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Medical imaging refers to the techniques and processes used to create images of the human body (or parts thereof) for clinical purposes (medical procedures seeking to reveal, diagnose or examine disease) or medical science (including the study of normal anatomy and function). An image (from Latin imago) or picture is an artifact usually two-dimensional that has a similar appearance to some subject &mdashusually A medical procedure is a course of action intended to achieve a result in the care of patients used by medical or paramedical personnel Diagnosis is the identification by Process of elimination, of the nature of anything A disease is an abnormal condition of an organism that impairs bodily functions and can be deadly As a discipline and in its widest sense, it is part of biological imaging and incorporates radiology (in the wider sense), radiological sciences, endoscopy, (medical) thermography, medical photography and microscopy (e. Biological imaging may refer to any Imaging technique used in Biology. Radiology is the medical specialty directing Medical imaging technologies to diagnose and treat diseases Radiology is the medical specialty directing Medical imaging technologies to diagnose and treat diseases Endoscopy means looking inside and typically refers to looking inside the body for medical reasons using an instrument called an endoscope. wiki stranglesnakejpg|thumb|Thermographic image of a Snake held by a human]] Infrared Thermography, thermal imaging, or thermal video, is a type of Microscopy is the technical field of using microscopes to view samples or objects g. for human pathological investigations). Measurement and recording techniques which are not primarily designed to produce images, such as electroencephalography (EEG) and magnetoencephalography (MEG) and others, but which produce data susceptible to be represented as maps (i. An image (from Latin imago) or picture is an artifact usually two-dimensional that has a similar appearance to some subject &mdashusually Magnetoencephalography ( MEG) is an imaging technique used to measure the Magnetic fields produced by electrical activity in the A map is a visual representation of an area—a symbolic depiction highlighting relationships between elements of that space such as objects, Regions, and Themes e. containing positional information), can be seen as forms of medical imaging.

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. Radiology is the medical specialty directing Medical imaging technologies to diagnose and treat diseases Radiology is the medical specialty directing Medical imaging technologies to diagnose and treat diseases Diagnostic radiography designates the technical aspects of medical imaging and in particular the acquisition of medical images. For medical radiography see Radiology Radiography is the use of X-rays to view unseen or hard-to-image objects The radiographer or radiologic technologist is usually responsible for acquiring medical images of diagnostic quality, although some radiological interventions are performed by radiologists. A radiologic technologist, or radiographer, is a healthcare professional who creates medical images of the body to help health care providers diagnose and treat illness and injury Radiology is the medical specialty directing Medical imaging technologies to diagnose and treat diseases

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. Biomedical engineering ( BME) is the application of engineering principles and techniques to the medical field Medical physics is the application of Physics to Medicine. It generally concerns physics as applied to Medical imaging and Radiotherapy, although Medicine is the art and science of healing It encompasses a range of Health care practices evolved to maintain and restore Human Health by the 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. For medical radiography see Radiology Radiography is the use of X-rays to view unseen or hard-to-image objects Biomedical engineering ( BME) is the application of engineering principles and techniques to the medical field Medical physics is the application of Physics to Medicine. It generally concerns physics as applied to Medical imaging and Radiotherapy, although Computer science (or computing science) is the study and the Science of the theoretical foundations of Information and Computation and their Medical imaging refers to the techniques and processes used to create Images of the human body (or parts thereof for clinical purposes ( Medical procedures seeking to Radiology is the medical specialty directing Medical imaging technologies to diagnose and treat diseases Neuroscience is a field devoted to the scientific study of the nervous system Cardiology (from Greek grc καρδίᾱ kardiā, "heart" and grc -λογία -logia) is the branch of Internal medicine Psychiatry is a medical specialty which exists to study, prevent, and treat Mental disorders in Humans Psychiatric Psychology (from Greek grc ψῡχή psȳkhē, "breath life soul" and grc -λογία -logia) is an Academic and Many of the techniques developed for medical imaging also have scientific and industrial applications. Science (from the Latin scientia, meaning " Knowledge " or "knowing" is the effort to discover, and increase human understanding For other uses of this term see Industry (disambiguation An industry (from Latin industrius, "diligent industrious"

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. Mathematics is the body of Knowledge and Academic discipline that studies such concepts as Quantity, Structure, Space and An inverse problem is the task that often occurs in many branches of Science and Mathematics where the values of some model parameter(s must be obtained from the 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. X-radiation (composed of X-rays) is a form of Electromagnetic radiation. Electromagnetic radiation takes the form of self-propagating Waves in a Vacuum or in Matter.

Contents

Modern imaging technology

Projection radiography

For main article see Projectional Radiography

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. Projectional radiography or plain film radiography is the practise of producing 2D X-ray images X-radiation (composed of X-rays) is a form of Electromagnetic radiation. 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. Radiopacity refers to the relative inability of electromagnetism to pass through a particular material particularly X-rays. Barium (ˈbɛəriəm is a Chemical element. It has the symbol Ba, and Atomic number 56 Colorectal cancer, also called colon cancer or large bowel cancer, includes Cancerous growths in the colon, Rectum and

Tomography

Tomography is the method of imaging a single plane, or slice, of an object resulting in a tomogram. Tomography is imaging by sections or sectioning A device used in tomography is called a tomograph, while the image produced is a tomogram. Tomography is imaging by sections or sectioning A device used in tomography is called a tomograph, while the image produced is a tomogram. There are several forms of tomography:

Further information: computed tomography

Ultrasound

Main article: Medical ultrasonography

Medical ultrasonography uses high frequency sound waves of between 2. 0 to 10. 0 megahertz that are reflected by tissue to varying degrees to produce a 2D image, traditionally on a TV monitor. The hertz (symbol Hz) is a measure of Frequency, informally defined as the number of events occurring per Second. This is often used to visualize the fetus in pregnant women. A fetus (or foetus or fœtus) is a developing Mammal or other Viviparous Vertebrate, after the Embryonic stage and Other important uses include imaging the abdominal organs, heart, male genitalia, and the veins of the leg. While it may provide less anatomical information than techniques such as CT or MRI, it has several advantages which make it ideal as a first line test in numerous situations, in particular that it studies the function of moving structures in real-time. It is also very safe to use, as the patient is not exposed to radiation and the ultrasound does not appear to cause any adverse effects, although information on this is not well documented. It is also relatively cheap 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.

Fluoroscopy

Main article: Fluoroscopy

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. Fluoroscopy is an imaging technique commonly used by Physicians to obtain real-time moving images of the internal structures of a patient through the use of a fluoroscope For medical radiography see Radiology Radiography is the use of X-rays to view unseen or hard-to-image objects X-radiation (composed of X-rays) is a form of Electromagnetic radiation. 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.

Magnetic resonance imaging (MRI)

Main article: Magnetic resonance imaging
A brain MRI representation
A brain MRI representation

A Magnetic Resonance Imaging instrument (MRI scanner) 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. Hydrogen (ˈhaɪdrədʒən is the Chemical element with Atomic number 1 The proton ( Greek πρῶτον / proton "first" is a Subatomic particle with an Electric charge of one positive In brief, MRI involves the use of three kinds of electromagnetic field: a very strong (of the order of units of teslas) static magnetic field to polarize the hydrogen nuclei, called the static field; a weaker time-varying (of the order of 1 kHz) 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. The electromagnetic field is a physical field produced by electrically charged objects. The tesla (symbol T) is the SI derived unit of Magnetic field B (which is also known as "magnetic flux density" and "magnetic Radio frequency ( RF) is a Frequency or rate of Oscillation within the range of about 3 Hz to 300 GHz An antenna is a Transducer designed to transmit or Receive electromagnetic waves In other words antennas convert electromagnetic waves into Like CT, MRI traditionally creates a 2D image of a thin "slice" of the body and is therefore considered a tomographic imaging technique. Tomography is imaging by sections or sectioning A device used in tomography is called a tomograph, while the image produced is a tomogram. 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 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 on the number of scans to which an individual can be subjected, in contrast with X-ray and CT. Image talkNew_radiation_symbol_ISO_21482svg for details --> Ionizing radiation X-radiation (composed of X-rays) is a form of Electromagnetic radiation. Computed tomography (CT is a Medical imaging method employing Tomography. 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. CT and MRI being sensitive to different properties of the tissue, 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, therefore the image quality when looking at soft tissues will be poor. 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, since it is so ubiquitous and returns much signal. This nucleus, present in water molecules, allows excellent soft-tissue contrast.

MRI, or "NMR imaging" as it was originally known, has only been in use since the early 1980s. Effects from long term, or repeated exposure, to the intense static magnetic field are not known.

Nuclear medicine

Main article: Nuclear Medicine

Images from gamma cameras are used in Nuclear Medicine to detect regions of biological activity that are often associated with diseases. Nuclear medicine is a branch of Medicine and Medical imaging that uses the nuclear properties of matter in diagnosis and therapy A gamma camera is a device used to image gamma radiation emitting radioisotopes a technique known as scintigraphy A short lived isotope, such as 123I is administered to the patient. Isotopes (Greek isos = "equal" tópos = "site place" are any of the different types of atoms ( Nuclides Iodine-123 (123I is a radioactive Isotope of Iodine used in Nuclear medicine imaging including Single photon These isotopes are more readily absorbed by biologically active regions of the body, such as tumors or fracture points in bones. A fracture is the (local separation of an object or material into two or more pieces under the action of stress.

Positron emission tomography (PET)

Main article: Positron Emission Tomography

Positron emission tomography is primarily used to detect diseases of the brain and heart. Positron emission tomography ( PET) is a Nuclear medicine imaging technique which produces a three-dimensional image or map of functional processes in the Similarly to nuclear medicine, a short-lived isotope, such as 18F, is incorporated into a substance used by the body such as glucose which is absorbed by the tumor of interest. Glucose (Glc a Monosaccharide (or simple Sugar) also known as grape sugar, is an important Carbohydrate in Biology. PET scans are often viewed alongside computed tomography scans, which can be performed on the same equipment without moving the patient. Computed tomography (CT is a Medical imaging method employing Tomography. This allows the tumors detected by the PET scan to be viewed next to the rest of the patient's anatomy detected by the CT scan.

Photoacoustic imaging

Main article: Photoacoustic imaging in biomedicine

Photoacoustic imaging is a recently developed hybrid biomedical imaging modality based on the photoacoustic effect. Photoacoustic imaging, as a hybrid biomedical imaging modality is developed 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.

Clinical imaging or biological imaging techniques

Electron microscopy

Main article: Electron microscope

The electron microscope is a microscope that can magnify very small details with high resolving power due to the use of electrons as the source of illumination, magnifying at levels up to 2,000,000 times. An electron microscope is a type of Microscope that uses Electrons to illuminate a specimen and create an enlarged image

Electron microscopy is employed in anatomic pathology to identify organelles within the cells. Pathology; please do not remove --> ( Its usefulness has been greatly reduced by immunhistochemistry but it is still irreplaceable for the diagnosis of kidney disease, identification of immotile cilia syndrome and many other tasks

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. Immunohistochemistry or IHC refers to the process of localizing proteins in cells of a tissue section exploiting the principle of antibodies binding specifically 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.

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. Ladan Bijani and Laleh Bijani (in Persian: لادن و لاله بیژنی ( January 17, 1974 &ndash July 8, 2003) were 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. Diffuse optical imaging (DOI or diffuse optical tomography (DOT is a Medical imaging modality which uses near Infrared light to generate images of the Elastography is a non-invasive method in which stiffness or strain Images of Soft tissue are used to detect or classify Tumors. Electrical Impedance Tomography (EIT is a Medical imaging technique in which an image of the conductivity or permittivity of part of the body is inferred from surface electrical Optoacoustic imaging ( Photoacoustic Imaging) is an Imaging technology based on the Photoacoustic effect, and can be used to obtain images of structures Ophthalmology is the branch of Medicine which deals with the diseases and surgery of the visual pathways including the Eye, Brain A-scan ultrasound biometry, commonly referred to as an A-scan, is routine type of diagnostic test used in Ophthalmology. B-scan ultrasonography, or B-scan, is a diagnostic test used in Ophthalmology to produce a two-dimensional cross-sectional view of the Eye and the Corneal topography, also known as photokeratoscopy or videokeratography, is a non-invasive Medical imaging technique for mapping the surface Optical coherence tomography (OCT is an optical signal acquisition and processing method allowing extremely high-quality micrometre-resolution three-dimensional images from within optical Scanning laser ophthalmoscopy is a method of examination of the Eye.

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. Neuroimaging includes the use of various techniques to either directly or indirectly image the structure, function/ Pharmacology of the Brain A brain-computer interface (BCI sometimes called a direct neural interface or a brain-machine interface, is a direct communication pathway between a human or animal

Medical imaging service

SMPTE Medical Diagnostic Imaging Test Pattern
SMPTE Medical Diagnostic Imaging Test Pattern

This is a specialized area of medical equipment service and repair, which is separate from the biomedical field, although a hospital with their own service group may include them in the biomed department. Medical equipment is designed to aid in the diagnosis monitoring or treatment of medical conditions Biomedical research (or experimental medicine) in general simply known as medical research, is the Basic research or Applied research conducted

At one time, there were only two ways to receive training for this field. One was to learn it in the military, and the other was on-the-job training (OJT) from the manufacturer. But since the 1980s several independent training centers have been started. One such school is RSTI [2].

There are different means of employment in this occupation. Working for the manufacturer's field service department (OEM), working for a hospital (in-house), and working for an independent (outside, or independent provider). The most stable positions are with the OEM or hospital, as you can remain current through on-going training, and the two have good working relationships.

The OEM service engineer can expect to spend a lot of time driving from one site to another during the work day, and working non-standard hours. They will install, remove, diagnose, repair, calibrate, perform preventive maintenance, and interface equipment, all while ensuring good customer relations. You may also be required to do yearly testing of the radiation sources for Federal [3] and State compliance.

The in-house person is employed by the hospital. With larger medical facilities, travel between the hospitals' other locations may be required to perform the required services. You may also be required to do yearly testing of the radiation sources for compliance. The OEM or independent will provide installation of purchased equipment, and can be used for back-up service.

An independent is typically someone who has left an OEM, and started their own service business. Staying up-to-date as an independent can be difficult and expensive, as the OEM is usually reluctant to provide training. However, non-OEM training facilities are available, such as the aforementioned RSTI. Competition for service can be aggressive, with OEM's giving hospitals or clinics a reduction in equipment purchase price if they retain some form of OEM service.

The independent may also sell and install refurbished equipment, or de-install equipment. They will repair, calibrate, and perform preventative maintenance. Because many of the tasks associated with imaging service require expensive, specialized equipment, there may be a financial limit to the independent. Typical equipment used routinely are a Storage Oscilloscope and multimeter (if servicing old vacuum-state equipment, a VOM would be helpful). An oscilloscope (commonly abbreviated to scope or O-scope) is a type of Electronic test equipment that allows signal Voltages to be viewed A multimeter or a multitester, also known as a volt/ohm meter or VOM, is an electronic Measuring instrument that combines several Additional equipment: Keithley dosimeter, mAs meter, Biddle contact tachometer, light to radiation template, etc.

See also

Open source software

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

As well as academic free software:

External links

Further reading

References

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