Quiz #1

What are x-rays?

A type of electromagnetic radiation

What is electromagnetic radiation?

A form of energy created by the movement of electrically charged particles such as electrons

How many types of electromagnetic radiation are there?

7

What is the electromagnetic spectrum?

Radiowaves, microwaves, infrared, visible light, UV, x-rays, and gamma rays

Each type of electromagnetic radiation is characterized by what?

Wavelength and frequency

What is wavelength?

The distance between two consecutive peaks

What is frequency?

The number of waves that form in a given length of time measured in wave cycles per second or hertz (Hz)

A shorter wavelength has a _______ frequency

Higher

X-rays are characterized by a….

Shorter wavelength and a higher frequency

When the wavelength is shorter, what happens to each electrically charged particle?

They have more energy

A longer wavelength has a ______ frequency

Lower

The x-ray tube is made of what two electrodes?

Cathodes (-) and Anodes (+)

Electrons are located where and contain what?

The cathode and a negative charge

Due to the electrons’ negative charge they are pulled to where?

The positive anode (A+)

When the electrons interact with the positive anode, a large amount of energy is produced in the form of….

X-rays and heat

How much heat is produced when the electrons interact with the positive anode?

99%

How many x-rays are produced when the electrons interact with the positive anode?

1% roentgen radiation

X-rays may change ______ but always travel in a ______ path.

Direction and straight

X-rays originate from where and spread apart as they travel in straight lines, gradually moving further and further apart from one another, i.e. they begin to fan out.

A single point of origin

Where is the source of electrons to be electrically charged?

Cathode

The cathode directs electrically charged electrons toward where?

The anode (A+)

The cathode contains what?

A wire filament made of tungsten that is heated by a low-energy circuit

Electrons are released when the wire filament is

Heated

The heat does what within the atoms of the tungsten filament?

Excites electrons

The heated electrons in the wire eventually exceed their binding energy and are available to what?

Accelerate across the tube to the anode

The number of electrons that are produced depends on what?

The amount of heat applied to the filament

Tungsten has a very high melting point which is ideal for x-ray production because….

Tungsten has a high atomic number which means the atoms have a higher number of electrons to give up when charged.

Because of tungsten’s high melting point it also does what to the life of the x-ray tube?

Extends it

The anode is the target for what?

The electrically charged electrons to strike

The area that the electrons strike is known as the what?

Focal spot

The size of the focal spot determines the what of the image?

Sharpness

The smaller the focal spot the….

Sharper the image

The anode draws heat….

Away from the target

The anode can withstand temperatures as high as….

1832°

Stationary anode (dental or portable radiograph units)

Not designed to withstand high heat

Rotating anode

Designed to handle higher heat signatures and are typically found in stationary units

Blue

Focal spot on target

Purple

Anode +

Green

Electrons

Yellow

Tungsten filament

Orange

Cathode -

Maroon

Collimator

The tube stand does what?

Supports the x-ray tube

Tube stand models vary

Portable handheld units, to tabletop stands, to large stands mounted from the ceiling

What do the shutters do in the collimator?

Controls the size of the primary x-ray field

Includes a visible light source to ‘view’ the x-ray field size

Collimator

The collimator assists with what

The accurate patient positioning (technique) and safety personnel (ALARA)

Absorbs scatter radiation to improve the quality of the image

The grid

The grid is positioned where?

Between the patient and the image receptor

The grid is built into what?

Potter-Bucky diaphragm

Grid patterns may be linear or crossed but which is most common?

Crossed

The grid ratio refers to what?

The height of the lead strips in the grid compared to the space between them

Higher grid ratios are more efficient because….

They absorb more scatter

Older machines required that grids be used only when….

The tissue thickness of the area to be imaged measured at least 10 cm

Digital radiograph machines are efficient which allows for…

The use of the grid for all images taken

The Potter-Bucky diaphragm has what….

Adjustable positioning to accommodate patients of different sizes

The Potter-Bucky Diaphragm contains what?

A built in grid to absorb scatter

Where is the Potter-Bucky diaphragm located?

Under the x-ray table or vertically in a wall mounted unit

Portable Potter Bucky diaphragms require what?

A person to manually support the cassette

Control panel has what?

On/off switch, Voltage compensator/High voltage circuit (surge protector), Low-Voltage circuit, Kilovoltage peak (kVp), Miliamperage and Time selector (mAs), Exposure pedal or button, and warning light

What is the Voltage compensation/High voltage circuit?

Basically a surge protector

What is the Low-Voltage circuit?

Applies heat to tungsten filament in miliamps

What is the kilovoltage peak selector?

Acceleration

What is the miliamperage and time selector?

Number of x-rays and time of active x-ray production

The x-ray field must be always directed….

Perpendicular or 90° to the patient and the image receptor

The Source of the Image Distance (SID) should always be how far?

40 inches

The anatomy of interest must be ______ with the image receptor/table top.

Parallel

The anatomy of interest must be positioned as ______ to the tabletop as possible.

Close

What are the anatomical landmarks?

Centering, collimation, and measurement

What do you center?

The x-ray field over the middle of the area of interest

What needs to be included when collimating?

The entire area of interest so that the entire area can be properly evaluated radiographically

What do you measure?

The thickest area within the collimated field to set the machine for appropriate density and contrast

What results in artifacts on the radiograph that interfere with interpretation?

Technical errors

What errors may result in artifacts?

positioning, preparation, and measurement

Patient position artifacts

magnification, foreshortening, elongation, and artifactual changes in density and contrast

Patient preparation artifacts

Food and feces, patient motion, leashes or collars, human anatomy

Patient measurement artifacts

Using the wrong landmark, measuring patient while sitting or standing, using the technique chart incorrectly

Always remember to include what in the area of collimation?

Positioning marker

Intentional artifacts include what?

Gunshot/birdshot, splints, casts, pins, screws, plates, and microchips

Radiographic density refers to the degree of what on the x-ray?

Brightness or darkness

What changes the brightness or darkness on the x-ray?

mAs

Radiographic contrast refers the difference in what on the x-ray?

Radiographic density between two areas

What changes the radiographic density between two different areas on the x-ray?

kVp

When disease is present in an organ or tissue what does it impact?

The radiographic density and contrast, as well as the visualization of surrounding anatomical structures.

What are common abnormal findings in an x-ray?

Fluid, air/gas, enlarged organs, displaced organs

What is wrong?

Pleural effusion

What is wrong?

Enlarged heart

What is wrong?

Pyometra

What is wrong?

GDV

What is wrong?

Hepatomegaly

Red

Lungs

Green

Liver

Yellow

Stomach

Purple

Kidneys

Blue

Large Intestine

Orange

Small Intestines

Maroon

Bladder

What is the anode heel effect?

Variation of the number of x-rays i.e. intensity of the x-rays of the primary x-ray field as they diverge from the point of origin.

The number of x-rays i.e. intensity of the x-rays are greatest where?

Closest to the cathode