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OCR AS Applied Science - Introduction to Medical Imaging

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Transcript of OCR AS Applied Science - Introduction to Medical Imaging

Medical Imaging Techniques
Describe & Explain term Medical Imaging

Compare & Contrast forms of Medical Imaging

Session Objectives: Introduce Medical Imaging
In groups of 3-4 take 2 mins to mind shower:

Describe what medical imaging is

List types of medical imaging


Research resources
1st X-Ray: Hand of Mrs Wilhelm Roentgen 1895
1895- X-Ray W.Roentgen
Nobel Prize Physics 1901
1906-12 Development of contrast agents
ingested to visualise organs & vessels
1913 - A.Solomon Mammography research :
X-Rays of gross anatomic mastectomy specimens- mammography in use from 1927
1913 - Hot Cathode X-Ray Tube invented
1931-33 First Electron microscope built E.Ruska
1946 - NMR Spectroscopy invented, 1st step to MRI - Bloch & Purcell
1950's - X-Ray Crystallography reveals helical structure of DNA - Rosalind Franklin & structure of Myoglobin & Haemoglobin proteins - Perutz & Kendrew
1953 1st PET application for medical diagnosis - Brownell & Sweet
1958 - NMI -H.Anger Method to detect tumours
imaging from gamma rays emitted by ingested radioactive isotopes - Nuclear Medicine 1950's
1959 - Ultrasound : High frequency sound waves > 20,000 p/s. I.Donald & colleagues developed practical technology & applications for obstetrics & gynaecology. Also called Sonography,
product a sonagram.
1960's evolution of Angiography
1968 - 1st prototype CT scanner - Hounsfield
1971 - 1st Clinical CT head scan
1973, Paul Lauterbur -chemist and an NMR pioneer, State University of New York, produced the first NMR image.
1972 - MRI adapted for medical purposes - Bloch, Purcell, Lauterber & Damadian
1972 - CAT Scan - Hounsfield & Cormack
1977, nearly five hours after the start of the first MRI test, the first human scan was made as the first MRI prototype.
1987 - (EPI) Echo Planar Imaging - real time movie imaging of a single cardiac cycle - P.Mansfield
30 Million MRI Scans by 2007

1950's - Medical Fluoroscopy
R.Morgan, Johns Hopkins University, E.Chamberlain Temple University & J.W.Coltman of Westinghouse Research Laboratories perfect a method of screen intensification that reduces radiation exposure & improves fluoroscopic vision. Their image intensifier is now universally used in medical fluoroscopy

By 2010 - 70 million CT Scans in the U.S.
Photoacoustic Mammography - Identifying the state of cancer cells by exposing blood vessels to light. Light & Ultrasound.
Angiography - technique visualises inside of blood vessels & organs of the body, especially arteries, veins and the heart chambers. This is traditionally done by injecting a radio-opaque contrast agent into the blood vessel & imaging using X-ray based techniques such as fluoroscopy.

Fluoroscopy is an imaging technique that uses X-rays to obtain real-time moving images of the internal structures of a patient through the use of a fluoroscope. The X-Rays project through the patient onto a fluorescent screen attached to an X-Ray image intensifier and CCD Video camera.
or Sonography

PET Scan -
Positron Emission Tomography
MRI Scan -
Magnetic Resonance Imaging, nuclear magnetic resonance imaging (NMRI), or magnetic resonance tomography (MRT)
CT or CAT Scan -
X-Ray Computed Tomography or Computer Assisted Tomography

X-Ray -
A photograph obtained by use of X-Rays
X-Rays - electromagnetic radiations that have an extremely short wavelength of less than 100 angstroms and can penetrate various thicknesses of solids, as well as producing secondary radiations by impinging on material bodies. They act on photographic films and plates as light does.
An important diagnostic & screening tool, produces 2D, B & W images of the anatomy and dense tissues.

1962 - 1st (PET) Positron Emission Tomography Transverse section instrument
-Rankowitz & Robertson
Mammography - Mammography is the process of using low-energy X-rays (usually around 30 kVp) to examine the human breast and is used as a diagnostic and a screening tool. The goal of mammography is the early detection of breast cancer, typically through detection of characteristic masses and/or microcalcifications.
Medical imaging procedure that uses 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

Advantages 3D image, refined, cross sectional

Disadvantages Large, expensive, still X-rays so ionising radiation
The method is used in radiology, archaeology, biology, geophysics, oceanography, materials science, astrophysics, quantum Information, and other sciences
Recent advances rely on using simultaneously integrated physical phenomena, e.g. X-rays for both CT and angiography, combined CT/MRI and combined CT/PET. By fusing PET and CT you can see the metabolic information of PET and the anatomic detail of CT at once. There are prototype PET/MR scanners now. People are talking about possible CT/MR scanners too.
Ionising radiation
Magnetic Resonance Imaging (MRI)
Positron Emission Tomography
Radioactive Tracer
Ultrasound / Sonography
X-Ray Computed Tomography / Computer Assisted Tomography (CT/CAT)
Ultrasound is an oscillating sound pressure wave with a frequency greater than the upper limit of the human hearing range. Ultrasonic imaging uses frequencies of 2 megahertz and higher; the shorter wavelength allows resolution of small internal details in structures and tissues

Advantages: no known risk, no ionising radiation, cheaper, smaller and more portable than other, however practice advised -

Disadvantages: Ultrasound does not reflect clearly from bone or air giving it limitations. For images of the lungs and bones other techniques are preferred
The ALARA (As Low As Reasonably Achievable) principle has been advocated for an ultrasound examination — that is, keeping the scanning time and power settings as low as possible but consistent with diagnostic imaging
MRI makes use of the property of nuclear magnetic resonance (NMR) to image nuclei of atoms inside the body. MRI can create more detailed images of the human body than are possible with X-rays.
PET - a nuclear medical imaging technique that produces a 3D image of functional processes in the body. The system detects pairs of gamma rays emitted indirectly by a positron-emitting radionuclide (tracer), which is introduced into the body on a biologically active molecule (commonly FDG a glucose analogue). 3D images of tracer concentration in the body are then constructed by computer analysis.
In modern scanners, 3D 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.

The Adaptive Optics Scanning Laser Ophthalmoscope (AO-SLO) - being developed in collaboration with Kyoto University is expected to enhance the value of the retinal examination, a procedure essential for the diagnosis of eye diseases.
NDE = nondestructive evaluation
By 2008 - 2 Billion X-Rays
per year in U.S
A1-3 CT; B1-3 PET; C1-3 PET/CT Fused Images
Fine artist Angela Palmer takes CT/MRI scanner of people and animals, engraves the data onto thin glass sheets that are then combined into 3D sculptures.
Medical Imaging Jobs
MRI Technologist
Diagnostic Technologist
Medical scientist
Biomedical engineer
Imaging physicist
Research scientist
Fig 1 Radiodensity as a function of composition, with thickness kept constant
Advantages - Identify cracks, infections, injury, abnormal bones & locating foreign objects inside the body. Identifying bone cancer. Cheaper than MRI/CT. Portable X-Ray equipment.

Disadvantages - Ionising radiation is hazardous. Less detailed data than alternatives. 2D static image
Advantages - Moving visualisation of soft tissue vessels, heart chambers etc.

Disadvantage - Modern Iodine based contrast agents side effects on patients, nausea, hot flushes and discomfort. Earlier number of forms radioactive and toxic substances. Spatial blurring factors that plague all x-ray imaging devices. Ionising radiation. 2D
Advantages sees soft tissues (cartilage, nerves, and organs), 3D movie images, no ionising radiation

Disadvantages no patients with pacemakers, claustrophobic, cost and time, dangerously powerful magnets
An MRI system can create images in any plane, CT scans were limited to one, the axial plane. Development of multi-detector CT scanners with near-isotropic resolution allows the CT scanner to produce data that can be retrospectively reconstructed in any plane with minimal loss of image quality
Advantages Imaging located to tumour sites, relatively low impact on resolution of small movements, reduces need for biopsy, earlier detection

Disadvantages Radioactive tracer, cost, relatively low spatial resolution when compared with other imaging techniques, patient discomfort with up to two hours immobility, PET scans require cyclotrons, an expensive machine that creates the radioisotopes that are used in the radioactive tracers required for PET imaging
Homework Assignments allocation
Your assignments are to produce a scientific poster for presentation to your peers in two weeks from today. You will work in assigned pairs. You may create a physical A2 poster, a Powerpoint poster or a Prezi.
Each team will be assigned a specific topic from the following list.
Physics of X-Ray, how it works & medical use examples
Physics of Angiography/Fluoroscopy, how it works & medical use examples
Physics of CT/CAT Scans, how it works & medical use examples
Physics of Ultrasound, how it works & medical use examples
Physics of MRI Scans, how it works & medical use examples
Physics of PET Scans, how it works & medical use examples
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