ARRT Registry Prep - Studying Outline

Flashcards on Image Production, Radiation Safety, Procedures, and Patient Care in Radiography

ARRT Content Specifications

Specifications provided by the ARRT outlining the content covered in the certification exam.

Radtech Bootcamp (RTBC)

Radiographic Image production, Electrical Physics section

Mosby Review Textbook

A review textbook for the ARRT registry exam.

Bontrager Procedures Textbook

A textbook detailing radiographic procedures.

Anode

The positive side of the x-ray tube.

Cathode

The negative side of the x-ray tube.

Glass Envelope

Maintains the vacuum inside the x-ray tube

Tube Housing

Provides thermal insulation and electrical grounding of the x-ray tube.

Rotating Anode

Rotating anodes can withstand higher heat loads, allowing for greater x-ray production

Anode Heel Effect

The effect where x-ray beam intensity is greater on the cathode side of the tube.

Line Focus Principle

Because the angling of the anode target allows a large area for heating while maintaining a small focal spot

Heat Units Formula

mA x kVp x s x factor

Series Circuit

Circuit with components arranged in a single path, current is the same throughout.

Parallel Circuit

Circuit with components arranged in multiple paths, voltage is the same across all branches.

Ohm's Law

Voltage = Current x Resistance

Amperes

The number of electrons flowing per second

Voltage

The electrical potential difference

Resistance

Opposition to current flow

Step-down transformer

Reduces voltage and increases current to heat the filament for thermionic emission.

Step-up transformer

Increases voltage and decreases current to produce x-rays.

Rectifier

Changes alternating current to direct current

Rheostat

Controls the amount of current supplied to the filament.

Tube Current (mA)

The quantity of x-rays produced.

mAs

mA x Time

Reciprocity Law

States that the same mAs value will produce the same receptor exposure regardless of the combination of mA and time values.

Tube Potential (kVp)

The energy of the X-ray beam

15% Rule

Increasing kVp by 15% will double the exposure

SID

Source to Image Distance

Inverse Square Law

As distance increases, intensity decreases.

Automatic Exposure Control (AEC)

Located behind the patient to reduce the amount of scatter radiation reaching the image receptor.

Backup Timer

The time to terminate the exposure in case of AEC failure.

Grid

Absorbs scatter radiation to improve image contrast.

Dead man switch

Stops the x-ray exposure if the technologist fails to release the button.

Grid Cutoff

Image artifacts due to improper grid usage

Direct Square Law

States that as distance increases, mAs must increase proportionally to maintain receptor exposure.

CR

Computed Radiography

Phosphor in CR

Barium fluorohalide

CR Imaging Process

Laser scans the imaging plate, causing light emission which is converted to an electrical signal

Latent Image

Image that exists on the exposed imaging plate prior to processing

Photomultiplier

Converts light into an electrical signal

Analog to Digital Converter (ADC)

Converts analog signal to digital signal

CR Plate Erasing

Erases any residual image from the CR plate.

Ghost Error

Artifact caused by incomplete erasure of a CR plate.

Moire Pattern

Artifact caused by grid lines running parallel to the CR plate reader's scan lines.

Digital Radiography Types

Indirect and Direct

Indirect DR

Uses a scintillator to convert x-rays into light, then a photodiode converts light into an electrical signal.

Indirect TFT Method

Amorphous silicon

Direct Capture Method

Amorphous selenium

Fill Factor

Percentage of the pixel area sensitive to x-ray or light.

DEL

Direct Element

Pixel

Picture element

Number of Pixels

The matrix size effects the pixel.

Dynamic Range

The range of exposures that can be captured by a detector.

Exposure Latitude

The range of exposures that will produce an acceptable image.

Mottle

A grainy or noisy appearance on the image due to insufficient signal.

Saturation

Occurs when the detector is overwhelmed with excessive exposure, resulting in a loss of signal.

Bit Depth

The number of bits used to represent each pixel, determining the number of shades of gray available.

Quantization

The process of assigning discrete values to the continuous electrical signals from the detector.

Histogram

A graphical representation of the pixel values in an image.

Histogram Analysis

Values of Interest (VOI)

Rescaling

Corrects for over or under exposure by shifting the histogram to the appropriate brightness level.

Look-Up Table (LUT)

Applies a predetermined set of algorithms to the image to achieve the desired contrast.

Annotation

Adding text to an image

Cropping/Masking

Blacking out white areas

Stitching

Joining multiple images into one single image

Region of Interest (ROI)

A user-defined area of interest used for quantitative analysis.

Flat Fielding

Corrects for variations in detector sensitivity.

Smoothing Filter

Decreases noise

Edge Enhancement Filter

Sharpens edges

PACS

Picture Archiving and Communication System

DICOM

Digital Imaging and Communications in Medicine

EHR

Electronic Health Record

RIS

Radiology Information System

Teleradiology

allows images to be interpreted at a distant location

Radiographic Contrast

The visible difference between adjacent densities in a radiographic image.

Gray Scale

The number of shades of gray in an image.

High Contrast

An image with few shades of gray.

Low Contrast

An image with many shades of gray.

Differential Attenuation

Differential absorption of the x-ray beam as it passes through the patient.

Attenuation

Conversion of the energy of the x-ray beam into heat as it passes through the patient

Air Gap Technique

In place of a grid

Subject Contrast

Patient-related factors (size, tissue density) that influence subject contrast.

Raw Image

The uncorrected image data received from the digital receptor.

LUT

A mathematical formula used in digital imaging to reconstruct the image.

Windowing

Post-processing technique that adjusts image brightness and contrast.

Window Level

Adjusts the brightness of the image.

Window Width

Adjusts the contrast of the image.

Signal to Noise Ratio (SNR)

The ratio of the desired signal to the unwanted noise in an image.

Detective Quantum Efficiency (DQE)

A measure of how efficiently a detector converts x-ray input signal into a useful output image

Receptor Exposure

The amount of radiation striking the image receptor.

Quantum Mottle

Occurs at low mAs

Saturation

Occurs at a high exposure

EI

Exposure Indicator

Collimation

Decreasing the field size

Spatial Resolution

The ability to distinguish between small, closely spaced objects in an image.

Measured Spatial Resolution

Measured in line pairs per millimeter (lp/mm)

Beam Divergence

Divergence

MTF

What does the MTF evaluate?

Modulator Transfer Function

Evaluation of digital imaging

Distortion

A geometric distortion of the image, always increases magnification.