Q.1 What is the primary physical principle behind ultrasound imaging?
Reflection of high‑frequency sound waves
Emission of X‑rays
Magnetic resonance of hydrogen atoms
Transmission of electrical currents
Explanation - Ultrasound imaging uses high‑frequency acoustic waves that are reflected at tissue interfaces to form images.
Correct answer is: Reflection of high‑frequency sound waves
Q.2 Typical diagnostic ultrasound frequencies range between:
1–5 kHz
2–15 MHz
20–100 kHz
100–300 MHz
Explanation - Clinical ultrasound transducers usually operate in the 2–15 MHz range, providing a balance between resolution and penetration depth.
Correct answer is: 2–15 MHz
Q.3 In B‑mode ultrasound, the brightness of a pixel is determined by:
The speed of sound in tissue
The amplitude of the reflected echo
The temperature of the probe
The electrical resistance of the tissue
Explanation - B‑mode (brightness mode) displays echo amplitude as gray levels; stronger echoes appear brighter.
Correct answer is: The amplitude of the reflected echo
Q.4 Which type of transducer element arrangement provides a wider field of view?
Linear array
Phased‑array
Curvilinear array
Single‑element
Explanation - Curvilinear (convex) arrays spread the beam, giving a larger sector and wider field of view, useful for abdominal imaging.
Correct answer is: Curvilinear array
Q.5 The acoustic impedance of a material is defined as:
Density × speed of sound
Density ÷ speed of sound
Speed of sound ÷ density
Square root of density
Explanation - Acoustic impedance Z = ρ·c, where ρ is density and c is the speed of sound in the medium.
Correct answer is: Density × speed of sound
Q.6 Which phenomenon primarily causes image artifacts known as "reverberation"?
Multiple reflections between two strong reflectors
Attenuation of the beam
Doppler shift of moving blood
Beam steering errors
Explanation - Reverberation artifacts arise when the ultrasound pulse bounces back and forth between two highly reflective interfaces.
Correct answer is: Multiple reflections between two strong reflectors
Q.7 In Doppler ultrasound, the frequency shift is directly proportional to:
The depth of the target
The velocity of the moving reflector
The acoustic impedance of the tissue
The pulse repetition frequency
Explanation - The Doppler shift Δf = (2·v·cosθ·f₀)/c, where v is the reflector velocity.
Correct answer is: The velocity of the moving reflector
Q.8 Which mode is used to measure the distance between two structures along the beam axis?
M‑mode
A‑mode
B‑mode
Color Doppler
Explanation - A‑mode (amplitude mode) plots echo amplitude versus depth, allowing precise distance measurement.
Correct answer is: A‑mode
Q.9 The speed of sound in soft tissue is approximately:
150 m/s
340 m/s
1540 m/s
3000 m/s
Explanation - Soft tissues have an average acoustic speed of about 1540 m/s, a value used for depth calculations.
Correct answer is: 1540 m/s
Q.10 Which safety index is used to monitor the mechanical effects of ultrasound on tissue?
Thermal Index (TI)
Mechanical Index (MI)
Specific Absorption Rate (SAR)
Radiation Dose Index (RDI)
Explanation - MI predicts the likelihood of cavitation, a mechanical bio‑effect of ultrasound.
Correct answer is: Mechanical Index (MI)
Q.11 What is the main advantage of using a phased‑array transducer for cardiac imaging?
Higher axial resolution
Ability to electronically steer the beam
Wider field of view
Lower cost
Explanation - Phased‑array probes can steer and focus the beam electronically, enabling real‑time imaging of the moving heart through small windows.
Correct answer is: Ability to electronically steer the beam
Q.12 In ultrasound, the term "axial resolution" refers to:
The ability to distinguish two structures along the beam direction
The ability to differentiate structures laterally
The depth of penetration
The frame rate of the system
Explanation - Axial resolution depends on pulse length; shorter pulses improve the ability to separate reflectors in depth.
Correct answer is: The ability to distinguish two structures along the beam direction
Q.13 Which of the following causes attenuation of the ultrasound beam?
Scattering, absorption, and reflection
Only reflection
Only Doppler shift
Only beam steering
Explanation - Attenuation results from energy loss due to scattering, absorption, and reflection as the wave propagates.
Correct answer is: Scattering, absorption, and reflection
Q.14 What does the term "focal depth" describe in an ultrasound system?
The depth at which the beam width is narrowest
The maximum depth the probe can reach
The distance between the probe and the monitor
The frequency of the transmitted wave
Explanation - Focal depth is the point where the acoustic beam is most tightly focused, giving optimal resolution.
Correct answer is: The depth at which the beam width is narrowest
Q.15 Which artifact appears as a bright line at the near field of the image, caused by strong reflections from the transducer surface?
Side‑lobes
Mirror image
Near‑field artifact
Acoustic shadowing
Explanation - The near‑field (or reverberation) artifact results from multiple reflections between the probe and the tissue surface.
Correct answer is: Near‑field artifact
Q.16 In colour Doppler imaging, what does red colour typically represent?
Flow away from the transducer
Flow towards the transducer
Stationary tissue
High attenuation zones
Explanation - Standard display conventions show flow moving towards the probe in red and away in blue.
Correct answer is: Flow towards the transducer
Q.17 Which of the following is NOT a typical use of ultrasound in medical diagnostics?
Evaluating fetal development
Imaging bone density
Assessing blood flow in vessels
Guiding needle biopsies
Explanation - Ultrasound is limited by high acoustic impedance mismatch with bone, making it unsuitable for bone density measurements.
Correct answer is: Imaging bone density
Q.18 The term "pulse‑repetition frequency" (PRF) influences which imaging parameter the most?
Axial resolution
Maximum measurable Doppler shift
Depth of penetration
Lateral resolution
Explanation - Higher PRF reduces aliasing, allowing higher Doppler velocities to be measured without ambiguity.
Correct answer is: Maximum measurable Doppler shift
Q.19 Which method is commonly used to reduce side‑lobe artifacts?
Increasing the gain
Using apodization (windowing)
Decreasing the frequency
Increasing the frame rate
Explanation - Apodization applies amplitude weighting across the aperture, suppressing side‑lobes at the cost of some resolution.
Correct answer is: Using apodization (windowing)
Q.20 In elastography, what property of tissue is primarily measured?
Electrical conductivity
Acoustic impedance
Stiffness (elastic modulus)
Thermal conductivity
Explanation - Ultrasound elastography assesses tissue deformation under mechanical stress to estimate stiffness, useful in tumor detection.
Correct answer is: Stiffness (elastic modulus)
Q.21 The term "acoustic shadowing" is observed when:
A highly reflective interface is present
The beam passes through a fluid medium
The beam encounters a strongly attenuating structure
The probe is placed too close to the skin
Explanation - Acoustic shadowing appears as a dark area behind highly attenuating objects like calculi or bone.
Correct answer is: The beam encounters a strongly attenuating structure
Q.22 What does the term "gain" control in an ultrasound system?
The transmitted frequency
The amplification of received echoes
The mechanical pressure of the probe
The speed of sound used for calculations
Explanation - Gain adjusts the overall brightness of the image by amplifying the echo signals.
Correct answer is: The amplification of received echoes
Q.23 Which type of ultrasound transducer is best suited for imaging superficial structures such as the thyroid?
Low‑frequency (2 MHz) convex array
High‑frequency (10–15 MHz) linear array
Phased‑array 1.5 MHz
3‑D matrix array
Explanation - Higher frequencies provide better resolution at shallow depths, ideal for superficial organs.
Correct answer is: High‑frequency (10–15 MHz) linear array
Q.24 In a B‑mode image, why does bone appear bright (hyperechoic) with an acoustic shadow behind it?
Bone reflects most of the incident sound and strongly attenuates the beam
Bone absorbs all the sound energy
Bone transmits sound without scattering
Bone has a low acoustic impedance
Explanation - The large acoustic impedance mismatch causes strong reflection and attenuation, creating a bright echo and downstream shadow.
Correct answer is: Bone reflects most of the incident sound and strongly attenuates the beam
Q.25 What is the purpose of the "time‑gain compensation" (TGC) control?
To adjust for depth‑dependent attenuation
To change the transmitted frequency
To modify the pulse length
To steer the beam laterally
Explanation - TGC amplifies echoes from deeper regions to compensate for loss of signal strength with depth.
Correct answer is: To adjust for depth‑dependent attenuation
Q.26 Which of the following best describes the principle of "harmonic imaging"?
Using the fundamental frequency only
Imaging at twice the transmitted frequency generated by tissue non‑linearity
Applying a magnetic field to enhance contrast
Utilizing only the first echo from the tissue
Explanation - Harmonic imaging captures the second‑harmonic signal produced by nonlinear propagation, improving resolution and reducing artifacts.
Correct answer is: Imaging at twice the transmitted frequency generated by tissue non‑linearity
Q.27 The "Nyquist limit" in Doppler ultrasound determines:
The maximum depth that can be imaged
The highest measurable velocity without aliasing
The axial resolution limit
The minimum frequency that can be transmitted
Explanation - Nyquist limit = PRF/2; velocities exceeding this produce aliasing artifacts.
Correct answer is: The highest measurable velocity without aliasing
Q.28 In 3‑D ultrasound, which technique is used to acquire volumetric data?
Mechanical sweeping of a 2‑D probe
Electronic steering of a matrix array
Increasing the gain
Using a lower frequency
Explanation - Matrix array transducers electronically steer and focus in three dimensions, capturing volumetric datasets.
Correct answer is: Electronic steering of a matrix array
Q.29 Which safety guideline limits the Mechanical Index (MI) to ≤1.9 for diagnostic ultrasound?
ALARA principle
FDA 510(k) clearance
AIUM (American Institute of Ultrasound in Medicine) recommendations
IEC 60601‑2‑37
Explanation - AIUM sets MI limits (≤1.9) to minimize risk of cavitation during diagnostic procedures.
Correct answer is: AIUM (American Institute of Ultrasound in Medicine) recommendations
Q.30 What is the main advantage of using a "compound imaging" technique?
Increases frame rate
Reduces speckle noise and improves contrast resolution
Decreases depth of penetration
Eliminates the need for TGC
Explanation - Compound imaging combines multiple frames acquired at different angles, averaging speckle and enhancing image quality.
Correct answer is: Reduces speckle noise and improves contrast resolution
Q.31 Which parameter is most directly responsible for the axial resolution of an ultrasound system?
Transducer bandwidth
Pulse length
Lateral beam width
Gain setting
Explanation - Shorter pulses (fewer cycles) improve axial resolution by reducing the distance between successive echoes.
Correct answer is: Pulse length
Q.32 In obstetric ultrasound, the "biophysical profile" assesses:
Maternal blood pressure
Fetal well‑being using multiple parameters
Placental thickness only
Uterine wall thickness
Explanation - The biophysical profile combines fetal movement, tone, breathing, amniotic fluid volume, and heart rate reactivity.
Correct answer is: Fetal well‑being using multiple parameters
Q.33 Which of the following is a limitation of ultrasound compared to MRI?
Inability to image bone
Limited soft‑tissue contrast
Exposure to ionizing radiation
High cost
Explanation - Bone strongly reflects and attenuates ultrasound, making it unsuitable for detailed bone imaging, unlike MRI.
Correct answer is: Inability to image bone
Q.34 The term "beamforming" in ultrasound refers to:
Generating electrical power for the transducer
Shaping and steering the acoustic beam using electronic delays
Measuring the speed of sound in tissue
Cooling the probe during operation
Explanation - Beamforming applies precise timing to each element's signal, allowing dynamic focusing and steering.
Correct answer is: Shaping and steering the acoustic beam using electronic delays
Q.35 What does the "Thermal Index" (TI) indicate in an ultrasound examination?
Likelihood of cavitation
Potential for tissue heating
Amount of acoustic shadowing
Degree of Doppler shift
Explanation - TI estimates the rise in tissue temperature relative to baseline, helping prevent thermal bioeffects.
Correct answer is: Potential for tissue heating
Q.36 Which imaging mode is specifically designed for high‑resolution imaging of the eye?
A‑mode
B‑mode
U‑mode (Ultrasonography of the eye)
M‑mode
Explanation - U‑mode uses high‑frequency probes (10–20 MHz) for detailed ocular imaging.
Correct answer is: U‑mode (Ultrasonography of the eye)
Q.37 During a contrast‑enhanced ultrasound (CEUS), microbubbles are used primarily because they:
Emit X‑rays
Increase the acoustic impedance of blood
Provide strong nonlinear responses to ultrasound
Cool the tissue
Explanation - Microbubbles resonate nonlinearly, generating harmonic signals that enhance vascular imaging.
Correct answer is: Provide strong nonlinear responses to ultrasound
Q.38 Which factor most influences the lateral resolution of an ultrasound image?
Transducer frequency
Pulse repetition frequency
Aperture size (element width) and focusing
Depth of imaging
Explanation - Lateral resolution improves with a larger aperture and tighter focusing of the beam.
Correct answer is: Aperture size (element width) and focusing
Q.39 What is the primary reason for using a "low‑frequency" transducer (e.g., 2 MHz) for abdominal imaging?
To achieve higher axial resolution
To increase penetration depth through deeper tissue
To reduce acoustic shadowing
To produce stronger color Doppler signals
Explanation - Lower frequencies suffer less attenuation, allowing the beam to reach deeper structures like the liver or kidneys.
Correct answer is: To increase penetration depth through deeper tissue
Q.40 In ultrasound, the term "speckle" refers to:
A type of artifact caused by random interference of scattered echoes
The noise generated by the probe's electronics
The bright echo from bone
The shadow behind a cyst
Explanation - Speckle is a granular texture resulting from constructive and destructive interference of many weak scatterers.
Correct answer is: A type of artifact caused by random interference of scattered echoes
Q.41 Which of the following best describes a "phantom" used in ultrasound quality control?
A living patient used for training
A synthetic material that mimics acoustic properties of tissue
A software simulation of the human body
An MRI scanner
Explanation - Phantoms provide standardized targets for evaluating image quality, resolution, and artifact levels.
Correct answer is: A synthetic material that mimics acoustic properties of tissue
Q.42 What is the effect of increasing the transducer’s bandwidth on image quality?
Improves axial resolution and reduces pulse length
Decreases lateral resolution
Increases acoustic shadowing
Reduces frame rate
Explanation - A broader bandwidth yields shorter pulses, enhancing axial resolution.
Correct answer is: Improves axial resolution and reduces pulse length
Q.43 Which of the following is a common clinical use of transcranial Doppler (TCD) ultrasound?
Measuring intra‑abdominal pressure
Assessing cerebral blood flow velocity
Evaluating fetal heart rate
Imaging the thyroid gland
Explanation - TCD measures blood flow in basal cerebral arteries through the thin temporal bone window.
Correct answer is: Assessing cerebral blood flow velocity
Q.44 The "focus zone" in an ultrasound scan is:
The region where the beam is widest
The depth range where the beam is dynamically focused
The area of maximum attenuation
The near‑field region only
Explanation - Dynamic focusing adjusts the focal point throughout the depth, improving resolution across the zone.
Correct answer is: The depth range where the beam is dynamically focused
Q.45 What is the typical speed of sound in fat tissue compared to muscle?
Higher in fat than in muscle
Lower in fat than in muscle
The same in both tissues
Variable, depends on temperature
Explanation - Fat has a speed of ~1450 m/s, while muscle is ~1580 m/s; differences affect depth calculations.
Correct answer is: Lower in fat than in muscle
Q.46 Which ultrasound mode is most suitable for measuring the thickness of the intima‑media of an artery?
M‑mode
B‑mode
Color Doppler
3‑D mode
Explanation - M‑mode provides high temporal resolution along a single line, ideal for precise wall thickness measurement.
Correct answer is: M‑mode
Q.47 In ultrasound physics, the term "attenuation coefficient" is expressed in:
dB/cm
W/m²
Hz
kg/m³
Explanation - Attenuation is quantified as decibels per centimeter, indicating loss per unit depth.
Correct answer is: dB/cm
Q.48 Which of the following best describes "acoustic radiation force imaging" (ARFI)?
A technique that measures temperature changes
A method that uses a short high‑intensity pulse to generate tissue displacement
A Doppler method for measuring blood flow velocity
A method for visualizing bone density
Explanation - ARFI applies a focused push pulse to create localized displacement, which is then measured to assess tissue stiffness.
Correct answer is: A method that uses a short high‑intensity pulse to generate tissue displacement
Q.49 The primary advantage of using a "matrix array" transducer for 3‑D imaging is:
Lower cost compared to linear arrays
Ability to electronically steer and focus in both azimuth and elevation
Higher frequency operation
Simpler beamforming algorithms
Explanation - Matrix arrays have a 2‑D grid of elements, enabling true volumetric beam steering and focusing.
Correct answer is: Ability to electronically steer and focus in both azimuth and elevation
Q.50 When performing a Doppler study of the carotid artery, the angle of insonation should be kept:
Below 30° for accurate velocity estimation
Between 60° and 90°
Exactly 0°
Any angle; angle does not affect results
Explanation - Small insonation angles (<30°) minimize cosine error in the Doppler equation, improving velocity accuracy.
Correct answer is: Below 30° for accurate velocity estimation
Q.51 Which artifact appears as a duplication of structures on the opposite side of a strong reflector?
Mirror image artifact
Reverberation artifact
Side‑lobe artifact
Shadowing artifact
Explanation - Mirror artifacts occur when the beam reflects off a strong interface and re‑enters the tissue, creating a false duplicate.
Correct answer is: Mirror image artifact
Q.52 In the context of ultrasound transducers, "piezoelectric" materials are used because they:
Emit visible light
Convert electrical energy into mechanical vibrations and vice versa
Absorb sound waves completely
Generate magnetic fields
Explanation - Piezoelectric crystals expand and contract when voltage is applied, creating and receiving ultrasound waves.
Correct answer is: Convert electrical energy into mechanical vibrations and vice versa
Q.53 What is the main limitation of color Doppler imaging compared with spectral Doppler?
Lower spatial resolution
Inability to measure exact velocities
Higher susceptibility to motion artifacts
Longer acquisition time
Explanation - Color Doppler provides relative flow information; precise velocity values require spectral (pulse‑wave) Doppler.
Correct answer is: Inability to measure exact velocities
Q.54 Which ultrasound technique is most appropriate for evaluating the elasticity of the liver in chronic disease?
Transient elastography (FibroScan)
M‑mode imaging
B‑mode high‑frequency imaging
Color Doppler flow mapping
Explanation - Transient elastography uses a shear‑wave pulse generated by an ultrasound transducer to quantify liver stiffness.
Correct answer is: Transient elastography (FibroScan)
Q.55 In a typical ultrasound system, the "display gain" is adjusted to:
Control the depth of imaging
Modify the frequency of the transmitted pulse
Compensate for overall signal attenuation
Change the probe’s physical size
Explanation - Display gain uniformly amplifies the received signal, affecting overall image brightness.
Correct answer is: Compensate for overall signal attenuation
Q.56 Which of the following best describes "harmonic imaging" benefits?
Improved penetration depth
Reduced side‑lobe artifacts and better resolution
Higher frame rates
Lower frequency operation
Explanation - Harmonic imaging emphasizes the second‑harmonic signal, which has a narrower beam and fewer artifacts.
Correct answer is: Reduced side‑lobe artifacts and better resolution
Q.57 What is the purpose of "spatial compounding" in ultrasound?
To combine images obtained from different beam angles to reduce speckle
To increase the transmitted power
To shorten the pulse length
To enhance color Doppler flow velocity
Explanation - Spatial compounding averages multiple frames from varied angles, reducing speckle and improving contrast.
Correct answer is: To combine images obtained from different beam angles to reduce speckle
Q.58 In the Doppler equation, the cosine of the angle between the ultrasound beam and blood flow is used to:
Correct for the direction of flow
Calculate attenuation
Determine the beam width
Set the mechanical index
Explanation - The cosine term accounts for the angle, converting the measured frequency shift to true velocity.
Correct answer is: Correct for the direction of flow
Q.59 Which ultrasound frequency range is most commonly used for imaging the eye (e.g., retina and vitreous)?
2–5 MHz
7–10 MHz
12–20 MHz
30–40 MHz
Explanation - High‑frequency probes (12–20 MHz) provide the resolution required for ocular structures while maintaining sufficient penetration.
Correct answer is: 12–20 MHz
Q.60 The term "frame rate" in ultrasound refers to:
Number of pulses transmitted per second
Number of image frames displayed per second
Frequency of the transducer
Depth of the imaging sector
Explanation - Higher frame rates improve temporal resolution, important for moving structures like the heart.
Correct answer is: Number of image frames displayed per second
Q.61 Which of the following is an advantage of using a "wide‑band" transducer?
Greater depth penetration
Higher axial resolution due to shorter pulses
Reduced electrical power consumption
Elimination of all artifacts
Explanation - A wide bandwidth allows for shorter pulses, which improves axial resolution.
Correct answer is: Higher axial resolution due to shorter pulses
Q.62 In ultrasound-guided biopsies, the term "in‑plane" needle approach means:
The needle is visualized along its entire length within the imaging plane
The needle is inserted perpendicular to the imaging plane
The needle is not visualized at all
The needle tip is only seen in a single frame
Explanation - In‑plane technique keeps the needle within the ultrasound slice, allowing continuous visualization.
Correct answer is: The needle is visualized along its entire length within the imaging plane
Q.63 Which parameter is directly related to the lateral resolution of an ultrasound image?
Pulse duration
Element pitch of the transducer array
Transmit frequency
Thermal Index
Explanation - Element pitch (spacing) determines beamwidth and thus lateral resolution; tighter spacing improves resolution.
Correct answer is: Element pitch of the transducer array
Q.64 The main physical mechanism behind "cavitation" in ultrasound is:
Formation and collapse of gas bubbles due to pressure fluctuations
Reflection of sound at tissue interfaces
Absorption of ultrasound energy as heat
Diffraction of the acoustic beam
Explanation - Cavitation occurs when negative pressure phases cause gas bubbles to form and violently collapse, potentially damaging tissue.
Correct answer is: Formation and collapse of gas bubbles due to pressure fluctuations
Q.65 Which ultrasound mode is primarily used to assess fetal cardiac motion in real time?
M‑mode
B‑mode
Color Doppler
Spectral Doppler
Explanation - M‑mode provides high‑temporal resolution along a single line, useful for detailed motion analysis of the fetal heart.
Correct answer is: M‑mode
Q.66 In a diagnostic ultrasound system, the "dynamic range" setting controls:
The range of echo amplitudes displayed (contrast)
The transmitted frequency
The mechanical index
The depth of imaging
Explanation - Dynamic range determines the gray‑scale mapping of echo intensities, affecting image contrast.
Correct answer is: The range of echo amplitudes displayed (contrast)
Q.67 Which of the following statements about ultrasound contrast agents (microbubbles) is TRUE?
They are permanently retained in the bloodstream
They only enhance static tissues
They enhance backscatter through nonlinear oscillation
They emit ionizing radiation
Explanation - Microbubbles resonate nonlinearly, producing strong harmonic signals that improve vascular imaging.
Correct answer is: They enhance backscatter through nonlinear oscillation
Q.68 The "near field" (Fresnel zone) of an ultrasound transducer is characterized by:
A region of low beam quality and complex interference patterns
Uniform beam width and high resolution
Maximum penetration depth
Zero acoustic pressure
Explanation - In the near field, interference between waves from different elements creates a pattern of maxima and minima.
Correct answer is: A region of low beam quality and complex interference patterns
Q.69 Which imaging technique uses multiple low‑frequency plane‑wave transmissions to achieve ultra‑high frame rates?
Compound imaging
Coherent plane‑wave compounding
Spatio‑temporal adaptive processing (STAP)
High‑frequency B‑mode
Explanation - Plane‑wave compounding sends several low‑angle plane waves and coherently sums them, providing high frame rates (up to several thousand fps).
Correct answer is: Coherent plane‑wave compounding
Q.70 In the context of ultrasound safety, the term "ALARA" stands for:
As Low As Reasonably Achievable
Acoustic Limitation of Acoustic Radiation
Automatic Level Adjustment for Radiology
Acoustic Low‑Amplitude Repetitive Activation
Explanation - ALARA is a safety principle to minimize exposure (thermal and mechanical) while obtaining diagnostic information.
Correct answer is: As Low As Reasonably Achievable
Q.71 What is the primary reason for using a "low‑mechanical‑index" (MI) setting during obstetric scans?
To increase image brightness
To reduce the risk of fetal tissue heating and cavitation
To enhance color Doppler flow signals
To shorten the scan time
Explanation - Lower MI limits the acoustic pressure, minimizing bioeffects on the developing fetus.
Correct answer is: To reduce the risk of fetal tissue heating and cavitation
Q.72 Which ultrasound artifact results from the side lobes of the beam interacting with a strong reflector?
Mirror artifact
Side‑lobe artifact
Reverberation artifact
Shadowing artifact
Explanation - Side‑lobe energy can reflect off strong interfaces, creating false echoes away from the main beam.
Correct answer is: Side‑lobe artifact
Q.73 What is the main clinical use of "intracavitary" ultrasound probes?
Imaging deep abdominal organs
Scanning superficial muscles
Evaluating internal cavities such as the uterus and rectum
Assessing bone fractures
Explanation - Intracavitary probes (e.g., endovaginal) provide high‑frequency, close‑range imaging of internal hollow organs.
Correct answer is: Evaluating internal cavities such as the uterus and rectum
Q.74 The "bandwidth" of an ultrasound transducer is defined as:
The ratio of highest to lowest frequency it can emit
The difference between the highest and lowest frequencies (in percentage) where the response is above –6 dB
The physical width of the transducer crystal
The maximum depth it can reach
Explanation - Bandwidth is expressed as a percentage of the center frequency and indicates the range over which the transducer operates effectively.
Correct answer is: The difference between the highest and lowest frequencies (in percentage) where the response is above –6 dB
Q.75 In Doppler ultrasound, “aliasing” occurs when:
The blood flow exceeds the Nyquist limit
The probe is angled more than 90° to the vessel
The gain is set too high
The patient moves during acquisition
Explanation - Aliasing produces a wrap‑around effect in the spectral display when velocities surpass half the PRF.
Correct answer is: The blood flow exceeds the Nyquist limit
Q.76 Which of the following is a key benefit of using “fusion imaging” (ultrasound‑MRI or ultrasound‑CT) in interventional procedures?
Higher frame rates than pure ultrasound
Combining real‑time ultrasound guidance with high‑resolution anatomical detail from other modalities
Elimination of the need for contrast agents
Reduced need for operator training
Explanation - Fusion imaging overlays ultrasound with MRI/CT data, improving targeting accuracy while maintaining real‑time feedback.
Correct answer is: Combining real‑time ultrasound guidance with high‑resolution anatomical detail from other modalities
Q.77 What does the term "acoustic impedance mismatch" describe?
When two tissues have identical acoustic properties
When there is a large difference in acoustic impedance between two media, causing strong reflection
When the transducer is not properly calibrated
When the speed of sound changes with temperature
Explanation - Impedance mismatch leads to reflection of the incident wave, which is fundamental to image formation.
Correct answer is: When there is a large difference in acoustic impedance between two media, causing strong reflection
Q.78 In ultrasound elastography, the term "strain ratio" refers to:
The ratio of tissue temperature before and after exposure
The ratio of displacement (strain) between a lesion and surrounding tissue
The ratio of transmitted to received acoustic energy
The ratio of probe frequency to depth
Explanation - Strain ratio quantifies relative stiffness, assisting in differentiating benign from malignant lesions.
Correct answer is: The ratio of displacement (strain) between a lesion and surrounding tissue
Q.79 Which of the following best explains why ultrasound is limited in imaging air‑filled structures like the lungs?
Air has a very high acoustic impedance causing most of the wave to be reflected at the air‑tissue interface
Lungs absorb all ultrasound energy
Ultrasound frequencies are too low for air
The transducer cannot be placed on the chest
Explanation - The large impedance difference at the pleural surface leads to near‑total reflection, preventing deeper lung imaging.
Correct answer is: Air has a very high acoustic impedance causing most of the wave to be reflected at the air‑tissue interface
Q.80 What is the main advantage of using a “synthetic aperture” technique in ultrasound imaging?
Higher frame rates
Improved lateral resolution across the entire imaging depth
Reduced need for coupling gel
Lower power consumption
Explanation - Synthetic aperture combines data from multiple transmit‑receive events to synthesize a large aperture, enhancing resolution.
Correct answer is: Improved lateral resolution across the entire imaging depth
Q.81 In a B‑mode image of the liver, a well‑defined anechoic area with posterior acoustic enhancement most likely represents:
A solid tumor
A cyst
Calcified gallstone
Acoustic shadowing from bone
Explanation - Cysts are fluid‑filled, producing anechoic regions; the lack of attenuation yields posterior enhancement.
Correct answer is: A cyst
Q.82 Which of the following ultrasound transducer characteristics primarily determines the depth of penetration?
Element spacing
Operating frequency
Number of channels
Gain setting
Explanation - Lower frequencies experience less attenuation, allowing deeper penetration at the expense of resolution.
Correct answer is: Operating frequency
Q.83 The term "acoustic window" in transcranial Doppler refers to:
A period of low acoustic pressure
A thin area of bone that allows ultrasound transmission to the brain
A software filter for Doppler signals
A type of probe
Explanation - Acoustic windows (e.g., temporal bone) provide enough transparency for Doppler assessment of cerebral vessels.
Correct answer is: A thin area of bone that allows ultrasound transmission to the brain
Q.84 Which imaging mode is specifically designed for visualizing tissue motion over time along a single line?
M‑mode
B‑mode
Color Doppler
3‑D mode
Explanation - M‑mode displays motion versus time along one scan line, useful for cardiac valve and wall motion analysis.
Correct answer is: M‑mode
Q.85 What does the "backscatter coefficient" quantify in ultrasound tissue characterization?
The amount of sound reflected back toward the transducer per unit volume
The speed of sound in the tissue
The attenuation per centimeter
The temperature rise due to absorption
Explanation - Backscatter coefficient is a quantitative measure of tissue scattering properties, useful for tissue classification.
Correct answer is: The amount of sound reflected back toward the transducer per unit volume
Q.86 In a Doppler ultrasound, a high "pulse‑repetition frequency" (PRF) is required when:
Imaging very deep structures
Measuring slow blood flow
Measuring fast blood flow to avoid aliasing
Improving axial resolution
Explanation - High PRF raises the Nyquist limit, allowing accurate measurement of high velocities.
Correct answer is: Measuring fast blood flow to avoid aliasing
Q.87 Which of the following describes the principle of "plane‑wave imaging"?
A single focused beam is swept across the field of view
A broad, unfocused wavefront is transmitted, and echoes are reconstructed to form an image
Only the fundamental frequency is used
The transducer mechanically rotates during acquisition
Explanation - Plane‑wave imaging transmits a planar wave, allowing ultrafast acquisition when combined with coherent compounding.
Correct answer is: A broad, unfocused wavefront is transmitted, and echoes are reconstructed to form an image
Q.88 What is the main clinical advantage of using "ultrasound‑guided high‑intensity focused ultrasound" (HIFU) therapy?
Non‑invasive thermal ablation of target tissues under real‑time imaging guidance
Improved color Doppler flow mapping
Enhanced bone density measurement
Increased frame rates for cardiac imaging
Explanation - HIFU concentrates acoustic energy to thermally destroy tissue while ultrasound monitors the process.
Correct answer is: Non‑invasive thermal ablation of target tissues under real‑time imaging guidance
Q.89 Which of the following best explains why a "linear" probe provides better lateral resolution than a "curvilinear" probe at shallow depths?
Linear probes have a wider field of view
Linear probes have a smaller element pitch and flatter surface, yielding a narrower beam
Curvilinear probes operate at a higher frequency
Curvilinear probes use fewer channels
Explanation - The flat surface and tight element spacing of linear arrays produce a narrow beam, improving lateral resolution near the surface.
Correct answer is: Linear probes have a smaller element pitch and flatter surface, yielding a narrower beam
Q.90 In which situation is "spectral Doppler" preferred over "color Doppler"?
When a quick visual overview of flow direction is needed
When precise quantitative velocity measurement is required
When evaluating tissue elasticity
When imaging the fetal heart
Explanation - Spectral Doppler provides a waveform with exact velocity values, while color Doppler gives a qualitative map.
Correct answer is: When precise quantitative velocity measurement is required
Q.91 Which of the following ultrasound artifacts is most commonly associated with a highly reflective interface such as bone?
Acoustic enhancement
Acoustic shadowing
Speckle noise
Mirror artifact
Explanation - Strong reflectors like bone absorb and reflect most of the beam, casting a dark shadow behind them.
Correct answer is: Acoustic shadowing
Q.92 What does the "gain‑time curve" (GTC) represent in an ultrasound system?
The variation of gain with depth (time) to compensate for attenuation
The frequency response of the transducer
The mechanical index over time
The frame rate during a scan
Explanation - GTC (or TGC) adjusts gain as a function of depth, ensuring uniform brightness across the image.
Correct answer is: The variation of gain with depth (time) to compensate for attenuation
Q.93 In ultrasound imaging, the "axial resolution" is primarily limited by:
The width of the transducer element
The pulse length (number of cycles)
The speed of sound in tissue
The gain setting
Explanation - Shorter pulses (fewer cycles) reduce the axial spread of the echo, improving resolution along the beam axis.
Correct answer is: The pulse length (number of cycles)
Q.94 Which of the following best describes "shear‑wave elastography"?
Measuring the speed of longitudinal sound waves
Generating shear waves via acoustic radiation force and measuring their propagation speed to infer tissue stiffness
Using color Doppler to map tissue elasticity
Applying an external mechanical probe to deform tissue
Explanation - Shear‑wave elastography quantifies stiffness by tracking shear‑wave speed, which increases with tissue rigidity.
Correct answer is: Generating shear waves via acoustic radiation force and measuring their propagation speed to infer tissue stiffness
Q.95 The term "acoustic impedance" (Z) has units of:
kg·m⁻²·s⁻¹
W·m⁻²·sr⁻¹
Pa·s·m⁻¹
N·s·m⁻³
Explanation - Z = ρ·c, where ρ (kg/m³) and c (m/s) give units of kg·m⁻²·s⁻¹.
Correct answer is: kg·m⁻²·s⁻¹
Q.96 Which of the following is an advantage of using a "dual‑frequency" (fundamental + harmonic) transducer?
Simultaneous imaging at two different depths
Enhanced penetration with fundamental frequency and improved resolution with harmonic frequency
Reduced need for coupling gel
Automatic elimination of all artifacts
Explanation - Dual‑frequency operation leverages deep penetration of low frequencies and the high resolution of harmonic imaging.
Correct answer is: Enhanced penetration with fundamental frequency and improved resolution with harmonic frequency
Q.97 During a breast ultrasound, a lesion shows irregular margins, posterior shadowing, and a heterogeneous internal echo pattern. This appearance most likely suggests:
A simple cyst
A benign fibroadenoma
A malignant tumor
Calcified plaque
Explanation - Irregular borders, shadowing, and heterogeneity are typical sonographic features of malignancy.
Correct answer is: A malignant tumor
Q.98 Which of the following best describes the role of "apodization" in ultrasound beamforming?
Increasing the transmitted power
Applying a tapering window to the aperture to suppress side lobes
Changing the frequency of the transmitted pulse
Adjusting the mechanical index
Explanation - Apodization reduces side‑lobe intensity, improving image contrast at the expense of a slightly wider main lobe.
Correct answer is: Applying a tapering window to the aperture to suppress side lobes
Q.99 In ultrasound, the "far field" (Fraunhofer zone) is characterized by:
A region where the beam width is constant and diffraction dominates
Maximum beam intensity
Highly irregular interference patterns
Zero acoustic pressure
Explanation - Beyond the focal zone, the beam diverges predictably, and its width is governed by diffraction.
Correct answer is: A region where the beam width is constant and diffraction dominates
Q.100 Which parameter must be minimized to reduce the likelihood of thermal bioeffects during a prolonged ultrasound exam?
Mechanical Index (MI)
Thermal Index (TI)
Pulse Repetition Frequency (PRF)
Gain
Explanation - TI estimates tissue temperature rise; keeping it low limits heating during long scans.
Correct answer is: Thermal Index (TI)
Q.101 The "speed of sound" used for depth calculations in most diagnostic ultrasound machines is:
300 m/s
1540 m/s
5000 m/s
0.5 m/s
Explanation - A standard value of 1540 m/s for soft tissue is built into most scanners for distance conversion.
Correct answer is: 1540 m/s
Q.102 Which of the following is a typical use of "contrast‑enhanced ultrasound" (CEUS) in liver imaging?
Measuring liver stiffness
Assessing vascular perfusion of focal lesions
Detecting biliary stones
Measuring gallbladder wall thickness
Explanation - CEUS highlights microvascular flow, aiding characterization of benign vs malignant liver lesions.
Correct answer is: Assessing vascular perfusion of focal lesions
Q.103 In a Doppler spectral display, the "envelope" of the waveform represents:
The range of velocities over the cardiac cycle
The gain setting
The frequency of the transmitted pulse
The depth of imaging
Explanation - The spectral envelope shows peak systolic, end‑diastolic, and mean velocities.
Correct answer is: The range of velocities over the cardiac cycle
Q.104 Which ultrasound imaging mode is most appropriate for evaluating the structure of the fetal spine?
M‑mode
B‑mode with a high‑frequency linear probe
Color Doppler
3‑D/4‑D mode
Explanation - 3‑D/4‑D reconstructions allow volumetric assessment of complex fetal anatomy such as the spine.
Correct answer is: 3‑D/4‑D mode
Q.105 What is the purpose of a "hydrophone" in ultrasound transducer testing?
To emit high‑frequency sound waves
To measure the acoustic pressure field generated by the transducer
To calibrate the gain settings
To provide visual feedback to the operator
Explanation - Hydrophones are calibrated sensors used to assess output pressure, frequency response, and beam patterns of transducers.
Correct answer is: To measure the acoustic pressure field generated by the transducer
Q.106 In an ultrasound system, the "dynamic focusing" technique is used to:
Adjust the focal point continuously during reception to improve resolution at all depths
Increase the transmitted power
Change the probe frequency on the fly
Reduce the frame rate
Explanation - Dynamic focusing applies time delays to received signals, sharpening resolution throughout the imaging range.
Correct answer is: Adjust the focal point continuously during reception to improve resolution at all depths
Q.107 Which of the following is NOT a common cause of "acoustic shadowing"?
Calcifications
Air pockets
Fluid‑filled cysts
Dense bone
Explanation - Cysts transmit sound with little attenuation, often causing posterior enhancement rather than shadowing.
Correct answer is: Fluid‑filled cysts
Q.108 When performing a transrectal prostate ultrasound, the recommended frequency range of the probe is:
1–3 MHz
5–9 MHz
10–15 MHz
20–30 MHz
Explanation - Intermediate frequencies balance resolution and penetration for prostate imaging.
Correct answer is: 5–9 MHz
Q.109 Which of the following best describes the effect of "frequency‑dependent attenuation" on ultrasound imaging?
Higher frequencies are attenuated less, allowing deeper imaging
Attenuation increases linearly with depth regardless of frequency
Higher frequencies experience greater attenuation, limiting depth but improving resolution
Attenuation is independent of frequency
Explanation - Attenuation ∝ frequency; thus, high‑frequency waves lose energy faster, reducing penetration.
Correct answer is: Higher frequencies experience greater attenuation, limiting depth but improving resolution
Q.110 The main advantage of "ultrasound‑based navigation" in minimally invasive surgery is:
Elimination of ionizing radiation
Higher resolution than MRI
Ability to image bone directly
Automatic suturing
Explanation - Ultrasound provides real‑time imaging without radiation, assisting surgeons in guiding instruments safely.
Correct answer is: Elimination of ionizing radiation
Q.111 Which of the following ultrasound imaging techniques is specifically designed to visualize blood flow velocity vectors in three dimensions?
Color Doppler
Power Doppler
3‑D Vector Flow Imaging
M‑mode
Explanation - 3‑D Vector Flow Imaging captures volumetric velocity fields, enabling full‑directional flow assessment.
Correct answer is: 3‑D Vector Flow Imaging
Q.112 What is the primary purpose of using a "gel” between the ultrasound transducer and the skin?
To increase acoustic impedance mismatch
To provide a conductive path for electrical signals
To eliminate air gaps, ensuring efficient transmission of acoustic energy
To cool the transducer
Explanation - Ultrasound does not transmit well through air; the gel creates a continuous medium for sound propagation.
Correct answer is: To eliminate air gaps, ensuring efficient transmission of acoustic energy
Q.113 In a B‑mode image, the term "hyperechoic" refers to:
An area that appears darker than surrounding tissue
An area that appears brighter than surrounding tissue
An area with no echoes
An area with variable echo intensity
Explanation - Hyperechoic structures reflect more sound, yielding increased brightness on the image.
Correct answer is: An area that appears brighter than surrounding tissue
Q.114 Which of the following statements about "ultrasound attenuation" is correct?
Attenuation only depends on tissue density
Attenuation is inversely proportional to frequency
Attenuation is directly proportional to frequency and depth
Attenuation does not affect image quality
Explanation - Higher frequencies and greater depths both increase attenuation, reducing signal strength.
Correct answer is: Attenuation is directly proportional to frequency and depth
Q.115 The term "acoustic radiation force" is utilized in which modern ultrasound application?
Color Doppler imaging
Shear‑wave elastography
B‑mode imaging
M‑mode imaging
Explanation - Acoustic radiation force pushes tissue to generate shear waves for stiffness assessment.
Correct answer is: Shear‑wave elastography
Q.116 In ultrasound, a "transducer" converts:
Light into sound
Electrical energy into acoustic energy and back
Heat into mechanical energy
Magnetic fields into electric current
Explanation - Piezoelectric crystals in the transducer perform the bidirectional conversion needed for imaging.
Correct answer is: Electrical energy into acoustic energy and back
Q.117 Which of the following best describes the effect of "beam steering" on image acquisition?
It changes the frequency of the transmitted pulse
It alters the direction of the acoustic beam without moving the probe
It increases the mechanical index
It reduces the frame rate
Explanation - Electronic beam steering uses phase delays to change the beam angle, allowing rapid scanning of different lines.
Correct answer is: It alters the direction of the acoustic beam without moving the probe
Q.118 During a Doppler exam of the carotid artery, a peak systolic velocity of 250 cm/s is observed. This finding most likely indicates:
Normal flow
Severe stenosis
Arterial occlusion
Low cardiac output
Explanation - High peak systolic velocities (>200 cm/s) suggest significant arterial narrowing.
Correct answer is: Severe stenosis
Q.119 Which imaging modality combines ultrasound with magnetic resonance data to enhance tumor localization?
Ultrasound‑CT fusion
Ultrasound‑MRI fusion
Contrast‑enhanced Doppler
Shear‑wave elastography
Explanation - Fusion of real‑time ultrasound with high‑resolution MRI improves lesion localization during interventions.
Correct answer is: Ultrasound‑MRI fusion
Q.120 The primary cause of "acoustic enhancement" behind a fluid‑filled cyst is:
Increased attenuation within the cyst
Reduced attenuation allowing more sound to reach deeper tissues
Reflection from the cyst wall
Side‑lobe interference
Explanation - Fluid has low attenuation, so more acoustic energy passes through, brightening tissue behind the cyst.
Correct answer is: Reduced attenuation allowing more sound to reach deeper tissues
Q.121 Which ultrasound technique is most suitable for real‑time imaging of myocardial strain?
M‑mode
Speckle‑tracking echocardiography
Color Doppler
3‑D static imaging
Explanation - Speckle‑tracking follows natural acoustic markers to quantify myocardial deformation (strain).
Correct answer is: Speckle‑tracking echocardiography
Q.122 In a typical clinical ultrasound machine, the "dynamic range" setting is adjusted to:
Change the depth of the image
Modify the frequency of the transmitted pulse
Control the contrast between bright and dark areas
Increase the mechanical index
Explanation - Dynamic range determines the gray‑scale mapping, affecting image contrast.
Correct answer is: Control the contrast between bright and dark areas
Q.123 Which of the following phenomena is exploited in "contrast‑enhanced ultrasound" to improve lesion detection?
Nonlinear oscillation of microbubbles producing harmonic signals
Increased attenuation of surrounding tissue
Thermal heating of the lesion
Magnetic susceptibility of the contrast agent
Explanation - Microbubbles resonate nonlinearly, emitting strong harmonic echoes that increase lesion conspicuity.
Correct answer is: Nonlinear oscillation of microbubbles producing harmonic signals
Q.124 The "focal law" in an ultrasound system refers to:
The set of time delays applied to each transducer element to focus the beam at a specific depth
The regulatory standards for safety
The method for calculating attenuation
The algorithm for converting echoes to pixel intensity
Explanation - Focal laws define the delays needed for dynamic or static focusing of the acoustic beam.
Correct answer is: The set of time delays applied to each transducer element to focus the beam at a specific depth
Q.125 Which of the following statements about “ultrasound speckle reduction” is true?
Speckle can be completely eliminated without affecting image quality
Speckle reduction techniques improve visual perception but may slightly reduce spatial resolution
Speckle is only present in Doppler modes
Speckle reduction increases thermal index
Explanation - Algorithms such as spatial compounding reduce speckle noise but can blur fine details.
Correct answer is: Speckle reduction techniques improve visual perception but may slightly reduce spatial resolution
Q.126 In the context of ultrasound, the term "frame‑averaging" is used to:
Increase the frame rate
Reduce speckle by averaging multiple frames
Enhance color Doppler sensitivity
Adjust the mechanical index
Explanation - Frame‑averaging combines consecutive frames, smoothing random speckle while preserving structural information.
Correct answer is: Reduce speckle by averaging multiple frames
Q.127 Which of the following is the primary reason for using a “high‑frequency” linear probe in musculoskeletal ultrasound?
To achieve deeper penetration into muscle
To provide superior resolution for superficial tendons and ligaments
To reduce the need for coupling gel
To increase the field of view
Explanation - High frequencies (10‑15 MHz) yield fine detail essential for visualizing superficial musculoskeletal structures.
Correct answer is: To provide superior resolution for superficial tendons and ligaments
Q.128 During an obstetric ultrasound, the "crown‑rump length" (CRL) measurement is most accurate at which gestational age range?
5–7 weeks
8–13 weeks
14–20 weeks
21–28 weeks
Explanation - CRL provides the most reliable estimate of gestational age during the first trimester (8–13 weeks).
Correct answer is: 8–13 weeks
Q.129 Which of the following best describes the effect of "apodization" on the main lobe width of an ultrasound beam?
It narrows the main lobe
It widens the main lobe slightly
It eliminates the main lobe
It has no effect on the main lobe
Explanation - Apodization suppresses side lobes, but the trade‑off is a modest increase in main‑lobe width.
Correct answer is: It widens the main lobe slightly
Q.130 What does the "acoustic impedance" mismatch between soft tissue and bone primarily cause?
Increased transmission into bone
Strong reflection and acoustic shadowing
Reduced attenuation in bone
Enhanced color Doppler signals
Explanation - The large impedance difference causes most of the incident sound to be reflected, producing a shadow behind bone.
Correct answer is: Strong reflection and acoustic shadowing
Q.131 In ultrasound, the term "beam width" is directly related to:
Axial resolution
Lateral resolution
Depth of penetration
Mechanical index
Explanation - Beam width determines the ability to distinguish two objects side‑by‑side; a narrower beam improves lateral resolution.
Correct answer is: Lateral resolution
Q.132 Which of the following is the most suitable ultrasound technique for evaluating fetal cardiac anatomy in real time?
M‑mode
B‑mode with high‑frequency linear probe
Four‑dimensional (4‑D) echocardiography
Transcranial Doppler
Explanation - 4‑D (real‑time 3‑D) provides volumetric cardiac images, allowing detailed assessment of fetal heart structures.
Correct answer is: Four‑dimensional (4‑D) echocardiography