MOCK Flashcards
The weak nuclear force binds the nucleons together in the nucleus
False. (The strong nucleae force binds nucleons together in the nucleus)
The weak nuclear force is responsible for beta decay
True
The letter ‘A’ is used to denote atomic number
False. (The letter A is used to denote the mass number. The letter Z is used to denote atomic number.)
An alpha particle contains 2 protons and 2 neutrons
True. (An alpha particle is a helium nucleus, consisting of 2 protons and 2 neutrons)
Beta particle (B-) emission from a nucleus involves the conversion of a proton to a neutron
False. (B- emission involves the conversion of a neutron into a proton)
Technetium 99m is the main radioisotope used for imaging
True. (Its popularity arises from its ideal characteristics eg. 6hr half life)
Technetium 99m is produced in a cyclotron
False. (Tc99m is produced from Mo in a technetium generator. Fluorine-18 is produced in a cyclotron)
A typical administered activity for an isotope bone scan would be 500 becquerels
False. (It is typically much higher. Usually measured in MEGAbecquerels)
The use of a collimator increases the sensitivity of a gamma camera
False. (The use of a collimator decreases the sensitivity of a gamma camera by reducing the overall number of gamma rays that reach the detector)
Molybdenum is produced in a cyclotron
False (It is most commonly produced in nuclear reactors. Fluorine-18 is produced in a cyclotron)
Molybdenum breakthrough cannot be measured with a well counter
False. (Molybdenum breakthrough CAN be measured with a well counter)
Gallium67 is the main isotope used in lung perfusion scans
False. (Tc-99m MAA is most commonly used in lung perfusion scans)
The patient should be positioned as far away from the collimator as possible to improve extrinsic resolution
False. (The patient should be positioned AS CLOSE AS POSSIBLE to the collimator ro improve extrinsic resolution)
The collimator in a gamma camera is not used for an isotope bone scan
False. (The collimator IS used for an isotope bone scan)
A collimator improves the spatial resolution of a gamma camera
False
The use of a collimator increases the sensitivity of the gamma camera
False. (The use of a collimator decreases the sensitivty of a gamma camera)
The collimator in a gamma camera can help to reduce scatter
True. (Although it is not its main function, it does reduce scatter)
The size of the aperture of an ultrasound probe is directly related to the length of the near field
True
The speed of the ultrasound waves in bone is faster than soft tissue
True
Ultrasound is a form of electromagnetic wave
False.
In Ultrasound, The spatial pulse length (SPL) determines axial resolution
True
In ultrasound, the velocity in soft tissue is approximately 1500 ms-1
True
Sound waves can travel in a vacuum
False. (Sound waves need a medium to pass through)
Matching the acoustic impedance of two media will insure maximum reflection of the ultrasound beam
False. (BIG DIFFERENCES in acoustic impedance will result in strong reflection - impedances should be matched to allow for minimal reflection)
Typical ultrasound absorption in tissue is approximately 10dB per cm per MHz (10dB cm-1 MHz-1)
False. (It is 1dB per cm per MHz)
The thickness of the piezoelectric crystal is one quarter of the wavelength of the emitted ultrasound wave
False. (Crystal thickness is half the wavelength of the US beam)
Axial resolution is superior to lateral resolution
True
A Doppler Ultrasound transducer uses a long spatial pulse length
True. (Doppler imaging uses a longer SPL than normal u/s as this results in a narrower bandwidth)
The pulse repitition frequency (PRF) can be ignored during Doppler ultrasound
False. (PRF is critical to Doppler as it affects the ability to measure velocity)
In MRI, slice thickness is determined by the steepness of the slice selection gradient
True. (and also by the bandwidth of the RF pulse)
T1 is called the longitudinal relaxation time constant
True
In MRI, the value of T1 is independent of the magnetic field strength
False. (The value of T1 DEPENDS on magnetic field strength B0 - T2 does not)
The Mz magnetisation vector recovers fully in a time of twice the value of T1 following a 90 degree pulse
False. (The full recovery of Mz takes much longer - about 5 times the value of T1)
Quenching is a common problem in a resistive magnet scanner
False. (It is more commonly a problem in SUPERCONDUCTIVE magnet scanners)
Gradient echo sequences have better SNR than conventional Spin Echo sequences
False. (GE sequences have reduced SNR)
Fast spin echo sequences reduce scan time by not using 180 degree rephasing pulses
False. (FSE uses multiple 180 degree rephasing pulses - this allows for the acquisition of multiple echos in a shorter amount of time)
A STIR sequence is used for suppression of the signal from fat
True
The noise produced in an MRI unit is due to the vibration of the surface coils.
False. (The noise is produced due to the GRADIENT coils)
A hip replacement causes susceptibility artefact on an image
True
Mascara should be removed prior to an MR scan of the orbits or brain
True. (Many mascaras contain metallic particles that could interfere with the magnetic field)
The use of gadolinium contrast agent lengthens the T1 value of tissues
False. (Gd SHORTENS both T1 and T2 of tissues.)
T2 values for tissue are independent of the strength of B0
True.
Tissue heating from the RF pulse is more of an issue with low field strength magnets
False. (Tissue heating from the RF pulse is more of an issue with high field strength magnets)
Inversion recovery sequence cannot be used to produce a T1 weighted image
False. (In fact, IR sequence is used if strong T1 weighting is required.)
The Echo Train Length in a FSE sequence is a measure of the number of 90 degreee pulses used within the Tr time interval.
False. (The ETL is a measure of the number of 180 degree pulses and their corresponding echos.)
The projectile effect is not a safety issue with low field strength MR scanners
False. (It depends on the rate of change of the magnetic fielld, rather than field strength. Therefore low field strength magnets are just as dangerous.)
The frequency encoding step is the time limiting factor in the production of an MR image
False. (It takes very little time to do the frequency encoding. The phase encoding steps are the rate limiting factor.)
The central lines in k-space contain most of the spatial resolution information contained in the image.
False. (Image contrast resolution is determined by the central lines. Spatial resolution is determined by the peripheral lines.)
Chemical shift artefact of the second kind is seen in Spin Echo sequences.
False. (This only occurs in GE sequences)
There is a risk of patient asphyxiation with quenching of the magnet.
True
Specific Absorption Rate (SAR) can be ignored in abdominal MR scans
False. (SAR cannot be ignored.)
Half Fourier scanning improves the SNR
False. (It shortens imaging time at the expense of SNR)
Wrap around artefact can be removed by reducing the FOV
False. (FOV needs to be increased to prevent wrap around artefact.)
PET has a better spatial resolution than conventional nuclear medicine imaging
True
In PET, the main isotope used is FLuorine-18
True
Shielding requirements for PET are similar to that needed for a gamma camera installation
False. (Shielding requirements for a PET scan room are much higher)
In FDG PET imaging, uptake of the tracer is highest in metabolically inactive cells.
False. (Uptake of FDG is highest in metabollically active cells.)
The spatial resolution of a PET scanner is superior if we use Ga-68 rather than Fluorine-18
False. (F-18 typically provides better spatial resolution)
Filtered Back Projection can be used to reconstruct the image
True
Bismuth germanate is used as a scintillator in a PET scan
True. - ? not much anymore
Unlike SPECT, tissue attenuation correction is not needed in PET-CT
False. (Attenuation correction is needed in both SPECT and PET)
PET CT scanners use a half ring of detectors
False. (They use a full circular ring of detectors)
PET CT uses continuous table movement during the scan
False. (It moves a ‘block’ at a time)
Coincidence events form a line of response
True
Patient should be advised to exercise prior to a PET scan
False. (This will increase glucose metabolism in tissue)
Time of Flight technique can be used in PET-CT
True
In PET, a collimator is used to remove scattered photons
False. (PET imaging does not use a collimator)
A pulse height analyser is not used in PET imaging
False. (A PHA is used in PET imaging)
Patient dose from a PET-CT scan can be reduced by using a non-diagnostic CT scan as part of the imaging sequence
True
Caesium Iodide is the main scintillator used in PET detector elements
False. (Usually LGO or GSO)
A line of response (LOR) depicts the pathway of the positron within the tissue
False. (It depicts the pathway of the two gamma rays emitted following an annhiliation event)
Photomultiplier tubes are used in PET-CT
True
A typical patient dose in PET-CT would be 3-5 mSv
False. (Higher)
In SPECT, a dual-headed gamma camera is used
True
Technetium cannot be used in SPECT
False
Collimators are not required because of geometric considerations
False
In modern SPECT systems, tissue attenuation correction is done using an attached CT scanner
True
In Ultrasound, the length of the near field is inversely proportional to the frequency of the transducer
False. (The length of the near field is directly proportional to the frequency of the transducer)
In US, the focal plane lies within the Fraunhoffer zone
False. (It lies within the Fresnal zone)
In U/S, Time Gain Control can be switched off during abdominal imaging
False
Lateral resolution depends on pulse duration
False. (It depends on the width of the near field and the curve of the transducer surface)