1. Digital Radiography: An Overview Flashcards
workhorse of radiology since 1895
Film-screen Radiography (Conventional)
Goal of Radiology Department
- Eliminate film-based imaging systems
- Introduce new technologies for the purpose of improving diagnostic interpretation and digital image management (ex. PACS and RIS)
- Reduce the radiation dose to patients (and rad tech)
filmless imaging
Digital Radiography
Digital image Acquisition Modalities
a. CR (Computed Radiography)
b. DR (Digital Radiography)
c. Digital Mammography
d. Digital Fluoroscopy for routine GI (Gastrointestinal) Fluoroscopy and Vascular imaging
e. CT (Computed Tomography)
f. MRI (Magnetic Resonance Imaging)
g. Nuclear Medicine
h. Diagnostic Medical Sonography
a computer process data collected from patients using special electronic detectors that have replaced the x-ray film cassette
Digital Radiography
filmless radiography
Digital Radiography
the detectors measure and convert x-ray attenuation data from the patient into electronic (analog) signals that are subsequently converted into digital data for processing by a computer
Digital Radiography
the result of this processing is a digital image that must be converted so that it can be viewed in a computer monitor
Digital Radiography
the displayed image can then be manipulated using a variety of digital image processing techniques to enhance the interpretation of diagnostic radiology images
Digital Radiography
also includes image and information management systems, image storage, and image and data communications
Digital Radiography
FILM-BASED RADIOGRAPHY BASIC STEPS IN IMAGE FORMATION
- X-ray pass through the patient and fall upon the film to form a latent image
- Rendered visible using chemical processing
- Displayed on a view box for viewing and interpretation by a radiologist
More exposure produces ____ blackening
more
Less exposure produces ___ blackening
less
blackening in the image
Film Density
differences in densities in the image
Film Contrast
The film, therefore, converts the radiation transmitted by the various types of tissues (tissue contrast) into ____
film contrast
refers to the collection of X-rays transmitted through the patient
Data Acquisition
first step in the production of the image
Data Acquisition
For DR, ________ are used that replaced the X-ray film cassette used in film-based radiography
special electronic (digital) detectors
Converts x-rays into light, followed immediately by the conversion of light into electrical signals
Indirect Detector
Avoids the light-electricity conversion process and convert x-rays directly into electrical signals
Direct Detector
The analog signals must then be converted into _______ for processing by a computer
digital data
is an electrical integrated circuit used to convert the analog signals such as voltages to digital or binary form consisting of 1s and 0s
Analog to Digital Converter (ADC)
the ADC send digital data for processing by a computer
Computer Data Processing
the computer uses special software to create or build up digital images using the binary number system
Computer Data Processing
HUMANS – ______ SYSTEM
DECIMAL
COMPUTERS – ______ SYSTEM
BINARY
Base 10 (10 different numbers) 0, 1, 2, 3, 4, 5, 6, 7, 8, 9,
DECIMAL SYSTEM
Base 2 (2 different numbers) 0 or 1 (Binary digits or bits)
BINARY SYSTEM
smallest unit of data in a computer
Bits
are not continuous, they are discrete units
Bits
The output of computer processing, the digital image, must first be converted into an analog signal before it can be displayed on a monitor for viewing by the observer
Image Display and Post Processing
the vast amount of images generated for the wide range of digital radiology examinations must be stored not only for retrospective analysis but also for medico-legal purposes
Image storage
Types of Image Storage
- Magnetic tapes
- Disks
- Laser optical disks (long-term storage)
- RAID (Redundant Array of Independent Disks)
use of computer communication networks to transmit images from the acquisition phase to the display/viewing and storage phase
Image and Data Communications
image transmission within hospital (Intranet)
LANs
Outside hospital/Remote locations (Internet)
WANs
used for storing/archiving and communicating images in the digital radiology department
PACS
RIS/HIS is integrated with the PACS via computer networks, using communications standards such as DICOM and HL7, for effective managements of patient information
Information Systems
Important element of image and data communications is
image compression
all the data from the original file is preserved
Lossless or Reversible Compression
removes some data from the original file and saves the image with a reduced file size
Lossy or Irreversible Compression
method which eliminate unnoticeable data
Lossy or Irreversible Compression
refers to the use of PACS and RIS and HIS to manage the vast number of images and text data produced in a digital radiology department with databases and file management software
Image and Information Management
handle essential textual information
RIS/HIS
handle images generated by the various digital imaging modalities
PACS
concept of IHE originated in
1998
IHE
Integrating the Health Care Enterprise
RSNA
Radiological Society of North America
HIMSS
Healthcare Information and Management Systems Society
developed what they refer to as Technical Framework that is based on 3 essential elements
RSNA and HIMSS
3 essential elements of Technical Framework
- Data model
- An Actor
- An integration Profile
makes use of photostimulable or storage phosphors to produce digital images using existing x-ray imaging equipment
Computed Radiography
a computer is used to process data collected by radiographic means to produce digital images of the patient
Computed Radiography
In _____, Fuji Medical Systems introduced CR Imaging System
1983
CR Imaging System examples
AGFA, KODAK, KONICA and CANNON
BASIC STEPS IN THE PRODUCTION OF A CR IMAGE
- The IP is exposed to x-rays, which causes electrons in the phosphors to move to another energy level, where they remain trapped, creating a latent image
- The plate is then taken to the CR reader/processor (digital image processor) where it is scanned by a laser beam, which causes the trapped electrons to return to their original orbit, and in the process, light emitted
- The light is collected by a light guide and sent to a photomultiplier tube (PMT). The electrical signal output from the PMT is subsequently converted into digital data
- A digital processor processes the digital data to produce a CR image that can be viewed in a monitor
- The IP exposed to a bright light to erase it (the residual latent image is removed)
- The IP can now be used again
Limited ability to image detail (spatial resolution)
CR Systems
3-5 lp/mm
CR Systems
Contrast resolution can be manipulated
CR Systems
Better DQE (converts x-ray into useful image)
CR Systems
10-15 lp/mm
Film-Screen Radiography
Contrast resolution is fixed
Film-Screen Radiography
developed to overcome the shortcomings of CR systems
Flat-Panel Digital Radiography
designed as a flat-panel, totally different in design structure and function
Flat-Panel Digital Radiography
produces are effective strategies to ensure continuous quality improvement of a product
Quality Assurance and Quality Control
In Radiology, QA/QC policies and procedures and related activities are all intended to:
i. Ensure that patients are exposed to minimum radiation using the ALARA philosophy
ii. Produce optimum image quality for diagnosis
iii. Reduce the costs of radiology operations
DR IMAGING SYSTEM MAJOR COMPONENTS:
- Data Acquisition
- Computer Data Processing
- Image Display and Post-Processing
- Image Storage
- Image and Data Communications
- Image and Information Management
not processed image
latent image
digital replacement of conventional x-ray film
Computed Radiography
reduce usage of film and solutions (consumables)
Computed Radiography
imaging plates are reusable, no need to use a film for each patient
Computed Radiography
similar to conventional because there is a processor but conventional has manual processor and is already obsolete. Automatic processor is being used today
Computed Radiography
also known as daylight processing and has imaging plate (reusable up to 10,000x and has a phosphor plate inside)
Automatic processor
advanced form of x-ray, no need of a processor
Digital Radiography
the image will automatically will be displayed on a computer
Digital Radiography
happens in a flat panel
Digital Radiography
offers the highest quality images because of the minute tissues of the breast
Digital Mammography
Digital Mammography uses ____ monitor
5k
allows us to see deep structures in real time (moving)
Digital Fluoroscopy
provide cross-sectional images, usually used for emergency situations
Computed Tomography
similar to ultrasound; does not use ionizing radiation
and forms of images of the anatomy and physiology of the body
Magnetic Resonance Imaging
uses very small of radioactive materials or radiopharmaceuticals to examine organ function and structure
Nuclear Medicine
it is the patient that is generating x-rays that will be detected by the gamma camera
Nuclear Medicine
widely used for pregnant women because It does not use ionizing radiation
Diagnostic Medical Sonography
The analog signals must then be converted into ____ data for processing by a computer
digital
to reduce storage space (costs) and decrease the image transmission time
Image compression
DQE
Detective Quantum Efficiency