Six important roentgen signs such as
location, margins, number, opacity, size and shape
are used to describe the abnormalities detected on the radiograph. The limitation of radiography is the inability to assess the internal structure of the abdominal organs.
What are the 5 radiographic densities?
The five basic radiographic densities:
air, fat, water (soft tissue), bone, and metal
. Air is the most radiolucent (blackest) and metal is the most radiopaque (whitest).
What is superimposition in radiography?
Superimposition occurs because anatomic structures are often stacked on one another, forcing the x-ray beam to penetrate multiple structures before arriving at the film plate. Superimposition can
create the appearance of increased density of structures
, or the appearance of novel structures altogether.
What would be the whitest object appearing on a radiograph?
Dense structures absorb (attenuate) more of the x-ray beam than less dense structures. Thus, less of the beam passes through to hit the cassette and these structures appear white, termed ‘
radioopaque
‘. … Other dense structures include calcium, barium and iodine, all of which look white on radiographs.
How are xray images interpreted?
Interpreting an X-Ray
The interpretation of an x-ray film requires sound anatomical knowledge, and an understanding that
different tissue types absorb x-rays to varying degrees
: High density tissue (e.g. bone) – absorb x-rays to a greater degree, and appear white on the film.
Which would increase magnification?
It refers to the proportional increase in the dimensions of a radiographed object relative to the actual dimensions of that object and depends on the following factors:
Increasing object to film distance only
will result in an increase in magnification of the radiographic image.
What is the difference between density and contrast in radiography?
Radiographic contrast is the
density difference between neighboring regions on a plain radiograph
. High radiographic contrast is observed in radiographs where density differences are notably distinguished (black to white).
What is superimposition technique?
Abstract. Craniofacial superimposition is a
technique used in the field of forensic anthropology to assist in the analysis of an unknown skull
. The process involves superimposing an image of the recovered skull over an ante mortem image of the suspected individual.
How do you do cephalometric superimposition?
A cephalometric superimposition is an
analysis of lateral cephalograms of
the same patient taken at different times. It isused to evaluate a patient’s growth pattern between different ages and to evaluate changes in the dentoalveolar and basal relationships after a course of orthodontic or surgical treatment.
What is a radiopaque material?
Refers to
any substance having the property of absorbing X-rays and of thus influencing the radiological image obtained
. Barium and Iodineare the two main radiopaque substances used in radiology.
What does attenuation mean in radiology?
Attenuation is
the reduction of the intensity of an x-ray beam as it traverses matter
.
What does an underexposed radiograph look like?
An under-exposed radiograph means there was less penetration of the x-ray beam through the patient’s tissues. This results in an x-ray image that
looks overly white or light compared to a properly exposed radiograph
. That “whitewash” effect can make it more difficult to see certain lesions or abnormalities.
What is air gap technique?
Air gap technique is a
well-known method to reduce the amount of scattered x-ray radiation reaching the detector
, thus reducing noise and improving image contrast.
1
. It is rather commonly utilized instead of a conventional grid in plain radiography.
Does sod affect magnification?
Increasing SOD similarly
decreases magnification
. This can be easily seen if you imagine how the x-ray rays become more parallel as the source is moved farther and farther off. Alternatively, as the OID is increased, magnification increases.
What does Sid mean in radiology?
The
source image receptor distance
(SID), is the distance of the tube from the image receptor, affecting magnification.
Does kVp affect contrast?
kVp also
controls the amount of contrast
(the difference between whites and blacks on an image) seen on an x-ray. The amount of contrast visible in an image is referred to as gray scale. – If an image has high contrast, there will be white and black areas on the film, but very few grays in between.
