Flashcards in Radiology Deck (188)
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