Digital Multimedia Medical Conference Room

By Orlando Ortiz, MD, et al

Introduction

Multimedia equipment and techniques can significantly enhance the audience's comprehension and retention of information. The modern conference center provides a comfortable environment without distractions in which the speaker can use the most effective audiovisual and telecommunications equipment. What types of equipment are appropriate? How does one incorporate LAN, WAN, satellite teleconferencing, LCD projectors, video walls, flat panel displays and so forth? This paper provides an introduction to the equipment and terminology of the multimedia conference rooms. A glossary of terms and links to additional information resources are also provided.

Fundamentals of Multimedia Presentation

The perfect conference room design is based upon the science of photometry, which measures light and the spectral sensitivity of the cones in the human eye. Luminance, the light falling on a surface, is measured in lux. The conference room typically has full ambient lighting at approximately 300 lux. With bright ambient lighting, it is essential to have projectors with a strong output. A lumen is the unit used to measure the light energy seen by the eye (one lux = 1 lumen per square meters) and is therefore also used to describe projector output. The principles of photometry dictate that the intensity of light falling on a flat surface from a point source is inversely proportional to the square of the distance from the point source. If a projector is moved twice as far from the screen, the size of the projected area on the screen will increase fourfold but intensity (as measured in lumens) will drop to one quarter. In other words, a projector with too few lumens may give a large area of projection, but the room needs to be totally dark in order to see the image.

The high spatial resolution and contrast performance needed for medical images are produced with digital cameras, projectors, LCD (Liquid Crystal Display) & CRT (Cathode Ray Tube) monitors and plasma screens. Digital images are composed of a matrix of tiny light dots in rows and columns. Each cell of this matrix is called a picture element or pixel. Highest resolution is achieved when the matrix is larger and consequently each pixel will be smaller. In order of increasing spatial resolution, video displays may be classified as VGA (Video Graphics Array): 640x480 pixels; SVGA (Super VGA): 800x600 pixels; XGA (Extended Graphics Array) 1024x768 pixels; XSGA: 1280x1024 pixels or described by less common protocols. The contrast resolution of gray scale images, which are shown in shades of black and white, depends on the range of light intensities used to display the image. In color imaging, contrast resolution measures the dynamic range. A lower ratio has washed out colors, less detail, and is not well seen with high ambient light. Contrast ratios of 400:1 are common.

The dynamic range of an acoustic system, which is the difference between background noise and the sound that the system produces at maximal output, can be expressed in units of decibels. For audio signals, the power output of the amplifiers, as measured in watts, must be strong enough to achieve intelligible decibel levels. The monophonic amplifiers that are built into the desktop projectors designed for small conference rooms typically have a 2 to 3 watts power output. Amplified sound is delivered through speakers. To reduce sound feedback, microphones are employed sparingly. VHF (Very High Frequency) or UHF (Ultra High Frequency) band systems are used with wireless microphones. Conference rooms should have appropriate sound absorbing materials to decrease echoes. Infrared/FM transmitters and receivers can assist the hearing impaired. Computers and software may control the audio equipment in large conference rooms.

Room Design and Equipment Layout

Ideally, the conference room should be initially planned for multimedia presentations rather than be retrofitted. Movable dividing walls can expand the room to accommodate larger audiences. Strategically located redundant wall or floor mounted cable connection boxes allow flexible lectern placement. The multimedia speaker's lectern is best placed off center in the front of small conference rooms, where it will not obstruct the audience's view of the projection screen. However, the speaker must be able to either see the projector screen or a lectern monitor from which an electronic pointer can be operated. The speaker should also be able to make eye contact with his/her audience.

Duplication of monitors, audio speakers, and screens permits a variety of room configurations. A significant amount of equipment is required and equipment selection should be based upon the intended functionality of the room. Careful planning and equipment selection will control expenses. The list potentially includes data/video projectors, digital cameras, touch-display panels, interactive electronic white boards, VCRs, DVD players, LCD screens, lecterns, overhead projectors, audio system, plasma screens, projection screens, 35 mm projectors, remote mouse, laser pointer, video conferencing capability, video presenters, and computer equipment. The switches that control the ambient lighting, audio system volume, and movable projection screen deployment should be placed near the speaker. Some facilities have a projection or control room that is separated from the conference room by a large glass window. These require a back room projector rather than a mid room or front room projector.

Much of the audiovisual equipment can be operated by infrared or FM remote controls. LCD projectors (see separate article in this syllabus) can be ceiling mounted and concealed within the ceiling when not in use and may be mounted upside down to minimize image distortion ("keystoning"). One should plan the layout of cables and power lines, which run under the floor, in the walls or above the ceiling, to properly connect the many pieces of equipment. Demonstrations occurring elsewhere in the institution can be seen in the conference room by local networking. ISDN lines, fiber-optic network, or other broadband lines will facilitate Internet connections to offsite computers. A chart comparing different types of broadband connection can be found at (www.zdnet.com/products/ stories/reviews/0,4161,2475136,00.html.) A typical integrated control system may comprise the following:

Equipment

Overhead Optical Projectors

Overhead optical projectors provided a solution when one only wished to project transparencies such as radiographs onto a screen. However, these systems are being replaced by the more versatile multimedia digital systems.

Slide projectors

There are various projector models. For instance Kodak Corporation (www.kodak.com) makes the Carousel, Ektagraphic and Ektapro projectors. The Kodak Ektapro system allows 2 projector presentations in which preset dissolve times softly change 35mm slides. It has a no slide - no light feature. An interface can control up to 16 projectors through a computer. If a lamp burns out, the lamp changer automatically switches to new lamp. Some manufactures make 35mm slide projectors that have digital output for use with TV monitors, LCD or video projectors. Analog to digital converters can be added if needed.

CCD Cameras

Charge Coupled Devices (CCD) cameras detect the images on opaque objects (e.g. the picture on a page) or transparencies (e.g. a radiograph) and transmit the image to monitors or through LCD projectors onto screens. CCD cameras can be connected to a LAN, WAN or the Internet (see discussion below). CCDs are also incorporated in camcorders, teleconferencing, fluoroscopic imaging, and in astronomical telescopes. A CCD may be thought of as computer chip with an array of picture elements (pixels). When a light photon strikes a CCD pixel, it creates a charge that is presented to the image chain for further processing and digital image formation. The spatial resolution of the image depends upon the matrix size and layout of the computer chips. Color may be added by the use of red, green, and blue filters. Alternatively, color may be provided by single, double or triple chip technology. The triple chip technique provides the best spatial resolution with decreased distortion. For more information, see www.gordon-instruments.com/videolec/camerasv.html. The cameras can be synchronized with voice-activated microphones for teleconferencing.

Monitors: CRT vs. LCD

LCD flat-panel monitors may be used on the conference room wall or in notebook computers. They are thinner and lighter than CRT monitors minimizing mounting and space requirements. LCD displays, unlike CRTs, are digital and so a digital-to-analog converter is not required to present computer images or other digital data. However, they are more expensive and have technical limitations. Unlike CRT tubes, which work well at multiple resolutions, they have a single optimal resolution. To display a lower resolution image on an LCD monitor, one must either use only a portion of the monitor or scale up the pixels to fill the screen, which results in a blocky look. (For more information about LCD, visit plc.cwru.edu/tutorial/enhanced/files/textbook.htm.)

Projection Screens

The choice of projection screen is determined by many factors: front vs. rear projection, ceiling mounted vs. wall mounted, portable vs. fixed installation, manual vs. electronic deployment, broad vs. narrow room shape, type of projector used, height of the projector, maintenance requirements, etc. Screen height should be approximately equal to 1/6 the distance from the screen to the last row of seats and the bottom of the screen should be a minimum of 4 feet above the audience floor, allowing the entire audience to see the screen. The Da-Lite Company (www.da-lite.com) has extensive online information and an interactive program to select the correct screen.

Aspect ratio refers to the ratio of height to width of the projected image. The aspect ratio for video is 3:4, for conventional NTSC TV signals 4:3, and for HDTV 6:9. If the aspect ratio of the screen is not appropriate for the projected image, there may be uneven light distribution on the screen. Monitors and plasma displays do not suffer this problem. Special screens, such as parabolic, polarized and rear projection screens, display the image while limiting stray light. Direct view displays, such as flat panel or plasma displays, are not affected by ambient light since they produce an image with thousands of lumens.

Interactive Boards

Interactive white boards have flat electronic panels, plasma monitors or other touch-screens that are connected to a computer. One may write or draw on the screen with a dry marker or electronic pen and then save, print, e-mail, fax, or copy the image. PowerPoint, Excel tables, Teleconferencing, web browsing real-time net chatting, or other computer applications can be integrated into the presentation with software.

Laser Pointers

While the conventional laser-pointer is still in use, computers are used to direct arrows or other shaped pointers on the screen. Using Microsoft's PowerPoint or other programs, one may create an animated presentation where the cursor is programmed to move to the area of interest. Multimedia lecterns may have mechanical controls that allow one to easily move an electronic pointer on the screen. There are radio-frequency controlled pointers that allow the speaker to move a hand held "mouse" in the air from anywhere in the room and control the electronic cursor.

POCKET PCs:

Pocket PCs allow users to connect to a wide variety of wireless accessories. Using Microsoft software, connectivity is made possible through IEEE 802.11b, Bluetooth, Cellular Digital Packet Data (CDPD), Code Division Multiple Access (CDMA) and Global System Mobile communications (GSM). Pocket PCs allow a user to open and create Microsoft word and excel documents, read electronic books, take notes, record short voice memos, and beam files using the built-in infrared port, amongst other capabilities.

Pocket PC and PowerPoint Presentation:

Using a Pocket PC may be the next step in easily transporting and giving a PowerPoint presentation. A Compact Flash or PC card adapter allows one to connect a Pocket PC to the video-input source on nearly any monitor or projector. You can even create presentations without PowerPoint. Several programs are available which will run PowerPoint presentations on the Pocket PC, many even retaining the ability to run animations.

The hardware consists of a Compact Flash card or PC card to convert a Pocket PC's video to SVGA or XVGA, short cables for connecting to a monitor or projector directly or through a standard video cable, and a remote control to navigate the presentation manually.

Users also have a choice as to how to show the presentation. Slide the Compact Flash or PC card into the PDA's slot, connect the cable to the monitor or projector, and set the resolution. You can then set the presentation to run automatically using a set amount of time per slide, or move through the slides by pressing buttons on your PDA or the remote control. This type of setup will definitely lighten the amount of equipment you will have to bring to your next presentation.

Pocket PC and Interactive Board:

There are several options currently available for connecting Pocket PC's to an Interactive Board. Once a screen capture is saved as a PDF or HTML file, it can then be transferred to a Pocket PC. PDF files are viewed using Adobe Acrobat for Pocket PC whereas HTML files are viewed using the Pocket PC Internet Explorer application. These files can be emailed to recipients or synchronized at a later time using the included USB cradle. However, this cannot be done "at the spur of the moment" or "on the fly." In order to effectively and quickly transfer this information to the Pocket PC, wireless modes of data transfer need to be employed.

The easiest and most intuitive wireless method for the Cassiopeia E-200 (or any PDA with infrared capability) is infrared transfer (IR). However, beaming IR files to a Pocket PC is time intensive and can only be done one Pocket PC at a time. For instance, it can take up to 25 seconds to beam a 140 kb PDF file. The Cassiopeia E-200 is capable of beaming files at speeds of up to 115 Kbps. Clearly, a faster method of wireless data transfer would be optimal.

The two most popular wireless methods currently available today include Wireless PDA network cards and Bluetooth. Bluetooth utilizes radio waves around the 2.4 GHz frequency and allows any Bluetooth equipped device to automatically connect with any other Bluetooth equipped device within a typical indoor range of 30 feet. A single device running Bluetooth 1.1 can connect with up to 7-8 other devices at the same time. Typical data transfer rates are slightly less than 1 Mbps. No central routing source is required, making this method quite flexible, but not necessarily super fast, and certainly not ideal for transferring large files. The cards insert into the compact flash or PC card slot on a Pocket PC and typically cost slightly less than $100.

Wireless network cards utilize 802.11b "Wi-Fi" transmission, achieving up to 11 Mbps while connected. For a Pocket PC, these cards typically run from $100-160 and insert into a compact flash or PC card slot. Although they have greater speed and range than Bluetooth, they require a central access point (i.e., wireless server or router) and may drain the Pocket PCs power faster. These also operate around 2.4 GHz.

Upcoming technology is 802.11a which is even faster and utilizes a 5 GHz frequency for improved clarity and range of transmission.

Several issues are apparent pertaining to the use of wireless devices specifically within a radiology department. The most relevant is the possibility of interference due to the (relatively) high amount of lead lining in the walls used to attenuate X-Rays. Another potential source of concern is the possibility of these devices operating at 2.4 GHz interfering with other hospital equipment such as cardiac monitoring devices.

However, for the purposes of wirelessly transferring data from the SmartBoard to a Pocket PC within the confines of a lecture hall, either of the two solutions (wireless network cards or Bluetooth) should suffice.

PEN DRIVES:

A pen drive is a mobile data storage drive. Measuring around 4 inches long, it easily fits in a shirt pocket. Its memory capacity extends from 16 MB to 2 GB at present. Data retention can be for as long as 10 years' period of time. It is a plug and play device. Simply drag and drop digital files like presentations, etc. from any computer and store them for further use. No peripheral hardware is required. Pen drives enable one to carry digital images, work projects and DVD quality movies.

LAN, WAN Hook-up

The computer in a conference room can connect with more remote computers through a LAN (Local Area Network) or WAN (Wide Area Network). These networks help the users share information as well as devices like printers, interactive boards, etc. A LAN is a group of computers and associated devices that share a common communications line and typically share the resources of a single processor or server within a small geographic area (for example, within an office building). Ethernet is the hardware and protocol that is used to connect the computers in a LAN. WAN is a communications network used to connect computers and other devices across a large area. It can be a private connection or a public network using telephone lines, satellites, local wiring, etc. If these connections are incorrectly configured data will be lost. Special care must be taken in order to accommodate the difference in speed between LAN and WAN systems.

Web Cam

Various types of cameras can be interfaced with computers so that video or still images can be transmitted across the Internet or across LANs or WANs. Live presentations are possible. Using a Web Cam requires the selection of appropriate cameras and software. A tutorial on Web Cam's is available at developers.webcamworld.com.

Computer Connectivity

Computer ports are interfaces that connect to devices. Personal computers have various types of ports. Internally, there are several ports for connecting disk drives, internal modems, notebook display screens, and notebook keyboards. Externally, personal computers have ports for connecting external modems, printers, mice, and other peripheral devices. IBM PC and compatible computers come with two serial ports for connecting a external modem, mouse, or other device and a parallel port for connecting a printer. SCSI (Small Computer System Interface) ports support higher transmission speeds than do conventional ports and enable you to attach up to seven devices to the same port. All Apple Macintosh computers since the Macintosh Plus have a SCSI port. Increasingly, computers and other devices (such as printers) come with infrared ports, which enable the transfer of data from one device to another without any cables. The two devices must be within a few feet of each other and have a clear line of sight between them. Most computers have a video with an S-video output connector and modern computers have USB port(s) to which USB compliant peripherals (such as USB compliant laser projectors) can be connected with a USB cable. (For more information see www.usb.org.) Current computers with "Plug and Play programs" automatically recognize and operate attached peripheral devices. There are docking stations, which allow specific notebook computer models to be locked down for security. These stations may have input and output ports so that the cables need not be reattached to the computer each time it is docked. An excellent source of computer information is www.compinfo.co.uk/index.htm. Computer resources links for the visually impaired are at www.acb.org/Resources/computers.html.

Component Compatibility in the Multimedia System

A single broadcast television standard is not used throughout the world. It is necessary to have the appropriate VCR or Video input or output for the monitors used in a particular region. In the US we use the NTSC standard rather than PAL or SECAM standard. A listing of the standards used in each country can be found at www.fjm-media.com/worldtv.html.

There are several methods of transmitting signals from a device such as a camcorder, VCR, or satellite system to a television monitor, plasma screen, or video projector. S-video is one of the techniques that produce high quality images. If your system is configured for S-video, then the peripherals that you add to the system, such as a VCR or camcorder, should be S-video sources such as an S-VHS VCR. Other transmission methods that may be configured onto specific systems include component video, composite video, or RGB video. Appropriate connecting cables are needed.

Multimedia Lectern with an Integrated System

Gordon Instruments, Inc.'s Multimedia Lectern

The Multimedia lectern should be attractive and functional furniture that is compact, moveable, and contains secure compartments. It also must be designed to meet the radiologist's special needs. The radiologist may switch from plain radiographs of various sizes to notebook computer to videotape to teleconferencing to CD to slide projector presentations. An audio system is also required. The electrical components such as switch boxes, cables, projectors and VCRs need to be integrated. The lectern must be attached to cables that carry the speaker's electronic commands to the projectors. An example of a functional and attractive system designed for radiology is the Gordon Instruments, Inc.'s Multimedia Lectern (www.gordon-instruments.com). It comes equipped with either a single chip or optional three chip solid state CCD solid state imaging camera that can display color or black & white images on a monitor or video projector. An iris automatically controls the amount of light in the image and there is a power 10:1 zoom lens. The system projects either transparencies or opaque illustrations. The configuration was designed to allow easy handling of various size radiographs and a four way masking systems cones down on the desired portion of radiographs. A 9-inch color monitor on the lectern, electronic video pointer, backlit control panel and reading light all assist the presenter. A carousel projector and slide to video converter, an integrated audio system pre-wiring for the addition of a computer, S-VHS VCR or other S-video source and for output to external monitors and/or a video projector are included. Dual projection slide presentations require separate projectors.

Conclusion - 2004 and Beyond

Possible changes in future multimedia presentations include the following: DVD (digital video disc or digital versatile disc) is a new generation of optical disc storage technology that may replace CD-ROM, videotape, laser disc, and audio CD. It's essentially a bigger, faster CD that can hold cinema-like video, better than CD audio, and computer data. DVD has widespread support from major electronics companies, computer hardware companies, and movie and music studios. More information can be found at: dvddemystified.com.

NTSC video standards may diminish in importance with the impending arrival of HDTV (High-Definition TV.) The FCC is directing the television industry to implement digital television programming. For more information, see www.fcc.gov/dtv.

Plasma screen use may increase. Plasma displays are thinner than CRT displays and brighter than LCD displays and can be used to display either analog video signals or digital computer input. Unlike many LCD displays, a plasma display offers a very wide viewing angle. Plasma displays come in various sizes and aspect ratios for conventional PC display, home theater, high definition television, public displays, etc. Unlike other displays systems, plasma technology creates red, green and blue lights in every pixel, reducing the need for space. Charged electrodes between glass panels cause tiny pockets of inert gas to change a state of plasma. This produces UV light, which in turn reacts with the red, green, and blue phosphors in each pixel to produce visible light. Unlike traditional displays, where the image is scanned across the screen, plasma displays "light" all pixels at once. Having no electron beam, back lighting or light polarization, the image is inherently sharper and brighter.

Radiologists work in a dynamic world of clinical digital imaging. It is a natural extension for us to master the digital multimedia presentations.

Glossary of Terms

Aspect Ratio is the ratio of the width to the height of a screen.

Back Room Projector has a "long-throw" lens that is designed to be used from a projection booth or the back of an auditorium 50 to 100 feet from the screen.

Bandwidth is the maximum amount of data that can travel a communications path in a given time, usually measured in seconds.

CCD (Charged Coupled Device) array are the sensors used in scanners, camcorders, digital cameras, etc., to capture an image.

CD-R (CD-Recordable) Discs can be recorded but like standard pressed CDs can't be re-recorded with different data.

CD-RW (CD-Rewritable) Discs can be erased and rewritten.

Component Video is a common method of transmitting a television signal. Component video offers the best interface between a video signal source (e.g., DVD player) and a video display (e.g., analog TV, Digital TV-HDTV set).

Composite Video is a common method of transmitting a television signal to or from a device such a composite video VCR. The picture quality is inferior to that with S-video, RGB, or component video.

Contrast Ratio in gray scale imaging is the ratio of the most white to black pixels in a given area. In color projectors, it measures the dynamic range. A lower ratio has washed out colors without detail and is not well seen with high ambient light.

Digital Light Processing (DLP) uses Texas Instruments "micro-mirror arrays" - hundreds of thousands of pivoting mirrors to modulate the image, instead of using LCD's.

Front Room Projector has a short throw lens that typically is placed 7 to 10 feet back from the screen and produces an approximately 10 foot diagonal image.

Keystoning is projector image distortion where the image is trapezoid shaped, occurring when front room projectors are placed so that distance to the top of the image on the screen is much greater than to the bottom. It can be corrected.

LAN (local area network) is a group of computers and devices sharing a common communications line and typically sharing resources within a small geographic area.

LCD (Liquid Crystal Display) is a display that sandwiches an electrically active substance between two electrodes. Many digital projectors are LCD or DLP based. LCD's are also used in monitors, using much less power than CRT's.

Lumen is a measurement of the amount of visible light energy that comes from a light source and is perceived by the eye.

Mid Room Projector is typical placed 12.5 to 25 feet away from the screen.

NTSC Video Standards (National Television System Committee) is the US TV broadcast standard (525 lines/second), and also the term for one type of television signal for recording on tape formats such as VHS, 3/4" U-matic and Betacam.

Overhead Projector (OHP) is a device consisting of light source, glass platform and focusable lens assembly that projects images from transparencies to a screen.

PAL (Phase Alternation by Line) Video Standard has 625 line pairs per second. This is the television broadcast standard throughout Western Europe (except in France).

Pixel (Picture Element) is a single point in a graphic image array, arranged in rows and columns. The pixels are so close together that they appear connected.

Plasma Screens display a computer video display in which each pixel on the screen is illuminated by a tiny bit of plasma or charged gas.

Rear Screen Projection uses a projector behind an opaque, invisible to the audience, without blocking anyone's view and without keystoning.

RGB Video is the highest quality method of transmitting a television signal to or from a device. Most computers use RGB, which consists of three separate signals.

SECAM (Sequential Couleur avec Mémoire) Video Standard is the TV broadcast standard in France, Mid East, and East Europe with 819 lines pairs/second.

S-Video is one of the high quality methods of transmitting a television signal to or from a device such as an S-video Camcorder, or S-video VCR, etc.

USB (United Serial Bus) Port is a connection from computer to most peripherals. Modern computers automatically identify and correctly connect to an attached peripheral.

Video Projector or Panel displays video inputs such as VCRs, Laser disk players, camcorders, computer, CCD imaging camera, etc. (see other syllabus article.)

WAN (Wide Area Network) is a communications private or a public (phone) network connecting computers and other devices across a large area.

Web Cam is a video that is produced by a digital camera attached to a computer.

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