Chapter 4 · MCQ Read Mode

Medical Imaging

The continuous spectrum of X-rays produced when electrons are decelerated by the target nuclei is called:

Approximately what percentage of the kinetic energy of the electrons striking the anode is converted into X-rays?

The maximum photon energy in an X-ray beam produced at 100 kVp is:

The line focus principle allows an X-ray tube to have:

The anode heel effect results in radiation intensity that is:

The principal advantage of a rotating anode over a stationary anode is:

Doubling the mAs while keeping kVp constant will:

Total filtration of at least 2.5 mm aluminium equivalent is required above 70 kVp in order to:

The half-value layer of an X-ray beam is a measure of its:

Subject contrast in a radiograph arises principally from differences in:

A grid with a ratio of 12:1 compared with one of 5:1 will:

The use of a radiographic grid becomes appropriate when the body part exceeds about:

Radiation-induced cancer is classified as which type of biological effect?

The Hounsfield unit value of water is defined as:

A region of interest on a CT image measures -100 HU. The tissue is most likely:

Increasing the window width on a CT display will:

In a third-generation CT scanner:

A concentric ring artefact on a CT image is characteristic of:

The technology that made continuous-rotation helical scanning possible is the:

Pitch in helical CT is defined as:

Compared with simple back-projection, filtered back-projection:

Iterative reconstruction is increasingly used in CT principally because it:

If the mAs is quadrupled in a CT acquisition, image noise will be:

Cupping artefact and dark streaks between two dense bones are caused by:

Assigning an intermediate Hounsfield value to a voxel that contains two different tissues is called:

The CT dose descriptor that accounts for the length of the region scanned is:

The nucleus imaged in routine clinical MRI is:

The Larmor frequency of protons in a 1.5 tesla magnet is approximately:

T1 relaxation is defined as the time taken for the longitudinal magnetisation to recover to:

A T2-weighted image is produced using:

On a T1-weighted image, cerebrospinal fluid appears:

Which sequence is used to suppress the signal from cerebrospinal fluid and reveal periventricular lesions?

The MRI sequence that detects acute cerebral infarction within minutes of onset is:

Spatial localisation in MRI is achieved by:

The central region of k-space predominantly determines the image's:

Gadolinium-based contrast agents make enhancing tissue appear bright on T1-weighted images because they:

Gadolinium contrast should be used with particular caution in patients with:

A 180 degree refocusing pulse is used in a spin echo sequence in order to:

The most serious immediate physical hazard in the MRI environment is:

The speed of sound assumed by a diagnostic ultrasound machine in soft tissue is:

An echo returns 13 microseconds after the pulse was transmitted. The reflecting interface lies at a depth of approximately:

Coupling gel is essential in ultrasound scanning because:

Increasing the transducer frequency from 3 MHz to 10 MHz will:

The backing (damping) block behind the piezoelectric element serves to:

Axial resolution in ultrasound is equal to:

Bright echoes appearing deep to a fluid-filled cyst are an example of:

Which imaging mode displays the motion of a structure along a single line against time?

The Doppler shift is zero when the angle between the ultrasound beam and the direction of blood flow is:

For accurate quantitative velocity measurement in Doppler ultrasound, the angle of insonation should be kept below:

Aliasing in pulsed-wave Doppler occurs when the Doppler shift exceeds:

Power Doppler differs from colour Doppler in that it:

The mechanical index displayed on an ultrasound machine indicates the likelihood of:

In a digital image, the number of grey levels available is determined by the:

Computed radiography uses an imaging plate made of:

In a computed radiography reader, the imaging plate is scanned by a red laser and emits:

Direct conversion digital radiography detectors use:

The principal workflow advantage of DR over CR is that DR:

Dose creep in digital radiography refers to:

Detective quantum efficiency describes how well a detector:

In digital subtraction angiography, the mask image is:

The universal standard governing the format and exchange of medical images is:

Which system holds patient scheduling, worklists and radiology reports rather than the images themselves?

A DICOM file differs from an ordinary image file in that it also contains:

A major practical benefit of PACS in a country with difficult geography such as Nepal is:

Diagnostic display monitors in a PACS must be calibrated to:

The unit of radioactivity, equal to one disintegration per second, is the:

Which radionuclide accounts for the great majority of diagnostic nuclear medicine studies?

Technetium-99m is obtained in the hospital by elution of a generator containing:

The photon energy emitted by technetium-99m is:

Which type of radiation is of no use for imaging because it is stopped within a fraction of a millimetre of tissue?

The two photons detected in PET are produced by:

PET has much higher sensitivity than SPECT principally because it:

The commonest PET radiopharmaceutical, a glucose analogue trapped inside metabolically active cells, is:

The component of a gamma camera that determines its spatial resolution and rejects photons not travelling in the required direction is the:

The scintillation crystal of a conventional gamma camera is made of:

The pulse height analyser in a gamma camera is used to:

If a radionuclide has a physical half-life of 6 hours and a biological half-life of 3 hours, its effective half-life is:

The principal advantage of hybrid PET/CT over PET alone is that the CT provides: