Introductory Medical Radiation Science

Which of the following is a FALSE statement?

FID stands for [blank_start]Focalspot[blank_end] to [blank_start]Image[blank_end] [blank_start]Distance[blank_end]

FOD stands for [blank_start]Focal spot[blank_end] to [blank_start]Object[blank_end] [blank_start]Distance[blank_end]

OID stands for [blank_start]Object[blank_end] to [blank_start]Image[blank_end] [blank_start]Distance[blank_end]

What is this formula used for?

Label the anatomical parts of the body.

Label the anatomical planes.

Fill in the following body positions: [blank_start]erect[blank_end] standing or sitting [blank_start]decubitus[blank_end] lying down [blank_start]supine[blank_end] lying on back [blank_start]prone[blank_end] lying facedown [blank_start]lateral decubitus[blank_end] lying on one side [blank_start]right lateral[blank_end] right side touches the image plate [blank_start]left lateral[blank_end] left side touches the image plate

Label the parts of the x-ray tube.

Fill in the blanks with the appropriate terms: The [blank_start]anode[blank_end] disc has a target track made of 90% [blank_start]tungsten[blank_end] and 10% [blank_start]rhenium[blank_end]. Tungsten has a high [blank_start]melting point[blank_end] and high atomic number giving it a high [blank_start]thermal capacity[blank_end]. The addition of rhenium produces less [blank_start]roughening[blank_end]. The anode disk base is made of a [blank_start]molybdenum graphite alloy[blank_end] making it [blank_start]lightweight[blank_end] with [blank_start]good heat dissipation[blank_end]. The rotor is made of [blank_start]copper and iron[blank_end] giving it a high thermal capacity and [blank_start]conductivity[blank_end].

X-rays are produced by [blank_start]high voltage[blank_end] acceleration of electrons from a [blank_start]tungsten filament[blank_end] [blank_start]negative cathode[blank_end] (3) within a [blank_start]vacuum[blank_end], towards a [blank_start]tungsten target[blank_end] on a [blank_start]positive anode[blank_end] (4). This anode [blank_start]rotates[blank_end] to dissipate heat generated. [blank_start]Photons[blank_end] are generated through [blank_start]atom interaction[blank_end] in the anode and an [blank_start]x-ray beam[blank_end] (5) is directed towards the [blank_start]patient[blank_end].

[blank_start]Bremsstrahlung[blank_end] x-rays occur when an [blank_start]electron[blank_end] passes very near the [blank_start]nucleus[blank_end] of an atom and is slowed and deviated from the resulting [blank_start]electromagnetic interaction[blank_end]. In this process, the electron loses [blank_start]energy[blank_end] and a [blank_start]photon[blank_end] (x-ray) is emitted.

A [blank_start]characteristic[blank_end] x-ray is when a [blank_start]high energy[blank_end] electron (1) collides with an [blank_start]inner shell[blank_end] electron (2) in a tungsten [blank_start]atom[blank_end]. Both are ejected from the atom leaving a [blank_start]vacancy[blank_end] in the inner shell. This is filled by an [blank_start]outer shell[blank_end] electron (3) with a loss of energy emitted as an [blank_start]x-ray photon[blank_end] (4).

Ionising radiation is radiation that has enough enery to free an electron from an atom, creating an ion.

Match the keyword with the correct definition: [blank_start]kVp[blank_end] measure of the maximum voltage potential across an x-ray tube, responsible for acceleration of the electrons from the cathode to the anode [blank_start]mA[blank_end] determines current through filament, a measure of the total number of electrons flowing from cathode to anode [blank_start]time[blank_end] controls duration of electron flow being subjected to the voltage differential, determines duration of bombardment of anode by electrons [blank_start]mAs[blank_end] product of exposure time and x-ray tube current, becomes the Total Radiation Output

What is meant by the term resolution in medical imaging?

A lower spatial frequency (line pairs per millimetre) indicates better spatial resolution.

When an image is produced with [blank_start]few[blank_end] x-rays (i.e. [blank_start]low mAs[blank_end]) the quantum mottle will be [blank_start]higher[blank_end] than if the image was produced with [blank_start]many[blank_end] x-rays (i.e. [blank_start]high mAs[blank_end]).

The following can all be used to reduce scatter radiation: collimation, compression band, grid, air gap technique.