•AKA Light Beam Diaphragm (LBD) "It provides the radiographer with an easy to use accurate method of controlling the size of the X-ray field and placing it over the area of interest, thus reducing the radiation dose to the patient and improving the quality of the image. •It is vulnerable to knocks often resulting in inaccuracy of the light beam/X-ray beam coincidence blown light bulbs, electrical and mechanical problems.

collimator

TRUE OR FALSE COLLIMATOR -Visual inspection •Accuracy of scales •Change a light bullo •Light beam/x-ray beam alignment and centering • Lead shutter efficiency

true

TRUE OR FALSE VISUAL INSPECTION -Rotation - Stability -Knobs for shutter control -Accuracy of shutter setting scales (if present) -Shutter chain drive •Shutters •Housing -Window -Light timer -Timer switch -Cables -Plugs -Light bulb -Light/ x-ray beam alignment

true

Frequency of collimator

every 6 months

TRUE OR FALSE Method collimators -Set 100 cm focus to tabletop distance -Using the 100cm FFD (SID) scale on the collimator, set various aperture sizes with the light on and measure the resultant light areas at table top level. "Compare with settings on the collimator. •Evaluation •Light area measured should be the same as the setting on collimator •Action •If settings are not accurate and the solution is not a simple one, call an X-ray engineer "File a report

true

Frequency of changing a light bulb

as necessary

Frequency of light beam or xray beam alignment test

6 months or as necessary

TRUE OR FALSE LIGHT BEAM/X-RAY BEAM ALIGNMENT TEST The purpose of the light in a collimator is to allow more accurate collimation of the X-ray beam. The light must, therefore, coincide with the X-ray beam. The light beam relies on the accurate positioning of the light bulb and angled mirror inside the collimator. Frequency: every 6 months or as necessary •Equipment required One 24 x 30 cm loaded cassette. Alignment test tool. Commercially made test tools are available, but a simple alternative is to use eight coins or four paper clips Lead marker or ninth coin

true

Closing the shutters in the collimator fully should prevent any radiation from reaching the film. Useful for testing radiation safety when discharging capacitor discharge mobiles or making tube warm up exposures. -Frequency: every 6 months •Equipment required: One loaded 24 x 30 cm cassette.

shutter efficiency test

Frequency of shutter efficiency test

every 6 months

Frequency of cassette inspection

yearly or as necessary

Method of cassette inspection

hinges,catches,casing,cleanliness

Frequency of light leakage test

yearly or as necessary

Frequency intensifying screen inspection

monthly

Frequency of film or screen contact test

yearly or as necessary

The purpose of the _________ is to reduce the amount of scattered radiation reaching the film. This greatly improves the quality of the image A _________ looks like a simple thin sheet of soft metal, but it is in fact a precision made piece of equipment and easily damaged It is made up of a large number of fine lead ships interspaced between radiolucent strips. If the lead strips become distorted the grid will be less efficient and irregular densities will be created on the film.

grid

Types of grid

stationary,moving,parallel line

• A loose grid which can be placed directly over the face of the cassette. • The grid and cassette size must be the same. • The grid ratio is usually 6: 1 or 8: 1. • Cassettes are available with a built in, or added, grid.

stationary grid

• Two sets of lead strips superimposed and running at 90 degrees to one another. • Generally a stationary grid, used only for relatively high kV work and when no tube angulation is necessary. • This design is used only in stationary grids.

cross hatch

• A grid used in a potter bucky system, which moves from side to side during the X-ray exposure, in order to defuse out the images of the lead strips. • The grid ratio is usually 10: 1 or 12: 1. • The grid ratio should be 16: 1 if used for high kV work.

moving grid

Moving grid ratio usually

10:1 or 12:1

Stationary grid ratio usually

6:1 or 8:1

• Lead strips run parallel to one another in one direction only. • There are two types of parallel line grid, focused and non-focused. • Moving and stationary grids are all of parallel construction.

parallel line grids

• A parallel line grid. • Relationship of lead strips uniform to one another throughout.

non focused

• A parallel line grid. • Differs from the non focused grid only in that the lead strips progressively incline more inward, the further they are from the centre line, so that they are focused to a predetermined point above the grid.

focused

The ratio of the height of the lead strips to the distance between them.

grid ratio

The number of lead strips in a grid. Stated as the number of lead strips to the centimetre (or to the inch).

grid line

Grids are designed to be used within given focus film distances {source image distances} dependent on the way the lead strips have been focused.

focal range

The direction in which the grid lines travel is indicated by a line down the center of the grid on the tube side. Crosshatch grids have a second line running at _______ to the first.

90 degrees

Frequency of grid damage test

6 months or as necessary

A viewing box, or light box, is a simple but important aid to viewing radiographs and is commonly used throughout X-ray departments. It consists of an even light source of sufficient light intensity to allow optimum viewing. Viewing a radiograph under good viewing conditions is important in order to visualise the maximum amount of information.

viewing box or negatoscope

Frequency of Visual inspection of positioning pads

weekly or as necessary

Frequency of positioning pad test in xray

6 months or as necessary