Imaging modalities Part 3 Flashcards
First introduced in 1966 by Godfrey Hounsfield
Computed tomography
imaging of Layer/Slice.
Tomography
is the process of creating a cross-sectional tomographic plane of any part of the body.
Computed tomography
The patient is scanned by an x-ray tube rotating around the body part being examined.
Computed tomography
A detector assembly measures the radiation exiting the patient and feeds back the information, referred to as primary data, to the host computer.
Computed tomography
Once the computer has compiled and calculated the data according to a pre-selected algorithm, it as embles the data in a matrix to form an axial image.
Computed tomography
Each image, or slice, is then displayed on a cathode ray tube (CRT) in a cross-sectional format.
Computed tomography
a tightly collimated x-ray beam is directed through the patient from different angles, resulting in an image that represents a cross section of the area scanned.
CT examination
This technique essentially the superimposition of body structures.
Computed tomography
controls the method of acquisition, the slice thickness, the reconstruction algorithm, and other factors related to image quality.
CT technologist
Large box-like machine with hole in the middle
CT scan
Patient lies on narrow table that slides in and out of this hole.
CT scan
X-ray tube and electronic x-ray detectors rotate around you (gantry).
CT scan
Computer processes the information and is operated by a technologist who works scanners and monitors the exam
CT scan
Used For Diagnose cancers, CV disease, infectious disease, appendicitis, trauma. and muscular-skeletal disorders
CT scan
translate and rotate, pencil beam, single detector, 5-minute imaging time.
First-generation imaging system
translate and rotate, fan beam, detector array, 30-second imaging time.
Second-generation imaging system
rotate and rotate, fan beam, detector array, subsecond imaging time.
Third-generation imaging system
rotate and stationary, fan beam, detector array, subsecond imaging time.
Fourth-generation CT imaging system
a technique that uses a magnetic field and radio waves to create detailed images of the organs and tissues within the body.
Magnetic Resonance imaging (MRI)
Nikola Tesla discovered the Rotating Magnetic Field in 1882 in Hungary
Magnetic Resonance Imaging (MRI)
discovered the Rotating Magnetic Field in 1882 in Hungary
Nikola Tesla
observed the quantum phenomenon dubbed nuclear magnetic resonance (NMR).
1937, Professor Isidor I. Rabi
He recognized that the atomic nuclei show their presence by absorbing or emitting radiowaves when exposed to a sufficiently strong magnetic field.
Professor Isidor I. Rabi
a physician, discovered that hydrogen signal in cancerous tissue is different from that of healthy tissue because tumors contain more water.
Raymond Damadian
a chemist, produced the first NMR image.
1973, Paul Lauterbur
Components of MRI
- Magnet
- Gradient Coils
- Radio Frequency (RF) coils
- MRI Patient Table
- Antenna/Computer System
Has a horizontal tube that runs through the magnet and is called a bore.
Magnet
Most MRI magnets use a magnetic field of 0.5 to 2.0 tesla. (Earth’s magnetic field is only 0.5 gauss.)
Magnet
The magnetic field is produced by passing current through multiple coils that are inside the
Magnet
create a variable field (x, y, z) that can be increased or decreased to allow specific and different parts of the body to be scanned by altering and adjusting the main magnetic field.
Gradient coils
Transmit radio frequency waves into the patient’s body.
Frequency (RF) Coils
There are different coils located inside the MRI scanner to transmit waves into different body parts.
Frequency (RF) coils
If a certain area of the body is specified, then all the RF coils usually become focused on the body part being imaged to allow for a better scan
Frequency (RF) coils
This component simply slides the patient into the MRI machine.
Patient table
The position at which the patient lies down on the table is determined by the part of the body that is being scanned.
Patient table
Area under examination is placed in the exact centre of the magnetic field (isocentre).
Patient table
detects the RF signals emitted by a patient’s body and feeds this information into the computer system.
Antenna
function is to receive, record, and analyze the images of the patient. It interprets the data produce an understandable image.
The computer system
