Topic 2 : Radiography Flashcards
What PPE should be used when doing X-rays?
- lead aprons, sleeves and gloves - mobile shields - personal radiation monitors - thyroid shields - goggles
What is focal film distance?
The distances between the x-ray tube and the xray film - should be 75-100cm (depending on type of x-ray and machine)
What are the two different systems of applying identification labels?
- daylight system - darkroom system
What is the daylight system? (using “x-rite tape” and using lead letters)
X-rite tape or similar - graphite tape comes in a roll in a box, pull out and tear off the length required, remove the black paper to expose the sticky surface which is stuck on the outside of the top of the cassette.
What is the dark room system?
Using a light box marker in the darkroom
What markers must be on a X-ray? (3)
- Collimator marks 2. Marker (L) or (R), for vs hind, view (lat, DV or VD) 3. Identification label name of practice, owners name, record number, date of xray
What are the 3 ranks use in developing fluids chamber?
The developer The fixer Water heater
What does the developer fluid do?
Changes the silver bromide and the film to black metallic silver and is the first solution into which the film is placed.
What does the fixer fluid do?
The fixer renders the film insensitive to light. Also combined with hardener which hardens the film.
What does contract media used for?
Contract media is used to give more detail of a particular organ or body system by administering compounds that will appear on the radiograph by outlining the interior lining and/or cavity.
What substances are used as contrast medias?
Iodine and barium - due to chemical structure
What is positive contrast?
Positive contrast agents have a high atomic number, either barium sulphate or iodine, and appear more radiopaque than the surrounding tissue.
What is negative contrast?
Negative contrast agents are gases of low density (air, oxygen, carbon dioxide) which appear radiolucent.
How is barium sulfate used as contrast media and what does it show?
Used orally to radiograph the digestive tract
How is iodine contrast media and what does it show?
Intravenously When injected into a blood vessel, which can be either an artery or a vein, it not only shows the inside of the blood vessel on the image or picture but it can give information about how the organs supplied by that blood vessel are working. Good examples of this are the kidneys, brain and lungs.
What contrast media is used for the digestive tract?
Compounds containing barium Sulfate
What is a barium series?
This is where a series of x-rays are taken over time to assess the motility of the gastrointestinal tract, and check for obstructions
What are contrast enemas?
a procedure in which liquid or gas is injected into the rectum to introduce drugs or permit X-ray imaging.
What cant barium be injected intravenously?
-very irritant -cause formation of granuloma within body cavities
Define granuloma
a mass of granulation tissue, typically produced in response to infection, inflammation, or the presence of a foreign substance.
What happens rapidly when water soluble iodine preparations are administered intravenously?
It is rapidly excreted by the kidneys.
What is the problem with injecting soluble iodine?
Causes nausea vomiting, so animals are usually anesthetized to prevent vomiting
What is iodine contrast used to X-ray?
Kidneys, ureters, bladder and urethra
What are double contrast studies of the bladder?
- bladder filled with positive contrast such as soluble iodine intravenously to directly via catheter into the bladder, then fluid is drained from the bladder which is then filled with gas
Why is double contrast used on the bladder
To detect filling defects and can be used in other organs such as the colon
What does this image display
Double contrast studies of the bladder
How do you perform contrast medias on the spinal cord?
Soluble iodine can be injected into the subarachanoid space to provide contrast in the CSF (Cerebrospinal fluid) so that dises of the spinal canal can be detected
eg. disc prostrusions, tumors
what is a myelogram?
A myelogram is a diagnostic imaging procedure done by a radiologist. It uses a contrast dye and X-rays or computed tomography (CT) to look for problems in the spinal canal, including the spinal cord, nerve roots, and other tissues. It is also known as myelography.
How do imaging faults occur? (3)
- inappropirate restrain or movement of patient
- failure to adequately maintain machine or equiptment
- problems with exposure sttings or the development process
What 3 factors does a good quality x-ray have?
Good density, contrast and definition
What is density?
Density is the degree of blackening of the film and depends on the amount of exposure the developing technique.
Define contrast
Radiographic contrast is the degree of density difference between two areas on aradiograph. Contrast makes it easier to distinguish features of interest, such as defects, from the surrounding area
What does it mean if the film is too black?
The film has been exposed to too many x-rays
ie. the setting may have been to high
The kV, mA, s (time) , film focal distance need to be checked
What is kVp
The measure of the degree of contrast (or shades of gray) on a radiograph, which is controlled by the intensity at which the electrons are shot. High kVp produces a long scale of contrast, which is necessary for soft tissue radiographs where subtle changes need to be seen. Low kVp produces short scales of contrast that are necessary for bone visualization.
Usually ranges between 40 - 125.
What are mA’s
Usually ranges from 50 - 400 depending on the type of machine you have. The number of electrons produced by the filament.
How to calculate MAs
(milliampere per second)?
The number of the electrons (mA) multiplied by the time (in seconds) during which x-rays are shot, which determines the density (or darkness) of a radiograph. Example: 300 mA at 1/60 seconds = 5 mAs
milliampere per second = number of the electrons (mA) X time (in seconds) during which x-rays are shot
what happens if mA is too low?
what happens if mA is too high?
too high - overexposed
too low - underexposed
What happened if the image including the background is too pale?
Underdeveloped
Causes:
- exhauted developer
- developer to cold
- diluted developer
- development for too short a time
Causes of underdeveloped images
- exhausted developer
- developer too cold
- diluted developer
- development for too short a time
What has happened if the overall appearance of a radiogrpah is back but contrast is retained
Overdeveloped
Causes:
- too long development time
- too high development temperature
- too high developer concentration
What are the causes of an overdeveloped image?
- too long development time
- too high development temperature
- too high developer concentration
How should you alter the exposure based on the tissue thickness?
Denser the tissue - high the exposure factors
Do you incraese or decrease exposure factors when using a grid
Increase exposure factors (mA)
What has happened if the film is too dark?
Over-development due to too much time in developer or temperature too high
What has happened if the film is too light
Under-developed due to low temperature or too short a developing time. Developer exhausted or diluted
What has happened if the film is grey/ lacks contrast
- Light lead in darkroom
- storage fog due to conditions too hot or too humid
- Chemical fog due to old cheical
- increased chemical temperature or increased time of development
- film out of date
- incorrect bulb wattage or filter for safe light in darkroom
What has happened if the film has back mars (not generalised)
Films sticking together during development. Static electricity.
Developer on folm before processing.
Fingerprints as a result of developer on hands while loading or unloading cassette.
What has happened if the film is a yelloe radiograph
Preamture age due to improper fixation. Films sticking together during fixing process. incomplete washing.
What has happened if the film has ckear areas on film (white marks)
Hair in cassette. Scratch in film emulsion. Scratch on screen surface. Air bubble on film during developing. Touching side of tand during manual processing. Fingerprint due to handling film with contaminated fixer splassed on film before developing.
What has happened if the film has heavy lines on radiogrpah
Roller marks as a result of film jammed in automatic processer. dirty rollers
What has happened if the film is too black
- mAs too high
- kV too high
- surge in incoming line voltage
- focal-film distance too short
- intensifying screen speed too fast
- forgot to use grid
- double exposure
What has happened if film is too white
- mAs too low
- kV too low
- drop in incoming line voltage
- focal-film distance too long
- intensifying screen speed too slow
- no exposure
- also, measured thickness wrongly; technique chart inaccurate
What has happened if film is – Grey film (fogged)
- accidental exposure of film to radiation
- scatter, secondary, direct
- no grid used with thick objects
- old film (out of date)
- stored film too hot, too humid
What has happened if film blurred
- movement of patient
- movement of cassette
- movement of x-ray machine
- focal-film distance too long - magnification and distortion
- poor centring of primary beam
What has happened if film has Black marks
- scratches on film
- rough handling - crescent mark (fingernail)
- top of film exposed to light while still in box - top of film is black
- cassette not closed properly (defective hinges/latches or carelessness) - exposed to
- light - black areas around film margins
What has happened if the film has white marks
- dirt/hair between film and screen
- crack or defect in screen
- contrast medium on skin or cassette
- unprocessed film emulsion scratched off
What has happened if the film has lines
- grid - out of focal range
- grid - upside-down
- grid - damaged
- primary beam not centred
What has gone wrong
Increased Film Density- too dark
overdeveloped - too long
developer too hot
developer too concentrated
What has gone wrong
Decreased film density - too light
underdeveloped - too short a time
too cold
developer exhausted
developer too dilute or not mixed
developer contaminated (eg with water or fixer)
What has gone wrong
Fogged films
light leaking into dark room
- door, window, pipes, exhaust fan
wrong safelight intensity
lights turned on before film is finished being processed/handled
exposed to x-rays while in box or cassette
overdeveloping
contaminated developer
How to improve an xray if - film density too dark
Decrease mAs by 30 - 50%
Decrease kV by 10 - 15%
How to improve an xray if - film density too light
Increase mAs by 30 - 50%
Increase kV by 10 -15%
How do you improve the x-ray if (bones are white but soft tissue too dark) -
film density is too dark but contrast is OK
Should decrease the mAs
How do you improve an x-ray if film density is too dark and the bones are grey
Should decrease the kV
If film density is too light but anatomical features are visible (eg cranial abdo)
Should increase the mAs
How do you improve an x-ray if film density is too light and the anatomical features are not visible
Should increase the kV
