PACS Chp. 7

sound card

contains all circuitry for recording and reproducing sound on the PC it may be in the form of an expansion card, or it may be built into several chips found on the motherboard. ports are located externally to connect amplified speakers, headphones, microphone, and a CD player input into the computer. the sound card interprets many file types such as waveform audio (WAV) files, moving picture experts group audio layer 3 (MP3) files, and musical instrument digital interface (MIDI) files.

power supply

delivers all electricity to the PC and contains a fan to help keep the inside of the computer cool. it contains a transformer that converts the wall outlet alternating current (AC) to direct current (DC) in the voltages appropriate for each powered device. all components from the motherboard to the hard drive, get their power directly from the main supply through different colored wires that end in plastic shielded connectors. the power supplies deliver +-12 V, +-5 V, and in some machines +3.3V power supplies are rated in watts most power supplies deliver between 150 and 300 W, but some computers require a 400 W power supply. the power supply is designed to take the brunt of the force if the computer ever receives a power surge.

peripherals - scanners

devices that capture drawings or written paper documents and convert them into a digital image or document that can be edited they are used to convert an analog (film) image into a digital image. the purpose is to provide a way to compare a hard-copy image with a digital image on a PAC system

computers in the radiology department

in February 2011, the Food and Drug Administration cleared the first application for diagnostic of computer tomography (CT), magnetic resonance imaging (MRI) and nuclear medicine images on a mobile device. this software app was developed by MIM Software Inc. for Apples iPhone and iPad products. radiologists and other health care practitioners to use when a full diagnostic workstation is unavailable

the bus

is a series of connections, controllers, and chips that creates the information highway of the computer. there are several buses throughout the computer that connect the microprocessor, the system memory, and various peripherals. most modern PCs have what is called a peripheral component interconnect (PCI) bus on the motherboard to serve as the connection of information to the various adapters. other buses found within the computer are for the small computer system interface (SCSI) connections, the accelerated graphics port (AGP) for video adapters, and the universal serial bus (USB) for a variety of devices. the bus provides the connections for the information to flow within the computer.

hard drive

main repository for programs and documents on a PC made up of many hard, thin magnetic platters that are stacked one on top of the other with only enough space for a read-write head to glide over the surface of the disks the disks are spun at a fast speed by a small motor, and the read/write head glides to the area that houses the particular information needed to reads or writes as asked. the early disks had a storage capacity of 10 MB and could be accessed in approximately 80ms. in 1980 a 26MG drive was priced at $5000 the more modern disks can hold upward of 3 terabytes (TB) with an access speed of 4ms at a price of $160 in 1980 this 3TB of storage would have cost approximately $19.7 million. the price per GB of storage has drastically decreased. the drives are still the slowest part of the PC because they are both mechanical and electrical

complementary metal-oxide semiconductor (CMOS)

special type of memory chip that uses a small rechargeable or lithium battery to retain information about the PC's hardware while the computer is turned off the CMOS is also the location of the system clock that keeps track of the date and time. the system clock uses a vibrating quartz crystal to set the speed for the CPU. a single tick of the clock represents the time it takes to turn a transistor on and off. modern CPUs are measured in gigahertz, a PC with a 3 GHz CPU has a system clock that ticks 3 billion times per second. the CMOS chip will detect any changes in the system since the last basic system configuration and will prompt the system to install any new hardware

monitors

2 major types of monitors: 1) cathode ray tube (CRT; almost obsolete) 2) liquid crystal display (LCD; most common) 3) a third type just on the horizon is the organic light emitting diode (OLED) a basic picture element on a display is known as a *pixel*. a pixel is an individual controllable set of dot triads. a got triad is a grouping of one red dot, one green dot, and one blue dot. the number of pixels on a display is known as *resolution* the more pixels on the image, the higher the resolution of the image and the more information can be displayed. resolution can also be defined as the process of capability of distinguishing between individual parts of an image that are adjacent. pixels are arranged in a matrix, a rectangular or square table of numbers that represents the pixel intensity to be displayed on the monitor. the last 4 matrices are common in image viewing applications with the 5-, 6-, and 10-mp monitors truly only needed in digital projection radiography and mammography. a third measurement is dot pitch. *dot pitch* is the measurement of how close the dots are located to one another within a pixel; the smaller the dot pitch of a display, the finer the resolution. dot pitch may be expressed as aperture grille pitch, pixel pitch, or slot pitch depending on the monitor maker. another measurement is the refresh rate for CRT and response rate for LCD. the *refresh rate* is the measure of how fast the monitor rewrites the screen or the number of times that the image is redrawn on the display each second. the refresh rate helps control the flicker seen by the user; the higher the refresh rate, the less flicker. the response rate refers to the amount of time that it takes the crystal to go from an off state to on and vice versa. a slower response time will cause blurring during viewing of dynamic images or moving images *aspect ratio* is the ratio of the width of the monitor to the height of the monitor. most CRT monitors have an aspect ratio of 4:3; LCD monitors have a ratio of 16:9 the *viewable area* is measured diagnostically from one corner of the display to the opposite corner.

the basic output/input system

BIOS contains a simple set of instructions for the computer. the microprocessor uses the BIOS during the bootup process of the computer to help being the computer to life. the BIOS also runs the start up diagnostics on the system to make sure all of the peripherals are functioning properly. the BIOS oversees the basic functions of receiving and interpreting signals from the keyboard and interchanging information with various ports. the intermediary between the operating system (OS) and the hardware.

cathode ray tube

CRT monitors were used in the first generation of PCs and are seldom in use today. the CRT consists of a cathode and anode within a vacuum tube. the cathode boils off a cloud of electrons and then a potential difference is placed on the tube. a stream of electrons is sent across to the monitors anode, which is a sheet of glass coated with a phosphor layer. the electrons strike the phosphor on the glass causing the glass to emit a color that is determined by the intensity of the interaction and area with which the electrons interacted. electrons interact with either a red, green, or blue dot to form the color and image that is being sent from the video card signal. the electron beam starts in the upper left corner and scans across the glass from side to side and top to bottom, and once it reaches the bottom, it starts again at the top left. on average, most monitors have 350 lines to be scanned. the refresh rate is 60 to 75 Hz. this equates to 350 lines being scanned to 60 to 75 times per second. the biggest disadvantage for CRT use was energy consumption, heat production, and the sheer size and weight of the monitors. CRT could produce a very bright image and has a very fast refresh rate, which would reduce the possibility of blur in dynamic imaging

the motherboard

The largest circuit board inside the computer. It contains a variety of slots, connectors, and plugs for hooking up all the other parts of a computer. all these small components to make the computer function properly. the central processing unit (CPU), basic input/output system (BIOS), bus, memory, ports, and complementary metal oxide semiconductors (CMOS)

compact disk/digital versatile disk drive

a CD is a thin injection molded polycarbonate plastic disk the disk is impressed from a mold to form microscopic bumps that indicate either a 1 or a 0 to the computer. over the bumps is a reflective layer of aluminum and over that is a clear protective coat of acrylic. a CD can hold up to 74 minutes of music or approximately 780 MB of data. a DVD holds up to seven times more than the CD, which equates to about 9.4 (single-sided) to 17 GB (double sided) of data. a DVD has multiple layers of polycarbonate plastic. aluminum is used behind the inner layers, and gold is used behind the outer layers. the gold is semi reflective so that it allows the laser to penetrate through to the inner layers of plastic. 3 main types of CD/DVD drives: 1) ROM 2) the R (write once-read many) 3) RW (read and write many times) CD-ROM drives were placed into early computers most modern computers have either a CD-RW or a CD/DVD-RW with an R or RW drive, information that needs to be saved, transported, or archived can be "burned" (information written on a disk) the information is burned onto the disk, starting in the center and spiraling out to the edge of the disk. the laser burns a tiny depression (pit) into the disk to represent the data being saved. the burned disk will be a series of pits and lands, or areas that were not burned by the laser. two-sided DVDs can be burned on both sides to double the capacity of the disk

how compact disk/compact disk drives work

a CD/DVD drive is found on the front of the encasement of a computer. the drive consists of a disk tray, a motor, a read head, and possibly a write head the drive has a small door that opens horizontally, and a tray appears for the disk to be placed. after the door closes, a motor constantly varies the speed of the disk so that the portion above the read head spins at a constant speed no matter its location over the disk. the laser beam of the read head penetrates the disk and strikes the reflective layer. if the laser strikes a land area the light reflects back; if the laser strikes a pit, the light is scattered. the light reflected back is read by a light sensing diode that translates the impulses into 1s and 0s for the computer to generate into recognize data

how does the computer work?

a computer consists of input, output, and processing devices input devices are keyboards, mice, microphones, barcode readers, touch screens, and image scanners, and any of these can be found in a modern radiology department. output devices are monitors, printers, and speakers. the processing information is done in the central processing unit the computer takes data from the user and processes it using a machine language of 1s and 0s, known as *binary code*. the computer processing is performed by a series of transistors, which are switches that are either on or off if the transistor circuit is closed and current passes through, it is assigned a value of 1. if no current passes because the circuit is open, it is assigned a value of 0. transistors can be switched on and off millions of times in a second. each 1 and each 0 represents a bit. a *bit* is a single unit of data. a *byte* is made up of eight bits and is the amount of memory needed to store one alphanumeric character. because one character takes up a byte of memory, memory is generally talked about in kilobytes (KB), megabytes, gigabytes (GB), and even terabytes

peripherals - mouse

a device with 2 or sometimes 3 buttons that allow the user to move the computers cursor to activate and perform functions within the computers software. 5 types of mouse connections: 1) serial mouse: uses a standard serial connection 2) bus mouse: uses a dedicated controller card that is connected to the motherboard 3) PS/2 mouse: a special connection for mice that does not use the standard serial port 4) USB mouse: attaches to a USB port 5) Infrared mouse: uses the computers infrared port (Wireless) 3 types of mice commonly used: -mechanical: uses a hard rubber ball inside an opening on the bottom that is surrounded by sensing devices. the ball moves around based on the movement of the users hand over the mouse and triggers the sensors within the mouse to move the cursor on the screen -optical: high intensity diode that bounces light off surfaces and back to a receiver inside the mouse. the cursor is made to move by the movements of the mouse over a hard surface and by the light that is reflected back to the sensors within the mouse. - optomechanical: hybrid of mechanical and optical mouse. it uses a rubber ball that interacts with rollers that triggers the optical sensors within the mouse. light is reflected back to the sensors based on the movement of the rollers

computer

a programmable electronic device that can store, retrieve, and process data

LCD cont.

an LCD monitor has two pieces of polarized glass with a nematic liquid crystal material sandwiched between the two. this polarized glass contains a filter running the length of the glass. if light runs perpendicular to the filter, it will be absorbed, and if it is parallel, it will be let through. the lenses in polarized sunglasses are analogous to the polarized glass in an LCD monitor. Light that is reflected off of pavement or the hood of a car will most likely not be parallel with the polarized filter of the glasses and therefore will be absorbed into the sunglasses. absorption reduces the amount of light glare that will reach the wearer. light is allowed through the first layer of glass, and when a current is applied to the liquid crystal, it aligns (straightens to an extent from its twisted structure depending on the amount of current) and allows light in varying intensities through to the next layer of glass through color filters to form the colors and images seen on the display. 3 major categories of LCD display panels being used in current LCD monitors: *twisted nematic (TN) panels*, *vertical alignment (VA) panels*, and *in-plane switching (IPS) panels* TN panels are the most common and least expensive, they have been around the longest. as the current is applied, the liquid crystal molecules will twist and untwist to allow varying light intensities through to the viewer. it has a fast response rate for dynamic images, thereby reducing the chance of blur. however, the viewing angle of the display and the displays ability to produce a wide range of colors, or in our case shades of gray. A TN monitor will produce a 6-bit of color or 64 shades. a vertical alignment panel arranges the crystals in a more vertical fashion and when current is applied the molecules will tilt to a particular position, allowing certain intensities of light through. the VA panel will produce blacker blacks, can produce 10-bit images (256 shades), allow for a greater viewing angle, and function in more extreme temperature variations. the VA panel is much more expensive than the TN panel. the in-plane switching panel is very similar to the TN panel in that current is applied and the molecules twist and untwist. in the IPS panel the molecules remain in the same plane of the panel, while in the TN panel the molecules become more perpendicular to the top panel. IPS panels produces superior color reproduction and a greater viewing angle, but as with the VA panel, it is more expensive than the TN panel. all LCD monitors for viewing images use a backlight technology to make the image visible (active matrix), unlike a calculator or wrist watch (passive matrix), which does not. the early LCD monitors used a cold cathode fluorescent lamp (CCFL) to backlight the LCD screens. these were a vast improvement over the CRT (size, energy consumption, heat produced, etc.) they had several drawbacks, primarily viewing angle and brightness. LEDs (light emitting diodes) have now taken over. the LEDs will either be all white or RGB (red green blue), depending on the function of the display. most current medial displays use an LED backlight with an ISP panel. OLEDs are being used by a few manufacturers in TVs and other handheld devices. they function similarly to the LCD-LED displays but instead of having separate layers like the LCD-LED, the OLED layers are deposited on top of one another, known as *monolithic design* OLED is made up of several organic layers sandwiched between two electrodes. these layers are most often deposited onto glass as the substrate or foundation of the display panel. manufacturers are using plastics and other flexible materials as the substrate to produce panels that can be placed on curved surfaces or even in a pen. OLED displays are being used in cell phone and handheld tablets. they use an active matrix OLED, meaning that an active matrix TFT array (coupled with OLED layers, and each pixel can be independently accessed, providing greater response.

liquid crystal display (LCD)

an LCD monitor produces images by shining or reflecting light through a layer of liquid crystal and a series of color filters. in the late 1880s to early 1900s, Freiderich Reinitzer (Austrian botanist and chemist) discovered a new phase of matter that occurred when heating certain solids. German physicist, Otto Lehman, the term "liquid crystal" was coined. heating certain solids, there was a new state of matter between solid to liquid, liquid to crystal. this new state of matter had properties of both a solid and a liquid used in digital displays. Pierre Gilles de Gennes (1960s), found that there are two major phases of liquid crystal - *nematic* and *smectic* nematic phase liquid crystals display properties more closely related to a liquid and smectic more closely related to a solid. in the nematic phase, the molecules will float around like a liquid but will be arranged in order and will have a twisted structure that reflects light. in the smectic phase, the molecules are ordered in layers and are unable to freely float around in the structure.

memory

memory in the computer is used to store information currently being processed within the CPU this memory is also known as random access memory (RAM) RAM is short-term storage for open programs. the microprocessor has a small amount of memory within itself but not enough to tackle the large amounts of data being generated by high level programs. the RAM will take the data from the CPU so that the CPU can handle the processing needs of the programs that are running. the RAM is only temporary; once the computer has been turned off, the RAM is wiped clean. many different kinds (DRAM, EDO RAM, VRAM, etc.) the most modern PCs have an synchronous dynamic random access memory (SDRAM)-DDR, specifically DDR3 SDRAM (double data rate type three SDRAM) memory is measured in bytes. (4GB, 8 GB, 12 GB and so on) in 1975, the Altair 8800 came with 0.25 KB of memory at a cost of $103; 1 GB would cost approximately $432 million more modern pricing, one can purchase 4 GB of DDR3 for approximately $25, which equates to $6.25 per GB

network card

network interface card (NIC) can come either as an expansion card plugged into a slot or as part of the PC motherboard circuitry. the network card will have an RJ-45 adapter jack at the rear of the PC for the acceptance of a twisted pair wire with RJ-45 connector. this network card will enable the PC to connect to other PCs that are on the same network.

the central processing unit

not the computers PC encasement as the CPU. the central processing unit (CPU), or microprocessor, is a small chip found on the motherboard. the microprocessor is the brain of the computer. it consists of a series of transistors that are arranged to manipulate data received from the software. they are manufactured by two different companies: 1) Intel 2) Advanced Micro Devices (AMD) CPU basic tasks to read data from storage, manipulate the data, and then move the data back to storage or send it to external devices, such as monitors or printers. the microprocessor is named after its manufacturer and the speed at which it manipulates data. the first microprocessor to be placed in a computer was made is *1979* by Intel and was called the *8088* it had clock speed of a mere 4.77 MHz. the more modern Pentium 4 microprocessor has speeds upward of 3.2 to 4.2 GHz. the 8088 needed about 12 cycles to complete one basic instruction and the modern Pentium processor can complete one instruction per cycle and at a speed of 4.2 GHz, it performs 4,200,000,000 clock cycles per second.

operating system (OS)

software that controls the computer hardware and acts as a bridge between applications and the hardware. 3 major OSs in use today are: -Windows by Microsoft -Macintosh OS -UNIX/Linux 4 types of OSs: - Real time OS: used to control specific machinery, scientific instruments, and industrial systems such as digital x-ray consoles found on modern x-ray equipment. -Single-user, single task: designed so that a computer can effectively do one task for one person at a time, such as a Palm OS for the handheld personal organizer. -Single-user, multitask: designed for one user to perform multiple functions at the same time, such as the OS on a PC -Multiuser: designed to handle multiple users and multiple tasks at the same time, such as UNIX running on a large server or as a mainframe computer supporting an entire company. the OS takes over just after the computer wakes up and allows the computer to begin doing tasks. All other software runs using the OS Early OSs, such as Microsoft-Disk Operating System (MS-DOS), were command based and very difficult to use. Today most computers use what is called graphical user interface (GUI) to perform various computer functions. A GUI is a picture/icon based program, where the mouse is used to point and click on the function that needs to be performed. it has an easy to use drop-down word menus that can be selected to perform various functions. large workstations that are used to complete multiple tasks may use Windows NT, or they may use UNIX or Linux for the OS. UNIX is a robust OS. it was first developed by Bell Laboratories and was given out free to universities. it is primarily used by industry for larger server applications. Linux was derived from UNIX by a Finnish computer science student and is widely used by computer aficionados. Linux is known as open-source software; programmers can make changes in the code as long as the changes are shared with others. all digital medical imaging devices have some sort of OS running behind the user interface. Most modern PACS use a Windows based platform, but some may still use UNIX on their large servers because of its exceptional multitasking capabilities

peripherals - speakers

speakers receive sound data from a sound card that is either built into the motherboard or is an expansion card. the sounds data are converted from an electrical signal to a series of vibrations in the speaker to create sound. they give audible signals from the software to alert us to various tasks

the case

the computer encasement is made from a sturdy metal and has two major functions: 1) to hold all of the components in a relatively cool, clean, and safe environment 2) to shield the outside environment from the radio frequencies being emitted by the electronic components of the computer two major configurations: *desktop* and the *tower* the desktop model is generally positioned in a horizontal encasement, whereas a tower model is in a vertical encasement. desktop models are placed on the desk underneath the monitor. the tower model is generally placed underneath the desk within arm's reach of the operator. the biggest disadvantages of the desktop model are: 1) the space it takes up on the desk 2) having less room for expansion and upgrades because of the smaller encasement. the tower model provides adequate room for the expansion of components, and it is easily placed out of the way and off the work surface

ports

the computers ports are a collection of connectors sticking out of the back of the PC that link adapter cards, drives, printers, scanners, keyboards, mice, and other peripherals that may be used. there are many types of ports such as parallel, serial, USB, integrated drive electronics (IDE), and SCSI a parallel port is a 25-pin connector. the parallel port was synonymous with a printer port because it was most often used for that purpose prior to the widespread use of the USB connection. it could send 8 bits of data through the connection, whereas a serial port could send only 1 bit of data down a single wire. a serial port can be universally used for many of the components plugged into the computer, such as the mouse, which does not require the speed of a parallel port. most serial ports are of the 9 pin variety, but some can have up to 25-pin connectors. a USB connection is the most common wired connection used between devices today. USB port is that multiple devices may be connected into one port. in older computers there were only ports for the keyboard and the mouse, one parallel port for a printer, and one serial port for a modern. by using USB ports the user can connect up to 127 devices to one single USB port. most computers have more than one USB port available, so the possible connections are many. IDE ports can be found on the motherboard and connect the hard drive, floppy drive, and compact disk read only memory (CD-ROM) drive to the board. a series of ribbon cables runs throughout the computer to connect the IDE devices to the IDE port on the motherboard. the 5th type of port is the SCSI port. it is the fastest and most versatile way for a PC to communicate with its peripherals. a single SCSI controller can manage up to seven devices through a daisy chain connection. the most common SCSI devices are hard drives, CD-ROM drives, scanners, and printers

peripherals - keyboards

two basic types of keyboards: soft and click if there is an audible sound when the keys are depressed, it is a click keyboard. the first keyboard made by IBM were click keyboards. most modern keyboards connect using an IBM programming system 2 (PS/2) connection and connect into the back of the box. some keyboards use the USB connection because of its versatility and ease of use. keyboard makers use either infrared or radio frequency (RF) signals a signal is sent through the switch to the motherboard, where it is interpreted in the keyboard microprocessor

peripherals - microphones

used to record voice or to use voice dictation software