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TYPES OF BIOMEDICAL INSTRUMENTS:

Diagnostic equipment includes medical imaging machines, used to aid in diagnosis. Examples are ultrasound and

MRI machines, PET and CT scanners, and x-ray machines.

Therapeutic equipment includes infusion pumps, medical lasers and LASIK surgical machines.

Life support equipment is used to maintain a patient's bodily function. This includes medical ventilators,

anaesthetic machines, heart-lung machines, ECMO, and dialysis machines.

Medical monitors allow medical staff to measure a patient's medical state. Monitors may measure patient vital

signs and other parameters including ECG, EEG, blood pressure, and dissolved gases in the blood.

Medical laboratory equipment automates or helps analyze blood, urine and genes.

Diagnostic Medical Equipment may also be used in the home for certain purposes, e.g. for the control of diabetes

mellitus

1-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.

IMPORTANT INVENTIONS of Biomedical Instruments:

1895, X-ray, by Wilhelm Röntgen

1903, electrocardiograph, by Willem Einthoven

1952, magnetic resonance imaging, by Herman Carr

1956, endoscope, by Basil Hirschowitz

1958, ultrasound scan, by Ian Donald

1958, Pacemaker, by Rune Elmqvist

1973, CT (CAT) scan, by Godfrey Hounsfield and Allan Cormack

1982, artificial heart, by Robert Jarvik[1]

LASIK

LASIK or Lasik (Laser-Assisted in Situ Keratomileusis), commonly referred to as laser eye surgery, is a type of

refractive surgery for the correction of myopia, hyperopia, and astigmatism.

The LASIK surgery is performed by an ophthalmologist who uses a laser or microkeratome to reshape the eye's cornea in

order to improve visual acuity.[1]

For most patients, LASIK provides a permanent alternative to eyeglasses or contact

lenses.[2]

Major side effects include halos, starbursts, night-driving problems, ectasia, and eye dryness. [3]

LASIK is most similar to another surgical corrective procedure, photorefractive keratectomy (PRK), and both represent

advances over radial keratotomy in the surgical treatment of refractive errors of vision.

For patients with moderate to high myopia or thin corneas which cannot be treated with LASIK and PRK, the implantable

collamer lens is a popular alternative.[4][5]

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STETHOSCOPE

The stethoscope is an acoustic medical device for auscultation, or listening to the internal sounds of an animal or human

body. It is often used to listen to lung and heart sounds. It is also used to listen to intestines and blood flow in arteries and

veins. In combination with a sphygmomanometer, it is commonly used for measurements of blood pressure. Less

commonly, "mechanic's stethoscopes" are used to listen to internal sounds made by machines, such as diagnosing a

malfunctioning automobile engine by listening to the sounds of its internal parts. Stethoscopes can also be used to check

scientific vacuum chambers for leaks, and for various other small-scale acoustic monitoring tasks. A stethoscope that

intensifies auscultatory sounds is called phonendoscope.

René-Théophile-Hyacinthe Laennec[1]

was a French physician. He invented the stethoscope in 1816, while working at

the Hôpital Necker and pioneered its use in diagnosing various chest conditions.

Types of stethoscopes

Acoustic

Electronic

Recording stethoscopes

Some electronic stethoscopes feature direct audio output that can be used with an external recording device, such as a

laptop or MP3 recorder. The same connection can be used to listen to the previously-recorded auscultation through the

stethoscope headphones, allowing for more detailed study for general research as well as evaluation and consultation

regarding a particular patient's condition and telemedicine, or remote diagnosis.

Fetal stethoscope

A fetal stethoscope or fetoscope is an acoustic stethoscope shaped like a listening trumpet. It is placed against the

abdomen of a pregnant woman to listen to the heart sounds of the fetus. The fetal stethoscope is also known as a

Pinard's stethoscope or a pinard, after French obstetrician Adolphe Pinard (1844–1934).

Doppler stethoscope

A Doppler stethoscope is an electronic device which measures the Doppler effect of ultrasound waves reflected from

organs within the body. Motion is detected by the change in frequency, due to the The Doppler effect, of the reflected

waves. Hence the Doppler stethoscope is particularly suited to deal with moving objects such as a beating heart

Artificial cardiac pacemaker

A pacemaker (or artificial pacemaker, so as not to be confused with the heart's natural pacemaker) is a medical device

that uses electrical impulses, delivered by electrodes contacting the heart muscles, to regulate the beating of the heart.

The primary purpose of a pacemaker is to maintain an adequate heart rate, either because the heart's native pacemaker

is not fast enough, or there is a block in the heart's electrical conduction system. Modern pacemakers are externally

programmable and allow the cardiologist to select the optimum pacing modes for individual patients. Some combine a

pacemaker and defibrillator in a single implantable device. Others have multiple electrodes stimulating differing positions

within the heart to improve synchronisation of the lower chambers (ventricles) of the heart.

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Endoscopy /ɛnˈdɒskəpi/ means looking inside and typically refers to looking inside the body for medical reasons using

an endoscope /ˈɛndəskoʊp/, an instrument used to examine the interior of a hollow organ or cavity of the body. Unlike

most other medical imaging devices, endoscopes are inserted directly into the organ. Endoscopy can also refer to using a

borescope in technical situations where direct line of-sight observation is not feasible.

An endoscope can consist of

a rigid or flexible tube

a light delivery system to illuminate the organ or object under inspection. The light source is normally outside the

body and the light is typically directed via an optical fiber system

a lens system transmitting the image from the objective lens to the viewer, typically a relay lens system in the

case of rigid endoscopes or a bundle of fiberoptics in the case of a fiberscope

an eyepiece

an additional channel to allow entry of medical instruments or manipulators.

ELECTROCARDIOGRAPHY (ECG or EKG )

is a transthoracic (across the thorax or chest) interpretation of the electrical activity of the heart over a period of time, as

detected by electrodes attached to the outer surface of the skin and recorded by a device external to the body.[1]

The

recording produced by this noninvasive procedure is termed as electrocardiogram (also ECG or EKG). An ECG test

records the electrical activity of the heart.

ECG is used to measure the rate and regularity of heartbeats, as well as the size and position of the chambers, the

presence of any damage to the heart, and the effects of drugs or devices used to regulate the heart, such as a

pacemaker.Most ECGs are performed for diagnostic or research purposes on human hearts, but may also be performed

on animals, usually for diagnosis of heart abnormalities or research.

Function of ECG:

An ECG is the best way to measure and diagnose abnormal rhythms of the heart,[2]

particularly abnormal rhythms caused

by damage to the conductive tissue that carries electrical signals, or abnormal rhythms caused by electrolyte

imbalances.[3]

In a myocardial infarction (MI), the ECG can identify if the heart muscle has been damaged in specific

areas, though not all areas of the heart are covered.[4]

The ECG cannot reliably measure the pumping ability of the heart,

for which ultrasound-based (echocardiography) or nuclear medicine tests are used. It is possible for a human or other

animal to be in cardiac arrest, but still have a normal ECG signal (a condition known as pulseless electrical activity).

The ECG device detects and amplifies the tiny electrical changes on the skin that are caused when the heart muscle

depolarizes during each heartbeat. At rest, each heart muscle cell has a negative charge, called the membrane potential,

across its cell membrane. Decreasing this negative charge towards zero, via the influx of the positive cations, Na+ and

Ca++

, is called depolarization, which activates the mechanisms in the cell that cause it to contract.

During each heartbeat, a healthy heart will have an orderly progression of a wave of depolarisation that is triggered by

the cells in the sinoatrial node, spreads out through the atrium, passes through the atrioventracular node and then

spreads all over the ventricles. This is detected as tiny rises and falls in the voltage between two electrodes placed either

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side of the heart which is displayed as a wavy line either on a screen or on paper. This display indicates the overall

rhythm of the heart and weaknesses in different parts of the heart muscle.

Arthroscopy –DONE BY ARTHROSCOPES

Arthroscopy (also called arthroscopic surgery) is a minimally invasive surgical procedure in which an examination and

sometimes treatment of damage of the interior of a joint is performed using an arthroscope, a type of endoscope that is

inserted into the joint through a small incision. Arthroscopic procedures can be performed either to evaluate or to treat

many orthopaedic conditions including torn floating cartilage, torn surface cartilage, ACL reconstruction, and trimming

damaged cartilage.

The advantage of arthroscopy over traditional open surgery is that the joint does not have to be opened up fully. Instead,

for knee arthroscopy for example, only two small incisions are made — one for the arthroscope and one for the surgical

instruments to be used in the knee cavity. This reduces recovery time and may increase the rate of surgical success due

to less trauma to the connective tissue.

It is especially useful for professional athletes, who frequently injure knee joints and require fast healing time. There is

also less scarring, because of the smaller incisions. Irrigation fluid is used to distend the joint and make a surgical space.

Sometimes this fluid leaks into the surrounding soft tissue causing extravasation and edema.

ELECTROENCEPHALOGRAPHY (EEG)

is the recording of electrical activity along the scalp. EEG measures voltage fluctuations resulting from ionic current flows

within the neurons of the brain.[1]

In clinical contexts, EEG refers to the recording of the brain's spontaneous electrical

activity over a short period of time, usually 20–40 minutes, as recorded from multiple electrodes placed on the scalp.

Diagnostic applications generally focus on the spectral content of EEG, that is, the type of neural oscillations that can be

observed in EEG signals. In neurology, the main diagnostic application of EEG is in the case of epilepsy, as epileptic

activity can create clear abnormalities on a standard EEG study.[2]

A secondary clinical use of EEG is in the diagnosis of

coma, encephalopathies, and brain death. A third clinical use of EEG is for studies of sleep and sleep disorders where

recordings are typically done for one full night, sometimes more. EEG used to be a first-line method for the diagnosis of

tumors, stroke and other focal brain disorders,[3]

but this use has decreased with the advent of anatomical imaging

techniques with high (<1 mm) spatial resolution such as MRI and CT. Despite limited spatial resolution, EEG continues to

be a valuable tool for research and diagnosis, especially when millisecond-range temporal resolution (not possible with

CT or MRI) is required.

MAGNETOENCEPHALOGRAPHY (MEG)

is a technique for mapping brain activity by recording magnetic fields produced by electrical currents occurring naturally in

the brain, using very sensitive magnetometers. Arrays of SQUIDs (superconducting quantum interference devices) are

currently the most common magnetometer, and SERF being investigated for future machines. Applications of MEG

include basic research into perceptual and cognitive brain processes, localizing regions affected by pathology before

surgical removal, determining the function of various parts of the brain, and neurofeedback.

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MEG vs. EEG

Although EEG and MEG signals originate from the same neurophysiological processes, there are important

differences.[20]

Magnetic fields are less distorted than electric fields by the skull and scalp, which results in a better spatial

resolution of the MEG. Whereas scalp EEG is sensitive to both tangential and radial components of a current source in a

spherical volume conductor, MEG detects only its tangential components. MEG therefore measures activity in the sulci

selectively, whereas scalp EEG measures activity both in the sulci and at the top of the cortical gyri. EEG is therefore

sensitive to activity in more brain areas, but activity that is visible in MEG can also be localized with more accuracy.

Scalp EEG is sensitive to extracellular volume currents produced by postsynaptic potentials. MEG primarily detects

intracellular currents associated with these synaptic potentials because the field components generated by volume

currents tend to cancel out in a spherical volume conductor[21]

The decay of magnetic fields as a function of distance is

more pronounced than for electric fields. MEG is therefore more sensitive to superficial cortical activity, which makes it

useful for the study of neocortical epilepsy.

ANGIOGRAPHY OR ARTERIOGRAPHY

is a medical imaging technique used to visualize the inside, or lumen, of blood vessels and organs of the body, with

particular interest in the arteries, veins and the heart chambers. This is traditionally done by injecting a radio-opaque

contrast agent into the blood vessel and imaging using X-ray based techniques such as fluoroscopy.

The word itself comes from the Greek words angeion, "vessel", and graphein, "to write" or "record". The film or image of

the blood vessels is called an angiograph, or more commonly, an angiogram.

Though the word itself can describe both an arteriogram and a venogram, in its everyday usage, the terms angiogram

and arteriogram are often used synonymously, whereas the term venogram is used more precisely.[1]

The term angiography is strictly defined as based on projectional radiography; however, the term has been applied to

newer vascular imaging techniques such as CT angiography and MR angiography. The term isotope angiography has

also been used, although this more correctly is referred to as isotope perfusion scanning.

DIAGNOSTIC SONOGRAPHY (ULTRASONOGRAPHY) is an ultrasound-based diagnostic imaging technique used for

visualizing subcutaneous body structures including tendons, muscles, joints, vessels and internal organs for possible

pathology or lesions. Obstetric sonography is commonly used during pregnancy and is widely recognized by the public.

In physics, the term "ultrasound" applies to all sound waves with a frequency above the audible range of normal human

hearing, about 20 kHz.

The frequencies used in diagnostic ultrasound are typically between 2 and 18 MHz.

DIAGNOSTIC APPLICATIONS OF ULTRASOUND:

Typical diagnostic sonographic scanners operate in the frequency range of 2 to 18 megahertz, though frequencies up to

50–100 megahertz have been used experimentally in a technique known as biomicroscopy in special regions, such as the

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anterior chamber of the eye.[citation needed]

The choice of frequency is a trade-off between spatial resolution of the image and

imaging depth: lower frequencies produce less resolution but image deeper into the body. Higher frequency sound waves

have a smaller wavelength and thus are capable of reflecting or scattering from smaller structures. Higher frequency

sound waves also have a larger attenuation coefficient and thus are more readily absorbed in tissue, limiting the depth of

penetration of the sound wave into the body.

Sonography (ultrasonography) is widely used in medicine. It is possible to perform both diagnosis and therapeutic

procedures, using ultrasound to guide interventional procedures (for instance biopsies or drainage of fluid collections).

Sonographers are medical professionals who perform scans which are then typically interpreted by radiologists,

physicians who specialize in the application and interpretation of a wide variety of medical imaging modalities, or by

cardiologists in the case of cardiac ultrasonography (echocardiography). Sonographers typically use a hand-held probe

(called a transducer) that is placed directly on and moved over the patient. Increasingly, clinicians (physicians and other

healthcare professionals who provide direct patient care) are using ultrasound in their office and hospital practices, for

efficient, low-cost, dynamic diagnostic imaging that facilitates treatment planning while avoiding any radiation exposure.

Sonography is effective for imaging soft tissues of the body. Superficial structures such as muscles, tendons, testes,

breast, thyroid and parathyroid glands, and the neonatal brain are imaged at a higher frequency (7–18 MHz), which

provides better axial and lateral resolution. Deeper structures such as liver and kidney are imaged at a lower frequency

1–6 MHz with lower axial and lateral resolution but greater penetration.

Anesthesia, or anaesthesia traditionally meant the condition of having sensation (including the feeling of pain) blocked

or temporarily taken away. It is a pharmacologically induced and reversible state of amnesia, analgesia, loss of

responsiveness, loss of skeletal muscle reflexes or decreased stress response, or all simultaneously. These effects can

be obtained from a single drug which alone provides the correct combination of effects, or occasionally a combination of

drugs (such as hypnotics, sedatives, paralytics and analgesics) to achieve very specific combinations of results. This

allows patients to undergo surgery and other procedures without the distress and pain they would otherwise experience.

An alternative definition is a "reversible lack of awareness," including a total lack of awareness (e.g. a general anesthetic)

or a lack of awareness of a part of the body such as a spinal anesthetic. The pre-existing word anesthesia was suggested

by Oliver Wendell Holmes, Sr. in 1846 as a word to use to describe this state

Echocardiography

Echocardiogram, often referred to cardiac echo or simply an echo is a sonogram of the heart. (It is not abbreviated as

ECG, which in medicine usually refers to an electrocardiogram.) Echocardiography uses standard two-dimensional, three-

dimensional, and Doppler ultrasound to create images of the heart.

Cardiology is a medical specialty dealing with disorders of the heart (specifically the human heart). The field includes

medical diagnosis and treatment of congenital heart defects, coronary artery disease, heart failure, valvular heart disease

and electrophysiology. Physicians who specialize in this field of medicine are called cardiologists. Physicians who

specialize in cardiac surgery are called cardiac surgeons.

3D ultrasound is a medical ultrasound technique, often used in obstetric ultrasonography (during pregnancy), providing

three dimensional images of the fetus.

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There are several different scanning modes in medical and obstetric ultrasound. The standard common obstetric

diagnostic mode is 2D scanning.[1]

In 3D fetal scanning, however, instead of the sound waves being sent straight down

and reflected back, they are sent at different angles. The returning echoes are processed by a sophisticated computer

program resulting in a reconstructed three dimensional volume image of fetus's surface or internal organs, in much the

same way as a CT scan machine constructs a CT scan image from multiple x-rays. 3D ultrasounds allow one to see

width, height and depth of images in much the same way as 3D movies but no movement is shown[dubious – discuss]

.

3D ultrasound was first developed by Olaf von Ramm and Stephen Smith at Duke University in 1987.[2]

Duplex ultrasonography (more commonly but less correctly known as duplex ultrasound) is a form of medical

ultrasonography that incorporates two elements:

1) Grayscale Ultrasound to visualize the structure or architecture of the body part. No motion or bloodflow is

assessed. This is the way plaque is directly imaged in a blood vessel, with the reader typically commenting on

crossectional narrowing (greater than 70% is typically considered worthy of treatment).

2) Color-doppler Ultrasound to visualize the flow or movement of a structure, typically used to image blood within

an artery. We see blood flow velocities increase through a region of narrowing, like a finger pressing up against

the end of a running garden hose. Increased velocities indicate a region of narrowing or resistance (velocities

greater than 250 cm/sec typically considered worthy of treatment).

MRI:

Magnetic resonance imaging (MRI), nuclear magnetic resonance imaging (NMRI), or magnetic resonance

tomography (MRT) is a medical imaging technique used in radiology to visualize internal structures of the body in detail.

MRI makes use of the property of nuclear magnetic resonance (NMR) to image nuclei of atoms inside the body.

An MRI scanner is a device in which the patient lies within a large, powerful magnet where the magnetic field is used to

align the magnetization of some atomic nuclei in the body, and radio frequency magnetic fields are applied to

systematically alter the alignment of this magnetization.[1]

This causes the nuclei to produce a rotating magnetic field

detectable by the scanner—and this information is recorded to construct an image of the scanned area of the body.[2]:36

Magnetic field gradients cause nuclei at different locations to precess at different speeds, which allows spatial information

to be recovered using Fourier analysis of the measured signal. By using gradients in different directions 2D images or 3D

volumes can be obtained in any arbitrary orientation.

MRI provides good contrast between the different soft tissues of the body, which makes it especially useful in imaging the

brain, muscles, the heart, and cancers compared with other medical imaging techniques such as computed tomography

(CT) or X-rays. Unlike CT scans or traditional X-rays, MRI does not use ionizing radiation.[3]

How MRI Works:

MRI machines make use of the fact that body tissue contains lots of water, and hence protons (1H nuclei), which get

aligned in a large magnetic field.[4]

Each water molecule has two hydrogen nuclei or protons. When a person is inside the

powerful magnetic field of the scanner, the average magnetic moment of many protons becomes aligned with the

direction of the field. A radio frequency current is briefly turned on, producing a varying electromagnetic field. This

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electromagnetic field has just the right frequency, known as the resonance frequency, to be absorbed and flip the spin of

the protons in the magnetic field. After the electromagnetic field is turned off, the spins of the protons return to

thermodynamic equilibrium and the bulk magnetization becomes re-aligned with the static magnetic field. During this

relaxation, a radio frequency signal (electromagnetic radiation in the RF range) is generated, which can be measured with

receiver coils.

Jemris is an open source MRI sequence design and simulation framework written in C++.

It was designed to most generally and numerically integrate the Bloch equation in a single-core or parallel fashion for

protons over a time course of a sequence on almost arbitrary samples with arbitrary excitation and acquisition setup. The

integration is performed with the CVODE variable time stepping solver.

Jemris experiment setups are completely managed with XML files. It understands and parses symbolic mathematics as

dynamic parameters to allow for maximum flexibility.

It has been used to operate a commercial MRI scanner.

HEART scan

The HEART scan is a rapid assessment tool for identifying haemodynamically significant cardiac abnormalities in the

critical care setting. It is similar to the Focused assessment with sonography for trauma scan in concept, although it is

directed at the heart rather than the abdomen. Often called a Calcium Scan it provides a score that can be used to

determine the risk of a coronary event. Unlike an EKG (which would mostly show the results of past heart attacks) and

Thallium Stress Test (which only shows up advanced blockages of 70% or more). It is an excellent way to determine if a

person has Coronary Arterial Disease.

Aims of the HEART scan are to assess:

Detect *Cardiovascular Disease

Haemodynamic status (e.g. hypovolaemia)

Heart_valve lesions

Pericardial_effusion

Magnetic immunoassay (MIA)

is a novel type of diagnostic immunoassay using magnetic beads as labels in lieu of conventional enzymes (ELISA),

radioisotopes (RIA) or fluorescent moieties (fluorescent immunoassays). This assay involves the specific binding of an

antibody to its antigen, where a magnetic label is conjugated to one element of the pair. The presence of magnetic beads

is then detected by a magnetic reader (magnetometer) which measures the magnetic field change induced by the beads.

The signal measured by the magnetometer is proportional to the analyte (virus, toxin, bacteria, cardiac marker,etc.)

quantity in the initial sample.

Positron emission tomography (PET)[1]

is a nuclear medical imaging technique that produces a three-dimensional image or picture of functional processes in the

body. The system detects pairs of gamma rays emitted indirectly by a positron-emitting radionuclide (tracer), which is

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introduced into the body on a biologically active molecule. Three-dimensional images of tracer concentration within the

body are then constructed by computer analysis. In modern scanners, three dimensional imaging is often accomplished

with the aid of a CT X-ray scan performed on the patient during the same session, in the same machine.

If the biologically active molecule chosen for PET is FDG, an analogue of glucose, the concentrations of tracer imaged

then give tissue metabolic activity, in terms of regional glucose uptake. Use of this tracer to explore the possibility of

cancer metastasis (i.e., spreading to other sites) results in the most common type of PET scan in standard medical care

(90% of current scans). However, on a minority basis, many other radiotracers are used in PET to image the tissue

CT-SCAN:

X-RAY COMPUTED TOMOGRAPHY, ALSO COMPUTED TOMOGRAPHY (CT SCAN) OR COMPUTED AXIAL

TOMOGRAPHY (CAT SCAN),

is a medical imaging procedure that utilizes computer-processed X-rays to produce tomographic images or 'slices' of

specific areas of the body. These cross-sectional images are used for diagnostic and therapeutic purposes in various

medical disciplines.[1]

Digital geometry processing is used to generate a three-dimensional image of the inside of an

object from a large series of two-dimensional X-ray images taken around a single axis of rotation.[2]

CT produces a volume of data that can be manipulated, through a process known as "windowing", in order to

demonstrate various bodily structures based on their ability to block the X-ray beam. Although historically the images

generated were in the axial or transverse plane, perpendicular to the long axis of the body, modern scanners allow this

volume of data to be reformatted in various planes or even as volumetric (3D) representations of structures.

Although most common in medicine, CT is also used in other fields, such as nondestructive materials testing.

Another example is archaeological uses such as imaging the contents of sarcophagi.

Usage of CT has increased dramatically over the last two decades in many countries.[4]

An estimated 72 million scans

were performed in the United States in 2007.[5]

It is estimated that 0.4% of current cancers in the United States are due to

CTs performed in the past and that this may increase to as high as 1.5-2% with 2007 rates of CT usage;[6]

however, this

estimate is disputed.[7]

Kidney problems following intravenous contrast agents may also be a concern in some types of

studies.

Diagnostic use of CT Scan:

Head :

CT scanning of the head is typically used to detect infarction, tumours, calcifications, haemorrhage and bone trauma. Of

the above, hypodense (dark) structures can indicate infarction and edema, hyperdense (bright) structures indicate

calcifications and haemorrhage and bone trauma can be seen as disjunction in bone windows. Tumors can be detected

by the swelling and anatomical distortion they cause, or by surrounding edema. Ambulances equipped with small bore

multi-sliced CT scanners respond to cases involving stroke or head trauma.

Lungs CT can be used for detecting both acute and chronic changes in the lung parenchyma, that is, the internals of the

lungs. It is particularly relevant here because normal two-dimensional X-rays do not show such defects. A variety of

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techniques are used, depending on the suspected abnormality. For evaluation of chronic interstitial processes

(emphysema, fibrosis, and so forth), thin sections with high spatial frequency reconstructions are used; often scans are

performed both in inspiration and expiration. This special technique is called high resolution CT. Therefore, it produces a

sampling of the lung and not continuous images.

Pulmonary angiogram

CT pulmonary angiogram (CTPA) is a medical diagnostic test used to diagnose pulmonary embolism (PE). It employs

computed tomography and an iodine based contrast agent to obtain an image of the pulmonary arteries.

Cardiac

With the advent of subsecond rotation combined with multi-slice CT (up to 320-slices), high resolution and high speed can

be obtained at the same time, allowing excellent imaging of the coronary arteries (cardiac CT angiography).

Abdominal and pelvic

CT Scan of 11 cm Wilms' tumor of right kidney in 13 month old patient.

CT is a sensitive method for diagnosis of abdominal diseases. It is used frequently to determine stage of cancer and to

follow progress. It is also a useful test to investigate acute abdominal pain.

Extremities

CT is often used to image complex fractures,

X-RAY:

X-radiation (composed of X-rays) is a form of electromagnetic radiation. X-rays have a wavelength in the range of 0.01

to 10 nanometers, corresponding to frequencies in the range 30 petahertz to 30 exahertz (3×1016

Hz to 3×1019

Hz) and

energies in the range 100 eV to 100 keV. They are shorter in wavelength than UV rays and longer than gamma rays. In

many languages, X-radiation is called Röntgen radiation, after Wilhelm Röntgen,[1]

who is usually credited as its

discoverer, and who had named it X-radiation to signify an unknown type of radiation.[2]

X-rays with photon energies above 5-10 keV (below 0.2-0.1 nm wavelength), are called hard X-rays, while those with

lower energy are called soft X-rays.[4]

Due to their penetrating ability hard X-rays are widely used to image the inside of

objects e.g. in medical radiography and airport security.

As a result, the term X-ray is metonymically used to refer to a radiographic image produced using this method, in addition

to the method itself.

Since the wavelength of hard X-rays are similar to the size of atoms they are also useful for determining crystal structures

by X-ray crystallography. By contrast, soft X-rays are easily absorbed in air and the attenuation length of 600 eV (~2 nm)

X-rays in water is less than 1 micrometer.[5]

The distinction between X-rays and gamma rays is somewhat arbitrary. The most frequent method of distinguishing

between X- and gamma radiation is the basis of wavelength, with radiation shorter than some arbitrary wavelength, such

as 10−11

m, defined as gamma rays.[6]

The electromagnetic radiation emitted by X-ray tubes generally has a longer

wavelength than the radiation emitted by radioactive nuclei.[7]

Historically, therefore, an alternative means of distinguishing between the two types of radiation has been by their origin:

X-rays are emitted by electrons outside the nucleus, while gamma rays are emitted by the nucleus.[7][8][9][10]

There is

overlap between the wavelength bands of photons emitted by electrons outside the nucleus, and photons emitted by the

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nucleus. Like all electromagnetic radiation, the properties of X-rays (or gamma rays) depend only on their wavelength and

polarization (or, in a polychromatic beam, the distributions of wavelength and polarization).

PROPERTIES OF X-RAY :

X-ray photons carry enough energy to ionize atoms and disrupt molecular bonds. This makes it a type of ionizing

radiation and thereby harmful to living tissue. A very high radiation dose over a short amount of time causes radiation

sickness, while lower doses can give an increased risk of radiation-induced cancer. In medical imaging this increased

cancer risk is generally greatly outweighed by the benefits of the examination. The ionizing capability of X-rays can be

utilized in cancer treatment to kill malignant cells using radiation therapy. It is also used for material characterization using

X-ray spectroscopy.

Hard X-rays can traverse relatively thick objects without being much absorbed or scattered. For this reason X-rays are

widely used to image the inside of visually opaque objects. The most often seen applications are in medical radiography

and airport security scanners, but similar techniques are also important in industry (e.g. industrial radiography and

industrial CT scanning) and research (e.g. small animal CT). The penetration depth varies with several orders of

magnitude over the X-ray spectrum. This allows the photon energy to be adjusted for the application so as to give

sufficient transmission through the object and at the same time good contrast in the image.

X-rays have much shorter wavelength than visible light, which makes it possible to probe structures much smaller than

what can be seen using a normal microscope.

Medical uses of X-rays:

Radiographs

Computed tomography

Fluoroscopy

Radiotherapy

An X-ray generator

is a device used to generate X-rays. These devices are commonly used by radiographers to acquire an x-ray

image of the inside of an object (as in medicine or non-destructive testing) but they are also used in sterilization

or fluorescence.

Artificial heart

An artificial heart is a device that replaces the heart. Artificial hearts are typically used to bridge the time to heart

transplantation, or to permanently replace the heart in case heart transplantation is impossible. Although other similar

inventions preceded it going back to the late 1940s, the first artificial heart to be successfully implanted in a human was

the Jarvik-7, designed by Robert Jarvik and implemented in 1982. The first two patients to receive these hearts, Barney

Clark and William Schroeder, survived 112 and 620 days beyond their surgeries, respectively.[1]

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An artificial heart is distinct from a ventricular assist device designed to support a failing heart. It is also distinct from a

cardiopulmonary bypass machine, which is an external device used to provide the functions of both the heart and lungs

and are only used for a few hours at a time, most commonly during cardiac surgery.

ULTRASOUND

is a cyclic sound pressure wave with a frequency greater than the upper limit of the human hearing range. Ultrasound is

thus not separated from "normal" (audible) sound based on differences in physical properties, only the fact that humans

cannot hear it. Although this limit varies from person to person, it is approximately 20 kilohertz (20,000 hertz) in healthy,

young adults. Ultrasound devices operate with frequencies from 20 kHz up to several gigahertz.

Ultrasound is used in many different fields. Ultrasonic devices are used to detect objects and measure distances.

Ultrasonic imaging (sonography) is used in human and veterinary medicine. In non-destructive testing of products and

structures, ultrasound is used to detect invisible flaws. Industrially, ultrasound is used for cleaning and for mixing, and to

accelerate chemical processes. Organisms such as bats and porpoises use ultrasound for locatin

Ultrasonics is the application of ultrasound. Ultrasound can be used for imaging, detection, measurement, and

cleaning. At higher power levels ultrasonics are useful for changing the chemical properties of substances.g prey and

obstacles.[1]