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81 Cards in this Set
- Front
- Back
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What is ionising radiation? |
Radiation consisting of particles with sufficient energy to cause ionisation in the substance it passes through. |
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What is ionisation? |
The process by which an atom or a molecule acquires a negative or positive charge by gaining or losing electrons to form ions |
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What effects does ionising radiation have on the body? |
Invisible, painless, latent, cumulative effects |
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What is a proton? |
Positively charged particle contained in the centre or nucleus of the atom |
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What is a proton? |
Positively charged particle contained in the centre or nucleus of the atom |
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What is a neutron? |
Also found in the nucleus but carry no electrical charge |
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What is an electron? |
Smaller, negatively charged particles that orbit around the nucleus |
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What is a positively charged ion called? |
Cation |
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What is a negatively charged ion called? |
Anion |
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What is the legal dose limit for employees over 18s? |
20 mSv per year |
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What is the legal dose limit for employees over 18s? |
20 mSv per year |
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What is the legal dose limit for 16-18 year olds? |
6mSv |
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What is the legal exposure limit for members of the public and pregnant people? |
1mSv |
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How do you work out the mAs? |
mA x seconds |
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How do you work out the mA? |
mAs / seconds |
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How do you work out the mA? |
mAs / seconds |
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How do you work out the seconds? |
mAs / mA |
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Who is the radiation protection advisor? |
An external person supporting the practice to comply with regulations |
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Who is the radiation protection advisor? |
An external person supporting the practice to comply with regulations |
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Who is the radiation protection supervisor? |
An appointed member of the practice team (VS/VN) - must have legislative training |
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What is the kilo voltage control? |
Determines the speed and energy in which electrons bombard the target resulting in the quality of the image |
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What is the X-ray tube head? |
Where X-ray photons are generated containing two electrodes - negatively charged cathode and positively charged anode |
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Where are electrons produced? |
Within the cathode |
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What is scintigraphy? |
Used for bone examination by injection of radioactive iodine IV |
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How should patients be prepared for scintigraphy? |
Must be housed in specialised units 72 hours before procedure Unit is a controlled area and anaesthesia is required Radio pharmaceuticals are excreted in urine so care with soiled bedding |
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What is the physical property of mAs? |
Quantity/amount of X-rays produced |
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What is the physical property of mAs? |
Quantity/amount of X-rays produced |
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What effects does mAs have on X-rays? |
Degree of blackening/radio graphic density |
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What are advantages of CT over digital radiography? |
Internal anatomy can be viewed in greater detail Tissue contrast is greater Can construct 3D images Views larger portions of the body |
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What are disadvantages of CT over digital radiography? |
High doses of radiation Time consuming Expensive Only suitable for certain tissues Less available Large/obese patients may not be accommodated |
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What are the two types of positive contrast media? |
Barium sulphate and water-soluble iodine |
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What is fistulography? |
A form of X-ray to look for abnormalities within the arterio-venous fistula- check blood flow and for blockages |
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What is arthography? |
Imaging to look at the joints |
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What is a positive contrast agent? |
Agents containing elements of high atomic number that also absorb a large proportion of the X-ray beam |
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What is barium sulphate used for? |
Gastrointestinal studies |
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What is fluoroscopy? |
A type of medical imaging which shows a continuous image on a monitor - used to see tissues and organs working |
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What are implications of fluoroscopy? |
Radiation induced injuries - burns to the skin and radiation induced cancers |
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What is myelography? |
The use of contrast dye and X-rays/CT to check for abnormalities within the spinal canal by injecting a dye to make this visible. |
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What are the possible implications of arthroscopy? |
Infection, thrombophlebitis, artery damage, haemorrhage, nerve damage and numbness at the incision sites |
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What is contrast media? |
A substance which is more radiopaque or radiolucent than the surrounding tissue |
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What are the properties of contrast media? |
Different absorptive power tissue Non-irritant / non-toxic Accurate view of an organ Persistent for long enough for the X-ray to be taken Able to be totally expelled from the body |
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What are examples of negative contrast media? |
Gases such as co2, 02 and N2O |
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What colour do positive contrast agents appear as? |
White |
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Where is barium sulphate commonly used? |
GI Tract |
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What are advantages of barium sulphate? |
Low toxicity Excellent mucosal detail Insoluble May sooth GI tract Palatable |
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What are disadvantages of barium sulphate? |
May cause aspiration pneumonia if inhaled Can cause constipation and turn faeces white If GI tract is perforated, may cause peritoneal adhesions or granulomas |
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What is water soluble iodine used for? |
Urinary tract Joints Spine Cardiovascular system Vascular system |
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Possible side effects of water soluble iodine? |
Allergic reactions Contrast induced nephrotoxicity Bradycardia Hypotension Extravasation causing irritation Apnoea Seizures - often on recovery from myelopathy |
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Where in the tube head are X-rays produced? |
Anode |
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Which control adjusts the penetrating power of the X-ray beam? |
Kilo-voltage |
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What is the function of the light beam diaphragm? |
Enables the radiographer to centre the X-ray Collimates the field of radiation to the area of interest |
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What is an example of a radiopaque material? |
Barium sulphate |
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Why do we use X-ray grids? |
Reduction of scatter radiation reaching the X-ray detector |
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What are the 7 cassette layers? |
Protective layer, phosphor layer, reflective layer, conductive layer, support layer, backing layer, barcode layer |
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What are the 7 cassette layers? |
Protective layer, phosphor layer, reflective layer, conductive layer, support layer, backing layer, barcode layer |
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How are images produced? |
Primary beam interacts with electrons in the barium florohalide crystals contained with the imaging plate This stimulates/gives energy to the electrons Crystals enter the conductive layer where they are trapped in the phosphor centre |
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What is indirect digital radiography? |
Involves an additional scintillator converting the X-rays into light |
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What does digital radiography contain? |
A semi-conductor system and a thin film transistor |
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What is scintigraphy? |
Use of radioactive chemicals (radionuclides) are injected IV and the uptake of this is increased in tissues where there is increased blood flow. A gamma camera is used to detect nuclear emissions and translate them to a visible image |
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What is scintigraphy used for? |
Examination of bone, thyroid tissue, detection of portosystemic shunt and comparative ventilation and perfusion in the lungs |
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What is the prep for scintigraphy? |
Anaesthesia is required Patients must be house in specialised units for up to 72 hours post administration Unit is a controlled area Radio pharmaceuticals are excreted in urine |
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How should you care for an ultrasound machine? |
Regular maintenance and checking equipment Making sure all connections are plugged in Check integrity of wiring, cables and transducers Follow recommended cleaning protocols |
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What is anechoic? |
Black imaging |
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What is anechoic? |
Black imaging |
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What is hypoechoic? |
Dark imaging |
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What is anechoic? |
Black imaging |
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What is hypoechoic? |
Dark imaging |
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What is hyper echoic? |
Bright imaging |
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What is contrast ultrasonography? |
Small quantities of phospholipid capsules are injected into the bloodstream to identify non-vascular structures |
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What are advantages of CT scanning? |
Painless, non-invasive and accurate |
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What are disadvantages of CT scanning? |
Expensive, animal has to be anesthetized, sometimes requires breath holding, contains ionizing radiation |
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What is the controlled area? |
An area where is it necessary to take precautions to limit exposure to ionising radiation |
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What features does the controlled area have?? |
2 meters from primary beam, protection from scatter radiation in walls and doors, should have warning light and sign displayed on control area door |
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What are the 3 possible effects of radiation on the body? |
Somatic, carcinogenic and genetic |
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What are 3 ways x-ray interact with matter? |
Absorption, scatter and passing through unchanged |
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What colourare x-rays when alot hit the film? |
Black |
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What colour are x-rays when no x-rays hit the film? |
White |
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Which process in the tube head determines the mA? |
Cathode - changes the number of electrons produced |
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Which process in the tube head applies the kV? |
Applied between cathode and anode |
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How can people be limited to exposure to ionising radiation? |
Correct PPE, obey local rules, ensure beam is directed vertically, collimate beam to smallest size practical |
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What do the production of x-rays rely on? |
A source of electrons, a means of rapidly accelerating the electrons, a means of rapidly decelerating the electrons |
