The following statements are true when using a gamma camera with a parallel hole colimator:

Increasing hole size increases sensitivity

Increasing the number of holes decreases sensitivity

Increasing hole diameter decreases resolution

Typically the resolution is about 7mm

Typically the sensitivity is about 10%

Concerning radionuclides:

The physical half-life of Technetium- 99m is 13 hours

The energy of the principal photon emission of Technetium-99m is 140keV

Thallium-201 is produced in a generator

The half life of Krypton-81m is 13 seconds

Gallium-67 decays by isomeric transition

Concerning ultrasound

The decibel is a measure of the absolute intensity of an ultrasound beam

The direction of oscillation of the tissue is perpendicular to the direction of transmission of the resultant waveform

The amount of attenuation of an ultrasound beam is inversely proportional to its frequency

Lateral or azimuthal resolution can be improved by using focused tranducers

Intensity of an ultrasound beam can be expressed as watts/m²

Concerning CT scanning:

Noise can be reduced by narrowing slice thickness

In spiral (helical) CT a subject is moved incrementally through a continuously rotating gantry

The Hounsfield number of fat is -100 to -60

The field size is the product of the matrix size and pixel width

Spatial resolution improves as the pixel size gets smaller

Concerning MRI

The gyromagnetic ratio is constant for all materials

Precession frequency is proportional to magnetic field strength

Water has a long T2 and a short T1

A typical range for T1 is 300-2000 ms

Paramagnetic substances lengthen relaxation times of surrounding protons

The following affect the quality of the continuous spectrum of an X-ray beam:

kVp

Z (atomic number of target)

mA (tube current)

Filtration

Waveform

The following statements are true concerning Compton scatter

It is due to an interaction with "free" electrons

Scattered photons must pass in a forward direction

Probability is inversely proportional to the photon energy (E) cubed

The recoil electron may pass in any direction

Scattered photons are easily removed by filters

Double contrast examination of the upper gastro-intestinal tract

Requires a high density barium suspension, e.g. 150-200 % W/V

Requires a low viscosity barium suspension

Requires 800-1000ml of gas to adequately distend the stomach

Demonstration of the areae gastricae in the stomach is a criterion of good coating

In the supine projection, the duodenum usually overlaps the distal antrum and pylorus

Concerning intravascular contrast media

The osmolalities of all conventional ionic water-soluble media are 4-7 times the osmolality of blood

Conventional monomeric ionic contrast media have a ratio of three iodine atoms to two dissolved particles in solution

The incidence of adverse reactions to intravenous injections is about one-third of that following intra-arterial injections

Gadolinium-DPTA crosses the intact blood-brain barrier

The use of a test dose is recommended in individuals at risk of a reaction

The following statements are true concerning skull radiographs

In the 30deg fronto-occipital (Townes) view, the beam direction is angled 30deg towards the head (cephalad) relative to the baseline

In trauma, the lateral should be performed with a horizontal beam

In the 20deg occipito-frontal view, the radiographic baseline should be 20deg to the film

In the submento-vertex (SMV) view the radiographic baseline is parallel to the film

The radiographic baseline is at 90deg to the auricular line