RT202: Finals

Filament

serves as the source of electrons for x-ray production

1 to 2 cm

Filaments are small tungsten wire coils, _______ in length

Thoriated Tungsten

Withstands high heat during x-ray production

Thermionic emission

occurs when a current heats the filament

Focusing cup

focuses the space charge to a target area on the anode during exposure

Rotating target

Circular, disk-like with a beveled edge; receives electrons from the cathode

Stem

Attaches the rotating target to the rotor; usually made of copper

Rotor

Shaft-like structure primarily made of copper; serves as the rotation device for the stem and target area

Focal spot

the specific area on the focal track hit by electrons during exposure

Line-focus principle

Allows a larger area to be hit by electrons, resulting in a smaller effective focal spot projected toward the patient

Line-focus principle

Actual focal spot size is larger than the effective focal spot

Exposure timer

Determines the length of time x-rays will be produced

Mechanical timer

Simple type, like a spring-set dial

Synchronous timer

Motor-driven devices; Utilize the 60-Hertz alternating current in the United States.

Electronic timer

Most common type in radiographic equipment today; Designed with sophisticated, complex circuitry

Oscilloscope

Three-phase and capacitor discharge units do not produce the same pulsed radiation

Pulse counter device

Used for both single-phase and three-phase generators

mA/mAs meter

Indicates the total amount of electrical current passing through the x-ray tube

Automated exposure timers

Designed to assist radiographers in producing high-quality radiographs with appropriate radiation exposure to the film

Phototimer

Uses a light-sensitive device to monitor the amount of radiation reaching the image receptor

Under the grid and the film

Phototimer is located ________

between the patient and film

Ionization chambers are located in the ______

Wilhelm Konrad Roentgen

Discovered X-rays

luminescence

When x-ray photons strike certain substances, visible light is emitted, a phenomenon known as ________

Adhesive layer

Applied to the base before adding the emulsion to ensure maximum contact with the emulsion layer

Latitude

describes the range of exposures that the film can accurately capture and still produce a usable image

contrast

refers to the range of densities (from black to white) that the film can reproduce

Speed

This refers to how quickly the film responds to exposure to x-rays. Faster films require less exposure to produce an image compared to slower films

Fast films

Assigned values like 200, 300, etc

Slow films

Assigned values 50 or less

Average speed films

Typically assigned a value of 100

Film latitude

refers to the inherent characteristic of the film emulsion that allows for a moderate or acceptable range of densities to be recorded

Exposure latitude

refers specifically to the ability of selected exposure factors (such as mAs and kVp) to record an image with the appropriate range of densities on the film

Exposure latitude

ensures that the chosen exposure parameters are sufficient to achieve the desired contrast and detail in the image

Film contrast

refers to the inherent ability of the emulsion to record minute differences in density across the film

Screen film

Typically the choice for diagnostic radiology, designed to be used with intensifying screens to enhance image brightness and reduce patient exposure to radiation

Direct exposure film

Used without intensifying screens, directly exposed to x-rays

Single emulsion film

Contains emulsion on only one side of the base

Duplication film

Specifically designed for duplicating existing x-ray films

Subtraction film

Used in advanced imaging techniques like digital subtraction angiography

Mammography film

Specifically designed for mammography, optimized for breast tissue imaging

Blue sensitive film

sensitive to blue-violet light

Panchromatic

sensitive to all colors in the visible light spectrum

Orthochromatic

green-sensitive; sensitive to almost all colors in spectrum except RED

Subtraction film

Produces a copy that is the exact opposite of the original radiograph

Latent image

the invisible change in the film emulsion when exposed to x-ray photons and fluorescent light from intensifying screens

Intensifying screen

The most important component inside the cassette

Reflective layer

Made of a very thin layer of a white shiny substance, usually titanium dioxide

Phosphor layer

Converts energy from x-ray photons into visible light photons

Luminescence

The ability to give off light

Fluorescence

the emission of visible light resulting from radiation absorption

Zinc sulfide

Preferred for fluoroscopic devices due to its response to low-intensity radiation

Protective coating

Made of cellulose, forming a protective layer

Blue-sensitive film

sensitive to blue light, so an orange-red safelight avoids premature exposure

Green-sensitive film

sensitive to greenish light, requiring a darker red safelight to prevent unwanted exposure

Technique

refers to the systematic procedure used to produce high-quality radiographs

Kilovoltage

Defined as the force applied to accelerate (push) the electrons from the cathode to the anode during exposure

wave pattern

Voltage applied between the cathode and anode can be graphed as a ________

kilovoltage peak (kVp)

The highest level of energy, or crest of the waveform, represents the x-ray photon energy, referred to as the _______

Wavelength

describes one full wave pattern or cycle

Penetration

Refers to selecting a kVp adequate to produce x-ray photons with sufficient energy to pass through the part

remnant

X-ray photons must emerge as ______ radiation to strike the film

mA or mAs

primary controlling factors for film blackening

scatter

Radiation produced by Compton interactions is called ______

Scatter radiation

Exits the body traveling in many different directions and with different energies

Scatter radiation

The object being imaged becomes the source of scatter radiation

Photoelectric effect

Occurs when lower energy x-ray photons are present

Photoelectric effect

X-ray photon does not have enough energy to penetrate the body part and is absorbed by body tissue

Milliamperes

Defined as the current flow through the cathode filament during exposure

Blooming effect

An increase in tube current (mA) can cause the actual focal spot size to increase

Quality

Characteristics of and object and indicates the degree of excellence an object may exhibit

Density

Refers to the blackening on the finished radiograph

Density

Produced by the development of exposed silver halide crystals in the film emulsion

Contrast

Represents variation in density levels across the film, making anatomic detail visible

Contrast

Described as a distribution of different density values; Functions to make structural detail visible

Definition

Refers to the clarity and distinctness of the fine structural lines or borders of anatomic part

Distortion

Misrepresentation or undesired change of the size and/or shape of the anatomic part of interest

Density

the degree of the overall blackening from the metallic silver deposited in the emulsion

Densitometer

a device used to numerically determine the amount of blackness on the radiograph

Densitometer

This device is constructed to emit a constant intensity of light (incident) into an area of the film and then measure the amount of light transmitted

Base density

Is the OD inherent in the base of the film

Base density

Is due to the composition of the base and the tint added to the base to make the radiograph more pleasing to the eye

Fog density

It is described as the development of silver grains that contain no useful information

Contrast

Degree of difference between adjacent densities

Visibility of detail

refers to the fact that the radiographic image is visible to the human eye only because sufficient contrast and density exists to permit structural details to be perceived

Film contrast

Is a result of the inherent properties manufactured into the type of film and how it is radiographed

Subject contrast

The range of differences in the intensity of the x-ray beam after it has been attenuated by the subject

Subject contrast

It is dependent on kilovoltage and the amount and type of irradiated material

Scale of contrast

the number of useful visible densities or shades of gray

Contrast Media

It is used when imaging anatomic tissues that have low subject contrast

Negative Contrast Media

Type of contrast that can pass through easily; it decreases attenuation

Positive Contrast Media

Type of contrast that absorb more x-ray beam; it increases the attenuation of x-rays

Good definition

Visible lines and details; it enables radiologist to evaluate for abnormalities

Recorded detail

Actual or visible detail of the part of interest recorded on the film

Umbra

The true object recorded on the film

Penumbra

The thin blurred area around the umbra

Film graininess

Caused by the uneven distribution of silver crystals in the film emulsion

Half Value Layer

The amount of absorbing material that will reduce the intensity of the primary beam to one-half its original value

Collimators

most advanced and effective beam restriction devices, offering flexibility, precision, and improved image quality while reducing scatter radiation

Aperture diaphragms

It is the simplest of all beam restricting devices