Radiologic Technology Chapters 7 and 8 Review

Comprehensive practice flashcards covering radiographic equipment, Digital Radiography (CR/DR), imaging factors (mA, kV, SID), and image quality properties (contrast, resolution, distortion).

Housing

The lead lined encasement of the x-ray tube.

Vacuum

The state maintained inside the tube envelope to house the cathode and anode.

Cathode

The negative electrode of the x-ray tube.

Anode

The positive electrode of the x-ray tube.

Thermionic emission

The process of heating the filament to emit electrons.

Speed of X-rays

The speed of light, which is equivalent to $186,000\,\text{miles/sec}$.

Filters

Components that eliminate the beam of long wavelengths in order to decrease patient skin dose.

Inherent filtration

Filtration provided by the tube envelope.

Added filtration

Filtration made of aluminum or copper.

Automatic Collimator (PBL)

Also known as Positive Beam Limitation; a beam restrictor that automatically collimates the x-ray beam to the size and shape of the image receptor.

Longitudinal movement

X-ray tube movement that moves the length of the table.

Transverse movement

X-ray tube movement that moves the width of the table.

Vertical movement

X-ray tube movement that moves the tube up and down.

Cephalic

The angling of the tube toward the patient’s head.

Caudad

The angling of the tube toward the patient’s feet.

Trendelenburg

Tilting the tabletop down so the head is lower than the feet.

Autotracking

The process that synchronizes the Bucky tray and the horizontal movement of the tube.

AEC

Automatic Exposure Control; previously known as a phototimer, it sets the exposure time automatically based on patient thickness.

Bucky tray

The component that holds the image receptor or detector.

Grid

A device with lead strips separated by plastic or aluminum that absorbs scatter/secondary rays before they reach the image receptor.

Europium activated Barium fluorohalide

The phosphors found in the imaging plate of CR cassettes.

Flat Panel Detectors (FPD)

Digital receptors used in DR (Digital Radiography) located in the table top.

ADC

Analog to Digital Converter.

Fluoroscopy

A radiographic technique that produces dynamic or moving images to view physiologic events or guide device insertion.

Image Intensifier

A device in fluoroscopy used to increase the brightness of the image.

Cumulative Timer

A safety feature in fluoroscopy set to sound a buzzer at $5$ minutes.

HIS and RIS

Hospital Information Systems and Radiology Information Systems.

PACS

Picture Archive & Communication Systems.

DICOM

Digital Imaging and Communication in Medicine; a standard that allows all equipment vendors to use the same language.

EHR

Electronic Health Records; used to record patient information digitally.

Leakage radiation

X-rays that exit the tube from parts other than the intended opening; prevented by the lead housing.

Primary radiation

X-rays exiting the x-ray tube toward the patient.

Secondary/scatter radiation

X-rays that interact with atoms of the patient, causing a fogging or graying effect on the image.

Remnant (Exit) radiation

X-rays that exit the patient and reach the image receptor.

Attenuated

A term describing x-rays that are partially absorbed; bone shows increased attenuation while air shows decreased attenuation.

Radiolucent

Materials, like air, that allow x-rays to pass through easily.

Radiopaque

Materials, like bone or barium, that prevent x-rays from passing.

mA (milliamperage)

The amount of electrons passing from cathode to anode.

mAs

The product of mA multiplied by time ($mAs = mA \times \text{time}$); it controls the quantity of x-rays and receptor exposure.

kV (Kilovoltage)

The speed or energy it takes to move electrons from cathode to anode; it controls beam penetration, quantity, and quality.

Optimum kV

The specific kV needed to penetrate a body part (e.g., $28$ for Mammo, $110$ for Barium study).

SID

Source to Image Receptor Distance; standard distances are $40"$ for most exams and $72"$ for chest x-rays.

Quantum Noise

A grainy or mottled appearance caused by an underexposed image (low kV or mAs).

Window level

The control that adjusts image brightness.

Window width

The control that adjusts contrast or grayscale.

Receptor exposure

The amount of radiation striking the image receptor.

Inverse square law

States that the intensity of the beam is inversely proportional to the square of the distance.

Air Kerma

The unit of measurement for intensity or exposure of the x-ray beam ($mGy$ or $cGy$).

Contrast

The visible differences between any two areas in a radiograph; categorized as short scale (blacks and whites) or long scale (grays).

Spatial resolution

The sharpness of structural edges as recorded in the image.

Distortion

The misrepresentation of the size and shape of the image.

Elongation and Foreshortening

The two specific types of shape distortion.