Animation The Archive Series
animation the archive series Maple syrup History Native Americans Pre-contact native peoples, living in the northeastern part of North America, were the first people known to have produced mapl...
animation the archive series
Maple syrupHistory Native Americans Pre-contact native peoples, living in the northeastern part of North America, were the first people known to have produced maple syrup and maple sugar. According to their oral traditions, as well as archaeological evidence, maple tree sap was being processed for its sugar content long before Europeans arrived in the region. The Algonquins recognized the sap as a source of energy and nutrition. At the beginning of the spring thaw, they used stone tools to make V-shaped incisions in the trees, then inserted reeds or concave pieces of bark to run the sap into buckets, which were often made from birch bark. The maple sap, already rich in sugar content and yet not sweet-tasting, was concentrated either by dropping hot cooking stones into the buckets, or by leaving them exposed to the cold temperatures overnight, and disposing of the layer of ice which formed on top. First Nations and Native Americans also used earthenware cooking pots to boil the maple sap. They heated it over simple fires protected only by a roof of tree branches. Colonial to modern times A 19th-century illustration, "Sugar-Making Among the Indians in the North" (note the use of metal containers, introduced as a result of European contact) In the early stages of European colonization, in north-eastern North America, native peoples showed the arriving colonists how to tap (into) the trunks of certain types of maple tree during the end-of-winter/early-spring thaw, harvest the sap, and boil it to evaporate some of the water, concentrating the sugar content within the remaining liquid, and altering its taste somewhat, by heat-caramelizing some of the sugars. This activity quickly became an integral part of colonial life. Well before the beginning of the 1700s, European settlers and fur traders, as well as Native Americans, were intensively involved in the industry. During the 17th and 18th centuries, processed maple sap was a major source of concentrated sugar, in both liquid and crystallized-solid form. The Europeans revised the processing methods somewhat, with their access to more advanced technologies; particularly in metallurgy, toolmaking, and the use of domesticated animals. Typically, maple sugaring parties began to operate at the start of the spring thaw in regions of woodland known to contain sufficiently large numbers of maples, concentrated within a reasonable range of transportation to justify the effort. They first bored holes in the trunks of the maples, usually more than one hole per large tree, inserted home-made (usually carved wooden) spouts into the holes, and then hung a wooden bucket from the protruding end of each spout to collect the sap. The buckets were commonly made by cutting bucket-sized cylindrical segments from an appropriately large tree-trunk and then hollowing out each segment's core from one end of the cylinder, creating a seamless watertight container. Sap slowly filled the buckets, drop by drop. Periodically, members of the sugaring party returned to retrieve the sap that had accumulated. It was then either transferred to larger holding vessels ( barrels, large pots, or hollowed-out wooden logs) often mounted on sledges or wagons pulled by draft animals or it was carried in buckets, or similarly convenient containers. The sap-collection buckets were returned to the spouts mounted on the trees, and the process was repeated for as long as the flow of sap remained "sweet". The specific weather conditions of the late-winter/early-spring "thaw" period were, and still are, critical in determining the length of the "sugaring" season. As the weather continues to warm, a maple tree's normal early spring biological process eventually alters the taste of the sap, making it unpalatable. Depending on conditions, a sugaring party could spend several days to several weeks engaged in these activities. The boiling process was time consuming. The harvested sap was transported back to the party's base camp, where it was then poured into large, (almost always) metal vessels and boiled to achieve the desired consistency. The sap was usually processed at a central collection point, either over a fire built out in the open, or inside a shelter built for that purpose. To protect themselves from the weather conditions of the very early spring, sugaring parties built a small camp. Often, whole families moved into the woods together to collect and boil the sap producing both maple syrup and maple sugar. By the 1850s, the "sugar shack" or "sugarhouse" (the outdoor shack or building used to boil down the sap) arrived as we know it today. The settlers had refined the methods for collecting the sap. The sap was transported using large barrels pulled by horses or oxen and brought to the sugar shack for processing. At this time, maple sugar was the only sugar available as other types of sugar were hard to find and expensive and was called "country sugar". Production methods have been streamlined since colonial days, yet remain basically the same. Sap must first be collected and boiled down carefully to obtain pure syrup without chemical agents or preservatives. Early maple syrup was made by boiling approximately forty gallons (160 l) of sap over an open fire until one gallon (4 l) of syrup was obtained. This process underwent little change over the first two hundred years of recorded maple syrup making. Around the time of the American Civil War, syrup makers started using a large flat sheet metal pan as it was more efficient for boiling than a heavy rounded iron kettle which let much of the heated air slide past. Virtually all syrup makers in the past were self-sufficient dairy farmers who made both syrup and sugar for their own use and for extra income. The process continued to evolve as a result of the innovations developed in their work. In 1864, a Canadian borrowed some design ideas from sorghum evaporators and put a series of baffles in the flat pans to channel the boiling sap. In 1872 a Vermonter developed an evaporator with two pans and a metal arch or firebox which greatly decreased boiling time. Seventeen years later, in 1889, another Canadian bent the tin that formed the bottom of a pan into a series of flues which increased the heated surface area of the pan and again decreased boiling time. The technology remained the same until the 1960s, when it was no longer a self sufficient enterprise with large families as farm hands. Because syrup making was so labor intensive, farmers could no longer afford to hire the large crews it took to gather all the buckets and haul the sap to the evaporator house. During the energy crunch of the 1970s, syrup makers responded with another surge of technological breakthroughs. Tubing systems, which had been experimented with since the early part of the century were perfected and the sap came directly from the tree to the evaporator house. Vacuum pumps were added to the tubing systems. Pre-heaters were developed to recycle heat lost in the steam. Reverse-osmosis machines were developed to take a portion of water out of the sap before it was boiled. Several producers even obtained surplus desalinization machines from the U.S. Navy and used them to take a portion of water out of the sap prior to boiling. The technological developments continue. Improvements in tubing, new filtering techniques, "supercharged" preheaters, and better storage containers have been developed. Research continues on pest control and improved woodlot management. In 2009, the University of Vermont unveiled a new type of tap which prevents backflow of sap into the tree, reducing bacterial contamination and preventing the tree from attempting to heal the bore hole. Production Maple syrup production is centered in northeastern North America, and is commonly associated with Quebec in Canada; however, given the correct weather conditions, it can be made wherever maple trees grow. Usually, the maple species used are the sugar maple (Acer saccharum) and the black maple (Acer nigrum), because of a high sugar content in the sap of roughly two percent. A maple syrup production farm is called a "sugar bush" or "the sugarwoods". Sap is often boiled in a "sugar house" (also known as a "sugar shack" or cabane sucre), a building which is louvered at the top to vent the steam from the boiling sap. Canada makes more than 80 percent of the world's maple syrup, producing about 26.5 million litres in 2005. The vast majority of this comes from Quebec: the province is by far the world's largest producer, with about 75 percent of the world production (24.66 million litres in 2005). Production in Quebec is controlled through a supply-management system, with producers receiving quota allotments from the Fdration des producteurs acricoles du Qubec. The province also maintains it own "strategic reserves" of maple syrup, which reached its highest point in 2004, when it totalled 60 million pounds, or 17.03 million litres.
The provinces of Ontario, Nova Scotia, New Brunswick, Prince Edward Island, and British Columbia produce smaller amounts. The province of Manitoba produces maple syrup using the sap of the Manitoba maple tree (Acer negundo, also known as the "box-elder"). Manitoba maple syrup has a slightly different flavor than sugar-maple syrup; because it contains less sugar and the sap flows more slowly, the Manitoba maple tree's yield is usually less than half that of a similar-sized maple tree. Traditional tap Two taps in a maple tree, using plastic tubing for sap collection. A small scale evaporation pan used in Ohio. A sugar house where sap is boiled down to maple syrup. Traditionally, maple syrup was harvested by tapping a maple tree through the bark and into the wood, then letting the sap run into a bucket, which required daily collecting; less labour-intensive methods such as the use of continuous plastic pipelines have since superseded this, in all but cottage-scale production. Production is concentrated in February, March, and April, depending on local weather conditions. Freezing nights and warm days are needed to induce sap flows. The change in temperature from above to below freezing causes water uptake from the soil, and temperatures above freezing cause a stem pressure to develop, which, along with gravity, causes sap to flow out of tapholes or other wounds in the stem or branches. To collect the sap, holes are bored into the maple trees and tubes (taps, spouts, spiles) are inserted. Sap flows through the spouts into buckets or into plastic tubing. Modern use of plastic tubing with a partial vacuum has enabled increased production. A hole must be drilled in a new location each year, as the old hole will produce sap for only one season due to the natural healing process of the tree, called walling-off. Maple sap is collected from the buckets and taken to the sugar house; if plastic tubing and pipelines are used, then the pipelines are arranged so that the sap will flow by gravity into the sugar house, or if that is not possible, into holding tanks from which the sap is pumped or transported by tanker truck to the sugar house. It takes approximately 40 litres (10 gal) of sap to be boiled down to 1 litre (1 quart) of syrup. A mature sugar maple produces about 40 litres of sap during the 4- to 6-week sugaring season. Trees are not tapped until they have a diameter of 25 cm (10 in) at chest-height and the tree is at least 40 years old. If the tree is more than 45 centimetres (18 in) it can be tapped twice on opposite sides. It is recommended that the drilled tap hole have a width of 8 mm ( in) and a depth of 25 to 40 mm (1.0 to 1.6 in). During cooking, the sap is fed automatically by pipe from a storage tank to a long and narrow ridged pan called the evaporator. The evaporator is usually divided into two sections, the front pan and the back pan. As the sap boils, the water evaporates; it becomes denser and sweeter. As the density of the sap increases, it works its way from the rear of the back evaporator pan to the front evaporator pan. The syrup is boiled until it reaches the correct density of maple syrup, 1333 kg/m3.[citation needed] The proper density of at least 66% sugar is reached when the boiling sap reached a temperature of 219 F (104 C). The density is tested with a hydrometer. If the density is too low the syrup will not be sweet enough and the syrup will spoil. If the density is too high the syrup will crystallize in bottles. When the syrup has reached the proper density, it is drawn off, filtered and bottled while hot. Starting in the 1970s, some maple syrup producers started using reverse osmosis to remove water from sap before being further boiled down to syrup. The use of reverse osmosis allows approximately 75 to 80% of the water to be removed from the sap prior to boiling, reducing energy consumption and exposure of the syrup to high temperatures. Microbial contamination and degradation of the membranes has to be monitored. Maple syrup is sometimes boiled down further to make maple sugar, a hard candy usually sold in pressed blocks, and maple taffy. Intermediate levels of boiling can also be used to create various intermediate products, including maple cream (less hard and granular than maple sugar) and maple butter (creamy, with a consistency slightly less thick than peanut butter). During the production season in New England, a traditional delicacy known as "sugar-on-snow" is often prepared by drizzling superheated maple syrup over snow or shaved ice, resulting in a chewy taffy-like confection. Starting in the mid 80's, northern communities in the province of Quebec began to open the "Cabane Sucre" or Sugar Shacks to the public. These sugar shacks were generally located on large maple farms and often were built solely for tourist purposes. These sugar shacks serve maple syrup direct to the public and also are often restaurants serving maple syrup inspired meals and treats. Grades Canadian, U.S., and Vermont grading U.S. Syrup grades. Left to right: Vermont Fancy, Grade A Medium Amber, Grade A Dark Amber, Grade B In Canada, there are three grades containing several color classes, ranging from Canada #1, including Extra Light (sometimes known as AA), Light (A), and Medium (B); through #2, Amber (C); and finally #3 Dark (D). A typical year's yield will include about 2530% of each of the #1 colors, 10% Amber, and 2% Dark. Number 2 grade syrups are aimed at baking and flavouring but are also popular on pancakes and waffles. In addition, Canada #2 Amber may be labeled Ontario Amber for farm sales in that province only. Number 3 grade syrup is heavy, and restricted for use in commercial flavourings.[citation needed] The United States uses somewhat different grading standards. Maple syrup is divided into two major grades: Grade A and Grade B. Grade A is further broken down into three subgrades: Light Amber (sometimes known as Fancy), Medium Amber, and Dark Amber. Grade B is darker than Grade A Dark Amber. The Vermont Agency of Agriculture Food and Markets uses a similar grading system of color and taste. The grade Vermont Fancy is similar in color and taste to U.S Grade A Light (Fancy). The Vermont grading system differs from the U.S. system in maintaining a slightly higher standard of product density. Vermont maple is boiled just a bit longer for a slightly thicker, denser product. The ratio of the volume of sap to the yielded volume of finished syrup is higher in the Vermont system. Maple syrup is sold by liquid volume, not weight. The Vermont graded product has one-half percent more solid material and less water in its composition. A non-table grade of syrup called commercial, or Grade C, is also produced. This is very dark, with a very strong flavor. Commercial maple syrup is generally used as a flavoring agent in other products. The grades roughly correspond to various times within the season when syrups are produced. Canada #1 Extra Light and U.S. Grade A Light Amber are early-season grades, while Canada #2 and #3 and U.S. Grade B are late-season grades. Typically #1 Extra Light and Grade A (especially Grade A Light Amber) has a milder, more delicate flavor than #3 or Grade B, which is very dark with a robust flavor. The dark grades of syrup are primarily used for cooking and baking. Off-flavours Sometimes off-flavours are found in maple syrup. While this is more common toward the end of the season in the production of commercial grade product, it may also be present early in the season during the production of Canada #1 grade or U.S. Grade A Light. Identification of off-flavour in table grades is cause for ceasing production and either dumping the product or reclassifying the product as commercial grade if the off-flavour is slight. Off-flavours are described as: metabolism, derived from metabolic changes in the tree as spring arrives and having either a woody, popcorn, or sometimes peanut butter-like flavour; buddy, referring to the swelling of the new buds and its impact on the flavour and having a bitter chocolate or burnt flavour; and ferment, an off-taste caused by fermentation and having a honey or fruity flavour, often accompanied by surface foam. Additionally, if trees are stressed or fighting off disease or insects (e.g. gypsy moths), they will produce a folic-like acid causing a bad taste. After an ice storm, trees may also produce the same acid. Use in food and cultural significance Maple syrup Nutritional value per 100 g (3.5 oz) Energy 1,093 kJ (261 kcal) Carbohydrates 67.09 g Sugars 59.53 g Dietary fiber 0 g Fat 0.20 g Protein 0 g Thiamine (Vit. B1) 0.006 mg (0%) Riboflavin (Vit. B2) 0.01 mg (1%) Niacin (Vit. B3) 0.03 mg (0%) Pantothenic acid (B5) 0.036 mg (1%) Vitamin B6 0.002 mg (0%) Folate (Vit. B9) 0 g (0%) Vitamin C 0 mg (0%) Calcium 67 mg (7%) Iron 1.20 mg (10%) Magnesium 14 mg (4%) Phosphorus 2 mg (0%) Potassium 204 mg (4%) Zinc 4.16 mg (42%) Percentages are relative to US recommendations for adults. Source: USDA Nutrient database Maple syrup and its artificial imitations are the preferred toppings for pancakes, waffles, and French toast in North America. Maple syrup can also be used for a variety of uses, including: biscuits, chicken, fresh donuts, fried dough, fritters, ice cream, hot cereal, and fresh fruit (especially grapefruit). It is also used as sweetener for applesauce, baked beans, candied sweet potatoes, winter squash, cakes, pies, breads, fudge and other candy, milkshakes, tea, coffee, and hot toddies. Maple syrup and maple sugar were used during the American Civil War and by abolitionists in the years prior to the war because most cane sugar and molasses was produced by Southern slaves. During food rationing in World War II, people in the northeastern United States were encouraged to stretch their sugar rations by sweetening foods with maple syrup and maple sugar, and recipe books were printed to help housewives employ this alternate source. In Quebec, New Brunswick, eastern Ontario, and New England, the process has become part of the culture. One tradition is going to sugar houses (cabanes sucre) in early spring for meals served with maple syrup. A typical offering is pancakes, baked beans and sausages, usually followed by a sugar on snow ("tire sur la neige" in Quebec), or sometimes by maple taffee in English Canada. Sugar on snow is thickened hot syrup poured onto fresh snow, and then eaten off sticks as it quickly cools. This thick maple syrup-based candy is occasionally served with yeast-risen doughnuts, sour dill pickles, and/or coffee. Owing to the sugar maple tree's predominance in southeastern Canada (where Europeans settled in what was to become Canada), its leaf has come to symbolize the country, and is depicted on its flag. Several U.S. states, including New York and Vermont, have the sugar maple as their state tree. A scene of sap collection is depicted on the Vermont state quarter as well as the tins of the Vermont Maple Sugar Makers' Association, a non-governmental agricultural organization that works to protect the integrity and purity of Vermont maple products, and to promote its historic significance to the culture of Vermont. Imitation maple syrup In the United States, "Maple syrup" must be made entirely from maple sap (small amounts of substances such as salt may be added). "Maple-flavored" syrups contain maple, but also other (cheaper) ingredients. "Pancake syrup", "waffle syrup", "table syrup", and similarly-named syrups are imitations, which are less expensive than real maple syrup. In these syrups, the primary ingredient is most often high fructose corn syrup flavored with sotolon, having no genuine maple content. They are usually thickened far beyond the viscosity of real maple syrup. U.S. labeling laws prohibit these products from having "maple" in their names. The fenugreek seed, a spice, can be prepared to have a maple syrup-like flavor, and is used to make a very strong commercial flavoring that is similar to maple syrup, but much less expensive; Mapleine is an example of this.[citation needed] Smells from a Frutarom fenugreek processing factory produced a maple syrup-like odor that occasionally covered New York City starting in 2005, being identified in 2009 as coming from a Hudson County Frutarom factory. Qubcois sometimes refer to imitation maple syrup as sirop de poteau ("pole syrup"), a joke referring to the syrup as having been made by tapping telephone poles. In 1905, Crescent Foods Inc. created the imitation maple flavoring called Mapleine. Bought out by McCormick spices, it still distributes "Crescent Mapleine" from limited production runs. In Australia and South Africa, imitation maple syrup is sold as "Maple flavoured syrup".[citation needed] Identification of maple trees Maple trees most commonly tapped for sap collection are Sugar Maple, Black Maple, Red Maple, and Silver Maple. These maple trees are common in Eastern Canada and the Northeast United States. The Sugar Maple and Black Maple provide the highest sugar content, and therefore are ideal for a better maple syrup yield and shorter boiling times. Quicker boiling often makes for a higher grade syrup. The bark on the Sugar Maple is dark gray to brown and has developed vertical grooves and ridges, often broken up by plates of bark. The leaf is rounded at the base, extending to generally 5 lobes without fine teeth (compared to Red and Silver Maples). The color is bright green, with a paler green underside. Sugar Maple fruit has seeds joined in a straight line, while the wings are separated by approximately 60 degrees. Each winged seed is about 1 inch (25 mm) long and matures in the fall. See also Food portal Agave nectar Birch syrup Hickory syrup Palm syrup Plant sap Rubber tapping Sweet sorghum Syrup Yacon syrup References ^ http://www.canadianmaplesyrup.com/maplehistory.html ^ http://www.boston.com/news/local/vermont/articles/2009/08/17/new_maple_tap_developers_foresee_a_sweet_season/ ^ http://www.nass.usda.gov/nh/mapleconf2005.pdf ^ Johnston, David (2009-03-01). "Producers fear consumers will sour on maple syrup". Montreal Gazette (Canwest). http://www.montrealgazette.com/Producers+fear+consumers+will+sour+maple+syrup/1334062/story.html. Retrieved 2009-03-01.
^ ^ E.g., 21 CFR 168.140 (USA). ^ E.g., 21 CFR 168.180 (USA). ^ 21 CFR 168.140(a), 168.180(c). ^ MacInnis, Craig (July 6, 2008). "Not just for breakfast anymore". The Ottawa Citizen. http://www.canada.com/ottawacitizen/news/life/story.html?id=600c9b51-d198-4796-acfe-464b8cdb8fe3. ^ HistoryLink Essay: Crescent Manufacturing Company ^ Identification of Maple Trees External links Wikimedia Commons has media related to: Maple syrup Wikibooks Cookbook has a recipe/module on Maple syrup The Canadian Encyclopedia: Maple Sugar Industry Statistics by State (U.S. Department of Agriculture, June 2005). Taste and nutrition: Nutritional Information Maple Sugar Sweetness Scale Production: "North American Maple Syrup Producers Manual" (1st edition), edited by Melvin R. Koelling and Randall B. Heiligmann, Ohio State University Extension (Bulletin 856), 1996. (archived at Internet Archive#Wayback Machine) "The Bible" of maple syrup production. "Maple Syrup Quality Control Manual" by Kathryn Hopkins, University of Maine Cooperative Extension (Bulletin 7038)
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Picture Archiving And Communication System Pacs
I. Introduction
Timely management of medical imaging information is one of the greatest challenges facing medicine today. Patients with complex medical problems may require a large number of radiologic studies, which may be performed at physically separate locations; as a result, preexisting studies may be inadvertently duplicated. Simultaneous access to radiologic images may be needed for accurate interpretation. In addition, multiple physicians caning for a patient may want to review the images. As medical centers increase in size, illnesses increase in complexity, and the demand for rapid transfer of information increases accordingly, the capacity of film-based radiologic systems to meet these demands decreases. Films are often unavailable or lost, and film storage costs are relatively high. Systems designed to store images in computers and display them on high-resolution monitors have been developed over the past 10-12 years. These picture archiving and communication systems (PACS) attempt to overcome the limitations of film-based systems by providing economical storage, rapid retrieval of individual images, access to images acquired with multiple modalities, and simultaneous access to the same image at multiple sites. However, acceptance of this new technology has been limited by high capital costs, limited spatial resolution of the display monitors, limited spatial resolution of digitization modalities for projection radiography, slow image display (compared with that in film-based systems), and the need for system redundancy to provide backup in case of component failure. Most PACS in current use are prototypes intended for research, although recently some have been incorporated into segments of larger radiology department
PACS are computers or networks dedicated to the storage, retrieval, distribution and presentation of images. The medical images are stored in an independent format. The most common format for image storage is DICOM (Digital Imaging and Communications in Medicine). Most PACSs handle images from various medical imaging instruments, including ultrasound (US), magnetic resonance (MR), positron emission tomography (PET), computed tomography (CT), endoscopy (ENDO), mammograms (MAMMO), digital radiography (DR), computed radiography (CR) etc.
II. Picture archiving and communication system
The principles of PACS were first discussed at meetings of radiologists in 1982. Various people are credited with the coinage of the term PACS. Cardiovascular radiologist Dr Andre Duerinckx reported in 1983 that he had first used the term in 1981. Dr Samuel Dwyer, though, credits Dr Judith M. Prewitt for introducing the term. Dr Harold Glass, a medical physicist working in London in the early 1990s secured UK Government funding and managed the project over many years which transformed Hammersmith Hospital in London as the first filmless hospital in the United Kingdom. Dr Glass died a few months after the project came live but is credited with being one of the pioneers of PACS Organizational techniques that enable small departments to function efficiently often fail as departments become larger. With the recent growth in imaging technology, the capacity of film-based systems to meet the increasing needs of radiology departments has decreased. Electronic PACS have been developed in an attempt to provide economical storage, rapid retrieval of images, access to images acquired with multiple modalities, and simultaneous access at multiplies sites. Input to a PACS may come from digital or analog sources (when the latter have been digitized). A PACS consists primarily of an image acquisition device (an electronic gateway to the system), data management system (a specialized computer system that controls the flow of information on the network), image storage devices (both short- and long-term archives), transmission network (which serves local on wide areas), display stations (which include a computer, text monitor, image monitors, and a user interface), and devices to produce hard-copy images (currently, a multiformat or laser camera). The goals of PACS are to improve operational efficiency while maintaining or improving diagnostic ability. A. Image Acquisition Modules
An image acquisition device is an electronic gateway to the PACS and may be an analog-to-digital converter or device that passes along digital information from a digital imaging device. The number of acquisition modules necessary for a PACS to function varies with the system and is based on its size and the mix of analog and digital input devices.
B. Data Management System
The data management system is a specialized computer that controls the
network, image storage devices, and image acquisition devices in order to maintain orderly traffic flow in the system. This computer manages patient information and images as well as the associated reports. The data management system must provide short- and long-term archiving capabilities. Usually, the short-term archive employs magnetic media, and the long-term archive employs optical media. The short-term anchive has low capacity but is frequently used (ie, high utilization), whereas the long-term archive has high capacity and low utilization.
C. Transmission Network
Data for images, text, and system commands are transmitted over networks serving local or wide areas. The network medium could be a twisted-pain wire, coaxial cable, on fibenoptic cable. A variety of network topologies (eg, star) are available, each with its own advantages and disadvantages. In addition, several
communication protocols (eg, transmission control protocol/internet protocol [TCP/IP]) exist for managing the information on the network. These protocols provide instructions on how data will be moved on the network.
D. Image Display Stations
Image display stations are the principal area of physician interface with a PACS. A display station includes a computer with local stunage, a text monitor, a variable number of image monitors, and a user interface. A display station that can duplicate the full range of tasks, speed of display, and spatial resolution available with film systems has not yet been constructed. In fact, the cost of creating such
a station would be formidable. To help minimize the potential costs, studies have been undertaken to determine the minimal spatial and contrast resolution necessary to perform a variety of imaging tasks. This information may then be used to create a series of workstations with different levels of sophistication so that appropriate equipment may be selected for the task at hand.
E. Hard-Copy Devices
Although the major mode of storage and display with a PACS is electronic, provision must also be made for creating a conventional im age on x-ray film. Multiformat cameras on laser cameras are currently the most common way of meeting this demand.
F. Interfaces to Other Systems
To function properly, the image management system must interface with other patient care management systems. These include but need not be limited to a radiology information system (IllS) and a hospital information system (HIS). The goals of interfacing the PACS to an RIS and an HIS are to maintain data integrity across the global system and to optimize the performance of each component system by using only the specific data needed fon each. The 1115 provides basic patient histories, reporting of results, and collection of data for department management. The HIS manages the demographic standards and distributes patient care information throughout the medical center.
III. A Radiologic Picture Archiving and Communication System for a Coronary Care Unit
I chose the radiologic picture archiving and communication system for a coronary care unit (CCU) at a 700-bed teaching hospital ,as an example in my project for PACS. The major components of this PACS module are located in the Radiology Department and are shared with the Pediatric Radiology PACS. An important design goal was to create a system in which acquisition, routing, and management of patients' image data are accomplished with minimal operator intervention. The automatic acquisition of images is achieved through linkage of a computed radiography (CR) unit, FCR-1 01 (Fuji Photo Film, Kanagawa, Japan) to an external host, VAX-i i /750 minicomputer (Digital Equipment Corporation, Maynard, MA.) These two components are integrated through an interface unit that was developed in-house. The host computer is used to manage the processing and flow of data from creation, storage, and archive to display.
Under normal conditions, the only manual operation required for data input and subsequent management of the data base is the entry of the patient's name, hospital identification (ID) number, and hospital section code at the CR console. This task is performed by the X-ray technologist at the time the imaging plate is processed. Once this is completed, the remainder of the process is fully automated. The software that is resident on the host computer detects the incoming imaging plate and initiates the data transfer from the CR unit. The hospital section code is used to route the image to an appropriate data base (in this case, the CCU data base). The raw image data acquired at 2048 x 2048 x 8 bit resolution are reformatted into the standard image file structure defined for the
PACS and then archived. Subsequently, the image file is subsampled to 51 2 x 51 2 x 8 bit resolution for display purposes and the patient directory is updated to include the new entry. Active patient images are stored on magnetic disk for rapid access. Forty-five megabytes of disk space have been allocated for the CCU data base, which provides a maximum of 180 images on-line. The images are also automatically archived to an optical disk library unit manufactured by Filenet Costa Mesa, CA) and Hitachi (Tokyo, Japan). When a patient is selected at the user terminal in the CCU, the image files are loaded on a Gould 1P8500 image processor (Fremont, CA), and the video output signals are transmitted in real-time to the CCU via a broadband network. Three channels are multiplexed with Blonder-Tongue video modulators (Oldbridge, NJ) operating with 8-MHz bandwidths. The viewing station in the CCU consists of three 13-in. (30-cm) diagonal, 5i 2-line display monitors (Panasonic Industrial Company, Secaucus, NJ) and a VT-i 00 terminal for user interface.
A. User Interface
The user interacts with the system through a VT-i 00 terminal keypad. A directory of patients and various image manipulation functions are provided in a menu format. In a typical viewing session, the clinician first selects a patient from the alphabetic active-patient directory. The terminal prompts the user to wait while the data base is searched. Images appear on the three monitors in reverse chronological order, starting with the most recent image (Fig. 2). The information appearing at the bottom portion of the image includes the patient's name and hospital identification number, as well as the date and time of image acquisition. At this point, the viewer may return to the directory, view more images of the current patient, or apply an image manipulation function. The image manipulation functions include zoom (by pixel replication), mean-and-window, grayscale inversion, left-right reversal, and image rotation.
B. Data Bases
The data bases use the indexed sequential access method (ISAM) files. The record for the patient data base contains information such as the patient's name, hospital identification number, number of images acquired to date, and the image code, which is issued automatically when the patient is entered into the data base for the first time. The image code also serves as the primary key for the image data-base record, which provides information associated with the individual image file, including the date of acquisition, procedure, current location of the image (magnetic disk, optical disk, or both), and the volume and physical address of the optical disk archive. The images are deleted from the magnetic disk according to a probability algorithm that determines which images are least likely to be reviewed.
For a returning patient, the most recent image is retrieved.
automatically from the optical disk library for comparison purposes.
C. Clinical Operation
The CCU is one of the largest intensive care units in the hospital. It is located five floors above and 1000 ft. (300 m) away from the Radiology Department. This busy unit has an average daily occupancy of 25.9 patients, and the average duration of stay in the unit is 4.4 days. During their stay in the CCU, 72% of patients have at least one chest radiograph. On the average, 10 chest examinations are performed each day, about half of them with a mobile unit. Because use of the mobile unit is often indicative of the critical condition of the patient, a protocol has been established to make these images (about five examinations per day) immediately available to the CCU physicians through the digital viewing system. Traditionally, in order to view films, the physician would have to walk to the Radiology Department to check out the patient's film jacket, a procedure that can be quite time-consuming. After a month long preclinical trial, the system was released to the CCU physicians for their use. The system was available at all times, and physicians could choose between the film-based viewing system and the digital viewing system. The decision to release the system for clinical use without restriction was based on the premise that the functionality of a computer-based system ought to be defined and evaluated within the normal task environment. The usage and performance of the system were logged into a file to provide (1) the name and hospital identification number of the patient reviewed, (2) the date and time of viewing, (3) image manipulation function(s) used, (4) the identification of the image manipulated, and (5) the speed of various operations.
IV. DICOM Images
DICOM stands for Digital Imaging and Communications in Medicine. Its standard was created by the National Electrical Manufacturers Association (NEMA) to aid the distribution and viewing of medical images, such as CT scans, MRIs, and ultrasound. Part 10 of the standard describes a file format for the distribution of images. This format is an extension of the older NEMA standard. Most people refer to image files which are compliant with Part 10 of the DICOM standard as DICOM format files. A single DICOM file contains both a header (which stores information about the patient's name, the type of scan, image dimensions, etc), as well as all of the image data (which can contain information in three dimensions). This is different from the popular Analyze format, which stores the image data in one file (*.img) and the header data in another file (*.hdr). Another difference between DICOM and Analyze is that the DICOM image data can be compressed (encapsulated) to reduce the image size. Files can be compressed using lossy or lossless variants of the JPEG format, as well as a lossless Run-Length Encoding format (which is identical to the packed-bits compression found in some TIFF format images).
A. The DICOM header
The below Image shows a hypothetical DICOM image file. In this example, the first 794 bytes are used for a DICOM format header, which describes the image dimensions and retains other text information about the scan. The size of this header varies depending on how much header information is stored. Here, the header defines an image which has the dimensions 109x91x2 voxels, with a data resolution of 1 byte per voxel (so the total image size will be 19838). The image data follows the header information (the header and the image data are stored in the same file).Furthermore, the DICOM header is shown. The DICOM requires a 128-byte preamble (these 128 bytes are usually all set to zero), followed by the letters 'D', 'I', 'C', 'M'. This is followed by the header information, which is organized in 'groups'. For example, the group 0002hex is the file meta information group, and (in the example on the left) contains 3 elements: one defines the group length, one stores the file version and the third stores the transfer syntax.
The DICOM elements required depends on the image type. For example, this image modality is 'MR' (see group : element 0008:0060), so it should have elements to describe the MRI echo time. The absence of this information in this image is a violation of the DICOM standard. In practice, most DICOM format viewers (including MRIcro and ezDICOM) do not check for the presence of most of these elements, extracting only the header information which describes the image size.
The NEMA standard preceded DICOM, and the structure is very similar, with many of the same elements. The main difference is that the NEMA format does not have the 128-byte data offset buffer or the lead characters 'DICM'. In addition, NEMA did not explicitly define multi-frame(3D) images, so element 0028,0008 was not present.
Of particular importance is group : element 0002:0010. This defines the 'Transfer Syntax Unique Identification'. This value reports the structure of the image data, revealing whether the data has been compressed. Note that many DICOM viewers can only handle uncompressed raw data. DICOM images can be compressed both by the common lossy JPEG compression scheme (where some high frequency information is lost) as well as a lossless JPEG scheme that is rarely seen outside of medical imaging (this is the original and rare Huffman lossless JPEG, not the more recent and efficient JPEG-LS algorithm). Note that as well as reporting the compression technique (if any), the Transfer Syntax UID also reports the byte order for raw data. Different computers store integer values differently, so called 'big endian' and 'little endian' ordering. Consider a 16-bit integer with the value 257: the most significant byte stores the value 01 (=255), while the least significant byte stores the value 02. Some computers would save this value as 01:02, while others will store it as 02:01. Therefore, for data with more than 8-bits per sample, a DICOM viewer may need to swap the byte-order of the data to match the ordering used by your computer.
In addition to the Transfer Syntax UID, the image is also specified by the Samples Per Pixel (0028:0002), Photometric Interpretation (0028:0004), the Bits Allocated (0028:0100). For most MRI and CT images, the photometric interpretation is a continuous monochrome (e.g. typically depicted with pixels in grayscale). In DICOM, these monochrome images are given a photometric interpretation of 'MONOCHROME1' (low values=bright, high values=dim) or 'MONOCHROME2' (low values=dark, high values=bright). However, many ultrasound images and medical photographs include color, and these are described by different photometric interpretations (e.g. Palette, RGB, CMYK, YBR, etc). Some color images (e.g. RGB) store 3-samples per pixel (one each for red, green and blue), while monochrome and paletted images typically store only one sample per image. Each images store 8-bits (256 levels) or 16-bits per sample (65,535 levels), though some scanners save data in 12-bit or 32-bit resolution. So a RGB image that stores 3 samples per pixel at 8-bits per can potentially describe 16 million colors' (256 cubed).
B. ezDICOM
The ezDICOM is a software that is easy to use, mature (stable, few if any bugs) and can view a wide range of medical images including proprietary formats as well as images in the DICOM standard. For example, In addition, most free DICOM viewers only read a small subset of the DICOM images available, while ezDICOM can view a broad range of images. In addition to DICOM images, the software will automatically recognize and display Analyze, GE (LX, Genesis), Interfile, Siemens (Magnetom, Somatom) and NEMA images. The greatest strength of ezDICOM is that it is free and open source. There are many variations of medical images 'in the wild' - many of these are poorly or incorrectly documented. By being free, ezDICOM has developed a wide user base, and this ensures the quality of the code. Thousands of people have used ezDICOM and sent in unusual and rare images, and the code is now mature and able to read virtually all the popular medical images.
Therefore, the users are the most important strength of this software. It is important to acknowledge the many people who shared their images with the developers. The advantage of being open source is that programmers can modify and improve the code if they want. The project was started by Wolfgang Krug and has been expanded and maintained by Chris Rorden. Development was particularly aided by Earl F. Glynn's general programming tutorials and David Clunie's medical imaging FAQ. This software is covered by the BSD open source license. You can distribute both compiled projects and the source code. However, you should also distribute the license (the compiled standalone program makes this easy: the license is built into the 'about' window). The license also notes that the software is provided 'as is', use it at your own risk. This software attempts to reproduce medical images accurately. However, it is not designed for clinical use: computer monitors can vary tremendously in image quality. All grayscale images are rendered in 256-levels of gray.
The standalone ezDICOM for windows program is a basic but useful tool for viewing medical images. This software will run on computers with Windows 95 or later and requires less than 300 Kb of disk space. To view an image, you simply drag and drop the image onto the program (or you can choose 'Open...' from the 'File' menu). Despite the ease of use, ezDICOM has a number of powerful features. For example, you can set the brightness and contrast of an image with great precision. You can also animate images that have multiple slices (e.g. see a heart beating over time or see different depths into the brain). The ezDICOM standalone application [version 1, release 19] is free software and is distributed as a compressed zip file - simply extract the files and double click on ezDICOM.exe. Delphi source code is also included, and a personal edition of this compiler is available for free.
D. DCM2JPG console application
DCM2JPG is a simple command-line Windows program. If you drop a file on the program it will create a JPEG version of the file (alternatively, if you name the program 'dcm2png.exe' or 'dcm2bmp.exe' it will create PNG or BMP format images). You can also call the program from the command line, to do special functions like change the image brightness or contrast (most grayscale DICOM images have much higher precision than can be saved to standard bitmap formats). Another nice feature is the ability to create nice zoomed versions of DICOM images - e.g. save a 128x128 pixel image as a 192x192 pixel bitmap (scaling is done using a bilinear-interpolation method to reduce any jaggy edges). Both a compiled program and the (ezDICOM-based) source code can be downloaded from the internet. The program has some command as follows:
b Brightness [window center]: a,h,-9999..9999 for auto, header, custom default: auto
c Contrast [window width]: a,h,0..9999 for auto, header, custom default: auto
-f Format of Output: b,p,j, txtfor bmp, png, jpg, txt default: jpg
-o Output Directory, e.g. 'C:TEMP' default: source directory
-s Silent [errors not reported]: y,n for yes or no default: no
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-z Zoom of Output, e.g. ''1.5'' for 150% zoom default: 1.0
V. Conclusion
This report gave brief description about Picture archiving and communication system PACs. It explains its setup components and how it works through an example of a Radiologic Picture Archiving and Communication System for a Coronary Care Unit. It show also the format of the file extension of the image of the PACs and how it can be shown in ezDICOM software. However, output format of the ezDICOM is can be converted easily to other format according to the requirements such as jpg by using simple software called DCM2JPG console application. It is really interesting in this life to see how science affected the life of the human being.
About the Author
- Senior Telecommunication Specialist in Arab National Bank (ANB).
- B.S Electrical Engineering in 1997 from King Fahd university of Petroleum and Minerals (KFUPM).
- KFUPM MBA in 2002.









