Flashcards in Radiology Deck (188):
Personnel who restrain animals should never do what?
sit on or lean over the x-ray table
T/F Radiographers must allow as much distance as possible between themselves and patients.
All personnel present in the radiography room when an exposure is made should wear?
appropriate protective lead apparel: gloves, gown, thyroid
T/F Genetic damage is not detectable until further generations are produced.
When radiographing a long bone, which joints must be included?
the joints immediately distal and proximal to the bone
T/F The smallest field size possible should be used for any given area of the body.
T/F Positional terms are named according to where the primary x-ray beam enters and exits the anatomic area of interest.
T/F As a general rule of thumb, canine patients tend to resist too much restraint and feline patients respond to a calm, authoritative approach to restraint.
Why should the patient's coat always be checked before taking radiographs?
to ensure that it is dry and as clean as possible
What is the purpose of the x-ray tube?
to produce a controlled x-ray beam
T/F Low kilovoltage peak (kVp) and high milliamperage second (mAs) techniques should be used as often as possible to prevent damage to the anode.
false-low kVp and low mAs
X-ray tube failure is usually a result of what error?
technical error, x-ray tubes should be cared for properly
The electrical components of the x-ray machine consist of?
the transformer, the generator, the line-voltage compensator, the timer, and the rectifer
Energy travels in ____ the length of which is measurable.
How do short wavelengths differ from longer ones?
shorter wavelengths have a higher frequency and penetrate farther than rays having longer wavelengths
______ is a form of electromagnentic radiation produced when electrons moving with great speed collide with matter.
The ability of x-rays to excite and ionize molecules within cells can cause what?
severe damage or death to those cells
The first written report concerning x-rays and their use for medical and surgical diagnosis was made in _____. The author and discovered was ____ _____
1895, Wilhelm Roentgen
The kVp controls what? What does the mAs control?
the wavelength and penetrating power of x-radiation, the number of x-rays produced
What is the most common artifact in veterinary radiography?
T/F Radiation of a longer wavelength has better penetrating ability and therefore produces a higher-quality radiograph.
A foam wedge should be placed under the sternum to elevate it to the same horizontal level as the spine for what views?
a lateral thoracic and thoracolumbar view
To obtain optimal radiographs of the spine, the disk spaces must be nearly _____ to the tabletop and in _____ alignment with each other.
T/F Manually extending a patient's front and rear limbs for a spinal view is not contraindicated if the patient has a spinal column injury.
T/F A ventrodorsal thoracic view is contraindicated in a patient in respiratory distress.
When subtle lung metastasis is suspected what is recommended?
both right and left lateral views of the thorax (3 views)
The thorax should be radiographed during peak _____, and the abdomen should be radiographed during peak _______
When viewing a radiograph of an animal's abdomen in a ventrodorsal or dorsoventral position, the animal's head is _____ of the viewbox and the patient's right is on the ____
top of, viewers left
T/F A slight difference in density is low contrast(long scale), a high difference in density is high contrast(short scale)
What is the most important questions to answer when evaluating the technique of a radiograph?
"is the film overpenetrated or underpenetrated(an indication of kVp)" in otherwords are the outlines of structures visible
For soft tissue what contrast is desirable? For bone tissue?
low contrast(many shades of gray), high contrast
The state of chemicals and screen-film combinations can affect the quality of what?
of radiographs and mimic inappropriate exposures
The darkroom must be clean, organized, and what else?
completely light proof
All chemicals must be kept at the same temperature to prevent what?
T/F Bacterial, fungal, and algal growth are a common problem in hand-processing tanks and can be controlled by cleaning tanks with 1% chlorine bleach when they are drained.
T/F The legal requirement for keep radiographs is 7 years; however, it is advisable to keep them until the patient dies.
T/F Approximately 95% of the exposure recorded on a film is due to the light emitted from the intensifying screens. Only 5% of the exposure of the film results from the ionization of x-rays.
T/F A cassette must contain close contact between the intensifying screens and the film.
The primary function of the ____ is to reduce the amount of radiation exposure required to produce a diagnostic radiograph
____ screen speeds require a small exposure and produce less detail; ___ screens require a larger exposure and produce greater detail.
T/F Screens don't have to be cleaned regularly because dirt and hair do not get on the screen.
What can cause artifacts on the screen and lead to a wrong diagnoses?
dirt and hair
X-ray film is manufactured with ____ and ____
various speeds and latitude
The purpose of a ____ is to reduce the amount of scatter radiation and increase the quality of the radiographic image.
What is the most effective way to reduce backscatter?
to limit the size of the x-ray beam to include only the image receptor
Exposure to the radiographic film to x-rays makes the film ____
T/F The higher the tissue density, the higher the radiographic density.
false-lower radiographic density
What is the most common cause of poor radiographic contrast?
inappropriate exposure factors (kVp, mAs, exposure time)
There are 5 radiographic densities with the exception of ____.
How does air appear on a radiograph? Where is it?
black, commonly seen in lungs and as gas in the intestines
How does fat appear on a radiograph? Where?
white, usually found in the abdomen and under the skin
How does soft tissue appear on an radiograph? Where?
white, consists of internal organs like the liver, kidney, and intestines
How does bone appear on a radiograph?
How does metal appear on a radiograph?
vivid white, an example is lead
One of the densities called ____ can be difficult to visualize if not surrounded by fat.
What tissues are most sensitive to radiation induced damage?
all living cells, rapidly dividing cells (bone marrow), reproductive organs (no pregnant women)
How old do you have to be to be involved in radiographic procedures?
18 or over
Other tissues that are readily sensitive to radiation are?
bone, lymphatic, dermis, leukopoietic, hemopoietic, and epithelial tissues
What are 3 primary method by which personnel are exposed to radiation during radiography?
primary beam, secondary (scatter) radiation caused by interaction of the primary beam with objects in its path, and leakage radiation from x-ray tube housing
Damage to the body induced by radiation that becomes manifest within the lifetime of the recipient is?
What are 10 things you can do to decrease your radiation exposure?
1. never hold the x-ray tube
2. wear film or TLD badges near the collar
3. maintain darkroom chemicals in good operating condition
4. have the x-ray machine calibrated annually
5. don't aim the x-ray beam directly at any personnel
6. use a 2.5mm aluminum filter to remove soft x-rays
7. use collimation whenever possible to decrease field size and scatter radiation
8. never let any part of the body within the primary beam
9. use mechanical restraints whenever possible (sandbags)
10. use chemical restraint whenever possible (anesthetize)
What is the name of the radiation monitoring device you wear?
film badge a type of dosimeter
What is the MPD? and who is responsible for setting dose limits?
maximum permissible dose is the maximum dose of radiation that a person may receive in a given period, NCRP national committee on radiation protection and measurements
The unit of absorbed dose is?
1 Gy =
The quantity of energy imparted by ionizing radiations to matter per unit of mass of the matter
The quantity obtained by multiplying the absorbed dose in tissue by the quality factor.
The unit of dose equivalent is?
What lead equivalent do gloves and gowns need to be in order to be safe?
at least 0.5mm thickness
How do you maintain protective gear?
aprons are hung vertically over a sound surface(not 3< cm in diameter) or laid flat when not in use, gloves are placed on vertical holders that allow air to circulate throughtout the inside, lead aprons and gloves should be inspected periodically for damage
Secondary radiation caused by interaction of the primary beam with objects in its path.
The amount of scatter radiation is determined by what 4 factors?
intensity of the beam, the composition of the structure being radiographed, the kVp level, and the thickness of the patient
What is primary radiation?
the path that the x-rays follow as they leave the tube
Several important factors must be considered if an accurate reproduction is to be made:
welfare of the patient, restraint and immobilization of the patient, minimal truama to the area of interest, and the least risk of exposing those assisting with the examination to radiation
What instrument is used to measure the anatomic area of interest? Measurements are in what increments?
a caliper measures part thickness in centimeters
What are the required views?
two views of each anatomic area taken at right angles to each other minimum
T/F X-rays produce a radiograph
The amount of electrical energy being applied to the anode
The amount of electrical energy being applied to anode and cathode to accelerate the electrons from the cathode to the anode
A number of x-rays traveling together through space at a rapid speed
A visible photograph record on film produced by x-rays passing though an object
A restricting device used to control the size of the primary beam
A decrease of x-ray intensity on the anode side of the x-ray beam caused by the anode target angle
Difference in density and mass of two adjacent anatomic structures
The distance between the source of x-rays and the image receptor or film
source image distance (SID) formerly called FFD
How does energy travel?
fast moving electrons is produced at the cathode(filament) and directed to the anode->as electrons collide and interact with the atoms of the target on the anode energy is produced
T/F 99% is the form of roentgen radiation and 1% is a great amount of heat.
_____ is the result of the interaction of the electrons and the atoms in the target.
What are the two electrodes found in an x-ray tube? What role do they play in the movement of the electrons?
anode and cathode, the negative charge at the cathode are attracted to the positive anode and collide producing x-rays and heat
What are the two types of anodes?
stationary and rotating anode
the _____ cannot withstand large amounts of heat, and the angle can range from 15 to 23 degrees altering the "focal spot" size.
_____ has a spindle that contains molybdenum which dissipates heat, but the smallness of the angle is limited to 20 degrees vertical
What is the purpose of the cathode? What metal is used to form the filament?
to provide a source of electrons and direct them toward the anode, a coiled wire filament that emits electrons when heated
How are x-rays produced?
1. a source of electrons
2. a method of accelerating the electrons
3. an obstacle-free path for the passage of the electrons
4. a target in which the electrons can interact releasing energy in the form of x-rays
5. a envelope(tube) to provide a vacuum environment to prevent rapid oxidation of the elements
How does the collimator help reduce unnecessary radiation exposure?
by controlling the size of the primary x-ray beam
What features are found on the control panel of an x-ray machine?
on/off switch, voltage compensator, kilovoltage selector, milliamperage selector, timer, exposure button, warning light
The mA is only up to how fast?
20mA X 1/2 sec =
300 mA X 1/60 sec =
_____ controls degree of darkness, ____ controls contrast shades of gray
Quality of x-rays change ____, quantity of x-rays ____
Describe how to collimate for lateral thoracic
right side down, inspiration, manubrium to last rib, sternum elevated, 7th cervical vertebral body to the first lumbar vertebral body
Describe how to collimate for ventrodorsal thoracic.
all thoracic vertebrae from c-7 to l-1, crainial legs extended, beam center over caudal border of scapula t-6, at highest point sternum
T/F Always have a marker on an x-ray in the field of view.
The degree of blackness or “darkness” on a radiograph
A device made of lead strips embedded in a spacing material, placed between the patient and the film, designed to absorb non-image-forming radiation.
This distortion occurs when the x-ray beam is not directed perpendicular to the film surface
Distortion of anatomic structure because the anatomic area is far from the image receptor
Distortion of anatomic structures when the image appears shorter than actual size due to the plane of interest not being parallel to the film surface
A lightproof encasement designed to hold x-ray film and intensifying screens in close contact
Sheets of luminescent phosphor crystals bound together and mounted on a cardboard or plastic base
The total number of x-rays that reach the film, the penetrating power of the x-rays, the developing time, or the temperature of the developer effect what?
Subject contrast, kVp level, scatter radiation, film type, and film fog effect what?
How does scatter radiation effect radiograph?
Since inappropriate areas of the film are being exposed, contrast is decreased and radiation arising from sources behind the image plane may be scattered back to the image or backscatter
A _____is a device placed between the patient and the radiographic film that is designed to absorb non-image-forming x-rays (scatter radiation).
What are factors that affect radiographic detail?
image sharpness, clarity, distinctness, and perceptibility
What are the 3 properties that determine the efficiency of a screen?
1. They must have a high level of x-ray absorption
2. They must have high x-ray-to-light conversion with suitable energy and color
3. There must be little or no “afterglow” once radiation has ceased
How is an intensifying screen constructed?
it has four integral layers: a base or support, a reflective layer, a phosphor crystal layer, and a protective coat
T/F Damage to the intensifying screen surface is permanent and cannot be repaired.
Name three things that x-ray film are sensitive to
light, humidity, moisture
What metal can be retrieved the developing solutions?
metallic black silver
Always store cassettes how?
vertically upright, lid on, lights off
if film is black what does it mean? Clear? Trees?
exposed, never exposed, static electricity
Collimation for abdomen ventrodorsal view
right side down, diaphragm to femoral head, expiration, beam center/meaurement should be caudal aspect of 13th rib
Collimation for abdomen later view
right side down, pull hind limbs caudally, foam pad placed between femurs, foam pad placed under the sternum, diaphragm to caudal femoral head, expiration, beam center/measurement caudal aspect of 13th rib
When taking a lateral thoracic where should the x be over? Where is the diaphragm located?
heart (caudal border of scapula), 6 ribs up or 7 ribs down
Heat resistant metal used in the filament of the cathode
This term refers to how easily details can be perceived on a radiograph
Primary factor affecting density is ____
Example of ________ damage include cancer, cataracts, aplastic anemia, sterility
Outer shadow of an object being radiographed
As the number of electrons increased this increases
The higher the ______, the faster the electrons accelerate increasing the energy of the x-rays produced when the electron cloud collides with the anode (target)
Some pathologic conditions including ascites, pleural effusion, and cardiomegaly require an increase in ___ up to 50% to increase radiographic density.
T/F When radiographing the pelvis in a lateral position, a foam wedge should be placed between the patient's stifles to keep the femurs parallel.
Measurement for the lateral pelvic view should be taken over the ____, and measurement for the ventrodorsal view should be taken at the ____.
T/F To use the PennHIP method of diagnosing canine hip dysplasia, the veterinarian and technician must receive special certification.
T/F Sedating the patient is not often used to take radiographs to diagnose hip dysplasia.
What should be on the film label?
1) name and address of the hospital practice or veterinarian
2) date the radiograph was taken
3) patient identification-name of owner, patient, age, sex, and breed
Why is it important to label film correctly?
so it can identified at a later date, and for legal reasons
T/F The only legal labeling of a radiograph is what is in the film emulsion.
What are the views and extremities?
ventrodorsal, lateral, craniocaudal, palmer, planter
State the four factors that must be considered for accurate reproduction of an anatomic area:
1) welfare of the patient
2) restraint and immobilization of the patient
3) minimal trauma to the area of interest
4) the least risk exposing those assisting with the examination to radiation
If a radiographer is unsure where to measure a particular part, the measurement should be made where?
over the thickest area
When there is a large difference in thickness in a particular area, it is advisable to make two separate radiographs with different?
T/F If only a small difference in tissue density exists, a compromise should be made.
Exposing a large area that is not necessary increases the amount of scatter radiation which decreases _________
When a marker is placed on a cassette for craniocaudal or caudocranial views, it should be placed on the _____ aspect of the extremity.
T/F In dorsoventral or ventrodorsal views, the marker should be placed on the cassette to identify one side or the other.
When a lateral projection of the abdomen or thorax is taken, the marker should indicate?
the side that is down on the table or cassette
When a lateral projection of an extremity is taken, the marker should be placed?
cranially to (in front of) the leg
T/F A radiograph is a two-dimensional picture of a three-dimensional structure.
T/F Two views of each anatomic area are taken at right angles to each other.
The importance of two views is exemplified when radiographing a ____.
How should a lateral thorax radiograph be placed on the view box for viewing?
all laterally positioned anatomy should face the viewer's left, with the spine at the top
What should the film look like for OFA(Orthopedic Foundation for Animals)?
extended view of the pelvis: wing of the ilium to stifle joint of long bone and the joint below it too (all three bones must be seen)
What is the purpose of the OFA?
lowering genetic diseases for breeders
How old must a patient be for OFA? PennHip?
24 months old, no age requirement
Which is better OFA or PennHip why?
PennHip because it gives a better evaluation by checking joint laxity with 3 different views
What is hip dysplasia?
abnormal formation of the hip socket
What does it mean for film to be "blue-sensitive?"
highly responsive to ultraviolet, violet, and blue spectrum of light
What is nonscreen film sensitive to?
ionizing radiation and pressure
List and describe the 6 developer components?
1) developing agents(chemical compounds that convert grains of silver into black metallic silver)
2) accelerators(chemicals that increase the activity of the developer)
3) preservatives(prevent rapid oxidation/prevent staining of emulsion layer)
4) restrainers(limit the action of the developing agent to the exposed silver crystals)
5) hardeners(harden film and prevent excessive swelling of the emulsion)
6) the solvent(has water to dissolve the chemicals)
What does the rinse bath do?
stops the developing process, rinses the developer from the film, prevents carryover contamination to the fixer
What are the purposes of the fix bath?
to clear the unexposed silver halide crystals from the film and it hardens the gelatin coating so it can be dried without damaging the film
What metal is retrieved from the developing soultions?
black metallic silver
What are the three solutions? What are they affected by?
developer, water, fixer based on temperature
A warmer temperature makes the developer?
How is a film developed?
develop->water->fixer(x2)->water(rinse bath 20 mins)->must dry it
T/F The duration of the fixation process is usually twice the clearing time and until after the film has lost its "milky" appearance.
Putting the film back into the fix tank after evaluation for a total of ___ is important to allow maximum hardening of the film.
How do you know if you've taken a good view of the pelvis? Field of view?
if the obterator foreman are the same size, tubercoles same size, femurs are straight and parallel, patellas are on top, FOV-pelvis, femurs, stifle joints
What are the two basic questions you ask yourself?
1) is the film too light or too dark
2) is there proper penetration
If you skip the rinse bath and go to the next chemical what color does the film turn?
For a dorsalventral view where should the heart be?
closet to the plate
Where should the area you're most interested in be?
as close to the image receptor as possibel
If bone is too dark than what needs to be decreased?
If bone is too white increase?
What does a bent film look like?
What do you look for on a radiograph?
collimation, artifacts, marker there and on correct side, label, straightness
What does a development issue look like on film?
How do you collimate for a lateral pelvis view?
the side of interest closest to the cassette, foam wedge placed between the stile joints to keep the femurs parallel with the cassette, the limb closest to the cassette should be pulsed slightly cranial and the top leg slightly caudal, it includes the entire pelvis and a portion of the lumbar spine and the femurs
The _______ view of the pelvis is standard for the evaluation of hip joints for hip dysplasia.
What does the mAs control?
What does the kVp control?
What does the mAs control?