Refers to a range of techniques that produces images (usually 2D still images but in some cases moving or 3D images).
The main purpose is to investigate the appearance of internal organs/structures without the need to open the body surgically.
Imaging equipment is operated by radiographers.
Types of Diagnostic Imaging
- X rays
- Contrast x rays
- CT scan
- PET scan
- Radionuclide scanning
- Ultrasound scanning
- Type of electromagnetic radiation - familiar to us in the form of light and radio waves.
- Extremely short wavelength.
- Allows them to penetrate soft tissue of the body - cannot go through bone/metal.
- Person lays the part to be x rayed on a photographic plate/paper.
- X ray machine is aligned above the area to be x rayed.
- Invisible beam is sent from the x ray machine directed at specific part of body.
- Penetrates the soft tissue.
- Different parts of the body blakcen and areas like bone are seen as a lighter shadow because the denser bones absorb more of the radiation than soft tissues.
- Image is transerred to a computer for examination - structures can be seen.
- Used on hollow or fluid filled organs such as the digestive tract (oesophagus, stomach and intestines) as do not show up on the x ray without contrast medium.
- Contrast medium - harmless solution of barium sulphate in water is used.
- Barium sulphate is a metal salt which x rays cannot pass through/opaque to x rays.
- Patient either swallows the liquid known as barium meal or it is pumped into the patient's rectum known as a barium enema.
- Time is then allowed to allow the liquid to reach its destination i.e. the intestines.
- Normal x ray is taken and the contrast will show up abnormalities in the body.
- The metal salts show up like bone would in a normal way so light shadows.
- Water-soluble iodine dyes can be carried around the bodyin the bloodstream, this can be used to check that the blood is flowing normally in the blood vessles.
CT Scan - Computerised Tomography Scanning
- Uses x rays to produce an image of a slice or cross section of the body.
- Patient lies on a table which moves into a cylinder containing the scanner.
- Scanner rotates around the patient emitting x rays.
- The radiation passes through some tissues, is reflected off other tissues and is analysed by the scanner.
- Information from a set of x ray receivers is processed by computer software to build a digital image in the form of slices.
- These slices can be processed into a 2D or a 3D structure of the body.
- Used for detecting and examining conditions affecting the brain, tumours, head injuries and damage from strokes. The entire digestive tract can be examined with the use of a contrast medium. Can produce images of structures encased in bone - such as the brain.
- If there is an RTA (Road Traffic Accident) and a patient comes in and the doctors cannot work out hatis wrong with them then the patient will be sent for a CT scan.
PET Scan - Position Emission Tomography
- Used to produce detailed 3D images of the inside of the body.
- It is a flat bed with a large circular scanner at one end.
- A radioactive substance (a radiotracer) is injected into a vein of the patient.
- The tracer gives off particles called positrons that releases gamma rays (a type of radiation)
- These are detected by the PET scanner.
- By tracking the movement of the tracer, the scaner builds up a detailed image of the body's functions as well as identifying areas of the body affected by disease.
- Often used to confirm how far a cancer has spread or if treatment has been effective.
- Hot spots
A way of imagine bones, organs, and other parts of the parts of the body using a small dose of a radioactive chemical.
- A rad (sometimes called an isotope) is a chemical which emits a type of radioactivity called gamma rays
- Injected into a vein or swallowed - time then allowed for it to travel to target areas. Depends on the organ/tissues being examinated different rads are used
- Lie on a bed and the gamma camera detects rays being emitted
- Cells which are most sctive will take up the rad and emit gamma rays
- Dectected by a gamma camera, converted into an electrical signal, sent to a computer which will build a picture
- different colours are seen - hotspots for overactivity or cold spots for little
- A bone scan
- Kidney scan
- Heart scan
- Thyroid scan
MRI- Magnetic Resonance Imaging
A type of scan used to diagnose health conditions that affect the organs, tissues and bones.
- A person is placed in a large horizontal cylinder equipped with a powerful electromagnet.
- Uses a strong magnetic field on the body and radio waves
- By focussing magnetic field on the body, it causes the hydrogen protons in body tissues to line parallel to each other
- A strong pulse of radio waves then vidrates these particles and knocks them out of alignment
- When the particles realign, they emit small radio signals which are picked up by the scanner receiver and converted by a computer into an image as a cross section
- These can be combined to make a 3D picture which is examined by a health professional
- Used for brain and spinal cord, bones and joints, breasts, heart and muscles and lungs and liverYou need to be conscious before this scan
A procedure that uses high frequecny soundwaves to create an image of part of the body
A lunricant gel is put on the skin
A small handheld device called a trasducer is used. The gel allows the transducer to move smoothly to ensure there is continuous contact between the sensor and the skin
The transducer is connected to a computer with a monitor
Pulses of ultrasound are sent from a probe in the transducer theorugh the skin and into teh body
These bounce back from the structure in the doby to be displayed as am inage on the monitor. They also show movement