Q.1 What does MRI stand for?
Magnetic Resonance Imaging
Multiple Resonance Imaging
Magnetic Radiance Imaging
Magnetic Resonator Imaging
Explanation - MRI stands for Magnetic Resonance Imaging, a non‑ionizing imaging modality that uses a strong magnetic field and radiofrequency pulses to produce detailed images of soft tissues.
Correct answer is: Magnetic Resonance Imaging
Q.2 Which imaging technique uses X‑rays to produce detailed bone images?
Ultrasound
CT Scan
X‑ray Radiography
MRI
Explanation - X‑ray radiography directly uses ionizing radiation to generate images, especially useful for visualizing bone structures.
Correct answer is: X‑ray Radiography
Q.3 What is the primary source of contrast in a CT scan?
Magnetic field
Radioactive tracer
X‑ray attenuation differences
Ultrasound waves
Explanation - CT images are generated by measuring how different tissues attenuate X‑ray beams; varying attenuation provides image contrast.
Correct answer is: X‑ray attenuation differences
Q.4 In ultrasound imaging, what determines the resolution of the image?
Frequency of the sound wave
Voltage applied to the transducer
Magnetic field strength
Contrast agent used
Explanation - Higher frequency sound waves provide better spatial resolution but penetrate less tissue.
Correct answer is: Frequency of the sound wave
Q.5 Which of the following is a major safety concern with PET imaging?
High magnetic field exposure
Radioactive decay products
Thermal injury from ultrasound
Laser eye damage
Explanation - PET uses short‑lived positron‑emitting radionuclides; managing radiation exposure is critical.
Correct answer is: Radioactive decay products
Q.6 What does the term 'temporal resolution' refer to in functional MRI?
Number of slices per volume
Time taken to acquire a single image
Signal strength of the MR sequence
Contrast agent half‑life
Explanation - Temporal resolution describes how quickly successive images can be captured, important for tracking dynamic brain activity.
Correct answer is: Time taken to acquire a single image
Q.7 Which imaging modality is most commonly used to monitor fetal heart rate during pregnancy?
MRI
Ultrasound
CT Scan
PET
Explanation - Ultrasound is safe for the fetus and provides real‑time monitoring of fetal heart activity.
Correct answer is: Ultrasound
Q.8 Which property of tissues is exploited in diffusion-weighted MRI?
Magnetic susceptibility
Diffusion of water molecules
Electrical conductivity
Acoustic impedance
Explanation - Diffusion-weighted imaging measures the random movement of water molecules to highlight areas of restricted diffusion, useful in stroke detection.
Correct answer is: Diffusion of water molecules
Q.9 Which component is essential for generating the static magnetic field in an MRI scanner?
Gradient coils
RF coils
Superconducting magnet
X‑ray tube
Explanation - A superconducting magnet creates the homogeneous static magnetic field (~1.5–3 T) necessary for MRI.
Correct answer is: Superconducting magnet
Q.10 In CT imaging, what is the purpose of the rotation of the X‑ray source and detectors?
To reduce radiation dose
To acquire projections from multiple angles
To cool the system
To increase magnetic field strength
Explanation - Rotating the source/detector provides multiple 2D projections that are reconstructed into a 3D image.
Correct answer is: To acquire projections from multiple angles
Q.11 Which contrast agent is most commonly used in MR angiography?
Gadolinium
Iodinated contrast
Barium sulfate
Technetium-99m
Explanation - Gadolinium chelates enhance blood vessel visibility in MRI by shortening T1 relaxation times.
Correct answer is: Gadolinium
Q.12 What does the term 'B0 field inhomogeneity' refer to?
Variation in static magnetic field across the imaging volume
Fluctuations in RF power
Temperature changes in the coil
Motion artifacts
Explanation - B0 inhomogeneity causes spatial variation in field strength, leading to image distortion and signal loss.
Correct answer is: Variation in static magnetic field across the imaging volume
Q.13 Which type of ultrasound transducer frequency is most suitable for imaging superficial structures like the thyroid?
1–3 MHz
5–10 MHz
15–20 MHz
25–30 MHz
Explanation - Higher frequency transducers provide better resolution for shallow tissues; 15–20 MHz is ideal for superficial organs.
Correct answer is: 15–20 MHz
Q.14 What imaging principle does PET rely on to localize metabolic activity?
Gamma ray emission from positron annihilation
X‑ray absorption differences
Acoustic wave reflection
Magnetic resonance decay
Explanation - PET detects pairs of 511 keV gamma photons produced when a positron annihilates with an electron.
Correct answer is: Gamma ray emission from positron annihilation
Q.15 Which artifact is commonly caused by patient movement during a CT scan?
Metallic streaks
Beam hardening
Motion blur
Chemical shift
Explanation - Rapid patient motion during acquisition smears the image, leading to blurring artifacts.
Correct answer is: Motion blur
Q.16 Which imaging modality is preferred for diagnosing acute intracranial hemorrhage?
MRI
CT Scan
Ultrasound
PET
Explanation - CT provides rapid, high‑contrast images of blood, making it the first choice for emergent hemorrhage detection.
Correct answer is: CT Scan
Q.17 What is the main advantage of using a 7 T MRI scanner over a 1.5 T scanner?
Lower cost
Higher image resolution
Shorter scan times
Reduced safety concerns
Explanation - Higher magnetic field strengths increase signal‑to‑noise ratio, enabling finer spatial resolution.
Correct answer is: Higher image resolution
Q.18 Which phenomenon limits the depth penetration of ultrasound imaging?
Beam hardening
Attenuation
Diffraction
Magnetic susceptibility
Explanation - As ultrasound travels through tissue, it loses energy via absorption and scattering, limiting depth.
Correct answer is: Attenuation
Q.19 In CT, what does the term 'kVp' represent?
Kilovolt peak, the maximum X‑ray tube voltage
Kilopascal, the pressure applied
Kilovolt per second, the rate of voltage change
Kilohertz peak, the RF frequency
Explanation - kVp determines the energy of X‑ray photons; higher kVp increases penetration.
Correct answer is: Kilovolt peak, the maximum X‑ray tube voltage
Q.20 Which of the following best describes the principle of dynamic contrast‑enhanced MRI?
Imaging changes over time after injection of a contrast agent
Using multiple coils to capture dynamic scenes
Simultaneous imaging in multiple modalities
Capturing real‑time blood flow with Doppler
Explanation - DCE‑MRI tracks the passage of contrast through tissues, revealing perfusion characteristics.
Correct answer is: Imaging changes over time after injection of a contrast agent
Q.21 Which safety precaution is critical when operating a CT scanner?
Shielding patients from X‑ray exposure
Using magnetic coils in proximity
Cooling the RF coils
Placing patients on a conductive table
Explanation - Lead aprons and automatic exposure controls are essential to minimize radiation dose.
Correct answer is: Shielding patients from X‑ray exposure
Q.22 What is the purpose of gradient coils in MRI?
Generate the main magnetic field
Produce spatially varying magnetic fields for encoding
Transmit RF pulses
Cool the magnet
Explanation - Gradient coils create linear magnetic field gradients to encode spatial information into the MR signal.
Correct answer is: Produce spatially varying magnetic fields for encoding
Q.23 Which of the following best describes 'beam hardening' in CT?
Reduction of low‑energy photons, causing streaks
Increase in high‑energy photons due to filtration
Hardening of the beam by magnetic fields
Hardening of the X‑ray tube
Explanation - Beam hardening occurs when low‑energy X‑rays are absorbed, leading to artifacts in reconstructed images.
Correct answer is: Reduction of low‑energy photons, causing streaks
Q.24 Which imaging modality uses magnetic fields and radiofrequency pulses to create images of soft tissues?
Ultrasound
CT Scan
X‑ray Radiography
MRI
Explanation - MRI utilizes magnetic resonance phenomena to visualize soft tissue contrast without ionizing radiation.
Correct answer is: MRI
Q.25 The 'echo time' (TE) in MRI primarily affects:
Image contrast (T2 weighting)
Signal strength (T1 weighting)
Acquisition time
Gradient strength
Explanation - TE determines how long the signal is allowed to decay, influencing T2 contrast.
Correct answer is: Image contrast (T2 weighting)
Q.26 Which of the following is a characteristic of a low‑kV CT scan?
Higher radiation dose
Better soft tissue contrast
Lower contrast resolution
Longer acquisition time
Explanation - Low‑kV settings increase X‑ray absorption differences, improving soft‑tissue contrast but may increase noise.
Correct answer is: Better soft tissue contrast
Q.27 What is the main limitation of using MRI for patients with metal implants?
Magnetic field attraction causing displacement
Heating of metal due to RF pulses
Beam hardening artifacts
Reduced acoustic noise
Explanation - RF fields can induce currents in metal, leading to localized heating and safety concerns.
Correct answer is: Heating of metal due to RF pulses
Q.28 Which imaging technique is used for visualizing bone fractures in real‑time during surgery?
MRI
Ultrasound
Intraoperative X‑ray (fluoroscopy)
PET
Explanation - Fluoroscopy provides live X‑ray images that guide surgical instruments.
Correct answer is: Intraoperative X‑ray (fluoroscopy)
Q.29 The term 'slice thickness' in CT refers to:
Number of slices per scan
Thickness of each individual image plane
Time per slice acquisition
Radiation dose per slice
Explanation - Slice thickness determines the spatial resolution along the z‑axis; thinner slices give higher detail.
Correct answer is: Thickness of each individual image plane
Q.30 Which property of tissues is most useful for differentiation in ultrasound imaging?
Electrical conductivity
Acoustic impedance
Magnetic susceptibility
Thermal conductivity
Explanation - Differences in acoustic impedance cause reflections that create image contrast in ultrasound.
Correct answer is: Acoustic impedance
Q.31 What is the typical field strength of a standard clinical MRI scanner?
0.5 T
1.5 T
3 T
7 T
Explanation - Most clinical MRI scanners operate at 1.5 Tesla; 3 T scanners are also common for research.
Correct answer is: 1.5 T
Q.32 Which of the following is a contraindication for MRI?
Pacemaker
Dental fillings
Earplugs
Pregnancy
Explanation - Traditional pacemakers are ferromagnetic and can move or malfunction in a strong magnetic field.
Correct answer is: Pacemaker
Q.33 In PET imaging, the radioactive tracer used is often labeled with:
Iodine-131
Technetium-99m
Fluorine-18
Carbon-14
Explanation - Fluorine‑18 (FDG) is the most common PET tracer due to its favorable half‑life and uptake in glucose‑metabolizing tissues.
Correct answer is: Fluorine-18
Q.34 Which technique is used to reduce noise in MRI images?
Increasing kVp
Using parallel imaging
Decreasing TR
Adding metal implants
Explanation - Parallel imaging techniques (e.g., SENSE, GRAPPA) accelerate acquisition and improve signal‑to‑noise ratio.
Correct answer is: Using parallel imaging
Q.35 Which of the following best describes 'aliasing' in CT imaging?
Signal lost due to low contrast
Image distortion from undersampling
Noise from patient motion
Artifacts from metal implants
Explanation - Aliasing occurs when sampling frequency is insufficient, leading to false structures.
Correct answer is: Image distortion from undersampling
Q.36 Which of these is a benefit of using ultrafast MRI sequences?
Higher spatial resolution
Reduced scan time
Lower magnetic field
Increased radiation dose
Explanation - Ultrafast sequences shorten acquisition time, improving patient comfort and reducing motion artifacts.
Correct answer is: Reduced scan time
Q.37 Which imaging modality is most sensitive for detecting small cortical bone fractures?
X‑ray Radiography
CT Scan
MRI
Ultrasound
Explanation - CT provides high spatial resolution and excellent bone detail, making it ideal for small fractures.
Correct answer is: CT Scan
Q.38 What does 'kW' refer to in the context of a CT scanner?
Kilowatts, the power of the X‑ray tube
Kilowatts, the cooling capacity
Kilowatt‑seconds, total energy
Kilowatts, the RF power
Explanation - kW indicates the electrical power consumed by the X‑ray tube during operation.
Correct answer is: Kilowatts, the power of the X‑ray tube
Q.39 Which parameter in MRI determines the length of time between successive RF pulses?
TR
TE
TI
FA
Explanation - TR (repetition time) is the interval between successive excitations in a pulse sequence.
Correct answer is: TR
Q.40 In ultrasound imaging, Doppler mode is used to:
Visualize tissue structure
Measure blood flow velocity
Detect bone fractures
Enhance contrast agent
Explanation - Doppler ultrasound shifts the frequency of returned echoes to infer flow speed and direction.
Correct answer is: Measure blood flow velocity
Q.41 Which of the following best explains the term 'partial volume effect' in MRI?
Signal averaging over multiple coils
Voxel containing multiple tissue types
Loss of signal due to motion
Effect of metal implants on signal
Explanation - When a voxel contains both high‑ and low‑contrast tissues, the resulting signal is an average, reducing contrast.
Correct answer is: Voxel containing multiple tissue types
Q.42 What is the main purpose of using a cryogenic RF coil in MRI?
Increase field strength
Reduce thermal noise
Cool the gradient coils
Enhance patient comfort
Explanation - Cooling the RF coil lowers electronic noise, improving signal‑to‑noise ratio.
Correct answer is: Reduce thermal noise
Q.43 Which imaging technique is best suited for functional brain activity mapping?
MRI
CT Scan
Ultrasound
PET
Explanation - Functional MRI (fMRI) measures changes in blood oxygenation to infer neuronal activity.
Correct answer is: MRI
Q.44 Which type of contrast agent is contraindicated in patients with severe renal impairment?
Gadolinium
Iodinated contrast
Barium sulfate
Technetium-99m
Explanation - Gadolinium can lead to nephrogenic systemic fibrosis in patients with kidney failure.
Correct answer is: Gadolinium
Q.45 What is the primary source of noise in CT images?
Beam hardening
Quantum noise from X‑ray detection
Gradient field instability
RF interference
Explanation - Statistical fluctuations in the number of detected photons cause inherent image noise.
Correct answer is: Quantum noise from X‑ray detection
Q.46 Which term describes the spatial resolution of MRI images?
Signal‑to‑noise ratio
Voxel size
Repetition time
Echo time
Explanation - Voxel size (matrix × field of view) determines how finely structures can be resolved.
Correct answer is: Voxel size
Q.47 Which imaging modality uses mechanical vibrations to produce images?
MRI
CT Scan
X‑ray
Ultrasound
Explanation - Ultrasound employs high‑frequency mechanical waves that bounce back to create an image.
Correct answer is: Ultrasound
Q.48 Which of the following is a characteristic of a 'T2‑weighted' MRI image?
Cerebrospinal fluid appears bright
Fat appears bright
Bone appears bright
Gray matter appears dark
Explanation - T2 weighting highlights fluid as high intensity, useful for detecting edema and cysts.
Correct answer is: Cerebrospinal fluid appears bright
Q.49 What is the function of a 'k‑space' in MRI?
Store raw frequency data
Define gradient strength
Control RF pulse power
Calibrate the X‑ray source
Explanation - K‑space holds the raw Fourier domain data that is transformed into an image.
Correct answer is: Store raw frequency data
Q.50 Which factor most directly affects the signal‑to‑noise ratio in an MRI scan?
Gradient coil size
RF coil sensitivity
Patient heart rate
Scanner room temperature
Explanation - Higher coil sensitivity captures more signal, improving SNR.
Correct answer is: RF coil sensitivity
Q.51 In CT, the term 'dose length product' (DLP) represents:
Total radiation dose times scan length
Total number of slices
Image contrast factor
Scanner cooling time
Explanation - DLP estimates the patient’s cumulative radiation exposure during a scan.
Correct answer is: Total radiation dose times scan length
Q.52 What is the main advantage of using a dual‑energy CT scanner?
Lower radiation dose
Increased image speed
Material differentiation capability
Reduced noise
Explanation - Dual‑energy CT acquires data at two energies to better distinguish tissues based on attenuation.
Correct answer is: Material differentiation capability
Q.53 Which artifact commonly appears in MRI due to patient motion?
Streak artifacts
Metallic artifacts
Ghosting
Beam hardening
Explanation - Ghosting shows up as repeated copies of structures offset by the motion period.
Correct answer is: Ghosting
Q.54 In PET imaging, what is the role of a 'collimator'?
Focus X‑rays
Filter gamma photons for directionality
Cool the detectors
Amplify RF signals
Explanation - The collimator blocks unwanted photons, ensuring only those traveling along specific paths reach the detectors.
Correct answer is: Filter gamma photons for directionality
Q.55 Which type of MRI contrast agent is considered 'first‑line' for vascular imaging?
Barium sulfate
Gadolinium
Technetium-99m
Fluorine-18
Explanation - Gadolinium chelates are the most common contrast agents for enhancing blood vessels in MRI.
Correct answer is: Gadolinium
Q.56 What is 'SNR' in the context of MRI?
Signal‑to‑Noise Ratio
Spin‑Nuclear Ratio
Saturation‑Noise Ratio
Signal‑Noise Rate
Explanation - SNR quantifies the clarity of an MRI image; higher values indicate better image quality.
Correct answer is: Signal‑to‑Noise Ratio
Q.57 Which of the following best describes 'beam‑splitter' in optical imaging?
Divides a laser beam into two paths
Separates X‑ray beams
Splits the ultrasound beam
Separates MRI gradients
Explanation - Beam‑splitters are used in optical imaging to direct light to multiple detectors.
Correct answer is: Divides a laser beam into two paths
Q.58 In MRI, what does 'FA' refer to?
Field Amplification
Flip Angle
Frequency Adjustment
Fat Attenuation
Explanation - FA is the angle by which the net magnetization vector is rotated by the RF pulse.
Correct answer is: Flip Angle
Q.59 What is a common source of image artifacts in CT scans involving metal implants?
Beam hardening
Doppler shift
Magnetic susceptibility
Chemical shift
Explanation - Metal strongly attenuates X‑rays, causing characteristic streaks and darkening.
Correct answer is: Beam hardening
Q.60 Which imaging technique is best for evaluating myocardial perfusion in real time?
MRI
CT Scan
Ultrasound (echocardiography)
PET
Explanation - Echocardiography can use Doppler to assess blood flow and perfusion quickly.
Correct answer is: Ultrasound (echocardiography)
Q.61 In ultrasound imaging, 'resolution' is defined by:
Beam width
Depth penetration
Frequency
Gain settings
Explanation - Higher frequencies produce finer axial resolution but reduce penetration depth.
Correct answer is: Frequency
Q.62 Which parameter is adjusted to improve T1 contrast in MRI?
TR (repetition time)
TE (echo time)
TI (inversion time)
FA (flip angle)
Explanation - Short TR emphasizes T1 differences, enhancing contrast between tissues.
Correct answer is: TR (repetition time)
Q.63 Which of the following is a benefit of using a multi‑channel RF coil?
Improved image homogeneity
Reduced scan time through parallel imaging
Lower cost
Enhanced contrast agent uptake
Explanation - Multiple coil elements allow simultaneous data acquisition, shortening scan duration.
Correct answer is: Reduced scan time through parallel imaging
Q.64 What is the most common imaging modality for diagnosing aortic dissection?
MRI
CT Angiography
X‑ray
Ultrasound
Explanation - CT angiography provides rapid, high‑resolution images of the aorta, critical for acute dissection diagnosis.
Correct answer is: CT Angiography
Q.65 Which factor primarily limits the temporal resolution of dynamic PET imaging?
Radiotracer half‑life
Scanner detector efficiency
Patient movement
X‑ray tube current
Explanation - The tracer decays quickly, limiting the time window for dynamic data acquisition.
Correct answer is: Radiotracer half‑life
Q.66 Which of the following is an example of a functional imaging modality?
CT Scan
MRI
X‑ray Radiography
Ultrasound
Explanation - Functional MRI (fMRI) assesses brain activity by detecting changes in blood oxygenation.
Correct answer is: MRI
Q.67 Which term describes the ability of a CT scanner to acquire images faster?
High resolution
High speed
High contrast
Low dose
Explanation - Fast gantry rotation speeds reduce scan time and motion artifacts.
Correct answer is: High speed
Q.68 What is the purpose of using a 'water phantom' in CT calibration?
To test bone imaging
To calibrate X‑ray beam intensity
To test acoustic properties
To calibrate magnetic field
Explanation - A water phantom simulates human tissue attenuation for dose and image quality checks.
Correct answer is: To calibrate X‑ray beam intensity
Q.69 In MRI, what does the term 'slice prescription' refer to?
Direction and orientation of the slice
Thickness of the slice
Number of slices acquired
Temporal resolution of the scan
Explanation - Slice prescription sets the plane (axial, coronal, sagittal) for image acquisition.
Correct answer is: Direction and orientation of the slice
Q.70 Which of the following is a common limitation of using ultrasound for deep organ imaging?
Beam hardening
Limited depth penetration
High radiation dose
Magnetic field interference
Explanation - Ultrasound signals attenuate with depth, making it difficult to image deep structures.
Correct answer is: Limited depth penetration
Q.71 Which type of imaging uses a 'photon counting detector'?
CT
MRI
PET
Ultrasound
Explanation - Photon counting detectors in modern CT scanners improve contrast and reduce dose.
Correct answer is: CT
Q.72 Which MRI sequence is best for visualizing brain white matter integrity?
T1‑weighted
T2‑weighted
Diffusion Tensor Imaging (DTI)
FLAIR
Explanation - DTI maps water diffusion along white matter tracts, revealing structural connectivity.
Correct answer is: Diffusion Tensor Imaging (DTI)
Q.73 Which factor is NOT typically adjustable in an MRI scanner?
Magnetic field strength
RF pulse frequency
X‑ray tube voltage
Gradient amplitude
Explanation - MRI does not use X‑rays; only magnetic fields, RF pulses, and gradients are involved.
Correct answer is: X‑ray tube voltage
Q.74 Which imaging modality is most effective for detecting liver metastases?
X‑ray Radiography
CT Scan
Ultrasound
PET
Explanation - PET with FDG highlights metabolically active tumor lesions in the liver.
Correct answer is: PET
Q.75 In CT, what is the purpose of 'iterative reconstruction'?
Increase image noise
Reduce radiation dose and improve image quality
Speed up scan time
Enhance magnetic field homogeneity
Explanation - Iterative algorithms reconstruct images from fewer projections, lowering dose.
Correct answer is: Reduce radiation dose and improve image quality
Q.76 Which of the following best describes a 'phantom' in medical imaging?
A patient with a known disease
A test object used for calibration
A type of contrast agent
A software model of a body part
Explanation - Phantoms are standardized objects mimicking tissue properties for testing imaging systems.
Correct answer is: A test object used for calibration
Q.77 What is the main advantage of using a 'dual‑coil' system in MRI?
Improved magnetic field strength
Enhanced image homogeneity
Faster scan times via parallel imaging
Reduced noise in X‑ray images
Explanation - Two coils capture data simultaneously, enabling parallel imaging techniques.
Correct answer is: Faster scan times via parallel imaging
Q.78 Which imaging modality uses 'echo planar imaging' (EPI) for rapid acquisition?
MRI
CT Scan
X‑ray
PET
Explanation - EPI is a fast MRI technique that acquires entire images in a single echo.
Correct answer is: MRI
Q.79 In PET imaging, what is the term for the time delay between positron emission and photon detection?
Half‑life
Time‑of‑flight
Decay constant
Annulus time
Explanation - Time‑of‑flight PET measures the arrival time difference to improve spatial resolution.
Correct answer is: Time‑of‑flight
Q.80 Which parameter is NOT a direct factor in determining the signal-to-noise ratio in MRI?
Field strength
RF coil sensitivity
Patient heart rate
Number of signal averages
Explanation - Heart rate does not directly affect MRI SNR; coil sensitivity and field strength do.
Correct answer is: Patient heart rate
Q.81 Which type of imaging is used for visualizing the micro‑vascular structure of the retina?
Fundus photography
Optical Coherence Tomography (OCT)
X‑ray Radiography
CT Scan
Explanation - OCT uses near‑infrared light to produce high‑resolution cross‑sectional images of the retina.
Correct answer is: Optical Coherence Tomography (OCT)
Q.82 In CT, increasing the pitch of the helical scan:
Reduces radiation dose
Increases scan speed
Decreases image resolution
All of the above
Explanation - Higher pitch shortens scan time and dose but can reduce resolution.
Correct answer is: All of the above
Q.83 Which of the following is NOT a typical use of functional MRI (fMRI)?
Mapping language areas
Studying motor cortex activation
Detecting bone fractures
Assessing mental tasks
Explanation - fMRI is used for brain function, not for imaging bone integrity.
Correct answer is: Detecting bone fractures
Q.84 Which of the following best describes 'magnetic susceptibility artifact' in MRI?
Image distortion due to varying tissue magnetization
Loss of signal due to patient motion
Noise from X‑ray detection
Beam hardening artifact
Explanation - Different magnetic susceptibilities cause local field inhomogeneities, leading to artifacts.
Correct answer is: Image distortion due to varying tissue magnetization
Q.85 Which imaging modality provides the highest spatial resolution for bone imaging?
X‑ray Radiography
CT Scan
MRI
Ultrasound
Explanation - CT offers fine spatial resolution and excellent bone contrast.
Correct answer is: CT Scan
Q.86 In MRI, what does the abbreviation 'SWI' stand for?
Signal‑Weighted Imaging
Susceptibility‑Weighted Imaging
Spectral Wave Imaging
Signal‑Wave Intensity
Explanation - SWI uses phase information to highlight susceptibility differences, useful for detecting microbleeds.
Correct answer is: Susceptibility‑Weighted Imaging
Q.87 What is the primary advantage of using a 'biplanar' X‑ray system?
Two simultaneous views reduce radiation dose
Improves depth perception during imaging
Allows for 3D reconstruction
All of the above
Explanation - Biplanar systems provide two orthogonal images, aiding depth perception and 3D reconstruction.
Correct answer is: All of the above
Q.88 Which of the following is a key parameter controlling the depth of penetration for MRI?
Gradient strength
RF coil size
Field strength
Transducer frequency
Explanation - Higher field strengths increase signal but can limit depth penetration due to increased energy requirements.
Correct answer is: Field strength
Q.89 In PET, what does the term 'dead time' refer to?
Time the scanner is offline
Time during which the detector cannot record events
Time the patient remains still
Time for image reconstruction
Explanation - Dead time limits counting rates, affecting image quality and quantification.
Correct answer is: Time during which the detector cannot record events
Q.90 Which of the following is NOT a type of ultrasound contrast agent?
Microbubbles
Gadolinum
Gold nanoparticles
Liposomes
Explanation - Gadolinum is used in MRI; ultrasound contrast agents are typically microbubbles or nanoparticles.
Correct answer is: Gadolinum
Q.91 What is the purpose of the 'reconstruction kernel' in CT?
To adjust beam energy
To filter raw data for image sharpness
To control patient positioning
To cool the detector
Explanation - The reconstruction kernel determines edge enhancement vs. noise suppression.
Correct answer is: To filter raw data for image sharpness
Q.92 Which imaging modality uses 'magnetic field gradient switching' for spatial encoding?
MRI
CT Scan
X‑ray
Ultrasound
Explanation - Gradient coils in MRI provide spatial encoding by varying the magnetic field linearly.
Correct answer is: MRI
Q.93 Which parameter in MRI is primarily responsible for determining the signal decay due to spin‑spin relaxation?
T1
T2
TR
TE
Explanation - T2 relaxation describes the decay of transverse magnetization due to spin‑spin interactions.
Correct answer is: T2
Q.94 In CT, the term 'dose modulation' refers to:
Adjusting X‑ray dose based on patient size
Increasing radiation dose for better images
Modulating the scan speed
Changing the gradient field
Explanation - Dose modulation tailors the X‑ray output to reduce radiation exposure while maintaining image quality.
Correct answer is: Adjusting X‑ray dose based on patient size
Q.95 Which of the following is an example of a 'contrast‑enhanced' MRI study?
T1‑weighted without gadolinium
T2‑weighted with gadolinium
FLAIR with iodine
Diffusion imaging with contrast
Explanation - Adding gadolinium to a T2 sequence enhances vascular and pathological tissues.
Correct answer is: T2‑weighted with gadolinium
Q.96 Which factor is most important for minimizing 'streak artifacts' from metal implants in CT?
Increasing kVp
Using a lower mAs
Applying metal artifact reduction algorithms
Decreasing slice thickness
Explanation - Special reconstruction algorithms can significantly reduce streak artifacts.
Correct answer is: Applying metal artifact reduction algorithms
Q.97 What is the main advantage of using 'phase‑contrast' MRI?
Imaging of static tissues
Measuring blood flow velocity
Detecting bone microfractures
Enhancing contrast agent distribution
Explanation - Phase‑contrast MRI encodes motion-induced phase shifts to quantify flow.
Correct answer is: Measuring blood flow velocity
Q.98 Which imaging modality is best suited for imaging the gastrointestinal tract?
MRI
CT Scan
X‑ray Radiography
Ultrasound
Explanation - CT provides rapid, high‑resolution images of the GI tract and can detect complications.
Correct answer is: CT Scan
Q.99 Which of the following best describes 'contrast‑enhanced CT'?
CT without any contrast agent
CT using iodine‑based contrast
CT using gadolinium contrast
CT using ultrasound waves
Explanation - Iodinated contrast enhances vascular and soft‑tissue structures in CT.
Correct answer is: CT using iodine‑based contrast
Q.100 In MRI, what does 'echo train length' (ETL) control?
The number of echoes per TR
The spatial resolution
The field strength
The duration of the RF pulse
Explanation - ETL determines how many echoes are captured before the next repetition.
Correct answer is: The number of echoes per TR
Q.101 Which imaging modality is most suitable for diagnosing soft‑tissue tumors in the brain?
X‑ray Radiography
CT Scan
MRI
PET
Explanation - MRI provides superior contrast between different soft tissues, essential for tumor evaluation.
Correct answer is: MRI
Q.102 Which of the following is a key benefit of '3D ultrasound'?
Provides volumetric data
Increases depth penetration
Reduces acoustic noise
Requires lower transducer power
Explanation - 3D ultrasound captures a volume dataset, enabling post‑acquisition manipulation.
Correct answer is: Provides volumetric data
Q.103 In CT, what does the term 'mAs' represent?
Milliampere‑seconds, controlling exposure time
Millimeter‑seconds, slice thickness
Milliampere, the X‑ray tube current
Mass‑area, patient weight factor
Explanation - mAs = current × time; it determines the total number of X‑ray photons produced.
Correct answer is: Milliampere‑seconds, controlling exposure time
Q.104 What is the most common imaging modality for detecting carotid artery stenosis?
MRI
CT Angiography
X‑ray Radiography
Ultrasound
Explanation - Carotid Doppler ultrasound is the first‑line, non‑invasive method for evaluating stenosis.
Correct answer is: Ultrasound
Q.105 Which factor most directly influences the 'signal-to-noise ratio' (SNR) in an MRI scan?
Field strength
Patient age
Radiation dose
X‑ray tube current
Explanation - Higher magnetic field strengths increase signal and improve SNR.
Correct answer is: Field strength
Q.106 Which imaging technique uses 'photon‑counting detectors' to improve image quality?
MRI
CT Scan
PET
Ultrasound
Explanation - Photon‑counting CT detectors can improve contrast-to-noise and lower dose.
Correct answer is: CT Scan
Q.107 In PET imaging, what does 'radiotracer biodistribution' refer to?
How the tracer is distributed throughout the body over time
The distribution of photons within the detector
The spatial distribution of magnetic fields
The distribution of ultrasound waves
Explanation - Biodistribution describes the pharmacokinetics of the tracer within tissues.
Correct answer is: How the tracer is distributed throughout the body over time
Q.108 Which of the following is a type of MRI sequence used specifically to suppress fat signal?
T1‑weighted
T2‑weighted
STIR (Short Tau Inversion Recovery)
DWI (Diffusion‑Weighted Imaging)
Explanation - STIR nulls fat signals, enhancing contrast for lesions in fatty tissues.
Correct answer is: STIR (Short Tau Inversion Recovery)
Q.109 Which imaging modality is used for real‑time guidance during interventional procedures such as biopsies?
MRI
CT Scan
X‑ray Fluoroscopy
PET
Explanation - Fluoroscopy provides live imaging during interventions.
Correct answer is: X‑ray Fluoroscopy
Q.110 What is the main difference between 'static' and 'dynamic' contrast‑enhanced imaging?
Static uses one image, dynamic captures a series over time
Dynamic uses a higher field strength
Static involves no contrast agent
Dynamic requires higher radiation dose
Explanation - Dynamic imaging tracks contrast kinetics by acquiring multiple frames.
Correct answer is: Static uses one image, dynamic captures a series over time
Q.111 Which of the following best describes the principle of 'Diffusion Tensor Imaging' (DTI)?
Measures the directionality of water diffusion in tissues
Visualizes bone micro‑architecture
Measures blood flow velocity
Enhances contrast in tumors
Explanation - DTI tracks diffusion anisotropy to map white‑matter tracts.
Correct answer is: Measures the directionality of water diffusion in tissues
Q.112 What is a common artifact in PET imaging caused by patient motion?
Beam hardening
Motion blur
Chemical shift
Streaking
Explanation - Movement during acquisition causes blurring of the reconstructed PET image.
Correct answer is: Motion blur
Q.113 Which type of ultrasound transducer frequency is typically used for abdominal imaging?
0.5–1 MHz
3–5 MHz
10–15 MHz
20–30 MHz
Explanation - Lower frequencies penetrate deeper, suitable for abdominal examinations.
Correct answer is: 3–5 MHz
Q.114 Which MRI parameter is most directly associated with tissue contrast in a T1‑weighted image?
Repetition time (TR)
Echo time (TE)
Flip angle
Gradient strength
Explanation - Short TR emphasizes T1 differences between tissues.
Correct answer is: Repetition time (TR)
Q.115 Which imaging modality provides the highest temporal resolution for cardiac imaging?
MRI
CT Scan
X‑ray Radiography
PET
Explanation - MRI cine sequences capture rapid heart motion with high temporal resolution.
Correct answer is: MRI
Q.116 Which of the following is a major disadvantage of PET imaging?
High spatial resolution
Low cost
Limited functional information
High radiation dose
Explanation - PET involves ionizing radiation and requires radiotracers, leading to higher dose.
Correct answer is: High radiation dose
Q.117 Which CT scanner feature reduces the impact of motion artifacts?
Higher pitch
Shorter gantry rotation time
Lower kVp
Higher slice thickness
Explanation - Faster rotation limits motion blur in the acquired data.
Correct answer is: Shorter gantry rotation time
Q.118 Which imaging modality uses 'magnetic resonance angiography' (MRA) to visualize blood vessels?
MRI
CT Scan
X‑ray Radiography
Ultrasound
Explanation - MRA is an MRI technique that visualizes vessels without ionizing radiation.
Correct answer is: MRI
Q.119 What is the primary advantage of using 'high‑field' MRI scanners?
Lower cost
Higher spatial resolution
Reduced acoustic noise
Shorter scan times
Explanation - Higher fields increase signal, allowing for finer detail imaging.
Correct answer is: Higher spatial resolution
Q.120 Which of the following best describes the 'knee joint' imaging preference?
CT for bone detail
MRI for soft tissue
X‑ray for cartilage
PET for joint inflammation
Explanation - MRI provides detailed images of ligaments, menisci, and cartilage.
Correct answer is: MRI for soft tissue
Q.121 In CT, what is the main purpose of the 'dose‑reduction' software?
To increase image noise
To adjust image brightness
To lower radiation dose while maintaining image quality
To speed up scan time
Explanation - Dose‑reduction algorithms help keep patient exposure within safe limits.
Correct answer is: To lower radiation dose while maintaining image quality
Q.122 Which imaging modality uses 'magnetic field gradients' to encode spatial information?
CT Scan
X‑ray Radiography
Ultrasound
MRI
Explanation - Gradient coils in MRI linearly vary the magnetic field, enabling spatial encoding.
Correct answer is: MRI
Q.123 Which of the following is a common application of 'dynamic contrast‑enhanced MRI' (DCE‑MRI)?
Bone fracture assessment
Evaluation of tumor vascularity
Detection of retinal micro‑bleeds
Assessing pulmonary function
Explanation - DCE‑MRI tracks how quickly contrast reaches a lesion, indicating blood supply.
Correct answer is: Evaluation of tumor vascularity
Q.124 Which imaging modality uses 'ultrasound waves' to create images?
CT Scan
X‑ray Radiography
PET
Ultrasound
Explanation - Ultrasound emits high‑frequency sound waves and records reflections to build an image.
Correct answer is: Ultrasound
Q.125 Which CT imaging technique reduces radiation exposure by using multiple lower‑dose scans?
High‑dose CT
Low‑dose CT
Iterative reconstruction
Dose‑modulated helical scanning
Explanation - Iterative reconstruction uses fewer photons and still produces acceptable images, lowering dose.
Correct answer is: Iterative reconstruction
Q.126 Which of the following is NOT a typical use of PET imaging?
Oncologic staging
Cardiac perfusion assessment
Brain metabolism mapping
Bone fracture detection
Explanation - PET is not used for diagnosing bone fractures; CT or X‑ray is preferred.
Correct answer is: Bone fracture detection
Q.127 Which imaging modality is best suited for evaluating lung parenchyma?
MRI
CT Scan
X‑ray Radiography
Ultrasound
Explanation - CT provides high‑contrast images of the lung parenchyma and airspaces.
Correct answer is: CT Scan
Q.128 Which parameter in MRI controls the duration between the start of one RF pulse and the next?
TR (repetition time)
TE (echo time)
FA (flip angle)
ETL (echo train length)
Explanation - TR is the time between successive excitation pulses in an MRI sequence.
Correct answer is: TR (repetition time)
Q.129 What is the primary disadvantage of using 'ultrasound' for imaging deep brain structures?
Limited spatial resolution
High radiation dose
Low depth penetration
Need for contrast agents
Explanation - Sound waves are heavily attenuated by skull bone, limiting deep brain imaging.
Correct answer is: Low depth penetration
Q.130 Which of the following best describes 'T1 mapping' in MRI?
Quantitative measurement of T1 relaxation times across tissue
Mapping of temperature distribution
Mapping of water content
Mapping of blood flow velocity
Explanation - T1 mapping provides pixel‑wise quantitative T1 values for tissue characterization.
Correct answer is: Quantitative measurement of T1 relaxation times across tissue
Q.131 Which imaging technique is used to assess the integrity of peripheral nerves?
MRI with neurography sequences
CT Scan
X‑ray Radiography
Ultrasound
Explanation - MRI neurography visualizes peripheral nerves using high‑resolution sequences.
Correct answer is: MRI with neurography sequences
Q.132 In CT, the term 'beam filtration' refers to:
Filtering of low‑energy photons to reduce patient dose
Filtering of high‑energy photons to sharpen image
Filtering of noise in the reconstruction
Filtering of the X‑ray beam to protect the detector
Explanation - Beam filters remove low‑energy photons that would be absorbed by tissue but contribute to dose.
Correct answer is: Filtering of low‑energy photons to reduce patient dose
Q.133 Which of the following imaging modalities uses a 'contrast‑enhanced' sequence with gadolinium to detect brain tumors?
MRI
CT Scan
X‑ray Radiography
Ultrasound
Explanation - Gadolinium‑enhanced MRI is the gold standard for tumor delineation.
Correct answer is: MRI
Q.134 Which CT parameter is directly related to the amount of radiation delivered?
kVp
mA
Scan time
All of the above
Explanation - kVp, mA, and scan time all influence total radiation dose.
Correct answer is: All of the above
Q.135 What is the primary purpose of a 'broadband' ultrasound transducer?
To focus on a single depth
To provide imaging at multiple frequencies
To reduce acoustic noise
To increase depth penetration only
Explanation - Broadband transducers can adjust frequency for different imaging needs.
Correct answer is: To provide imaging at multiple frequencies
Q.136 Which of the following best describes the term 'mip' in imaging?
Maximum intensity projection
Minimum intensity projection
Mean intensity projection
Multiple intensity projection
Explanation - MIP displays the brightest voxel along a viewing ray, useful for vascular imaging.
Correct answer is: Maximum intensity projection
Q.137 Which imaging modality is most commonly used to assess retinal blood flow?
Optical Coherence Tomography Angiography (OCTA)
MRI
CT Scan
Ultrasound
Explanation - OCTA non‑invasively visualizes retinal and choroidal vasculature with high resolution.
Correct answer is: Optical Coherence Tomography Angiography (OCTA)
Q.138 Which of the following is a common artifact seen in MRI due to patient respiration?
Ghosting
Metal streaks
Beam hardening
Chemical shift
Explanation - Respiratory motion can cause repeated copies of structures offset from the true position.
Correct answer is: Ghosting
Q.139 In PET imaging, which process is used to correct for photon attenuation?
Iterative reconstruction
Time‑of‑flight correction
CT‑based attenuation correction
All of the above
Explanation - CT provides a map of attenuation coefficients used to correct PET data.
Correct answer is: CT‑based attenuation correction
Q.140 What does the acronym 'DICOM' stand for?
Digital Imaging and Communications in Medicine
Diagnostic Imaging and Computer Output Module
Direct Imaging and Coding in Medicine
Digital Imaging and Computer Output in Medicine
Explanation - DICOM is the standard format for storing and transmitting medical images.
Correct answer is: Digital Imaging and Communications in Medicine
Q.141 Which imaging modality is most sensitive for detecting small pulmonary nodules?
CT Scan
MRI
X‑ray Radiography
Ultrasound
Explanation - High‑resolution CT detects tiny lung lesions with high sensitivity.
Correct answer is: CT Scan
Q.142 In ultrasound imaging, what is 'contrast‑enhanced' ultrasound used for?
Improving image resolution of bone
Visualizing blood flow and tumor vascularity
Enhancing acoustic attenuation
Reducing image noise
Explanation - Microbubble contrast agents enhance vascular imaging in ultrasound.
Correct answer is: Visualizing blood flow and tumor vascularity
Q.143 Which CT imaging parameter is responsible for controlling the slice thickness?
Pitch
kVp
Detector collimation
mAs
Explanation - Collimation sets the width of the X‑ray beam and thus the slice thickness.
Correct answer is: Detector collimation
Q.144 Which of the following best describes the principle of 'echo planar imaging' (EPI) in MRI?
Acquiring data in a single rapid echo train
Using high‑frequency RF pulses
Applying magnetic field gradients continuously
Capturing 3D data in a single acquisition
Explanation - EPI collects all necessary data in a single, fast sequence, ideal for functional imaging.
Correct answer is: Acquiring data in a single rapid echo train
Q.145 Which of the following is NOT a typical use of MRI spectroscopy?
Measuring metabolite concentrations
Mapping functional activity
Assessing tumor biochemistry
Evaluating lipid composition
Explanation - MR spectroscopy provides chemical information, not functional brain activity mapping.
Correct answer is: Mapping functional activity
Q.146 Which CT imaging technique uses a low‑kVp setting to improve soft‑tissue contrast?
Low‑dose CT
High‑contrast CT
Low‑kVp CT
Standard CT
Explanation - Lower kVp increases contrast between iodine‑enhanced blood vessels and surrounding tissues.
Correct answer is: Low‑kVp CT
Q.147 Which imaging modality is best suited for real‑time monitoring of fetal cardiac activity?
MRI
CT Scan
Ultrasound
PET
Explanation - Real‑time Doppler ultrasound is the gold standard for fetal cardiac monitoring.
Correct answer is: Ultrasound
Q.148 In PET, the term 'standard uptake value' (SUV) refers to:
The amount of tracer uptake per unit volume
The total body dose of radiation
The speed of photon arrival
The number of detected events
Explanation - SUV normalizes tracer uptake to injected dose and body weight, enabling lesion comparison.
Correct answer is: The amount of tracer uptake per unit volume
Q.149 Which imaging modality is preferred for detecting acute kidney injury due to contrast media?
CT Scan
MRI
X‑ray Radiography
Ultrasound
Explanation - Ultrasound can assess kidney size and perfusion without additional contrast.
Correct answer is: Ultrasound
Q.150 Which CT scanning mode is best for reducing motion artifacts in cardiac imaging?
Retrospective ECG‑gated
Prospective ECG‑triggered
Continuous acquisition
Static scan
Explanation - Prospective gating acquires data only at a specific cardiac phase, minimizing motion.
Correct answer is: Prospective ECG‑triggered
Q.151 Which MRI parameter is most influenced by the presence of fat in tissues?
T1 relaxation time
T2 relaxation time
TR
TE
Explanation - Fat has a short T1, causing bright signals on T1‑weighted images.
Correct answer is: T1 relaxation time
Q.152 Which of the following is a primary benefit of using 'real‑time' MRI for guiding interventions?
Increased radiation dose
Live visualization of moving organs
Lower cost than CT
Higher temporal resolution than ultrasound
Explanation - Real‑time MRI allows surgeons to see dynamic structures during procedures.
Correct answer is: Live visualization of moving organs
Q.153 Which imaging modality uses 'X‑ray photons' to generate images?
MRI
CT Scan
Ultrasound
PET
Explanation - CT utilizes X‑ray photons to create cross‑sectional images.
Correct answer is: CT Scan
Q.154 Which of the following best describes the function of a 'bloom filter' in CT reconstruction?
Reduces noise by smoothing data
Removes high‑frequency components
Sharpens edges
Prevents blooming artifacts from metal
Explanation - Bloom filter algorithms mitigate metal‑related blooming in CT images.
Correct answer is: Prevents blooming artifacts from metal
Q.155 Which imaging modality provides the best spatial resolution for bone imaging?
X‑ray Radiography
CT Scan
MRI
Ultrasound
Explanation - CT offers high‑resolution bone imaging with excellent contrast.
Correct answer is: CT Scan
Q.156 Which parameter in MRI determines how rapidly the magnetization returns to equilibrium along the longitudinal axis?
T1
T2
TR
TE
Explanation - T1 relaxation describes longitudinal recovery after RF excitation.
Correct answer is: T1
Q.157 Which imaging modality uses 'beam‑hardening corrections' to improve image quality?
MRI
CT Scan
X‑ray Radiography
Ultrasound
Explanation - Beam‑hardening corrections mitigate artifacts caused by X‑ray attenuation differences.
Correct answer is: CT Scan
Q.158 What is the primary advantage of using 'parallel imaging' in MRI?
Reduces scan time
Increases field strength
Reduces patient discomfort
Reduces RF power deposition
Explanation - Parallel imaging acquires data simultaneously from multiple coils, shortening acquisition.
Correct answer is: Reduces scan time
Q.159 Which imaging modality is most commonly used to diagnose thyroid nodules?
CT Scan
Ultrasound
MRI
PET
Explanation - Thyroid ultrasound is the first‑line imaging test for nodules.
Correct answer is: Ultrasound
Q.160 Which of the following imaging modalities is known for its ability to produce 'real‑time' 3D images?
MRI
CT Scan
Ultrasound
PET
Explanation - 3D ultrasound can capture volumetric data in real time, useful in obstetrics and cardiology.
Correct answer is: Ultrasound