Motion blurMotion blur - 1. Movement of the patient or the x-ray tube during exposure
results in blurring of the radiographic image. This loss of radiographic quality, called
motion blur, may result in repeated radiographs and therefore should be avoided.
2. Patient motion is usually caused by motion blur. Suspend respiration for exposures,
decrease exposure time, use a large SID and use a small OID.
Transverse - across the table, at right angles to longitudinal.
Longitudinal - along the long axis of the table.
Primary X-ray Beam - The x-ray beam that leaves the tube and is unattenuated, except
by air. The direction and location are predictable and controllable.
X-ray source - the x-ray tube between the cathode and anode.
kVp - Measure of the maximum electrical potential across an x-ray tube (expressed in
kilovolts).
mA - Measure of x-ray tube current
Remnant Radiation - X-rays that pass through the patient and interact with the image
receptor
Scatter Radiation - X-rays scattered back in the direction of the incident x-ray beam
Penetrate - ability to pass through an object. Related to the x-ray quality
Absorb - to soak up. Absorption of x-rays results in energy being scattered or converted
into new scatter x-rays.
Attenuation - the total reduction in the number of x-rays remaining in an x-ray beam
after penetration through a given thickness of tissue
X-ray attenuation - When a broad beam of x-rays is incident of any tissue, some of the
x-rays are absorbed and some are scattered. The result is a reduced number of x-rays.
Differential attenuation - X-rays can penetrate matter that is opaque to light. This
penetration is differential, depending on the mass density and thickness of the matter
Basis for subject contrast - i. determined by the size, shape, and x-ray attenuating
characteristics of the subject who is being examined and the energy of the x-ray beam
,Subject contrast - the range of differences in the intensity of the x-ray beam after it
exists the patient. It is affected by the kVp and the tissue density
Effects on air, bone, muscle and fat - i. X-rays penetrate air very readily. There is less
penetration of fat or oil, even less of water, which has about the same mass as muscle
tissue, and still less of bone.
Intensity - The intensity of the x-ray beam of an x-ray imaging system is measured in
milligray in air (mGya) and is called x-ray quantity.
Effects on intensity (quantity) of the x-ray beam on the radiographic image - i. X-ray
intensity is proportional to mAs.
ii. X-ray intensity is proportional to kVp2.
iii. X-ray intensity is inversely proportional to the square of the distance from the source.
X-rayintensityisreducedwhenfiltrationisadded
Extremity - soft tissue and bone / low kV = high contrast (short scale) kVp 50 - 70
Abdomen - organs, air, fluid, and bowel patterns /low subject contrast / kVp: 75 to 90
Chest - Many structures to evaluate with different densities: lung, ribs, heart, and
mediastinum high subject contrast / high kVp = low contrast (long scale) / kVp 100 - 120
Radiographic film - Base and the emulsion
Base - i. the foundation of radiographic film that provides a rigid structure onto which the
emulsion can be coated.
ii. The original was a glass plate. Replaced by cellulose nitrate which was flammable.
Replaced by cellulose triacetate "safety base."
As of the early 1960s this is now polyester
Film emulsion - i. Material with which x-rays or light photons from screens interact and
transfer information.
This is a mixture of gelatin and silver halide crystals
Speed - A. The sensitivity of the screen-film combination to x-rays and light
i. Speed is reported as the speed of the film and two radiographic intensifying screens.
Screen speed: ranges from 50 (slow) to 1200 (Fast).
, Latent image - Unobservable image stored in the silver halide emulsion
Manifest image - A. observable image that is formed when the latent image undergoes
proper chemical processing.
Optical density - Degree of blackening of a radiograph
Detail/spatial resolution film - A. sharpness of structural lines on a radiograph; ability to
image small objects that have high subject contrast.
Contrast resolution film - Ability to distinguish between and to image similar tissues
Spectral matching - Use of rare Earth screens only in conjunction with film emulsions
that have light absorption characteristics matched to the light emission of the screen
Film handling and storage - A. Make sure hands are clean and dry. Do not bend film.
i. Store film in a cool dry place at temperatures lower than 20° C (68°F) and store at
>60% humidity.
ii. Improper handling and storage result in poor radiographs with artifacts that interfere
with diagnosis
Fog - i. Unintended optical density on a radiograph that reduces contrast through light or
chemical contamination
Temperature/effects of heat - i. Radiographic film is sensitive to high temperatures and
heat will increase the fog and reduce the contrast.
Humidity-static - Radiographic film is sensitive to high humidity. Static increases when
humidity drops below 40%.
Light - i. light can expose the emulsion before processing and fog film or produce an
artifact on the film. Film should be place in a film bin that is in a light tight dark room.
Radiation fog - i. Artifact caused by unintentional exposure to radiation. Radiographic
film is more sensitive to radiation than to people. Scattered radiation, after coming in
contact with an exposed radiographic film, will create an image artifact by reducing
contrast and increasing fog.
Shelf life-age fog - check the expiration date of the film often. Shelf life of 45 days is a
reasonable maximum storage time for film
Pressure - i. pressure artifacts are marks that sometimes appear on the processed
radiograph.
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller VasilyKichigin. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $13.48. You're not tied to anything after your purchase.
