Diagnostic Techniques

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Ultrasound

  • Ultrasound scan uses a transducer - producing high frequency sound waves.
  • Sound waves penetrate through soft tissue.
  • Gel is applied to the skin.
  • Gel used to help transducer make better contact between transducer & skin.
  • Transducer places on skin.
  • Transducer requires receiver to detech sound waves.
  • Connected to computer - processed the data from transducer.
  • Computer creates image.
  • Shows abnormalities.

Advantages:

  • Non-invasive.
  • Low risk to foetus.
  • Can be used when X-Rays cannot.
  • Provides real time moving image.
  • Inexpensive compared to MRI.

Disadvantages:

  • Poor quality & shows less detail.
  • cannot penetrate bones - no good for scans on brain. 
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Lithotripsy

  • Gel cushion is placed over area required treatment.
  • Lithotripter produced high intensity sound waves.
  • High intensity sound waves bombard object.
  • Energy waves observed by object.
  • Object shatters.
  • Lithotripsy breaksing gallstones - able to pass through bile duct into intestine - be excreted.
  • Lithotripsy breaking stones - urinary tract - pass through urine.
  • Used for - treating kidney stone, breaking gallstones, treating stones in urinary tract.

Advangatges:

  • Less invasive than surgery to remove stones.
  • Avoids needs of surgery.

Disadvantages:

  • Stones can reoccur.
  • Doesn't prevent stones forming.
  • Stones could shatter & cause further problems. 
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X-Rays

  • Electromagnetic radiation of short wavelenghts.
  • Enables penetration of soft tissue - not bones.
  • Machine directs rays at affect area - underneath a photographic plate.
  • X-Rays pass through soft tissues - causing a change in film.
  • Patient having X-Ray - wear lead apron - covered in lead.
  • Medical practitioner - wear lead apron - stands being lead wall.

Advantages:

  • Quick & Easy.
  • Results obtained quickly.
  • Cheap.

Disadvantages:

  • Radiation - can cause damage to cells - leading to cancer. 
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Contrast X-Rays

  • Contrast medium - used to dye hollow or fluid organs.
  • Medium shows up on X-Rays.
  • E.g. Barium meals - digestive tract & Iodine - angiograms (heart).

Advantages:

  • Quick & easy.
  • Results obtained quickly.
  • Cheap.

Disadvantages:

  • radiation - can cuase damage to cells - leading to cancer. 
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CT Scans

  • Computerised tomography.
  • Uses X-Rays - build up an image - slice through body.
  • Patient put through tube contain scanner - rotating around body - emitting x-rays pulses.
  • Data received - processed using computer software. 
  • Need to lie still & breath normally.

Advantages:

  • Digital image.
  • 3D.
  • Clear images.
  • Can scan areas encased in bone.

Disadvantages:

  • Radiation risk - can cause cancer.
  • Expensive.
  • Large size of equipment.
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MRI Scans

  • Patient moves through cylinder - with electromagnets.
  • Causes magnet field in body - aligns all H atons in the body.
  • Radio waves pulses knock H atoms back out - causing detectable radio signals.
  • Strength of returned signal - determines what type of tissue it came from.
  • Tissue containing H atoms - bright white - tissue containing few H atoms - dark.

Advantages:

  • 3D image.
  • Greater contrast of abnormal cells.
  • No harmful radiation.

Disadvantages:

  • Expensive equipment.
  • Some patient worry about the process.
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Radionuclide Scanning

  • Isotopes of elements that decay quickly.
  • Level of radioactivity declines qucikly - not at particular risk.
  • Combined with other element - from radioactive versiokn of substance within the body - used to.
  • Substances introduced into patient's body - via drip - build up in target organs.
  • Number of scanning methods used to pick up radiation emitted from target organs. 
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PET Scans

  • Positron emission tomography.
  • Radionuclide introduced - patient placed on a gamma ray camera.
  • Receiver picks up emitted readiation from target organs.
  • Computer process image - colour image.
  • Red & yellow - most radioactivities - normally functioning areas.
  • Dark areas - not working normally - restriction of blood flow.

Advantages:

  • More effective on the brain.
  • Painless.

Disadvantages:

  • Equipment large.
  • Expensive chemicals.
  • Isotopes emit radiation - leading to cancer. 
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ECG

  • Diagnosis of disorders - circulatory system.
  • Electrodes places on patient's skin - by skick pads.
  • Electrodes attached to chest, wrist & ankles.
  • Electrodes linked to machine - recording electrical activity of the heart.
  • Electrodes show each contraction.
  • Producing an electrocardiogram - PQRST wave pattern.
  • Healthy heart - produces normal wave pattern - on moving graph monitor screen.
  • Anbromal wave pattern - indicates dsyfunction.
  • Trained cardiologist - interprets wave pattern.
  • Patient may be aksed to exercise while readings are taken place. 

Advantages:

  • Non-invasive.
  • Cheap.
  • Smaller equipment.

Disadvantages:

  • Further investigation needed.
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Biopsy

  • Sample of living tissue - taken from patient.
  • Insertion of hollow needle - capture clyinder of tissue.
  • Usually from area of abnormality - lumps.
  • Different types - punch biopsy (skin discs) - smear test - CVS.

Advantages:

  • reduced uncertainty.

Disadvantages:

  • Invasive & painful.
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Endoscopy

  • Used to view inaccessible areas of the body.
  • Camera equpped with a light - fibre optic cable.
  • Images shown on TV screen.
  • Used in conjunction with biopsy.
  • Name depends on target area - e.g. bronchoscopy used for lungs - gastroscopy used for stomach.

Advantages:

  • Tissues examination with little damage.
  • No incision needed.

Disadvantages:

  • Invasive.
  • Cause distress.
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Fluid Sampling

  • Urine - caught in pot - tested chemically - dipstick - culturing for infection.
  • Blood - sample taken - sent away for analysis - unless sugar test for diabetes.
  • Mucuc - sample taken - cultured.
  • Amniocentesis.
  • CFS - central spinal fluid.

Advantages:

  • Quick, easy, littel discomfort.
  • Wide range of information gathered.

Disadvantages:

  • Invasive with some risk - Amniocentesis & CFS.
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