Welcome  Logout

1. Regarding ultrasonic waves:
  True False  
The velocity in all tissues is constant.
Sound travels faster in a vacuum.
The velocity of sound through the human body is slowest through bone.
In constructive interference, the amplitude of the resulting wave is higher than the interfering waves.
Focusing improves the axial resolution at the depth of interest.
2. Beta particles:
  True False  
Are negatively charged particles.
They lack an electrical charge.
β – decay occurs in neutron deficient nuclides.
β + decay occurs in cases of neutron excess.
Are non ionizing.
3. Regarding effects of radiation:
  True False  
Skin erythema is a stochastic effect.
The higher the dose the more aggressive the cancer induced.
Irradiating any part of the body will cause the same amount of radiation induced damage.
The human skin is radioresistant.
Deterministic effects are common in medical imagine.
4. Answer true or false to the following:
  True False  
Only beta particles can cause ionization in tissue.
The range of photoelectrons in matter increases with an increase in its initial energy.
Gamma rays are produced by electron bombardment of a suitable target in a vacuum tube.
Gamma rays are usually of low energy.
Gamma decay usually follows another form of decay.
5. The ideal radiopharmaceutical:
  True False  
Produces very low energy gamma rays (<20 KeV) in order to keep the patients dose to a minimum.
Has a short effective half-live.
Would produce gamma rays with a very high HVL.
Has a photon energy between 100 & 200 keV.
Can be chemically incorporated in a number of stable compounds.
6. In mammography:
  True False  
Tungsten can be used as a target material.
Breast compression is rarely used in modern practice.
High HVL beams are used.
The mammography system aims to optimise both spatial and contrast resolution.
An air gap can be used to improve contrast resolution.
7. Resolution of an image intensifier:
  True False  
Is measured in pixels.
Is superior to conventional film.
Resolution improves by using a thicker input phosphor.
The input screen liberates electrons when stimulated by x-rays.
The output phosphor liberates light when bombarded by light photons.
8. In computed tomography:
  True False  
The CT number fat is higher than water.
Attenuation in aluminium is the reference value used to calculate the HU units of tissue.
The spatial resolution of CT is low at around 1 lp/mm.
High levels of scatter usually reach the CT detectors.
The CT number of iodinated contrast is +5000.
9. Regarding CT development:
  True False  
First generation scanners used a single detector.
The 1st generation scanners utilised a 360 spiral motion for imaging.
An electron beam bombards a ring target to generate X-rays in the 5th generation scanners.
3rd generation scanners succeeded in eliminating noise.
4th generation scanners use a complete stationary ring of receptors.
10. In diagnostic ultrasound:
  True False  
High frequency probes are used to explore deep structures.
Doppler US can only provide you with information regarding the direction of flow.
Bowel gas acts as a good acoustic window, through which the operator can visualise the retro peritoneal structures.
Curvilinear array probes provide a wider field of view “sector width” when compared to linear probes.
Contrast enhanced US utilises iodinated contrast medium.
11. Ultrasound used in medical diagnosis:
  True False  
Generates large amounts of heat in the imaged tissues.
Has an average speed in tissue of 1540 m/s.
Can cause tissue damage.
Has a frequency range of 1-20 Hz.
Can be used to measure blood velocity.
12. Regarding medical US:
  True False  
A cesium iodide crystal is used to produce diagnostic range US waves.
Setting the focus at the depth of interest will improve the resolution at this level.
The velocity of US in fat is equal to that in muscle.
High frequency probes are used in endoscopic ultrasound.
The absorption coefficient for fat is higher than water.
13. Regarding MRI:
  True False  
T2* relaxation takes a very long time which limits its practical diagnostic value.
The rephrasing pulse in usually a 180 degree one.
FLAIR stands for Fluid Attenuation Induction and Recovery.
The TR used to obtain T1W images is usually long.
T1 relaxation happens first closely followed by the initiating of T2 relaxation.
14. Regarding filters:
  True False  
Combined filters are used in mammography.
No filters are used in mammography.
Aluminium is the filtering material of choice in most typical conventional x-ray sets.
Using a filter will reduce the patient’s skin dose.
Lead is used as a filter in fluoroscopy.
15. Regarding radioactivity:
  True False  
Technetium 99m used in medical imaging is a pure beta emitter.
Molybdenum 99 gamma decays to technetium 99m.
Positron emitters are not used in medical imaging.
Taking more images using the gamma camera will significantly increase the patient’s dose.
The energy of the rays produced by technetium 99m is 140 KeV.
16. Regarding X-ray production:
  True False  
A large focal spot will produce sharper images.
Tungsten is used in both the anode and the cathode filament.
The cathode filament is heated to 200°c for it to emit electrons.
Gamma rays and x-rays are physically indistinguishable.
Oil is used to insulate the tube.
17. Increasing the Kv of the beam:
  True False  
Will make it less penetrating.
For the same receptor dose, will result in an increase in the patient’s skin dose.
Will increase the amount of scatter reaching the receptor.
Usually will necessitate a use of a grid or an air gap.
Is the mainstay of mammography.
18. Regarding regulations:
  True False  
Machine maintenance is the responsibility of the operator.
Every controlled area should be governed by a set of local rules.
If in a certain area an employee is likely to receive more than 6 mSv per year, this should be designated as a controlled area.
It is the responsibility of the employee to follow local rules and to utilize protective clothing and equipment provided by the employer.
The annual dose limit for a <18 year trainee is 6 mSv.
19. In computed tomography:
  True False  
Using bigger sized voxels will increase the spatial resolution.
Spatial resolution is greater than in plain films.
A CT of the head delivers the same dose to the patient as a typical barium enema.
Noise is reduced by reducing the tube mAs.
Multiplanar reconstructions increase the dose to the patient.
20. Regarding MR:
  True False  
The temperature inside a super conducting magnet is kept at absolute zero usually using liquid helium.
Only hydrogen protons can be imaged using MRI.
Gadolinium reduces T2 relaxation times.
The longitudinal relaxation time is always longer than the transverse relaxation time.
A short Te and a long Tr is used to produce a proton density image.

Your total score: