Q.1 Which of the following best describes the principle of ALARA?
Keep radiation levels as low as reasonably achievable.
Always avoid any radiation exposure.
Limit exposure to less than 1 millisievert per year.
Use the maximum possible radiation dose for imaging.
Explanation - ALARA stands for "As Low As Reasonably Achievable" and is a guiding principle in radiation protection to minimize dose while achieving clinical objectives.
Correct answer is: Keep radiation levels as low as reasonably achievable.
Q.2 Which unit measures the effective dose of ionizing radiation absorbed by the human body?
Gray (Gy)
Sievert (Sv)
Curie (Ci)
Rutherford (Rd)
Explanation - The sievert accounts for the biological effect of radiation, unlike the gray which measures absorbed energy.
Correct answer is: Sievert (Sv)
Q.3 What is the typical annual occupational exposure limit for medical X‑ray workers in the U.S.?
20 mSv
5 mSv
50 mSv
100 mSv
Explanation - The U.S. NRC limits occupational exposure to 20 millisieverts per year for radiation workers.
Correct answer is: 20 mSv
Q.4 Which shielding material is most effective against low‑energy X‑rays?
Lead
Aluminum
Copper
Plastic
Explanation - Lead has a high atomic number and density, making it excellent for attenuating low‑energy photons.
Correct answer is: Lead
Q.5 Which regulatory body in Canada regulates medical radiation protection?
Health Canada
Canadian Radiation Safety Board
Health and Safety Canada
Canadian Nuclear Regulatory Agency
Explanation - Health Canada is responsible for establishing standards and guidelines for radiation protection in medical settings.
Correct answer is: Health Canada
Q.6 The term 'dose rate' refers to:
Total dose received over a lifetime.
Amount of dose per unit time.
Dose at a specific point in the body.
Maximum permissible dose per procedure.
Explanation - Dose rate is the rate at which radiation dose accumulates over time, usually expressed in mSv/h.
Correct answer is: Amount of dose per unit time.
Q.7 Which of these is a non‑ionizing form of radiation used in medical imaging?
X‑rays
Gamma rays
Ultrasound
Computed tomography (CT)
Explanation - Ultrasound uses sound waves, a non‑ionizing form of radiation, unlike X‑rays and CT.
Correct answer is: Ultrasound
Q.8 What is the purpose of a lead apron in radiography?
To protect the patient’s skin.
To reduce scattered radiation to the operator.
To calibrate the X‑ray machine.
To increase image contrast.
Explanation - Lead aprons shield the operator’s and patient’s organs from scattered X‑ray photons.
Correct answer is: To reduce scattered radiation to the operator.
Q.9 Which of the following is NOT a component of the International Commission on Radiological Protection (ICRP) recommendations?
Dose limits for the public
Occupational exposure limits
Educational requirements for technologists
Radiation protection principles
Explanation - ICRP focuses on dose limits and principles; it does not set specific educational requirements.
Correct answer is: Educational requirements for technologists
Q.10 The 'effective dose' takes into account:
Only the energy deposited in the body.
The type of radiation and the sensitivity of organs.
The distance from the source.
The exposure time.
Explanation - Effective dose multiplies organ dose by tissue weighting factors to reflect biological risk.
Correct answer is: The type of radiation and the sensitivity of organs.
Q.11 In a CT scan, which parameter directly affects patient dose?
kVp (kilovoltage peak)
Table height
Patient height
Scanner brand
Explanation - Higher kVp increases photon energy and dose; it is a primary determinant of radiation output.
Correct answer is: kVp (kilovoltage peak)
Q.12 Which law governs the use of radioactive sources for medical diagnosis in the United States?
Nuclear Waste Policy Act
Public Health Service Act
Radiation Exposure Compensation Act
Radiological Health Act
Explanation - The Public Health Service Act authorizes the use of low‑activity radioactive sources for medical purposes.
Correct answer is: Public Health Service Act
Q.13 The minimum permissible dose of radiation for a patient undergoing a standard chest X‑ray is approximately:
0.01 mSv
1 mSv
10 mSv
100 mSv
Explanation - A chest X‑ray typically delivers about 0.01 millisieverts to the patient.
Correct answer is: 0.01 mSv
Q.14 Which type of detector is commonly used in PET scanners?
Photomultiplier tubes (PMTs)
Photodiodes
Scintillation crystals
Thermocouples
Explanation - PET detectors use scintillation crystals like LSO or BGO to convert gamma photons into light detected by photomultipliers.
Correct answer is: Scintillation crystals
Q.15 The ‘radiation protection triad’ consists of:
Time, Distance, Shielding
Time, Dose, Shielding
Shielding, Equipment, Training
Distance, Equipment, Dose
Explanation - The triad emphasizes limiting exposure time, maintaining distance from sources, and using proper shielding.
Correct answer is: Time, Distance, Shielding
Q.16 Which organ has the lowest tissue weighting factor for effective dose calculations?
Brain
Skin
Lung
Bone Marrow
Explanation - The skin has a tissue weighting factor of 0.01, the lowest among the listed organs.
Correct answer is: Skin
Q.17 In radiation safety, the term "scatter" refers to:
Radiation emitted directly from the source.
Radiation that is absorbed by the patient.
Radiation that is deflected from its original path.
Radiation that passes through shielding.
Explanation - Scattered radiation is photons that have changed direction due to interactions, posing exposure risk.
Correct answer is: Radiation that is deflected from its original path.
Q.18 Which of the following is a primary purpose of a radiation safety officer (RSO)?
Operating imaging equipment
Ensuring regulatory compliance and training
Prescribing imaging protocols
Analyzing images for diagnosis
Explanation - RSOs oversee radiation safety programs, maintain records, and train staff.
Correct answer is: Ensuring regulatory compliance and training
Q.19 What is the typical radiation dose from a single mammography exam?
0.001 mSv
0.05 mSv
1 mSv
10 mSv
Explanation - Mammography generally delivers about 0.05 millisieverts per breast.
Correct answer is: 0.05 mSv
Q.20 Which of the following regulations sets the maximum permissible dose for a nuclear medicine technologist?
Code of Federal Regulations Title 21
Code of Federal Regulations Title 42
Code of Federal Regulations Title 29
Code of Federal Regulations Title 15
Explanation - Title 21 deals with food and drugs, including nuclear medicine practices and dose limits.
Correct answer is: Code of Federal Regulations Title 21
Q.21 In the context of radiation protection, what does the acronym "DRR" stand for?
Diagnostic Reference Level
Dose Reduction Rate
Direct Radiation Regulation
Dose Rate Ratio
Explanation - DRL is a guideline dose used to help optimize protocols and compare against typical exposures.
Correct answer is: Diagnostic Reference Level
Q.22 The term "penetration power" of X‑rays refers to:
The speed at which X‑rays travel through matter.
The ability to pass through dense materials.
The energy required to produce X‑rays.
The depth of absorption in the body.
Explanation - Higher energy X‑rays have greater penetration power and can pass through thicker tissues.
Correct answer is: The ability to pass through dense materials.
Q.23 Which organization publishes the International Commission on Radiological Protection (ICRP) recommendations?
World Health Organization (WHO)
International Atomic Energy Agency (IAEA)
American College of Radiology (ACR)
International Commission on Radiological Protection (ICRP)
Explanation - The ICRP is the body that issues guidelines on radiation protection and dose limits.
Correct answer is: International Commission on Radiological Protection (ICRP)
Q.24 Which of these is a potential health effect of chronic low‑dose radiation exposure?
Acute radiation syndrome
Increased risk of cancer
Immediate hair loss
Nausea and vomiting
Explanation - Long‑term low‑dose exposure primarily increases cancer risk rather than immediate acute effects.
Correct answer is: Increased risk of cancer
Q.25 What is the primary safety measure for protecting staff during an interventional fluoroscopy procedure?
Lead gloves only
Lead apron and thyroid shield
Lead helmet only
Distance of 5 meters
Explanation - Lead apron and thyroid shield protect the most vulnerable organs during fluoroscopic procedures.
Correct answer is: Lead apron and thyroid shield
Q.26 Which of the following statements about radiation shielding is FALSE?
Denser materials provide better shielding.
Lead is effective for both X‑rays and gamma rays.
All materials provide equal shielding for all photon energies.
Shield thickness is calculated based on desired attenuation.
Explanation - Different materials have varying effectiveness depending on photon energy.
Correct answer is: All materials provide equal shielding for all photon energies.
Q.27 The term "half‑value layer" (HVL) refers to:
The thickness of a material that reduces radiation intensity by half.
The time taken for half the radiation to be absorbed.
The distance at which half the dose is received.
The energy level at which half the photons are absorbed.
Explanation - HVL is a standard measure used to characterize shielding materials.
Correct answer is: The thickness of a material that reduces radiation intensity by half.
Q.28 Which type of imaging modality is most likely to involve radioactive isotopes?
MRI
CT
X‑ray radiography
PET
Explanation - Positron Emission Tomography uses radioactive tracers to visualize metabolic activity.
Correct answer is: PET
Q.29 The American College of Radiology (ACR) has guidelines that recommend:
All patients should receive CT scans.
Radiation doses should be as high as possible for image quality.
Use of reference doses to optimize protocols.
No need to monitor patient dose.
Explanation - ACR promotes dose optimization using diagnostic reference levels (DRLs).
Correct answer is: Use of reference doses to optimize protocols.
Q.30 Which of the following best describes the role of a radiologic technologist?
Prescribing imaging studies.
Operating imaging equipment under physician supervision.
Analyzing diagnostic images for disease.
Developing imaging protocols.
Explanation - Technologists perform imaging tasks while following protocols and safety guidelines.
Correct answer is: Operating imaging equipment under physician supervision.
Q.31 What does the term "diagnostic reference level" (DRL) help radiologists to do?
Set maximum exposure limits for patients.
Compare their dose levels with typical practice.
Determine the exact dose for each patient.
Choose the type of contrast agent.
Explanation - DRLs serve as a benchmark for evaluating and optimizing patient dose in imaging.
Correct answer is: Compare their dose levels with typical practice.
Q.32 The main safety concern when using a fluoroscopic procedure in a pediatric patient is:
High contrast dose.
High radiation dose relative to body size.
Longer procedure time.
Need for sedation.
Explanation - Children are more sensitive to radiation and have a longer lifetime for potential effects.
Correct answer is: High radiation dose relative to body size.
Q.33 Which of the following is an example of a non‑radiologic imaging modality?
Ultrasound
CT
X‑ray
PET
Explanation - Ultrasound uses sound waves and does not involve ionizing radiation.
Correct answer is: Ultrasound
Q.34 Which of these is a legal requirement for a facility that performs medical imaging involving ionizing radiation?
Having an operating budget over $1 million.
Maintaining a radiation safety program.
Using only digital imaging systems.
Hiring a medical physicist.
Explanation - Regulations mandate a comprehensive safety program for all ionizing radiation facilities.
Correct answer is: Maintaining a radiation safety program.
Q.35 The main advantage of digital radiography over film radiography is:
Lower cost of equipment.
No need for shielding.
Immediate image availability.
Higher radiation dose.
Explanation - Digital systems provide images instantly, allowing quick diagnosis and dose adjustments.
Correct answer is: Immediate image availability.
Q.36 The 'tissue weighting factor' in effective dose calculations represents:
The sensitivity of a tissue to radiation.
The thickness of the tissue.
The density of the tissue.
The atomic number of the tissue.
Explanation - It reflects the relative contribution of each organ to the risk of stochastic effects.
Correct answer is: The sensitivity of a tissue to radiation.
Q.37 Which of the following is a recommended practice to reduce radiation exposure for the radiology technologist during a CT scan?
Standing directly in the beam path.
Using a lead shield between them and the scanner.
Increasing scan speed.
Using only low‑kVp protocols.
Explanation - Shielding reduces exposure; standing away from the beam also helps.
Correct answer is: Using a lead shield between them and the scanner.
Q.38 Which regulatory act in the United States governs the licensing of nuclear medicine physicians?
Public Health Service Act
Radiation Exposure Compensation Act
Nuclear Waste Policy Act
Nuclear Regulatory Commission Act
Explanation - The Public Health Service Act covers licensing for nuclear medicine practitioners.
Correct answer is: Public Health Service Act
Q.39 In radiation protection, the term "dose limit" refers to:
The maximum dose an individual can receive from a single exposure.
The maximum permissible dose over a specified period.
The dose received by a specific organ.
The dose that a machine can deliver.
Explanation - Dose limits are set for occupational, public, and patient exposures over defined timeframes.
Correct answer is: The maximum permissible dose over a specified period.
Q.40 Which of the following best describes the concept of "photon energy"?
The speed of photons.
The mass of photons.
The amount of energy carried by a photon.
The wavelength of photons.
Explanation - Photon energy is directly related to its frequency (or inversely to its wavelength).
Correct answer is: The amount of energy carried by a photon.
Q.41 The U.S. regulatory limit for the public's annual exposure to background radiation is about:
1 mSv
3 mSv
20 mSv
50 mSv
Explanation - The public exposure limit is set at 3 millisieverts per year for all non‑occupational exposures.
Correct answer is: 3 mSv
Q.42 Which of these isotopes is commonly used in bone scintigraphy?
Technetium‑99m
Iodine‑131
Cobalt‑60
Radium‑226
Explanation - Technetium‑99m is widely used for bone scans due to its short half‑life and suitable energy.
Correct answer is: Technetium‑99m
Q.43 A radiology technician should always wear which of the following to protect against scatter during fluoroscopy?
Lead glasses
Lead gloves
Lead apron
Lead shoes
Explanation - The lead apron shields the torso and vital organs from scattered photons.
Correct answer is: Lead apron
Q.44 Which of these is a characteristic of gamma radiation?
It is non‑ionizing.
It is produced by the collapse of the nucleus.
It is produced by accelerated electrons.
It has no mass and no charge.
Explanation - Gamma rays are high‑energy photons emitted from nuclear transitions.
Correct answer is: It is produced by accelerated electrons.
Q.45 What is the typical dose of radiation for a full‑body PET scan?
0.05 mSv
5 mSv
50 mSv
100 mSv
Explanation - A typical PET scan delivers about 5 millisieverts to the patient.
Correct answer is: 5 mSv
Q.46 The phrase "maximum permissible dose" (MPD) is used to refer to:
The highest dose a patient can receive.
The maximum dose a worker can receive during a shift.
The dose limit set by regulatory agencies.
The dose from the most powerful X‑ray machine.
Explanation - MPD is a regulatory term that sets limits for occupational or public exposure.
Correct answer is: The dose limit set by regulatory agencies.
Q.47 Which of these is an example of a stochastic effect of radiation exposure?
Skin burns
Lung fibrosis
Cancer induction
Organ failure
Explanation - Stochastic effects, like cancer, have no threshold dose and probability increases with dose.
Correct answer is: Cancer induction
Q.48 In a nuclear medicine procedure, the activity of the administered radioactive drug is usually expressed in:
Sieverts (Sv)
Grays (Gy)
Curies (Ci)
Joules (J)
Explanation - Radioactive activity is measured in curies (or becquerels), reflecting decays per second.
Correct answer is: Curies (Ci)
Q.49 Which of the following best describes a 'phantom' in radiology?
A patient with a specific disease.
An artificial model used for testing image quality.
A software program for image reconstruction.
A type of imaging contrast agent.
Explanation - Phantoms simulate human tissues for calibration and quality assurance.
Correct answer is: An artificial model used for testing image quality.
Q.50 The main reason for using low‑kVp settings in pediatric CT scans is:
To increase image contrast.
To reduce radiation dose.
To shorten scan time.
To improve spatial resolution.
Explanation - Lower kVp reduces the energy of photons, thus decreasing patient dose.
Correct answer is: To reduce radiation dose.
Q.51 Which of these is a component of the radiation protection system in a CT room?
Lead glass walls
Lead-lined walls
Transparent glass doors
Steel doors
Explanation - Lead‑lined walls provide attenuation of scattered radiation within the imaging suite.
Correct answer is: Lead-lined walls
Q.52 The International Atomic Energy Agency (IAEA) publishes guidelines on:
Radiation therapy protocols.
Radiation safety and protection.
Medical imaging equipment manufacturing.
Pharmaceutical drug safety.
Explanation - The IAEA provides international standards and recommendations for radiation protection.
Correct answer is: Radiation safety and protection.
Q.53 Which of the following best describes the 'dose‑area product' (DAP) in X‑ray imaging?
Dose per unit area of the patient's skin.
The total dose multiplied by the irradiated area.
The dose divided by the exposure time.
The area irradiated at a specific dose.
Explanation - DAP provides a measure of the overall energy delivered to the patient and helps estimate risk.
Correct answer is: The total dose multiplied by the irradiated area.
Q.54 Which of the following is a legal requirement for the disposal of radioactive waste generated in a hospital?
Immediate burial on site.
Transport to a licensed disposal facility.
Recycling in the hospital's waste stream.
Incineration in an unlicensed incinerator.
Explanation - Regulations require safe disposal of radioactive waste at licensed facilities.
Correct answer is: Transport to a licensed disposal facility.
Q.55 A diagnostic reference level (DRL) of 150 mGy for a head CT is meant to:
Set the absolute dose limit.
Serve as a target to be exceeded.
Provide a benchmark for optimization.
Define the maximum permissible dose.
Explanation - DRLs are used to identify high‑dose practices and guide dose reduction efforts.
Correct answer is: Provide a benchmark for optimization.
Q.56 Which of these is a type of ionizing radiation that does not require ionization to be emitted?
X‑rays
Gamma rays
Alpha particles
Beta particles
Explanation - Gamma rays are electromagnetic radiation, unlike alpha/beta particles which are matter emissions.
Correct answer is: Gamma rays
Q.57 Which of these is a common method for monitoring patient dose during a CT scan?
Fluoroscopy time
CT dose index volume (CTDIvol)
Kilowatt measurement
Exposure time
Explanation - CTDIvol provides a standardized measurement of dose in a CT scan.
Correct answer is: CT dose index volume (CTDIvol)
Q.58 The 'tissue equivalence' of a phantom material is important for:
Simulating human tissue response to radiation.
Providing electrical conductivity.
Measuring thermal properties.
Calculating mechanical strength.
Explanation - Tissue‑equivalent phantoms mimic the interaction of radiation with real body tissues.
Correct answer is: Simulating human tissue response to radiation.
Q.59 The main purpose of a radiation safety audit is to:
Increase image quality.
Evaluate compliance with regulatory standards.
Reduce equipment costs.
Train patients on radiation safety.
Explanation - Audits assess adherence to safety protocols and identify areas for improvement.
Correct answer is: Evaluate compliance with regulatory standards.
Q.60 Which of the following is NOT a factor influencing patient dose in radiographic imaging?
Tube voltage (kVp)
Exposure time (mAs)
Patient's age
Manufacturer brand
Explanation - While brand can affect design, dose depends on kVp, mAs, and patient size, not brand name.
Correct answer is: Manufacturer brand
Q.61 In an X‑ray tube, the cathode emits electrons which:
Generate X‑rays when hitting the anode.
Are absorbed by the tube wall.
Produce gamma radiation.
Travel directly to the detector.
Explanation - High‑speed electrons striking the anode produce bremsstrahlung X‑rays.
Correct answer is: Generate X‑rays when hitting the anode.
Q.62 The most common cause of radiation‑induced skin burns in medical imaging is:
Overuse of contrast agents.
Excessive exposure to high‑kVp beams.
Using too much lead shielding.
Long patient positioning times.
Explanation - High‑energy beams deliver more dose to skin, causing burns if exposure is prolonged.
Correct answer is: Excessive exposure to high‑kVp beams.
Q.63 What does the term 'half‑life' refer to in nuclear medicine?
Time for half the dose to be absorbed by the body.
Time for half the atoms to decay.
Time for half the imaging session to complete.
Time for half the image to develop.
Explanation - Half‑life is the period in which half of a radioactive isotope decays.
Correct answer is: Time for half the atoms to decay.
Q.64 The main advantage of using a lead shield during interventional procedures is to:
Prevent the spread of infections.
Reduce scatter radiation exposure.
Improve image clarity.
Decrease contrast usage.
Explanation - Lead shields intercept scattered photons, protecting staff from unnecessary dose.
Correct answer is: Reduce scatter radiation exposure.
Q.65 Which of the following is a recommended action when a radiation detector indicates a sudden increase in ambient dose rate?
Increase the image exposure.
Shut down the machine immediately.
Notify the radiation safety officer.
Ignore the reading.
Explanation - A sudden rise may indicate a malfunction; the RSO must assess the situation.
Correct answer is: Notify the radiation safety officer.
Q.66 The use of a collimator in an X‑ray system primarily serves to:
Increase image contrast.
Define the shape and size of the beam.
Reduce patient dose.
Both B and C.
Explanation - Collimators limit the beam, reducing scatter and dose while controlling image geometry.
Correct answer is: Both B and C.
Q.67 In radiation protection, the term "dose‑area product" (DAP) is used to estimate:
The effective dose to the patient.
The scatter dose to staff.
The total energy delivered to the body.
The beam width.
Explanation - DAP is a product of dose and irradiated area, indicating overall exposure.
Correct answer is: The total energy delivered to the body.
Q.68 Which of these is an example of a deterministic effect of radiation?
Cancer
Skin erythema
Chromosomal mutation
Carcinogenesis
Explanation - Deterministic effects have a threshold dose and increase in severity with higher doses.
Correct answer is: Skin erythema
Q.69 The main reason for using a rotating gantry in a CT scanner is to:
Provide a steadier image.
Reduce radiation exposure.
Capture images from multiple angles.
Increase patient throughput.
Explanation - The rotating gantry allows the detector to image the patient from various angles to reconstruct a 3D volume.
Correct answer is: Capture images from multiple angles.
Q.70 What is the primary protective measure against gamma radiation?
Lead shielding
Water shielding
Air shielding
Plastic shielding
Explanation - Lead is dense and highly effective at attenuating gamma photons.
Correct answer is: Lead shielding
Q.71 Which of the following is a standard unit for measuring radiation exposure dose equivalent?
Gray (Gy)
Sievert (Sv)
Curie (Ci)
Röntgen (R)
Explanation - Sieverts account for biological effect; Gray measures absorbed dose.
Correct answer is: Sievert (Sv)
Q.72 A 'radiation safety program' is required in any facility that:
Uses any form of radiation.
Uses ionizing radiation for medical imaging.
Has a staff of more than 10 people.
Operates a non‑ionizing laser system.
Explanation - Regulatory bodies mandate safety programs where ionizing radiation is employed.
Correct answer is: Uses ionizing radiation for medical imaging.
Q.73 The typical half‑life of Iodine‑131 used in thyroid imaging is approximately:
2 days
8 days
30 days
6 months
Explanation - Iodine‑131 has a half‑life of about 8 days, suitable for diagnostic imaging.
Correct answer is: 8 days
Q.74 The term 'dose‑area product' (DAP) is usually measured in:
Gray (Gy)
Gray‑cm² (Gy·cm²)
Sievert (Sv)
Millisievert (mSv)
Explanation - DAP is expressed as dose times area, e.g., Gy·cm².
Correct answer is: Gray‑cm² (Gy·cm²)
Q.75 Which of these is an example of a stochastic effect of radiation exposure?
Skin erythema
Bone marrow suppression
Cancer induction
Hair loss
Explanation - Stochastic effects are probabilistic and have no dose threshold.
Correct answer is: Cancer induction
Q.76 Which of the following statements about the ‘kVp’ setting on an X‑ray tube is true?
It determines the beam current.
It influences photon energy and penetration.
It is measured in milliamperes.
It has no effect on image contrast.
Explanation - Higher kVp increases photon energy, improving penetration but reducing contrast.
Correct answer is: It influences photon energy and penetration.
Q.77 Which of these is a typical radiation safety training topic for radiology technologists?
Basic anatomy.
Image post‑processing.
Radiation dose calculation.
Pharmacology of contrast agents.
Explanation - Training includes dose calculation to optimize patient safety.
Correct answer is: Radiation dose calculation.
Q.78 The main advantage of using digital detectors in medical imaging is:
Higher radiation dose to patients.
Immediate image availability.
Reduced need for shielding.
Increased exposure time.
Explanation - Digital imaging eliminates film processing time and enables quick review.
Correct answer is: Immediate image availability.
Q.79 The regulatory limit for the public’s exposure to background radiation is about:
0.1 mSv per year
1 mSv per year
3 mSv per year
10 mSv per year
Explanation - The U.S. public dose limit for background radiation is roughly 3 millisieverts annually.
Correct answer is: 3 mSv per year
Q.80 Which of the following is a major source of patient radiation dose in a CT scan?
Tube voltage (kVp).
Tube current (mA).
Scan length.
All of the above.
Explanation - Dose depends on kVp, mA, and scan length, among other factors.
Correct answer is: All of the above.
Q.81 What is the main purpose of a diagnostic reference level (DRL) for a given imaging procedure?
Set the maximum dose allowed.
Provide a guideline for typical dose levels.
Determine patient eligibility for the procedure.
Regulate the number of scans per year.
Explanation - DRLs help identify unusually high doses and drive optimization.
Correct answer is: Provide a guideline for typical dose levels.
Q.82 Which of these is an example of a radiation‑induced deterministic effect?
Cancer
Radiation dermatitis
Genetic mutation
Carcinogenic transformation
Explanation - Deterministic effects show a threshold dose and increased severity with dose.
Correct answer is: Radiation dermatitis
Q.83 In radiation protection, the term "tissue weighting factor" refers to:
The thickness of tissue.
The mass of the tissue.
The relative importance of tissue in dose calculation.
The density of the tissue.
Explanation - Weighting factors represent each organ’s contribution to overall risk.
Correct answer is: The relative importance of tissue in dose calculation.
Q.84 Which of these is a regulatory body that issues guidelines for radiation protection in the United Kingdom?
NRC
NHS
Health Protection Agency (HPA)
European Commission
Explanation - HPA provides guidelines for radiation safety in the UK.
Correct answer is: Health Protection Agency (HPA)
Q.85 What is the typical radiation dose from a single mammography exam for a woman?
0.0001 mSv
0.01 mSv
1 mSv
10 mSv
Explanation - Mammography delivers a very low dose, roughly 0.01 millisieverts.
Correct answer is: 0.01 mSv
Q.86 Which of the following is NOT an ionizing radiation type used in medical imaging?
X‑rays
Gamma rays
Ultrasound waves
Beta particles
Explanation - Ultrasound uses sound waves, which are non‑ionizing.
Correct answer is: Ultrasound waves
Q.87 The most common source of ionizing radiation exposure in a hospital environment is:
CT scanners
MRI machines
X‑ray rooms
Ultrasound devices
Explanation - CT delivers the largest dose among routine imaging modalities.
Correct answer is: CT scanners
Q.88 Which of the following is a requirement of the American College of Radiology (ACR) regarding radiation dose management?
Mandatory use of lead aprons in all procedures.
Documentation of all doses delivered.
Only use of digital imaging systems.
No exposure limits for patients.
Explanation - ACR requires recording of dose metrics for quality assurance.
Correct answer is: Documentation of all doses delivered.
Q.89 The term 'kW' refers to:
Kilowatt of power delivered.
Kilovolt‑ampere of electrical input.
Kilopascal of pressure.
Kilogram per watt of energy.
Explanation - kW stands for kilovolt‑ampere, indicating electrical output in X‑ray tubes.
Correct answer is: Kilovolt‑ampere of electrical input.
Q.90 Which of the following is a common method for shielding against scatter radiation in a radiology suite?
Lead glass walls.
Wooden partitions.
Acoustic panels.
Plastic barriers.
Explanation - Lead glass is widely used to shield against scattered X‑rays.
Correct answer is: Lead glass walls.
Q.91 The phrase "diagnostic reference level" (DRL) is used to:
Set maximum permissible dose.
Indicate the standard dose for a procedure.
Guide optimization of radiation exposure.
Define the patient's radiation sensitivity.
Explanation - DRLs help compare typical doses to identify high‑dose practices.
Correct answer is: Guide optimization of radiation exposure.
Q.92 Which of the following statements about radiation shielding is FALSE?
Higher atomic number materials provide better shielding.
Lead is effective against X‑rays and gamma rays.
Shielding thickness is independent of photon energy.
Lead is the most common shielding material.
Explanation - Shielding effectiveness depends on both material and photon energy.
Correct answer is: Shielding thickness is independent of photon energy.
Q.93 Which of these is a key component of a radiation safety training program?
Understanding of radiation physics.
Basic anatomy and physiology.
Marketing of imaging services.
Advanced image reconstruction techniques.
Explanation - Knowledge of radiation physics is fundamental for safe imaging practices.
Correct answer is: Understanding of radiation physics.
Q.94 The use of a high‑kVp setting in CT imaging is intended to:
Increase patient dose.
Reduce image noise and improve image quality.
Decrease scan time.
Improve patient comfort.
Explanation - Higher kVp reduces noise but may lower contrast.
Correct answer is: Reduce image noise and improve image quality.
Q.95 Which of the following is an example of a deterministic effect of ionizing radiation?
Skin erythema
Cancer
DNA mutations
Chromosomal abnormalities
Explanation - Deterministic effects have a threshold and increase in severity with dose.
Correct answer is: Skin erythema
Q.96 In a CT scanner, the term 'mAs' refers to:
Milliamperes multiplied by seconds, controlling tube current.
Milliamperes per second.
Maximum amperage of the tube.
Mean amplitude of the signal.
Explanation - mAs determines the quantity of X‑ray photons produced.
Correct answer is: Milliamperes multiplied by seconds, controlling tube current.
Q.97 Which of the following is a primary purpose of a radiation safety officer (RSO) in a medical imaging facility?
Perform radiographs.
Administer contrast agents.
Monitor radiation dose and compliance.
Diagnose patient conditions.
Explanation - RSOs ensure safety protocols and regulatory compliance are upheld.
Correct answer is: Monitor radiation dose and compliance.
Q.98 Which of the following is a typical patient dose for a standard chest CT?
0.01 mSv
0.5 mSv
2 mSv
20 mSv
Explanation - Chest CTs typically deliver about 2 millisieverts to a patient.
Correct answer is: 2 mSv
Q.99 The term 'half‑value layer' (HVL) is used in radiation protection to characterize:
The thickness of a material that reduces radiation intensity by half.
The time it takes for a material to absorb half the dose.
The distance at which half the dose is received.
The amount of dose absorbed per unit area.
Explanation - HVL indicates how well a material attenuates radiation.
Correct answer is: The thickness of a material that reduces radiation intensity by half.
Q.100 Which of these is an example of a stochastic effect of radiation?
Radiation dermatitis
Bone marrow suppression
Cancer induction
Skin burns
Explanation - Stochastic effects have no threshold and increase in probability with dose.
Correct answer is: Cancer induction
Q.101 The 'diagnostic reference level' (DRL) is a:
Maximum allowed dose for a procedure.
Typical dose benchmark for comparison.
Absolute dose limit set by regulators.
Dose delivered to the most sensitive organ.
Explanation - DRLs guide optimization by indicating typical doses for procedures.
Correct answer is: Typical dose benchmark for comparison.
Q.102 Which of these is a common source of radiation in a hospital's operating room?
X‑ray fluoroscopy.
MRI magnets.
Ultrasound devices.
Laser scalpels.
Explanation - Fluoroscopy provides real‑time imaging but emits ionizing radiation.
Correct answer is: X‑ray fluoroscopy.
Q.103 What is the main function of a collimator in an X‑ray system?
Increase beam intensity.
Define the shape and size of the X‑ray beam.
Reduce scatter.
Both B and C.
Explanation - Collimators shape the beam and limit scatter, reducing dose.
Correct answer is: Both B and C.
Q.104 Which of the following statements about lead shielding is correct?
Lead is effective only for alpha particles.
Lead thickness is unrelated to photon energy.
Lead provides attenuation for X‑rays and gamma rays.
Lead should never be used near patients.
Explanation - Lead is a common high‑Z material for shielding ionizing radiation.
Correct answer is: Lead provides attenuation for X‑rays and gamma rays.
Q.105 Which of these is NOT a type of ionizing radiation used in diagnostic imaging?
X‑rays
Gamma rays
Ultrasound
Beta particles
Explanation - Ultrasound is a non‑ionizing imaging modality.
Correct answer is: Ultrasound
Q.106 The primary goal of radiation protection in medical imaging is:
Maximize image quality regardless of dose.
Minimize radiation exposure while achieving diagnostic quality.
Ensure the highest possible patient dose.
Eliminate all radiation exposure.
Explanation - Radiation protection seeks to balance dose and diagnostic benefit.
Correct answer is: Minimize radiation exposure while achieving diagnostic quality.
Q.107 The term 'dose index volume' (DIW) refers to:
The dose delivered to a single point in the body.
An indicator of the average dose over the volume of an imaging study.
The maximum dose recorded in a study.
A measure of image resolution.
Explanation - DIW reflects average dose across the scanned volume.
Correct answer is: An indicator of the average dose over the volume of an imaging study.
Q.108 Which of these is a recommended practice for reducing radiation dose in pediatric CT scanning?
Use higher kVp settings.
Use lower kVp and reduce mA.
Increase scan length.
Avoid using automatic exposure control.
Explanation - Lower energy and current reduce dose, especially important in children.
Correct answer is: Use lower kVp and reduce mA.
Q.109 Which of the following is a deterministic effect that occurs at doses above approximately 2 Gy?
Hair loss
Radiation dermatitis
Lung fibrosis
Bone marrow suppression
Explanation - Dermatitis is a deterministic effect that appears at higher doses.
Correct answer is: Radiation dermatitis
Q.110 The primary unit of measurement for the dose equivalent is:
Gray (Gy)
Sievert (Sv)
Curie (Ci)
Tesla (T)
Explanation - Sieverts account for the biological effect of radiation.
Correct answer is: Sievert (Sv)
Q.111 The typical dose from a full‑body PET scan is approximately:
0.5 mSv
2 mSv
5 mSv
10 mSv
Explanation - PET scans deliver roughly 5 millisieverts of radiation.
Correct answer is: 5 mSv
Q.112 Which of the following is a key component of a radiation safety program?
Routine dose monitoring.
Regulatory compliance audits.
Both A and B.
Only equipment maintenance.
Explanation - Monitoring and audits are essential for an effective safety program.
Correct answer is: Both A and B.
Q.113 Which of these is a common type of ionizing radiation used for imaging bones?
X‑rays
Ultrasound
MRI
Infrared
Explanation - X‑ray radiography is standard for bone imaging.
Correct answer is: X‑rays
Q.114 The most common source of radiation exposure for patients in a hospital is:
Nuclear medicine scans.
CT imaging.
MRI scans.
Physical therapy.
Explanation - CT is the highest‑dose imaging modality among routine procedures.
Correct answer is: CT imaging.
Q.115 Which of the following statements about radiation shielding is correct?
Lead glass is effective only for visible light.
Lead is ineffective for gamma radiation.
Lead attenuates both X‑rays and gamma rays.
Lead shielding is not required in imaging suites.
Explanation - Lead’s high density and atomic number provide effective attenuation.
Correct answer is: Lead attenuates both X‑rays and gamma rays.
Q.116 The typical radiation dose from a single mammogram is approximately:
0.001 mSv
0.01 mSv
0.1 mSv
1 mSv
Explanation - A mammogram delivers a very low dose, around 0.01 millisieverts.
Correct answer is: 0.01 mSv
Q.117 Which of the following is an example of a stochastic effect?
Skin burns
Radiation sickness
Cancer
Hair loss
Explanation - Stochastic effects, like cancer, are probabilistic and increase with dose.
Correct answer is: Cancer
Q.118 In radiation protection, the term "dose limit" refers to:
The dose that an organ can receive from a single exposure.
The maximum permissible dose over a defined time period.
The dose measured in a specific body part.
The dose delivered by a particular machine.
Explanation - Dose limits are set for occupational or public exposures over specified durations.
Correct answer is: The maximum permissible dose over a defined time period.
Q.119 The primary protective measure for staff during a fluoroscopic procedure is:
Lead gloves.
Lead apron.
Lead glasses.
All of the above.
Explanation - All mentioned items protect different body parts from scattered radiation.
Correct answer is: All of the above.
Q.120 The typical patient dose from a full‑body PET scan is about:
0.5 mSv
2 mSv
5 mSv
10 mSv
Explanation - PET scans usually deliver around 5 millisieverts.
Correct answer is: 5 mSv
Q.121 In an X‑ray tube, increasing the tube current (mA) will:
Decrease photon output.
Increase photon output.
Decrease the beam energy.
Have no effect.
Explanation - Higher mA increases the number of electrons, producing more photons.
Correct answer is: Increase photon output.
Q.122 Which of the following is a typical regulatory limit for patient exposure in CT imaging?
0.05 mSv
1 mSv
10 mSv
20 mSv
Explanation - CT doses typically range up to 10 mSv, though lower doses are preferred.
Correct answer is: 10 mSv
Q.123 The 'dose area product' (DAP) is used to estimate:
The effective dose to the patient.
The total energy delivered to the body.
The amount of scattered radiation to staff.
The area irradiated.
Explanation - DAP combines dose with irradiated area to indicate overall exposure.
Correct answer is: The total energy delivered to the body.
Q.124 The main function of a lead apron in radiography is to:
Reduce patient dose.
Protect the technologist’s organs from scatter.
Improve image contrast.
Increase radiation dose.
Explanation - Lead aprons shield vital organs from scattered X‑rays.
Correct answer is: Protect the technologist’s organs from scatter.
Q.125 Which of these is a common source of ionizing radiation in a medical setting?
MRI scanners.
X‑ray machines.
Ultrasound probes.
Light therapy devices.
Explanation - X‑ray machines generate ionizing photons for imaging.
Correct answer is: X‑ray machines.
Q.126 The 'diagnostic reference level' (DRL) is:
A maximum dose limit.
A typical dose benchmark.
A required dose for each patient.
A radiation safety program.
Explanation - DRLs serve as a reference to evaluate and optimize dose.
Correct answer is: A typical dose benchmark.
Q.127 Which of the following is an example of a stochastic effect?
Skin burns
Radiation dermatitis
Cancer induction
Bone marrow suppression
Explanation - Cancer is stochastic; its probability increases with dose.
Correct answer is: Cancer induction
Q.128 The term "kVp" in an X‑ray tube refers to:
The tube current.
The tube voltage.
The exposure time.
The detector sensitivity.
Explanation - kVp determines the maximum photon energy produced.
Correct answer is: The tube voltage.
Q.129 Which of the following is a requirement for a facility using ionizing radiation?
No training required for staff.
A radiation safety program.
Only use digital imaging.
Unlimited patient exposure.
Explanation - All facilities with ionizing sources must have a safety program.
Correct answer is: A radiation safety program.
Q.130 The main advantage of a lead apron is:
It increases patient dose.
It reduces scatter to the operator.
It eliminates radiation.
It is used for image processing.
Explanation - Lead aprons shield the operator’s organs from scattered photons.
Correct answer is: It reduces scatter to the operator.
Q.131 Which of these is a typical patient dose for a CT angiography study?
1 mSv
5 mSv
15 mSv
30 mSv
Explanation - CTA typically delivers about 15 millisieverts, though lower doses are achievable.
Correct answer is: 15 mSv
Q.132 Which of the following statements about radiation dose is true?
Higher kVp always reduces dose.
Dose is independent of exposure time.
Dose depends on kVp, mA, and exposure time.
Dose is only relevant for patients.
Explanation - The product of these factors determines the overall radiation dose.
Correct answer is: Dose depends on kVp, mA, and exposure time.
Q.133 The main function of the lead glass in a radiology department is to:
Shield the room from X‑rays.
Provide a clear view for staff.
Both A and B.
Increase patient dose.
Explanation - Lead glass walls shield radiation while allowing staff visibility.
Correct answer is: Both A and B.
Q.134 The term "dose‑area product" (DAP) is measured in:
Gray (Gy)
Gray‑cm² (Gy·cm²)
Sievert (Sv)
Curies (Ci)
Explanation - DAP is expressed as dose times irradiated area, e.g., Gy·cm².
Correct answer is: Gray‑cm² (Gy·cm²)
Q.135 Which of these is a typical dose limit for the public from background radiation?
0.1 mSv/yr
1 mSv/yr
3 mSv/yr
10 mSv/yr
Explanation - Public exposure limits are around 3 millisieverts annually.
Correct answer is: 3 mSv/yr
Q.136 The most common radiation safety training topic for technologists is:
Image reconstruction.
Radiation physics and dose calculation.
Patient scheduling.
Contrast agent selection.
Explanation - Knowledge of physics and dose is essential for safe practice.
Correct answer is: Radiation physics and dose calculation.
Q.137 The main goal of ALARA in medical imaging is:
Avoid all radiation.
Keep doses as low as reasonably achievable.
Maximize image quality regardless of dose.
Eliminate need for imaging.
Explanation - ALARA aims to minimize exposure while obtaining diagnostic information.
Correct answer is: Keep doses as low as reasonably achievable.
Q.138 Which of these is an example of a deterministic effect of radiation?
Cancer
Hair loss
Radiation dermatitis
Genetic mutation
Explanation - Deterministic effects have a threshold dose and increase severity with dose.
Correct answer is: Radiation dermatitis
Q.139 The typical patient dose from a single bone scan is approximately:
0.01 mSv
0.1 mSv
1 mSv
10 mSv
Explanation - Bone scans deliver around 1 millisievert to the patient.
Correct answer is: 1 mSv
Q.140 In radiation protection, the term "tissue weighting factor" refers to:
The density of the tissue.
The relative importance of the tissue in dose calculation.
The thickness of the tissue.
The mass of the tissue.
Explanation - Weighting factors represent each organ’s contribution to overall risk.
Correct answer is: The relative importance of the tissue in dose calculation.
Q.141 Which of the following is a typical radiation dose for a standard CT head scan?
0.1 mSv
1 mSv
5 mSv
20 mSv
Explanation - A head CT typically delivers around 5 millisieverts.
Correct answer is: 5 mSv
Q.142 The primary purpose of a lead shield in a radiology room is to:
Increase patient dose.
Reduce scatter radiation to staff.
Improve image contrast.
Decompose radiation.
Explanation - Lead shielding limits scattered photons and protects staff.
Correct answer is: Reduce scatter radiation to staff.
Q.143 Which of these statements about the diagnostic reference level (DRL) is true?
DRL is a legal dose limit.
DRL is a recommended dose for every patient.
DRL is a guideline for comparing typical doses.
DRL sets the maximum permissible dose for a procedure.
Explanation - DRLs guide optimization by indicating typical dose values for procedures.
Correct answer is: DRL is a guideline for comparing typical doses.
Q.144 Which of these is an example of a deterministic effect?
Radiation dermatitis
Cancer induction
Genetic mutation
Chromosomal abnormalities
Explanation - Deterministic effects appear only above a threshold dose and worsen with dose.
Correct answer is: Radiation dermatitis