Tuesday, March 16, 2010

technology

Medical technology

Medical technology is a part of the Health technology which encompasses a wide range of health care products and, in one form or another, is used to diagnose, monitor or treat every disease or condition that affects humans. These innovative technologies (application of science and technology) are improving the quality of health care delivered and patient outcomes through earlier diagnosis, less invasive treatment options and reductions in hospital stays and rehabilitation times. medical technology is any format of machinery that is used to operate or perform medical procedures Health technology is:

Any intervention that may be used to promote health, to prevent, diagnose or treat disease or for rehabilitation or long-term care. This includes the pharmaceuticals, devices, procedures and organizational systems used in health care.

Allied health profession

The term Medical technology may also refer to the duties performed by clinical laboratory professionals in various settings within the public and private sectors. The work of these professionals encompass clinical applications of chemistry, genetics, hematology, immunohematology (blood banking), immunology, microbiology, serology, urinalysis and miscellaneous body fluid analysis. These professionals may be referred to as Medical Technologists (MT) and Medical Laboratory Technicians (MLT) or as Clinical Laboratory Scientists (CLS) and Clinical Laboratory Technicians (CLT) depending on education, certification and/or licensure. The term medical technologist in this sense is sometimes considered a misnomer due to the fact that these professionals do not actually produce novel medical technology but rather apply the ones already in place in conjunction with the knowledge of the scientific principles of clinical laboratory science, which has been considered a more appropriate term for the discipline

Medical equipment

Medical equipment is designed to aid in the diagnosis, monitoring or treatment of medical conditions. These devices are usually designed with rigorous safety standards. The medical equipment is included in the category Medical technology.

There are several basic types:

A biomedical equipment technician (BMET) is a vital component of the healthcare delivery system. Employed primarily by hospitals, BMETs are the people responsible for maintaining a facility's medical equipment.

 Diagnosis

Diagnosis (Greek:διάγνωση, from δια dia- "apart-split", and γνώση gnosi "to learn, knowledge") is the identification of the nature of anything, either by process of elimination or other analytical methods. Diagnosis is used in many different disciplines, with slightly different implementations on the application of logic and experience to determine the cause and effect relationships. Below are given as examples and tools used by the respective professions in medicine, science, engineering, business. Diagnosis also is used in many other trades and professions to determine the causes of symptoms, mitigations for problems, or solutions to issues. ==Uses==

In medicine

In computing

Tools

Logic

 

List of medical devices

High risk devices

High risk devices are life supports, critical monitoring, energy emitting and other devices whose failure or misuse is reasonably likely to seriously injure patient or staff. Examples include:

  • Anesthesia units
  • Anesthesia ventilators
  • Apnea monitors
  • Argon enhanced coagulation units
  • Aspirators
  • Auto transfusion units
  • Electrosurgical units
  • External pacemaker
  • Fetal monitors
  • Heart Lung Machine
  • Incubators
  • Infusion pump
  • Invasive Blood pressure units
  • Pulse oximeters
  • Stent

Medium risk devices

These are devices including many diagnostic instruments whose misuse, failure or absence (e.g. out of service) with no replacement available would have a significant impact on patient care, but would not be likely to cause direct serious injury. Examples include:

  • ECG
  • EEG
  • Treadmills
  • Ultrasound sensors
  • Phototherapy units
  • Endoscopes
  • Surgical drill and saws
  • Laparoscopic insufflators
  • Phonocardiographs
  • radiant warmers (Adult)
  • Zoophagous agents (e.g., medicinal leeches; medicinal maggots)
  • Lytic Bacteriophages

Low risk devices

Devices in this category are those whose failure or misuse is unlikely to result in serious consequences. Examples include:

  • Electronic thermometer,
  • Breast pumps
  • Surgical microscope
  • Ultrasonic nebulizers
  • Sphygmomanometers
  • Surgical table
  • Surgical lights.
  • Temperature monitor
  • Aspirators
  • X-rays diagnostic equipment
  • lensometer
  • keratometer

Medical imaging

Medical imaging is the technique and process used to create images of the human body (or parts and function thereof) for clinical purposes (medical procedures seeking to reveal, diagnose or examine disease) or medical science (including the study of normal anatomy and physiology). Although imaging of removed organs and tissues can be performed for medical reasons, such procedures are not usually referred to as medical imaging, but rather are a part of pathology.

As a discipline and in its widest sense, it is part of biological imaging and incorporates radiology (in the wider sense), nuclear medicine, investigative radiological sciences, endoscopy, (medical) thermography, medical photography and microscopy (e.g. for human pathological investigations).

Measurement and recording techniques which are not primarily designed to produce images, such as electroencephalography (EEG), magnetoencephalography (MEG), Electrocardiography (EKG) and others, but which produce data susceptible to be represented as maps (i.e. containing positional information), can be seen as forms of medical imaging.

Overview

In the clinical context, medical imaging is generally equated to radiology or "clinical imaging" and the medical practitioner responsible for interpreting (and sometimes acquiring) the images is a radiologist. Diagnostic radiography designates the technical aspects of medical imaging and in particular the acquisition of medical images. The radiographer or radiologic technologist is usually responsible for acquiring medical images of diagnostic quality, although some radiological interventions are performed by radiologists. While radiology is an evaluation of anatomy, nuclear medicine provides functional assessment.

As a field of scientific investigation, medical imaging constitutes a sub-discipline of biomedical engineering, medical physics or medicine depending on the context: Research and development in the area of instrumentation, image acquisition (e.g. radiography), modelling and quantification are usually the preserve of biomedical engineering, medical physics and computer science; Research into the application and interpretation of medical images is usually the preserve of radiology and the medical sub-discipline relevant to medical condition or area of medical science (neuroscience, cardiology, psychiatry, psychology, etc) under investigation. Many of the techniques developed for medical imaging also have scientific and industrial applications.

Medical imaging is often perceived to designate the set of techniques that noninvasively produce images of the internal aspect of the body. In this restricted sense, medical imaging can be seen as the solution of mathematical inverse problems. This means that cause (the properties of living tissue) is inferred from effect (the observed signal). In the case of ultrasonography the probe consists of ultrasonic pressure waves and echoes inside the tissue show the internal structure. In the case of projection radiography, the probe is X-ray radiation which is absorbed at different rates in different tissue types such as bone, muscle and fat.

Imaging technology

Radiography

Two forms of radiographic images are in use in medical imaging; projection radiography and fluoroscopy, with latter useful for intraoperative and catheter guidance. These 2D techniques are still in wide use despite the advance of 3D tomography due to the low cost, high resolution, and depending on application, lower radiation dosages. This imaging modality utilizes a wide beam of x rays for image acquisition and is the first imaging technique available in modern medicine.

  • Fluoroscopy produces real-time images of internal structures of the body in a similar fashion to radiography, but employs a constant input of x-rays, at a lower dose rate. Contrast media, such as barium, iodine, and air are used to visualize internal organs as they work. Fluoroscopy is also used in image-guided procedures when constant feedback during a procedure is required. An image receptor is required to convert the radiation into an image after it has passed through the area of interest. Early on this was a fluorescing screen, which gave way to an Image Amplifier (IA) which was a large vacuum tube that had the receiving end coated with cesium iodide, and a mirror at the opposite end. Eventually the mirror was replaced with a TV camera.
  • Projectional radiographs, more commonly known as x-rays, are often used to determine the type and extent of a fracture as well as for detecting pathological changes in the lungs. With the use of radio-opaque contrast media, such as barium, they can also be used to visualize the structure of the stomach and intestines - this can help diagnose ulcers or certain types of colon cancer.

Magnetic resonance imaging (MRI)

Magnetic resonance imaging instrument (MRI scanner), or "nuclear magnetic resonance (NMR) imaging" scanner as it was originally known, uses powerful magnets to polarise and excite hydrogen nuclei (single proton) in water molecules in human tissue, producing a detectable signal which is spatially encoded, resulting in images of the body. MRI uses three electromagnetic fields: a very strong (on the order of units of teslas) static magnetic field to polarize the hydrogen nuclei, called the static field; a weaker time-varying (on the order of 1 kHz) field(s) for spatial encoding, called the gradient field(s); and a weak radio-frequency (RF) field for manipulation of the hydrogen nuclei to produce measurable signals, collected through an RF antenna.

Like CT, MRI traditionally creates a two dimensional image of a thin "slice" of the body and is therefore considered a tomographic imaging technique. Modern MRI instruments are capable of producing images in the form of 3D blocks, which may be considered a generalisation of the single-slice, tomographic, concept. Unlike CT, MRI does not involve the use of ionizing radiation and is therefore not associated with the same health hazards. For example, because MRI has only been in use since the early 1980s, there are no known long-term effects of exposure to strong static fields (this is the subject of some debate; see 'Safety' in MRI) and therefore there is no limit to the number of scans to which an individual can be subjected, in contrast with X-ray and CT. However, there are well-identified health risks associated with tissue heating from exposure to the RF field and the presence of implanted devices in the body, such as pace makers. These risks are strictly controlled as part of the design of the instrument and the scanning protocols used.

Because CT and MRI are sensitive to different tissue properties, the appearance of the images obtained with the two techniques differ markedly. In CT, X-rays must be blocked by some form of dense tissue to create an image, so the image quality when looking at soft tissues will be poor. In MRI, while any nucleus with a net nuclear spin can be used, the proton of the hydrogen atom remains the most widely used, especially in the clinical setting, because it is so ubiquitous and returns a large signal. This nucleus, present in water molecules, allows the excellent soft-tissue contrast achievable with MRI.

Nuclear medicine

Nuclear medicine encompasses both diagnostic imaging and treatment of disease, and may also be referred to as molecular medicine or molecular imaging & therapeutics. Nuclear medicine uses certain properties of isotopes and the energetic particles emitted from radioactive material to diagnose or treat various pathology. Different from the typical concept of anatomic radiology, nuclear medicine enables assessment of physiology. This function-based approach to medical evaluation has useful applications in most subspecialties, notably oncology, neurology, and cardiology.

  • Gamma cameras are used in nuclear medicine to detect regions of biologic activity that may be associated with disease. Relatively short lived isotope, such as 123I is administered to the patient. Isotopes are often preferentially absorbed by biologically active tissue in the body, and can be used to identify tumors or fracture points in bone. Images are acquired after collimated photons are detected by a crystal that gives off a light signal, which is in turn amplified and converted into count data. Gamma cameras can have a variable number of detector heads with two being the most common configuration. 2D planar images can be acquired of the body or multiple time-capture images can be combined into a dynamic sequence cine of a physiologic process over time. A 3D tomographic technique known as SPECT uses gamma camera data from many projections and can be reconstructed in different planes. A dual detector head gamma camera combined with a CT scanner, which provides localization of functional SPECT data, is termed a SPECT/CT camera, and has shown utility in advancing the field of molecular imaging.
  • Positron emission tomography (PET) uses coincidence detection to image functional processes. Short-lived positron emitting isotope, such as 18F, is incorporated with an organic substance such as glucose, creating F18-fluorodeoxyglucose, which can be used as a marker of metabolic utilization. Images of activity distribution throughout the body can show rapidly growing tissue, like tumor, metastasis, or infection. PET images can be viewed in comparison to computed tomography scans to determine an anatomic correlate. Modern scanners combine PET with a CT, or even MRI, to optimize the image reconstruction involved with positron imaging. This is performed on the same equipment without physically moving the patient off of the gantry. The resultant hybrid of functional and anatomic imaging information is a useful tool in non-invasive diagnosis and patient management.
  • Nuclear medicine therapy includes treatment with unsealed radioactive material in various forms, including free beta radiation emitting isotope, bound to antibody (radioimmunotherapy), and directly administered, as in resin microsphere therapy. Imaging aspects to many of these therapeutic procedures can add to the evaluation of efficacy.

 

Photoacoustic imaging

Photoacoustic imaging is a recently developed hybrid biomedical imaging modality based on the photoacoustic effect. It combines the advantages of optical absorption contrast with ultrasonic spatial resolution for deep imaging in (optical) diffusive or quasi-diffusive regime. Recent studies have shown that photoacoustic imaging can be used in vivo for tumor angiogenesis monitoring, blood oxygenation mapping, functional brain imaging, and skin melanoma detection, etc.

Breast Thermography

Needs main article Digital Infrared Imaging Thermography is based on the principle that metabolic activity and vascular circulation in both pre-cancerous tissue and the area surrounding a developing breast cancer is almost always higher than in normal breast tissue. Cancerous tumors require an ever-increasing supply of nutrients and therefore increase circulation to their cells by holding open existing blood vessels, opening dormant vessels, and creating new ones (neoangiogenesis). This process frequently results in an increase in regional surface temperatures of the breast. Digital Infrared Imaging uses extremely sensitive medical infrared cameras and sophisticated computers to detect, analyze, and produce high-resolution diagnostic images of these temperature variations. Because of DII’s sensitivity, these temperature variations may be among the earliest signs of breast cancer and/or a pre-cancerous state of the breast[2].

Tomography

Tomography is the method of imaging a single plane, or slice, of an object resulting in a tomogram. There are several forms of tomography:

  • Linear tomography: This is the most basic form of tomography. The X-ray tube moved from point "A" to point "B" above the patient, while the cassette holder (or "bucky") moves simultaneously under the patient from point "B" to point "A." The fulcrum, or pivot point, is set to the area of interest. In this manner, the points above and below the focal plane are blurred out, just as the background is blurred when panning a camera during exposure. No longer carried out and replaced by computed tomography.
  • Poly tomography: This was a complex form of tomography. With this technique, a number of geometrical movements were programmed, such as hypocycloidic, circular, figure 8, and elliptical. Philips Medical Systems produced one such device called the 'Polytome.' This unit was still in use into the 1990s, as its resulting images for small or difficult physiology, such as the inner ear, was still difficult to image with CTs at that time. As the resolution of CTs got better, this procedure was taken over by the CT.
  • Zonography: This is a variant of linear tomography, where a limited arc of movement is used. It is still used in some centres for visualising the kidney during an intravenous urogram (IVU).
  • Orthopantomography (OPT or OPG): The only common tomographic examination in use. This makes use of a complex movement to allow the radiographic examination of the mandible, as if it were a flat bone. It is often referred to as a "Panorex", but this is incorrect, as it is a trademark of a specific company.
  • Computed Tomography (CT), or Computed Axial Tomography (CAT: A CT scan, also known as a CAT scan, is a helical tomography (latest generation), which traditionally produces a 2D image of the structures in a thin section of the body. It uses X-rays. It has a greater ionizing radiation dose burden than projection radiography; repeated scans must be limited to avoid health effects.

 Ultrasound

Medical ultrasonography uses high frequency broadband sound waves in the megahertz range that are reflected by tissue to varying degrees to produce (up to 3D) images. This is commonly associated with imaging the fetus in pregnant women. Uses of ultrasound are much broader, however. Other important uses include imaging the abdominal organs, heart, breast, muscles, tendons, arteries and veins. While it may provide less anatomical detail than techniques such as CT or MRI, it has several advantages which make it ideal in numerous situations, in particular that it studies the function of moving structures in real-time, emits no ionizing radiation, and contains speckle that can be used in elastography. It is very safe to use and does not appear to cause any adverse effects, although information on this is not well documented. It is also relatively inexpensive and quick to perform. Ultrasound scanners can be taken to critically ill patients in intensive care units, avoiding the danger caused while moving the patient to the radiology department. The real time moving image obtained can be used to guide drainage and biopsy procedures. Doppler capabilities on modern scanners allow the blood flow in arteries and veins to be assessed.

Medical imaging topics

Creation of three-dimensional images

Recently, techniques have been developed to enable CT, MRI and ultrasound scanning software to produce 3D images for the physician.  Traditionally CT and MRI scans produced 2D static output on film. To produce 3D images, many scans are made, then combined by computers to produce a 3D model, which can then be manipulated by the physician. 3D ultrasounds are produced using a somewhat similar technique. In diagnosing disease of the viscera of abdomen,ultrasound is particularly sensitive on imaging of biliary tract,urinary tract and female reproductive organs(ovary,fallopian tubes).As for example,diagnosis of gall stone by dilatation of common bile duct and stone in common bile duct . With the ability to visualize important structures in great detail, 3D visualization methods are a valuable resource for the diagnosis and surgical treatment of many pathologies. It was a key resource for the famous, but ultimately unsuccessful attempt by Singaporean surgeons to separate Iranian twins Ladan and Laleh Bijani in 2003. The 3D equipment was used previously for similar operations with great success.

Other proposed or developed techniques include:

Some of these techniques are still at a research stage and not yet used in clinical routines.

Non-diagnostic imaging

Neuroimaging has also been used in experimental circumstances to allow people (especially disabled persons) to control outside devices, acting as a brain computer interface.

Archiving and Recording

Used primarily in ultrasound imaging, capturing the image a medical imaging device is required for archiving and telemedicine applications. In most scenarios, a frame grabber is used in order to capture the video signal from the medical device and relay it to a computer for further processing and operations.

Open source software

Several open source software packages are available for performing analysis of medical images:

Proprietary software

 Medical monitor

A medical monitor or physiological monitor or display, is an electronic medical device that measures a patient's vital signs and displays the data so obtained, which may or may not be transmitted on a monitoring network. Physiological data are displayed continuously on a CRT or LCD screen as data channels along the time axis, They may be accompanied by numerical readouts of computed parameters on the original data, such as maximum, minimum and average values, pulse and respiratory frequencies, and so on.

In critical care units of hospitals, bedside units allow continuous monitoring of a patient, with medical staff being continuously informed of the changes in general condition of a patient. Some monitors can even warn of pending fatal cardiac conditions before visible signs are noticeable to clinical staff, such as atrial fibrillation or premature ventricular contraction (PVC).

Analog monitoring

Old analog patient monitors were based on oscilloscopes, and had one channel only, usually reserved for electrocardiographic monitoring (ECG). So, medical monitors tended to be highly specialized. One monitor would track a patient's blood pressure, while another would measure pulse oximetry, another the ECG. Later analog models had a second or third channel displayed in the same screen, usually to monitor respiration movements and blood pressure. These machines were widely used and saved many lives, but they had several restrictions, including sensitivy to electrical interference, base level fluctuations, and absence of numeric readouts and alarms. In addition, although wireless monitoring telemetry was in principle possible (the technology was developed by NASA in the late 1950s for manned spaceflight, it was expensive and cumbersome.

Digital monitoring

With the development of digital signal processing (DSP) technology, however, medical monitors evolved enormously, and all current models are digital, which also has the advantages of miniaturization and portability. Today the trend is toward multiparameter monitors that can track many different vital signs at once. The parameters (or measurements) now consist of pulse oximetry (measurement of the saturated percentage of oxygen in the blood, referred to as SpO2, and measured by an infrared finger cuff), ECG (electrocardiograph of the QRS waves of the heart with or without an accompanying external heart pacemaker), blood pressure (either invasively through an inserted blood pressure transducer assembly, or non-invasively with an inflatable blood pressure cuff), and body temperature through an adhesive pad containing a thermoelectric transducer. In some situations, other parameters can be measured and displayed, such as cardiac output (via an invasive Swan-Ganz catheter), capnography (CO2 measurements, referred to as EtCO2 or end-tidal carbon dioxide concentration), respiration (through a thoracic transducer belt, an ECG channel or via EtCO2, when it is called AWRR or airway respiratory rate), etc.

Besides the tracings of physiological parameters along time (X axis), digital medical monitors have automated numeric readouts of the peak and/or average parameters displayed on the screen, and high]low alarm levels can be set, which alert the staff when some parameter exceeds of falls the level limits, using audible signals.

Several models of multiparameter monitors are networkable, i.e., they can send their output to a central ICU monitoring station, where a single staff member can observe and respond to several bedside monitors simultaneously. Ambulatory telemetry can also be achieved by portable, battery-operated models which are carried by the patient and which transmit their data via a wireless data connection.

Monitor/Defibrillators

Some digital patient monitors, especially those used EMS services,often incorporate a defibrillator into the patient monitor itself. These monitor/defibrillators usually have the normal capabilities of an ICU monitor, but have have manual (and usually semi-automatic AED)defibrillation capability. This is particular good for EMS services, who need a compact, easy to use monitor and defibrillator, as well as for inter- or intrafacility patient transport. Most monitor defibrillators also have transcutaneous pacing capability via large AED like adhesive pads (which often can be used for monitoring, defibrillation and pacing)that are applied to the patient in an ANTERIOR-POSTERIOR configuration. The monitor defibrillator units often have specialized monitoring parameters such as waveform capnography,invasive BP, and in some monitors, Masimo Rainbow SET pulse oximetry. Examples of monitor defibrillators are the Lifepak 12, 15 and 20 made by Physio control, and the Phillips Heartstart MRx. 

A Welch Allyn PIC 50 monitor/defibrillator from an Austrian EMS service. 

A closeup view of the screen of the PIC 50.

Special applications 

There are special patient monitors for several applications, such as anesthesia monitoring, which incorporate the monitoring of brain waves (EEG, gas anesthetic concentrations, bispectral index (BIS), etc. They are usually incorporated into anesthesia machines. In neurosurgery intensive care units, brain EEG monitors have a larger multichannel capability and can monitor other physiological events, as well.

Portable heart monitors are now very common too, and they exist in several configurations, ranging from single-channel models for domestic use, which are capable of storing or transmitting the signals for appraisal by a physician, to 12-lead complete, portable ECG machines which can store for 24 hours or more (so-called Holter monitoring devices). There are also portable monitors for blood pressure (MAPA) and EEG.

Monitor types

Monitors may be classified as:

  1. Handheld
  2. Portable
  3. Monitor/Defibrillator (usually portable)
  4. Tabletop
  5. Networkable / non-networkable
  6. Wired / wireless data transmission
  7. Mains powered or mains + battery powered

Integration with EHR

Digital monitoring has created the possibility, which is being fully developed, of integrating the physiological data from the patient monitoring networks into the emerging hospital electronic health record and digital charting systems, using appropriate health care standards which have been developed for this purpose by organizations such as IEEE and HL7. This newer method of charting patient data reduces the likelihood of human documentation error and will eventually reduce overall paper consumption. In addition, automated ECG interpretation incorporates diagnostic codes automatically into the charts. Medical monitor's embedded software can take care of the data coding according to these standards and send messages to the medical records application, which decodes them and incorporates the data into the adequate fields.

Patient safety

Medical monitors have been safety engineered so that failures are either apparent or unimportant.Some monitors (for example ECG and EEG) have an electrical contact with the patient, so they can be hazardous if electrical current passes through these electrodes in case of grounding failures. There are strict limits on how much current and voltage can be applied, even if the unit fails or becomes wet. They must typically withstand electrical defibrillation without damage.

 

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