person working receives more than:
EFFECTIVE DOSE: 6mSv per year
EQUIVALENT DOSE: 15mSv to LENS
EQUIVALENT DOSE: 150mSv to SKIN or EXTREMETIES
RCA: 6/15/150
RSA: 1/5/50
Radiology controlled areas:
Required with equivalent dose of 15mSv to eye or
150mSv to skin or extremities.
True.
RCA: 6/15/150
RSA: 1/5/50
Radiology Supervised area:
If effective dose is greater than 1mSv per year
True
RCA: 6/15/150
RSA: 1/5/50
Radiology Supervised area:
If equivalent dose is 5mSv to lens or 50mSv to extremities.
True
RCA: 6/15/150
RSA: 1/5/50
Regarding controlled areas:
Dose rate exceeds 7.5 micro Sv per hour averaged over the day.
True.
Regarding controlled areas:
Are required where a person working is likely to receive a radiation dose greater than three-tenths of any dose limit.
True.
An employer is required to designate a person as being classified if that person is likely to receive an effective (whole body) dose in excess of 6mSv/y, or more than three-tenths of the dose limit to the extremities (150 mSv/y).
Regarding controlled areas:
Are required where the external dose rate could exceed 5 µSv per hour averaged over the working day.
FALSE.
Regarding controlled areas:
Dose rate exceeds 7.5 micro Sv per hour averaged over the day.
Regarding controlled areas:
An intervention suite is an example.
True.
Regarding controlled areas:
True.
IRR 2017:
All imaging AND INJECTING ROOMS will be controlled areas due to prevailing dose rates AND RISK OF CONTAMINATION.
Staff exposed to potential contamination should have appropriate PPE.
Ideally hot and cold waiting areas should be separate.
Controlled areas:
Are required where a person working is likely to receive an equivalent dose more than 6mSv per year:
FALSE.
EFFECTIVE dose >6 mSv / year
Controlled areas:
May be required where there is a risk of radioactive contamination.
TRUE.
Controlled areas:
Must be described in the local rules.
TRUE.
Ionising Radiations Regulations 2017 (IRR 2017), “controlled areas” must be - clearly described and outlined
- within the “local rules”
- that an employer is required to establish for radiation protection purposes
- must detail specific procedures and restrictions
Controlled areas:
D. Are permitted areas for pregnant staff.
True.
IRR 2017:
EMPLOYER must take steps to
- minimise radiation exposure,
- with the goal of keeping the equivalent dose to the fetus below 1 millisievert (mSv) for the remainder of the pregnancy
Controlled areas:
Are monitored by the Radiation Protection Advisor
FALSE.
Controlled area:
MONITORING: Radiation protection SUPERVISOR
ENFORCING: Health and Safety Executive (HSE) in most situations, or the Office for Nuclear Regulation (ONR) for nuclear sites
Supervised areas:
Are required only where a person working is likely to receive an effective dose more than 3mSv per year.
FALSE:
IRR 2017:
Are required only where a person working is likely to receive an effective dose more than 1 mSv per year.
The radiation worker dose limit in mSv/year in IRR 2017
The radiation worker dose limit of 20 mSv/year in IRR17
Supervised areas:
Are required only where a person working there is likely to receive a radiation dose greater than three-tenths of any dose limit.
FALSE.
3/10 x 20 = 6 mSv - this is the limit for a controlled area
RSA = 1 mSv per year or 1/20th
Supervised areas:
C. The waiting room for patients who have been injected with a radiopharmaceutical is an example.
True.
Supervised areas:
Must be clearly marked with warning signs.
True.
IRR 2017: RCA and RSA’s:
is adequately described in local rules; and
(b) has suitable and sufficient signs displayed in suitable positions warning that the area has
been so designated a
Supervised areas:
Can become a controlled area.
True: If the dose limits are exceeded and should be monitored regularly.
Regarding IRR 2017:
The employer must consult a Radiation Protection Supervisor prior to installing new equipment.
FALSE.
Radiation protection adviser must be consulted for new equipment.
Regarding IRR 2017:
The Healthcare Commission must be informed of the use of ionizing radiation by the employer.
False.
Ionising radiation use must inform health and safety executive (HSE)
IRR 2017:
Part 2 (General principles and procedures—Regulations 5–13)
Regulation 5 requires certain work with ionising radiation to be notified to the appropriate authority (either the Health and Safety Executive (“the Executive”) or,
where the work relates to
particular nuclear-related sites, the Office for Nuclear Regulation (“the ONR”)).
Regarding IRR 2017:
The Radiation Protection Supervisor (RPS) is invariably a medical physics expert.
FALSE.
Any suitably trained staff member, e.g. radiographer, can take up the role of RPS.
According to the Ionising Radiations Regulations (IRR) 2017, a “Radiation Protection Supervisor” (RPS) can be any individual appointed by an employer to oversee the implementation of local rules and ensure compliance with the IRR 2017 regarding radiation protection within their workplace; this could be a staff member directly involved in radiation work, a team leader, or another suitable person with the necessary training and authority to monitor radiation practices and enforce safety procedure
Regarding IRR 2017:
Critical examination of equipment is the responsibility of the employer.
FALSE. By Installer:
(2) Where a person erects or installs an article for use at work, being work with ionising
radiation, that person must—
(a) undertake a critical examination of the way in which the article was erected or installed
for the purpose of ensuring, in particular, that—
(i) any safety features and warning devices operate correctly; and
(ii) there is sufficient protection for persons from exposure to ionising radiation;
consult with the radiation protection adviser that they appointed, or that the employer
engaged in work with ionising radiation appointed, with regard to the nature and extent of
any critical examination and the results of that examination
Regarding IRR 2017:
The Radiation Protection Supervisor (RPS) must be an employee of the organization.
FALSE. They can be contracted out.
https://www.luciongroup.com/services/radiation-protection-supervisor-contractor-hire/
Regarding IRR 2017:
The regulations govern the safety of staff, patients, and public.
False: The regulations govern the safety of staff and public but not patients.
Regarding IRR 2017:
The Health and Safety Executive is the governing authority.
True.
And for radionculides:
Office for Nuclear Regulation
Regarding IRR 2017:
The local rules should include descriptions of all designated areas.
True.
Regarding IRR 2017:
The equivalent dose limits are concerned with stochastic effects.
FALSE.
EQUIVALENT dose limits are designed to ensure doses are kept below the threshold doses for DETERMINISTIC effects.
Regarding IRR 2017:
The effective dose limits are designed to prevent deterministic effects.
FALSE.
EFFECTIVE dose limits are designed to prevent STOCHASTIC effects (cancer / inheritable effects).
The following annual dose limits apply:
The effective dose to a member of public is 2mSv.
FALSE.
IRR 2017 Whole body EFFECTIVE dose:
Over 18: 20 mSv (same as lens)
Under 18 workers: 6mSv
Public: 1mSv
The following annual dose limits apply:
The equivalent dose to the lens of the eye of an employee is 500mSv.
FALSE.
IRR 2017:
Equivalent dose limits for LENS:
Over 18:
20mSv per year.
OR 100mSv over 5 years, with max 50mSv in any one year.
Under 18 or anyone else:
15 mSv per year
The following annual dose limits apply:
The equivalent dose to the skin of an employee is 500mSv.
TRUE.
IRR 2017:
EQUIVALENT dose to skin:
Over 18: 500 mSv
Under 18 workers: 150 mSv
Public: 50 mSv
The following annual dose limits apply:
The dose to the abdomen of a woman of reproductive age should not be more than 13mSv in any consecutive 3-month period.
FALSE.
IN IR 1999
https://www.legislation.gov.uk/uksi/1999/3232/schedule/4/part/I/made/data.xht?view=snippet&wrap=true
BUT NOT 2017
https://www.legislation.gov.uk/uksi/2017/1075/schedule/3
The following annual dose limits apply:
The equivalent dose to the extremities of an employee is 150mSv.
False. True for only under 18 year olds:
EQUIVALENT dose to skin or extremities:
Over 18: 500 mSv
Under 18 workers: 150 mSv
Public: 50 mSv
The following annual dose limits apply:
The equivalent dose to the skin of a member of the public is 50mSv.
TRUE.
EQUIVALENT dose to skin or extremities:
Over 18: 500 mSv
Under 18 workers: 150 mSv
Public: 50 mSv
The following annual dose limits apply:
The foetus of a pregnant employee should not receive more than 0.1mSv.
FALSE.
A dose constraint of 1mSv is applied as the foetus is regarded as a member of the public.
IRR 2017:
EMPLOYER must take steps to
- minimise radiation exposure,
- with the goal of keeping the equivalent dose to the fetus below 1 millisievert (mSv) for the remainder of the pregnancy
The following annual dose limits apply:
The equivalent dose to the lens of a member of the public is 15mSv.
FALSE.
Equivalent dose limits for LENS:
Over 18:
20mSv per year.
OR 100mSv over 5 years, with max 50mSv in any one year.
Under 18 or anyone else:
15 mSv per year
The following annual dose limits apply:
The equivalent dose to the extremities of a member of the public is 150mSv.
FALSE.
EQUIVALENT dose to skin or extremities:
Over 18: 500 mSv
Under 18 workers: 150 mSv
Public: 50 mSv
The following annual dose limits apply:
The effective dose to an employee is 10mSv.
FALSE.
IRR 2017 Whole body EFFECTIVE dose limit:
Over 18: 20 mSv (same as lens)
Under 18 workers: 6mSv
Public: 1mSv
IRR 17 states that the following people may enter controlled areas:
Classified employees.
True
IRR 17 states that the following people may enter controlled areas:
Radiographers
False.
IRR 17 states that the following people may enter controlled areas:
Non-classified employees entering under a written agreement.
True.
https://assets.publishing.service.gov.uk/media/5fdb807ed3bf7f3a334ed39d/JSP_392Chapter_05-WRITTEN_ARRANGEMENTS__Alt_Text.pdf
IRR 17 states that the following people may enter controlled areas:
Patients having radionuclide imaging.
False.
IRR 17 states that the following people may enter controlled areas:
Operators
False.
Non-classified workers are not permitted to enter controlled areas.
False: Local rules may allow non-classified workers to enter a controlled area.
Controlled areas: Require special working procedures to restrict exposure.
True.
Access of radiology staff to controlled areas must be restricted.
True.
Controlled areas:
Are needed for portable x-ray units.
True.
For mobile X-ray sets, the controlled radiation area extends in the direction of the Xray beam until the beam is sufficiently attenuated by distance (approximately 8 m) or
shielding (e.g. solid floor or wall) and out to 3 m in all other directions
https://assets.publishing.service.gov.uk/media/5fdcc23ee90e07452df92f09/JSP_392Chapter_26-MEDICAL_X-RAY__Alt_Text.pdf
Controlled areas:
Must be clearly marked with warning signs and indicate the nature of the source and risk
True.
The following events must be reported if a patient receives:
15 times the intended dose for a chest x-ray
https://www.cqc.org.uk/guidance-providers/ionising-radiation/ionising-radiation-medical-exposure-regulations-irmer/criteria-making-notification/notification
https://www.radiologyinfo.org/en/info/safety-xray
FALSE.
15 X 0.1 mSv = 1.5mSv
As per CQC:
Intended dose less than 0.3mSv
Criteria for notification:
3mSv or above (adult)
1mSv or above (child)
The following events must be reported if a patient receives:
8 times the intended dose for a mammogram.
https://www.cqc.org.uk/guidance-providers/ionising-radiation/ionising-radiation-medical-exposure-regulations-irmer/criteria-making-notification/notification
https://www.radiologyinfo.org/en/info/safety-xray
FALSE.
Normal mammogram = 0.21 mSv (double a CXR)
8 x 0.21 - 1.6 mSv
As per CQC:
Intended dose less than 0.3mSv
Criteria for notification:
3mSv or above (adult)
1mSv or above (child)
The following events must be reported if a patient receives:
10 times the intended dose for a lumbar spine x-ray.
https://www.cqc.org.uk/guidance-providers/ionising-radiation/ionising-radiation-medical-exposure-regulations-irmer/criteria-making-notification/notification
https://www.radiologyinfo.org/en/info/safety-xray
TRUE.
Lumbar Spine 1.4 mSv
10 x 1.4 m Sv = 14 mSv
Intended dose between 0.3 mSv and 2.5 mSv
so 10 or more = REPORTABLE.
The following events must be reported if a patient receives:
1.5 times the intended dose for a CT abdomen.
https://www.cqc.org.uk/guidance-providers/ionising-radiation/ionising-radiation-medical-exposure-regulations-irmer/criteria-making-notification/notification
https://www.radiologyinfo.org/en/info/safety-xray
FALSE.
Single Phase = 7.7 mSv
Dual Phase = 15.4 mSv
1.5 of single phase = 11.6 mSv
Intended dose between 2.5mSv and 10mSv
Reportable is over 25mSv
1.5 of dual phase = 23.1 mSv
Intended dose more than 10mSv
Reportable 2.5 x or more.
The following events must be reported if a patient receives:
Twice the intended dose for a barium enema.
FALSE.
Intended dose = 6 mSv
2 x 6 = 12mSv
Intended dose between 2.5mSv and 10mSv
Reportable over 25 mSv
The following events must be reported to the HSE:
https://www.cqc.org.uk/guidance-providers/ionising-radiation/ionising-radiation-medical-exposure-regulations-irmer/notify-us-about-exposure
False.
HSE needs to be informed of events secondary to equipment faults; those due to operator errors need to be reported to the Care Quality Commission, previously known as the Healthcare Commission.
When there is an accidental or unintended exposure to ionising radiation, and the IR(ME)R employer knows or thinks it is significant or clinically significant, they must investigate the incident and report it to the appropriate UK IR(ME)R enforcing authority (under Regulation 8(4)).
The following events must be reported to the HSE:
A patient receives 1.6 times the intended dose for an angiogram.
True.
The following events must be reported to the HSE:
Loss of radioactive material.
True
The following events must be reported to the HSE:
Spillage of any amount of radioactive material.
False.
The following events must be reported to the HSE:
A patient receives 1.3 times the intended dose during radionuclide therapy.
False. Reportable to CQC.
Delivered dose to the planned treatment volume or organs at risk is 1.1 or more times (whole course) or 1.2 or more times (any fraction) the intended dose.
According to IRR 2017:
The RPA is responsible for quality assurance.
FALSE.
According to the Ionising Radiations Regulations 2017 (IRR 2017), the employer is solely responsible for ensuring quality assurance when it comes to radiation protection practices in the workplace, including establishing procedures, protocols, and quality assurance programs to manage radiation exposure and comply with regulations; this responsibility encompasses ensuring all necessary equipment is properly tested and maintained.
According to IRR 2017:
The RPS is responsible for designation of radiation areas.
True.
The prime duty of the RPS is to ensure compliance with the IRR17 in respect of work carried out in the designated area – in
According to IRR 2017:
The RPA must be an employee of the organization.
False.
Can be an external consultant.
According to IRR 2017:
The RPA is responsible for supervising staff dose monitoring.
False.
The RPS is responsible for supervising staff dose monitoring.
According to IRR 2017:
The RPS must be consulted prior to the installation of new x-ray equipment.
False.
The RPA must be consulted prior to the installation of new x-ray equipment.
Regarding classified workers:
The annual effective dose limit is 6mSv.
FALSE.
Above 6mSv is what makes them classified.
Annual limit is 20 mSv.
https://www.legislation.gov.uk/uksi/2017/1075/part/5#:~:text=%E2%80%94(1)%20Subject%20to%20paragraph,skin%20or%20the%20extremities%20and
Regarding classified workers:
An employee above the age of 16 years can be classified.
FALSE.
They must be over 18.
https://www.legislation.gov.uk/uksi/2017/1075/part/5#:~:text=%E2%80%94(1)%20Subject%20to%20paragraph,skin%20or%20the%20extremities%20and
Regarding classified workers:
The records of classified workers must be kept for 25 years beyond the date that the individual stops working as a classified personnel.
FALSE.
[CHANGED FROM 50 YEARS!]
Classified worker records should be kept for 30 years since last entry or when they reach 75.
https://www.legislation.gov.uk/uksi/2017/1075/part/5#:~:text=%E2%80%94(1)%20Subject%20to%20paragraph,skin%20or%20the%20extremities%20and
Regarding classified workers:
They must undergo annual health checks.
True.
https://www.legislation.gov.uk/uksi/2017/1075/part/5#:~:text=%E2%80%94(1)%20Subject%20to%20paragraph,skin%20or%20the%20extremities%20and
Regarding classified workers:
Staff working in nuclear medicine are classified workers.
False.
Staff working in nuclear medicine are very rarely required to be classified.
Regarding standards for x-ray equipment:
For portable x-ray equipment the total filtration of the tube and its assembly should not be less than 1.5mm of aluminium.
FALSE.
For portable x-ray equipment the total filtration of the tube and its assembly should not be less than 2.5 mm of aluminium.
Regarding standards for x-ray equipment:
A Leakage radiation from the tube must be less than 1mGy/hr at 1 metre from the focus.
TRUE.
Leakage radiation is the term given to radiation escaping the X-ray tube housing other than
through the tube port. This must be limited to less than 1 mGy hr-1 averaged over an area of
1 m2 at a distance of 1 metre from the focal spot.
https://www-pub.iaea.org/MTCD/publications/PDF/Pub1578_web-57265295.pdf
https://www.bir.org.uk/media/414334/final_patient_shielding_guidance.pdf
https://www.radiologycafe.com/frcr-physics-notes/radiation-dosimetry-protection-and-legislation/radiation-protection/
Regarding standards for x-ray equipment:
Skin entrance dose rates for ftuoroscopy should not exceed 100mGy/min.
True.
Regarding standards for x-ray equipment:
For mobile x-ray equipment the position of the exposure switch should be designed such that the operator can stand at least 1m from the tube and x-ray beam.
False.
About 1.8 - 2m
The installer or RPA can complete the critical examination of new equipment.
True
Farr’s 3rd Ed:
Installer has a duty to check all the critical warning lights and safety features are operational which may be in conjunction with or supervised by the RPA
Tests on all equipment, annually at least, are mandatory.
FALSE.
Just all instruments used for RADIATION PROTECTION SERVICES.
Regulations 20(3) of the Ionising Radiations Regulations 2017 (IRR17) requires that all instruments used for radiation protection purposes for fulfilling the requirements of the Regulations shall be adequately tested and thoroughly examined at appropriate intervals by or under the supervision of a Qualified Person. The Approved Code of Practice (ACoP) recommends the interval to be at least once every year.
https://www.ukhsa-protectionservices.org.uk/radmet/services/legal
Quality assurance:
Requires the equipment used for testing to be calibrated.
True
Quality assurance:
Is not a requirement under IRMER 2017.
FALSE.
“Quality assurance IRMER 2017” refers to the quality assurance procedures required under the Ionising Radiation (Medical Exposure) Regulations 2017 (IR(ME)R), which mandate employers to establish comprehensive quality assurance programs for all aspects of medical radiation procedures, including written protocols, equipment functionality, and practitioner practices, to ensure patient safety and minimize unnecessary radiation exposure
Quality assurance:
Is a requirement under IRR 17
True.
The Ionising Radiations Regulations (IRR) 2017 (IRR17) establish quality assurance measures for radiation protection in the workplace. These measures include:
Regarding dose limits and dose constraint:
Dose limits do not apply to patients.
True.
Regarding dose limits and dose constraint:
The dose limits can be relaxed for comforters and carers.
True.. Depending on local policy.
IRMER 2017:
In the case of regulation 3(d), the employer’s procedures must provide that appropriate
guidance is established for the exposure of carers and comforters.
Regarding dose limits and dose constraint:
A dose constraint is a dose limit of radiation.
FALSE.
Dose constraints
– are not dose limits
– are selected at some fraction of the dose limit
– should be selected based on good practice and on what can
reasonably be achieved
https://www.icrp.org/docs/anne%20mcgarry%20dose%20constraints%20in%20occupational.pdf
Regarding dose limits and dose constraint:
The relaxation of dose limits can routinely be applied to employees.
E. False: They can be relaxed only in cases of emergencies.
According to IRR 2017:
A radiation dose of 30mSv in a single year may be acceptable to a classified worker.
https://www.legislation.gov.uk/uksi/2017/1075/schedule/3
True: As long as the dose received by the individual does not exceed 100mSv over 5 years.
For the purposes of regulation 12(2), the limit on effective dose for employees or trainees of 18 years or above is 100 mSv in any period of five consecutive calendar years subject to a maximum effective dose of 50 mSv in any single calendar year.
According to IRR 2017:
A classified worker is one whose radiation dose is likely to exceed one-tenths of any dose limit.
False.
A classified worker is one whose radiation fse is likely to exceed three-tenths of any dose limit. *
According to IRR 2017:
The RPA is responsible for the review of local rules.
False: This is the responsibility of the Radiation Protection Supervisor:
According to IRR 2017: The RPA can carry out critical examination of equipment.
False.
The RPA should supervise the critical examination performed by the installer.
According to IRR 2017:
An x-ray department can have more than one Radiation Protection Supervisor.
False.
Under IRR 2017:
The RPA may also be a medical physics expert.
True.
Under IRR 2017:
The annual equivalent dose limit to the lens of the eye of a trainee employee under the age of 18 years is 150mSv.
https://www.legislation.gov.uk/uksi/2017/1075/schedule/3
False.
IRR 2017:
Equivalent dose limits for LENS:
Over 18:
20mSv per year.
OR 100mSv over 5 years, with max 50mSv in any one year.
Under 18 or anyone else:
15 mSv per year
Under IRR 2017:
The annual effective dose limit for a trainee employee under the age of 18 years is 6mSv.
TRUE.
IRR 2017 Whole body EFFECTIVE dose limit:
Over 18: 20 mSv (same as lens)
Under 18 workers: 6mSv
Public: 1mSv
Under IRR 2017:
The RPS is responsible for ensuring monitoring equipment is calibrated.
False. The RPA ensures equipment is calibrated.
Under IRR 2017:
To work as a classified person the individual must be certified as being medically fit to work prior to employment.
True.
They must undergo a health check.
An effective dose of 6mSv:
Carries a risk of about 1 in 3000 of a fatal cancer.
True.
Risk of fatal cancer = 1 in 20,000 per mSv
6/20,000
= 3 / 10,000
= 1 / 3333
An effective dose of 6mSv:
Would be excessive for a barium enema examination.
False.
Approximate effective radiation dose for a barium enema is 6mSv anyway!
https://www.radiologyinfo.org/en/info/safety-xray
An effective dose of 6mSv:
Is the annual dose limit for a trainee classified worker.
False: The annual dose limit for trainees is 6mSv, but trainees cannot be classified.
An effective dose of 6mSv:
Is approximately 5 times the annual background radiation dose in the UK.
False. About twice background dose.
UK average annual radiation dose = 2.7 mSv
https://www.gov.uk/government/publications/ionising-radiation-dose-comparisons/ionising-radiation-dose-comparisons
An effective dose of 6mSv:
ls approximately 10 times the effective dose of an AP pelvis radiograph.
TRUE.
The radiation dose for an abdominal radiograph (0.6 mSv)
Under IRMER 2017:
It is binding on the employer to identify the referrer.
True.
Under IRMER 2017:
Only doctors and dentists may act as referrers.
False: Nurse practitioners and physiotherapists may act as referrers (but must be state registered).
Under IRMER 2017:
Radiographers can perform the role of practitioners.
True.
A radiographer can act as an IR(ME)R practitioner to justify the exposure and as an operator to perform the exposure
Under IRMER 2017:
The employer is responsible for ensuring patient doses are as low as reasonably practicable (ALARP).
True.
Meaning they must implement procedures and practices to minimize radiation exposure to patients while still achieving the necessary diagnostic information.
Under IRMER 2017:
A referrer is not liable for prosecution.
False. They must also have knowledge of IRMER.
Regarding Diagnostic Reference Levels (DRLs):
An investigation must be initiated if a patient DRL has been exceeded.
False.
DRLs are not dose limits but guidance for dose levels for typical examinations in standard-sized patients.
Regarding Diagnostic Reference Levels (DRLs):
Can be different for the same examination in different hospitals.
True.
Set locally with input from the medical physics expert.
Regarding Diagnostic Reference Levels (DRLs):
A DRL should be expressed as entrance surface dose.
False.
e:They can be expressed as DAP, kv, mAs, screening time, etc.
Regarding Diagnostic Reference Levels (DRLs):
Local DRLs cannot be higher than national levels.
False: They can be higher if justified on clinical grounds.
Regarding Diagnostic Reference Levels (DRLs):
The national DRL for a chest PA radiograph is 0.2mGy (ESD).
https://www.gov.uk/government/publications/diagnostic-radiology-national-diagnostic-reference-levels-ndrls/ndrl#national-drls-for-general-radiography-and-fluoroscopy
True - ish.
Chest PA 0.15 mGy
Chest AP 0.2 mGy
The following are true under IRMER 2017:
The operator is responsible for justification of an exposure.
False.
The practitioner justifies an exposure.
The following are true under IRMER 2017:
It does not apply to individuals participating voluntarily in a research programme.
False.
The following are true under IRMER 2017:
It does not apply to individuals for pre-employment occupational health assessment.
False.
Training is required for PRACTITIONERS (US) and operators (Radiographers).
The following are true under IRMER 2017:
Referrers need to be trained adequately for requesting radiological investigations.
https://www.gov.uk/government/publications/breast-screening-guidance-on-implementation-of-ionising-radiation-medical-exposure-regulations-2017/guidance-for-the-implementation-of-the-irmer-regulations-2017#training
False.
Under IRMER 2017 the practitioner and operator must be adequately trained.
The referrer must have access to local guidelines and understand requests within the scope of their practice.
The following are true under IRMER 2017:
Preparation of a radiopharmaceutical is the responsibility of the operator.
True.
A radiopharmacist operator, also known as a radiopharmaceutical scientist, prepares radioactive medicines for use in nuclear medicine studies
The following are true under IRMER 2017:
Only a practitioner can justify an exposure.
https://www.gov.uk/government/publications/breast-screening-guidance-on-implementation-of-ionising-radiation-medical-exposure-regulations-2017/guidance-for-the-implementation-of-the-irmer-regulations-2017#justifying-and-authorising-breast-screening-exposures
True.
Justification is the primary role of the IR(ME)R practitioner who must be a registered healthcare professional, such as a radiographer or radiologist. An assistant practitioner may not act as an IR(ME)R practitioner justifying exposures.
The following are true of IRR 2017:
It is mandatory to monitor doses of persons working with radiation.
False. Only classified workers or all other works in CONTROLLED areas.
The following are true of IRR 2017:
In conjunction with the employer the RPS investigates overexposures.
False: The RPA investigates overexposures.
The following are true of IRR 2017:
The employer is responsible for the training of employees.
True.
The following are true of IRR 2017:
Does not allow a trainee below the age of 18 years in supervised and controlled areas.
False.
Trainees are allowed but with lower dose limits.
According to the Ionising Radiations Regulations 2017 (IRR17), trainees working in a “controlled area” must receive specific training and be subject to strict access controls, meaning only authorized individuals with appropriate training can enter such areas, and their exposure to radiation must be carefully monitored and managed by the employer; this is particularly important for trainees under 18 years old due to lower dose limits applicable to them.
The following are true of IRR 2017:
The radiation dose records of classified workers need to be submitted to HSE certified dose record keeping authorities.
True.
Make sure your employees know their dose information is being kept by your ADS and that summaries are held in HSE’s Central Index of Dose Information (CIDI)
https://www.hse.gov.uk/radiation/ionising/doses/index.htm
https://www.ukhsa-protectionservices.org.uk/cms/assets/gfx/content/resource_5101cs48f7d3043b.pdf
Regarding radiation legislation:
MARS 1978 is responsible for the storage and disposal of radioactive substances.
False: MARS is concerned with the administration of radioactive substances.
Regarding radiation legislation:
he organization must hold an ARSAC (Administration of Radioactive Substances Advisory Committee) certificate to carry out nuclear medicine investigations.
True.
ARSAC advises the licensing authorities on applications from practitioners, employers and researchers who want to use radioactive substances on people.
https://www.gov.uk/government/organisations/administration-of-radioactive-substances-advisory-committee
Regarding radiation legislation:
An ARSAC certificate needs to be renewed every 3 years.
False:
An ARSAC licence is usually valid for 5 years and Research ARSAC licences for 2 years.
Regarding radiation legislation:
RSA 1993 is concerned with the protection of the population and environment.
True.
Radioactive Substances Act
1993https://www.legislation.gov.uk/ukpga/1993/12/contents
Regarding radiation legislation:
IRMER requires that the employee ensure that personal protective equipment is properly used.
False: IRMER applies to patients only.
This is a requirement of IRR 2017.
The principle of optimization is that the benefit from radiation exceeds the risks.
False: This is the principle of justification.
Also MPE helps with optimising protocols to achieve lowest possible dose for diagnostically useful imaging.
Following radionuclide imaging a lactating mother must interrupt breast feeding for 5 days.
False: The period of interruption depends on the radiopharmaceutical. Some do not require any interruption.
Side note:
in relation to an EMPLOYEE who is breastfeeding, that employee must not be engaged in any work involving a significant risk of intake of radionuclides or of bodily contamination.
A pregnant patient cannot have radionuclide imaging.
False.
They can as long as benefits outweigh risks.
Optimisation includes quality assurance programmes to ensure equipment performance.
True
E. The HSE must be notified if the wrong patient has undergone an investigation.
False.
CQC must be notified.
https://www.cqc.org.uk/guidance-providers/ionising-radiation/ionising-radiation-medical-exposure-regulations-irmer/notify-us-about-exposure
Females between the ages of 14 and 55 years being exposed to ionizing radiation must be asked about the possibility of pregnancy.
FALSE.
BETWEEN 12-55 years.
https://www.sor.org/getmedia/1d256f96-40cb-4eeb-b120-90fe27daf7e9/Inclusive-Pregnancy-Status-Guidelines-for-Ionising-Radiation_LLv2
Providing post procedure information to patients who have undergone a nuclear medicine investigation comes under the domain of optimization.
True
Radiation weighting factors are measured in Gray.
False. Weighting factors do not have units.
Lead aprons used in interventional radiology are generally 0.35mm lead equivalent.
False: 0.35mm lead equivalent aprons are used for general radiology and 0.5mm for interventional procedures.
12mm of barium will provide the same protection as 1mm of lead.
True.
A 2.5mm lead equivalent filter should be used for routine radiological procedures.
False:
2.5mm ALUMINIUM equivalent filter should be used.
Lead screen panels used in x-ray rooms to protect staff are usually 5mm thick.
False.
X-Ray room panels have 2mm of lead
In CT images: Noise is inversely proportional to the number of photons.
FALSE. INVERSE SQUARE ROOT OF PHOTONS
