Final Exam Questions Flashcards
what is said to be directly proportional to receptor exposure?
mAS, OID, SID, or grid ratio
mAS
what is the formula for mAS?
mA*time = mAS
how do you define grid ratio?
the ratio of the height of the lead strips to the distance between the lead strips in a radiographic grid
the construction of the grid provides for greater absorption of —- radiation than of —-
scatter, primary
grids are recommended for body parts measuring greater than — cm
12
The large number of exposures a DR detector can capture and display is its
dynamic range
If all other things are constant, increasing mAS is required when the part gets thicker in order to maintain
receptor exposure
what is the purpose of a beam restrictor?
minimizing scatter radiation, limit beam to precise anatomical area, and enhance contrast
a lead shield placed over male gonads can reduce dosage by as much as:
90%
more rows and columns will result in — pixels
smaller
the radiographic quality that is defined as misrepresentation of size/shape is?
distortion
what type of contrast is better for extremities and shows more detail?
high contrast
Which element is associated with indirect capture DR?
cesium iodide
Selecting from available shades of gray and assigning a numerical value to each pixel is known as;
quantization
what element is associated with direct capture DR?
a-selenium
what is not essential to the production of x-rays?
a rotating anode
the target of a diagnostic x-ray tube is usually made of what element?
tungsten
of total available energy, only about — % is converted to x-ray energy
less than 1%
the vast majority of available energy is transformed into:
heat
half-value layer
A materials half-value layer, or half thickness. Thickness of material at which the intensity of radiation entering it is reduced by one half
The interaction that usually occurs in the K or inner electron shell is:
photoelectron effect with true absorption
the acute dose of radiation that will result in the death of 50% of a group within 30 days (LD 50/30) is considered to be about – sv.
3
what is the typical exposure from a PA chest radiograph?
0.1-0.2mGy (10-20 mR)
the information for hereditary is contained in the:
nucleus
what stage of cell division is said to be the most sensitive time in cell life?
metaphase
an example of sensitive tissue is?
blood forming tissue, fast reproducing cells
the greatest contributor of exposure to radiation from manmade sources is:
medical x-rays
lead aprons are intended to protect the wearer from:
scattered radiation
an OSL radiation monitor can record exposures as low as — mSv
0.01
the annual occupation dose limit is currently:
50 mSv
the plane that divides the body into equal right and left portions is?
median sagittal plane aka anteroposterior plane
coronal plane
aka frontal plane, divides body into front and back portions
transverse plane
horizontal plane that divides body into top and bottom portions, aka axial plane
when an object is moving, it can be said to possess what type of energy?
kinetic
The position of an element on the periodic table is determined by:
number of protons
isotope
atoms having the same number of protons but different numbers of neutrons
high energy radiations will possess:
high frequency - short wavelength
anode heel effect
variation in x-ray intensity between the anode and cathode ends of the x-ray tube
a device used to provide radiographs of similar density, regardless of the part thickness:
phototimer (AEC)
A device in the x-ray circuit used to increase supplied voltage to kilovoltage is
step-up transformer
A device in the x-ray circuit used to change supplied AC to pulsating DC through the x-ray tube is:
rectifier bridge
The range of exposure factors that can produce an acceptable image at a reasonable dose is known as
exposure latitude
As each digital image is recorded, the exposure is recognized and a ______ is created and then adjusted.
histogram
what is the preferred unit of measure for effective dose?
sievert
Gy-a
gray of alpha radiation
Gy-t
gray of tissue
what is used to make primary beam more homogenous?
filter
the most effective method of sterilization is?
moist heat
The production of x-rays occurs with the rapid deceleration of fast moving _________ in an x-ray tube.
electrons
Blood pressure may be expressed as 120/95. What phase of cardiac action occurs during the “95”?
the phase of relaxation of the cardiac muscle tissue
Of the four stages of infection, which is the stage during which the infection is MOST communicable?
disease phase
Bone projections vs. Depressions
Projection - grows out of bone surface, depressions - indentation or hollows in the surface
Condyle
Rounded process that forms part of a joint
Coracoid
A pointed projection
Coronoid
Beaklike projection
Crest
A bony ridge
Epicondyle
A projection above a condyle
Facet
A small, smooth process that forms part of a joint
Head
Rounded, wide end of a long bone
Malleolus
A club shaped projection
Process
A general term for projection
Protuberance
General term
Spine
A sharp process/ridge
Styloid
A long, sharp process
Trochanter
One of the large rounded processes of femur
Tubercle
A small rounded process
Tuberosity
A rounded process larger than a tubercle, often used interchangeably
Fissure
A linear depression, a groove
Foramen
Foramina, a hole in bone for the passage of blood vessels and nerves
Fossa
A pit or hollow
Groove
A shallow linear depression
Sinus
A cavity or hollow space
Sulcus
A trenching depression, deep
Synarthrosis
Joint that does not move
Ampiarthrosis
Joint with very limited motion
Diathrosis
A joint that can move freely
Prone
Lying face down
Recumbent
Lying down, further described with the plane of body
Supine
Lying on back
Upright
Erect
Decubitus
Recumbent with CR horizontal or parallel to the floor
mA formula if you know mAS and seconds
mA= mAS/seconds
How much is exposure increased when distance is halved?
4 times
What are the 3 types of filters?
Inherent, added, and compensating
what does a grid do?
absorbs scatter radiation after its produced and before it reaches the receptor
what are IP plates made out of?
barium fluorohalide
what are CR plates made out of?
photostimulable phosphor
what is indirect conversion x-ray?
2 step process in which x-ray is converted to light and then into electrical signal
what is a scintillator?
a device that glows when hit by high energy x-ray protons
what is a scintillator made out of?
cesium iodide
what do complementary metal oxide semiconductors do?
convert light into electrons
what is direct conversion x-ray?
one step process that converts x-rays directly into electric signal through amorphous selenium
how does quantum mottle happen?
occurs when not enough photons in the detector to provide high quality image, kVp set too low
what does PACS stand for?
picture archiving communication system
bit depth
number of bits per pixel
modular transfer function
(MTF) measurement of resolution
what is the pixel size on a 14x14in receptor?
12mm? 17mm
pixel pitch
distance from the center of one pixel to the center of the next
what is typical bit depth for digital images?
8, 10, or 12 bits
what shell in an atom is the most important in x-ray?
k-shell
what is the sine wave formula for velocity?
wavelength x frequency = velocity
why is tungsten used for a filament material?
high melting point and high mass (74 eletrons)
bremsstrahlung radiation
“braking radiation” 100% under 70 kVp, and 85% above 70
characteristic radiation
no photons below 70 kVp, 15% above 70 kVp
the wavelength and energy of the x-ray beam is said to be ——
heterogenous
where is filament located in cathode?
hollow area in cathode called focusing cup
what target angle is needed for a 14x17 IR?
12 degrees
To demonstrate a left lower anterior rib injury, should the exposure be taken after inhalation or exhalation?
the exposure should be made after the patient exhales completely
The ridge that marks the bifurcation of the trachea into right and left primary bronchi is the:
carina
Aspirated foreign bodies in older children and adults are MOST likely to lodge in the:
right main bronchus
how any pairs of false ribs are there?
4
A structure of the neck which functions both in the respiratory and digestive tracts is the:
pharynx
The air sacs of the lungs are called the:
alveoli
what position will best demonstrate the left axillary portion of the ribs?
LPO
The external (lateral) oblique of the elbow best demonstrated the:
Radial head
The clavicle is a long bone that articulates with the ________ of the scapula, and medially with the ______________ .
acromion process, sternum
The patient has pain and tenderness in the area of the base of the fifth metatarsal. Which view will best demonstrate the area?
30 degree medial oblique
the knee joint is located:
½ inch inferior to the apex of the patella
In which of the following positions/projections will the talocalcaneal joint be visualized?
plantodorsal projection of the os calcis
Which of the following projections of the ankle would best demonstrate the distal tibiofibular joint?
medial oblique 45°
What articulates with the bases of the metatarsals?
the cuneiforms
The ulna articulates with what portion of the humerus to help form the elbow joint?
trochlea
In a PA projection of the hand, the central ray should be directed vertically to the:
3rd MPJ
With which of the following does the trapezium articulate?
first metacarpal
In order to decrease the OID for a PA projection of the wrist:
the fingers should be flexed
That portion of a long bone where cartilage has been replaced by bone is known as the:
metaphysis
The most medial of the following structures of the humerus is the:
trochlea
The spine of the scapula runs obliquely across the posterior surface of the scapula and ends in a flattened, triangular projection called the:
acromion
A depression on the anterior surface of the distal humerus just above the trochlea is the:
coronoid fossa
The superior border to the patella is called the:
base
The round prominence on the anterior surface of the proximal tibia is the:
tibial tuberosity
what are short-term effects of a high dose of radiation?
erythema, radiation sickness, compromised immune system
what are short-term effects of a lower dose of radiation?
affects the blood and blood-forming system of bone marrow
what are the most common radiation effects called?
long-term, short-term, somatic, and genetic
when are short-term effects observed after exposure?
3 months
what is the absorbed dose greater than for short-term effects?
500mGy-t
when are long-term effects observed after exposure?
several years after exposure, sometimes up to 30 years
what are somatic effects?
affect the body and the tissues, both short-term and long-term effects
what are genetic effects?
damage to the reproductive cells if the irradiated person. defects are observed in children or grandchildren
what is the lethal dose of radiation?
5000 mGy-t, LD 50% within 30 days LD 50/30
which effects are predictable? long-term or short-term
short-term
threshold dose
a dose level below which there is no effect of radiation on the biological response
non-threshold dose
a term used to describe the linear-no-threshold (LNT) model, which assumes that any amount of radiation exposure can cause health effect
