I.-Principle-of-Computed-Radiography

Objectives

  • Understand the history of computers.

  • Familiarize with the components of computers.

  • Gain knowledge of Computed Radiography (CR) and Digital Radiography (DR).

  • Differentiate between CR and DR.

History of Computers

  • The Abacus:

    • The earliest tool for calculation invented in ancient China.

    • Still used in some Asian regions.

  • Mechanical Calculators (17th Century):

    • Designed by Blaise Pascal and Gottfried Leibniz.

    • Used pegged wheels for basic arithmetic functions.

  • Analytical Engine (1842):

    • Designed by Charles Babbage for general calculations automatically.

  • Tabulating Machine (1890):

    • Created by Herman Hollerith to record the U.S. census data.

    • Utilized punched cards and eventually led to the founding of IBM.

  • First Electronic Digital Computer (1939):

    • Developed by John Atanasoff and Clifford Berry.

    • Colossus:

      • Built in December 1943 in Britain, the first operational working computer, used for deciphering German military codes.

  • ENIAC (1946):

    • First general-purpose electronic computer.

    • Developed by J. Presper Eckert and John Mauchly at the University of Pennsylvania.

  • Transistor Invention (1948):

    • Developed by William Shockley and team, pivotal for modern computing.

  • Modern Computers:

    • Identified with PC configurations as desktops, laptops, and tablets.

    • Transition from analog to digital technologies.

    • Binary digit: A bit is a single unit of data; 8 bits in a byte.

Evolution Timeline of Computers

  • 1835: Ada Byron - Punch cards in Babbage "engine."

  • 1642: Blaise Pascal - First mechanical adding machine.

  • 1890: Herman Hollerith - Punched card tabulator for census.

  • 1946: ENIAC - First electronic general-purpose computer.

  • 1970s-Present: Personal computers and smart devices evolution.

Hardware Components
The Motherboard

  • The largest circuit board in a computer housing key components (CPU, BIOS, memory).

The CPU (Central Processing Unit)

  • The brain of the computer, responsible for processing instructions.

  • Contains transistors that manipulate data.

BIOS (Basic Input/Output System)

  • Initiates boot-up process and runs diagnostics, managing hardware communication.

Memory (RAM)

  • Stores currently processed information.

  • RAM is short-term storage for active programs.

Ports

  • Connectors for peripherals (e.g., printers, scanners).

CMOS

  • Retains hardware configuration information while computer is off, powered by a rechargeable battery.

Network Card

  • Allows for connectivity to networks; can be an expansion card or part of the motherboard.

Sound Card

  • Handles audio input and output, with ports for speakers and microphones.

Power Supply

  • Supplies electricity, converting AC from the wall to various DC voltages for components.

Hard Drive

  • Main storage for data, consists of magnetic platters.

Keyboard and Mouse

  • Input devices translating user actions into computer commands.

Monitors
CRT (Cathode Ray Tube)

  • Popular monitor type using vacuum tubes.

LCD (Liquid Crystal Display)

  • Modernized display method using liquid crystals between glass panels.

Summary of Computed Radiography

  • Definition:

    • Computed radiography uses phosphor plates for image capture, functioning in standard X-ray rooms.

  • Components:

    • CR cassettes, plates, readers, quality control workstations, and image viewing equipment.

  • Historical introduction in 1983 by Fuji Medical Systems.

  • Transformation in the 1990s with improved technology, leading to wider adoption.

Digital Radiography (DR)

  • An ongoing shift from traditional radiography (analog) to digital, enhancing workflow and image quality.

  • The introduction of Computed Radiography in 1981 marked a significant advancement.

  • CR remains the most common DR modality.

Comparison of Imaging Techniques
Conventional vs. Computed Radiography vs. Digital Radiography

  • Conventional Radiography:

    • Uses film, requires chemical processing, less flexible.

  • Computed Radiography:

    • Utilizes phosphor plates, faster processing, retains some similarities to film.

  • Digital Radiography:

    • Fully digital setup with immediate image processing, greater efficiency.

Factors Considered in Imaging Techniques

  • Cost:

    • CR is more economical than DR but may have lower image quality.

  • Efficiency:

    • DR allows for rapid image acquisition and viewing.

  • Maintenance and Portability:

    • DR requires careful handling due to costs and operational dependencies.

Computed Radiography Terms

  • IP: Imaging Plate

  • PD: Photodiode

  • PSL: Photostimulable Luminescence

  • PMT: Photomultiplier Tube

  • PSP: Photostimulable Phosphor

Imaging Process
Mechanism of CR Systems

  • Involves excitation of electrons in photostimulable phosphors and resulting emission of light upon stimulation with infrared lasers.

  • Multiple layers in an imaging plate optimize light absorption and stimulate emission, aiding in image formation.